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Chris Lattner7a90b682004-10-07 04:16:33 +00001//===- GlobalOpt.cpp - Optimize Global Variables --------------------------===//
Misha Brukmanfd939082005-04-21 23:48:37 +00002//
Chris Lattner079236d2004-02-25 21:34:36 +00003// The LLVM Compiler Infrastructure
4//
Chris Lattner4ee451d2007-12-29 20:36:04 +00005// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
Misha Brukmanfd939082005-04-21 23:48:37 +00007//
Chris Lattner079236d2004-02-25 21:34:36 +00008//===----------------------------------------------------------------------===//
9//
Chris Lattner7a90b682004-10-07 04:16:33 +000010// This pass transforms simple global variables that never have their address
11// taken. If obviously true, it marks read/write globals as constant, deletes
12// variables only stored to, etc.
Chris Lattner079236d2004-02-25 21:34:36 +000013//
14//===----------------------------------------------------------------------===//
15
Chris Lattner7a90b682004-10-07 04:16:33 +000016#define DEBUG_TYPE "globalopt"
Chris Lattner079236d2004-02-25 21:34:36 +000017#include "llvm/Transforms/IPO.h"
Chris Lattnerfb217ad2005-05-08 22:18:06 +000018#include "llvm/CallingConv.h"
Chris Lattner079236d2004-02-25 21:34:36 +000019#include "llvm/Constants.h"
Chris Lattner7a90b682004-10-07 04:16:33 +000020#include "llvm/DerivedTypes.h"
Chris Lattner7d90a272004-02-27 18:09:25 +000021#include "llvm/Instructions.h"
Chris Lattner35c81b02005-02-27 18:58:52 +000022#include "llvm/IntrinsicInst.h"
Chris Lattner079236d2004-02-25 21:34:36 +000023#include "llvm/Module.h"
24#include "llvm/Pass.h"
Chris Lattner79066fa2007-01-30 23:46:24 +000025#include "llvm/Analysis/ConstantFolding.h"
Chris Lattner30ba5692004-10-11 05:54:41 +000026#include "llvm/Target/TargetData.h"
Duncan Sands548448a2008-02-18 17:32:13 +000027#include "llvm/Support/CallSite.h"
Reid Spencer9133fe22007-02-05 23:32:05 +000028#include "llvm/Support/Compiler.h"
Chris Lattner79066fa2007-01-30 23:46:24 +000029#include "llvm/Support/Debug.h"
Chris Lattner941db492008-01-14 02:09:12 +000030#include "llvm/Support/GetElementPtrTypeIterator.h"
Chris Lattner998182b2008-04-26 07:40:11 +000031#include "llvm/Support/MathExtras.h"
Chris Lattner5a6bb6a2008-12-16 07:34:30 +000032#include "llvm/ADT/DenseMap.h"
Chris Lattner81686182007-09-13 16:30:19 +000033#include "llvm/ADT/SmallPtrSet.h"
Chris Lattner55eb1c42007-01-31 04:40:53 +000034#include "llvm/ADT/SmallVector.h"
Reid Spencer551ccae2004-09-01 22:55:40 +000035#include "llvm/ADT/Statistic.h"
Chris Lattner670c8892004-10-08 17:32:09 +000036#include "llvm/ADT/StringExtras.h"
Chris Lattnerbce4afe2008-12-17 05:28:49 +000037#include "llvm/ADT/STLExtras.h"
Chris Lattnere47ba742004-10-06 20:57:02 +000038#include <algorithm>
Chris Lattner079236d2004-02-25 21:34:36 +000039using namespace llvm;
40
Chris Lattner86453c52006-12-19 22:09:18 +000041STATISTIC(NumMarked , "Number of globals marked constant");
42STATISTIC(NumSRA , "Number of aggregate globals broken into scalars");
43STATISTIC(NumHeapSRA , "Number of heap objects SRA'd");
44STATISTIC(NumSubstitute,"Number of globals with initializers stored into them");
45STATISTIC(NumDeleted , "Number of globals deleted");
46STATISTIC(NumFnDeleted , "Number of functions deleted");
47STATISTIC(NumGlobUses , "Number of global uses devirtualized");
48STATISTIC(NumLocalized , "Number of globals localized");
49STATISTIC(NumShrunkToBool , "Number of global vars shrunk to booleans");
50STATISTIC(NumFastCallFns , "Number of functions converted to fastcc");
51STATISTIC(NumCtorsEvaluated, "Number of static ctors evaluated");
Duncan Sands3d5378f2008-02-16 20:56:04 +000052STATISTIC(NumNestRemoved , "Number of nest attributes removed");
Duncan Sands4782b302009-02-15 09:56:08 +000053STATISTIC(NumAliasesResolved, "Number of global aliases resolved");
54STATISTIC(NumAliasesRemoved, "Number of global aliases eliminated");
Chris Lattner079236d2004-02-25 21:34:36 +000055
Chris Lattner86453c52006-12-19 22:09:18 +000056namespace {
Reid Spencer9133fe22007-02-05 23:32:05 +000057 struct VISIBILITY_HIDDEN GlobalOpt : public ModulePass {
Chris Lattner30ba5692004-10-11 05:54:41 +000058 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
59 AU.addRequired<TargetData>();
60 }
Nick Lewyckyecd94c82007-05-06 13:37:16 +000061 static char ID; // Pass identification, replacement for typeid
Dan Gohmanae73dc12008-09-04 17:05:41 +000062 GlobalOpt() : ModulePass(&ID) {}
Misha Brukmanfd939082005-04-21 23:48:37 +000063
Chris Lattnerb12914b2004-09-20 04:48:05 +000064 bool runOnModule(Module &M);
Chris Lattner30ba5692004-10-11 05:54:41 +000065
66 private:
Chris Lattnerb1ab4582005-09-26 01:43:45 +000067 GlobalVariable *FindGlobalCtors(Module &M);
68 bool OptimizeFunctions(Module &M);
69 bool OptimizeGlobalVars(Module &M);
Duncan Sandsfc5940d2009-03-06 10:21:56 +000070 bool OptimizeGlobalAliases(Module &M);
Chris Lattnerb1ab4582005-09-26 01:43:45 +000071 bool OptimizeGlobalCtorsList(GlobalVariable *&GCL);
Chris Lattner7f8897f2006-08-27 22:42:52 +000072 bool ProcessInternalGlobal(GlobalVariable *GV,Module::global_iterator &GVI);
Chris Lattner079236d2004-02-25 21:34:36 +000073 };
Chris Lattner079236d2004-02-25 21:34:36 +000074}
75
Dan Gohman844731a2008-05-13 00:00:25 +000076char GlobalOpt::ID = 0;
77static RegisterPass<GlobalOpt> X("globalopt", "Global Variable Optimizer");
78
Chris Lattner7a90b682004-10-07 04:16:33 +000079ModulePass *llvm::createGlobalOptimizerPass() { return new GlobalOpt(); }
Chris Lattner079236d2004-02-25 21:34:36 +000080
Dan Gohman844731a2008-05-13 00:00:25 +000081namespace {
82
Chris Lattner7a90b682004-10-07 04:16:33 +000083/// GlobalStatus - As we analyze each global, keep track of some information
84/// about it. If we find out that the address of the global is taken, none of
Chris Lattnercf4d2a52004-10-07 21:30:30 +000085/// this info will be accurate.
Reid Spencer9133fe22007-02-05 23:32:05 +000086struct VISIBILITY_HIDDEN GlobalStatus {
Chris Lattnercf4d2a52004-10-07 21:30:30 +000087 /// isLoaded - True if the global is ever loaded. If the global isn't ever
88 /// loaded it can be deleted.
Chris Lattner7a90b682004-10-07 04:16:33 +000089 bool isLoaded;
Chris Lattnercf4d2a52004-10-07 21:30:30 +000090
91 /// StoredType - Keep track of what stores to the global look like.
92 ///
Chris Lattner7a90b682004-10-07 04:16:33 +000093 enum StoredType {
Chris Lattnercf4d2a52004-10-07 21:30:30 +000094 /// NotStored - There is no store to this global. It can thus be marked
95 /// constant.
96 NotStored,
97
98 /// isInitializerStored - This global is stored to, but the only thing
99 /// stored is the constant it was initialized with. This is only tracked
100 /// for scalar globals.
101 isInitializerStored,
102
103 /// isStoredOnce - This global is stored to, but only its initializer and
104 /// one other value is ever stored to it. If this global isStoredOnce, we
105 /// track the value stored to it in StoredOnceValue below. This is only
106 /// tracked for scalar globals.
107 isStoredOnce,
108
109 /// isStored - This global is stored to by multiple values or something else
110 /// that we cannot track.
111 isStored
Chris Lattner7a90b682004-10-07 04:16:33 +0000112 } StoredType;
Chris Lattnercf4d2a52004-10-07 21:30:30 +0000113
114 /// StoredOnceValue - If only one value (besides the initializer constant) is
115 /// ever stored to this global, keep track of what value it is.
116 Value *StoredOnceValue;
117
Chris Lattner25de4e52006-11-01 18:03:33 +0000118 /// AccessingFunction/HasMultipleAccessingFunctions - These start out
119 /// null/false. When the first accessing function is noticed, it is recorded.
120 /// When a second different accessing function is noticed,
121 /// HasMultipleAccessingFunctions is set to true.
Alkis Evlogimenosf64ea9d2005-02-10 18:36:30 +0000122 Function *AccessingFunction;
123 bool HasMultipleAccessingFunctions;
124
Chris Lattner25de4e52006-11-01 18:03:33 +0000125 /// HasNonInstructionUser - Set to true if this global has a user that is not
126 /// an instruction (e.g. a constant expr or GV initializer).
Chris Lattner553ca522005-06-15 21:11:48 +0000127 bool HasNonInstructionUser;
128
Chris Lattner25de4e52006-11-01 18:03:33 +0000129 /// HasPHIUser - Set to true if this global has a user that is a PHI node.
130 bool HasPHIUser;
131
Chris Lattnercf4d2a52004-10-07 21:30:30 +0000132 GlobalStatus() : isLoaded(false), StoredType(NotStored), StoredOnceValue(0),
Alkis Evlogimenosf64ea9d2005-02-10 18:36:30 +0000133 AccessingFunction(0), HasMultipleAccessingFunctions(false),
Chris Lattner6a93fc02008-01-14 01:32:52 +0000134 HasNonInstructionUser(false), HasPHIUser(false) {}
Chris Lattner7a90b682004-10-07 04:16:33 +0000135};
Chris Lattnere47ba742004-10-06 20:57:02 +0000136
Dan Gohman844731a2008-05-13 00:00:25 +0000137}
Chris Lattnera4be1dc2004-10-08 20:59:28 +0000138
139/// ConstantIsDead - Return true if the specified constant is (transitively)
Devang Patel743cdf82009-03-06 01:37:41 +0000140/// dead. The constant may be used by other constants (e.g. constant arrays and
141/// constant exprs) as long as they are dead, but it cannot be used by anything
142/// else.
143static bool ConstantIsDead(Constant *C) {
Chris Lattnera4be1dc2004-10-08 20:59:28 +0000144 if (isa<GlobalValue>(C)) return false;
145
Devang Patel743cdf82009-03-06 01:37:41 +0000146 for (Value::use_iterator UI = C->use_begin(), E = C->use_end(); UI != E; ++UI)
147 if (Constant *CU = dyn_cast<Constant>(*UI)) {
148 if (!ConstantIsDead(CU)) return false;
Chris Lattnera4be1dc2004-10-08 20:59:28 +0000149 } else
150 return false;
151 return true;
152}
153
154
Chris Lattner7a90b682004-10-07 04:16:33 +0000155/// AnalyzeGlobal - Look at all uses of the global and fill in the GlobalStatus
156/// structure. If the global has its address taken, return true to indicate we
157/// can't do anything with it.
Chris Lattner079236d2004-02-25 21:34:36 +0000158///
Chris Lattner7a90b682004-10-07 04:16:33 +0000159static bool AnalyzeGlobal(Value *V, GlobalStatus &GS,
Chris Lattner5a6bb6a2008-12-16 07:34:30 +0000160 SmallPtrSet<PHINode*, 16> &PHIUsers) {
Chris Lattner079236d2004-02-25 21:34:36 +0000161 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
Chris Lattner96940cb2004-07-18 19:56:20 +0000162 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) {
Chris Lattner553ca522005-06-15 21:11:48 +0000163 GS.HasNonInstructionUser = true;
164
Chris Lattner7a90b682004-10-07 04:16:33 +0000165 if (AnalyzeGlobal(CE, GS, PHIUsers)) return true;
Chris Lattner670c8892004-10-08 17:32:09 +0000166
Chris Lattner079236d2004-02-25 21:34:36 +0000167 } else if (Instruction *I = dyn_cast<Instruction>(*UI)) {
Alkis Evlogimenosf64ea9d2005-02-10 18:36:30 +0000168 if (!GS.HasMultipleAccessingFunctions) {
169 Function *F = I->getParent()->getParent();
170 if (GS.AccessingFunction == 0)
171 GS.AccessingFunction = F;
172 else if (GS.AccessingFunction != F)
173 GS.HasMultipleAccessingFunctions = true;
174 }
Chris Lattnerc69d3c92008-01-29 19:01:37 +0000175 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
Chris Lattner7a90b682004-10-07 04:16:33 +0000176 GS.isLoaded = true;
Chris Lattnerc69d3c92008-01-29 19:01:37 +0000177 if (LI->isVolatile()) return true; // Don't hack on volatile loads.
Chris Lattner7a90b682004-10-07 04:16:33 +0000178 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
Chris Lattner36025492004-10-07 06:01:25 +0000179 // Don't allow a store OF the address, only stores TO the address.
180 if (SI->getOperand(0) == V) return true;
181
Chris Lattnerc69d3c92008-01-29 19:01:37 +0000182 if (SI->isVolatile()) return true; // Don't hack on volatile stores.
183
Chris Lattnercf4d2a52004-10-07 21:30:30 +0000184 // If this is a direct store to the global (i.e., the global is a scalar
185 // value, not an aggregate), keep more specific information about
186 // stores.
Anton Korobeynikov07e6e562008-02-20 11:26:25 +0000187 if (GS.StoredType != GlobalStatus::isStored) {
Chris Lattnercf4d2a52004-10-07 21:30:30 +0000188 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(SI->getOperand(1))){
Chris Lattnerbd38edf2004-11-14 20:50:30 +0000189 Value *StoredVal = SI->getOperand(0);
190 if (StoredVal == GV->getInitializer()) {
191 if (GS.StoredType < GlobalStatus::isInitializerStored)
192 GS.StoredType = GlobalStatus::isInitializerStored;
193 } else if (isa<LoadInst>(StoredVal) &&
194 cast<LoadInst>(StoredVal)->getOperand(0) == GV) {
195 // G = G
Chris Lattnercf4d2a52004-10-07 21:30:30 +0000196 if (GS.StoredType < GlobalStatus::isInitializerStored)
197 GS.StoredType = GlobalStatus::isInitializerStored;
198 } else if (GS.StoredType < GlobalStatus::isStoredOnce) {
199 GS.StoredType = GlobalStatus::isStoredOnce;
Chris Lattnerbd38edf2004-11-14 20:50:30 +0000200 GS.StoredOnceValue = StoredVal;
Chris Lattnercf4d2a52004-10-07 21:30:30 +0000201 } else if (GS.StoredType == GlobalStatus::isStoredOnce &&
Chris Lattnerbd38edf2004-11-14 20:50:30 +0000202 GS.StoredOnceValue == StoredVal) {
Chris Lattnercf4d2a52004-10-07 21:30:30 +0000203 // noop.
204 } else {
205 GS.StoredType = GlobalStatus::isStored;
206 }
207 } else {
Chris Lattner7a90b682004-10-07 04:16:33 +0000208 GS.StoredType = GlobalStatus::isStored;
Chris Lattnercf4d2a52004-10-07 21:30:30 +0000209 }
Anton Korobeynikov07e6e562008-02-20 11:26:25 +0000210 }
Chris Lattner35c81b02005-02-27 18:58:52 +0000211 } else if (isa<GetElementPtrInst>(I)) {
Chris Lattner7a90b682004-10-07 04:16:33 +0000212 if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
Chris Lattner35c81b02005-02-27 18:58:52 +0000213 } else if (isa<SelectInst>(I)) {
Chris Lattner7a90b682004-10-07 04:16:33 +0000214 if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
Chris Lattner7a90b682004-10-07 04:16:33 +0000215 } else if (PHINode *PN = dyn_cast<PHINode>(I)) {
216 // PHI nodes we can check just like select or GEP instructions, but we
217 // have to be careful about infinite recursion.
Chris Lattner5a6bb6a2008-12-16 07:34:30 +0000218 if (PHIUsers.insert(PN)) // Not already visited.
Chris Lattner7a90b682004-10-07 04:16:33 +0000219 if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
Chris Lattner25de4e52006-11-01 18:03:33 +0000220 GS.HasPHIUser = true;
Reid Spencere4d87aa2006-12-23 06:05:41 +0000221 } else if (isa<CmpInst>(I)) {
Chris Lattner8e108442009-03-08 03:37:35 +0000222 } else if (isa<MemTransferInst>(I)) {
Chris Lattner35c81b02005-02-27 18:58:52 +0000223 if (I->getOperand(1) == V)
224 GS.StoredType = GlobalStatus::isStored;
225 if (I->getOperand(2) == V)
226 GS.isLoaded = true;
Chris Lattner35c81b02005-02-27 18:58:52 +0000227 } else if (isa<MemSetInst>(I)) {
228 assert(I->getOperand(1) == V && "Memset only takes one pointer!");
229 GS.StoredType = GlobalStatus::isStored;
Chris Lattner7a90b682004-10-07 04:16:33 +0000230 } else {
231 return true; // Any other non-load instruction might take address!
Chris Lattner9ce30002004-07-20 03:58:07 +0000232 }
Chris Lattnera4be1dc2004-10-08 20:59:28 +0000233 } else if (Constant *C = dyn_cast<Constant>(*UI)) {
Chris Lattner553ca522005-06-15 21:11:48 +0000234 GS.HasNonInstructionUser = true;
Chris Lattnera4be1dc2004-10-08 20:59:28 +0000235 // We might have a dead and dangling constant hanging off of here.
236 if (!ConstantIsDead(C))
237 return true;
Chris Lattner079236d2004-02-25 21:34:36 +0000238 } else {
Chris Lattner553ca522005-06-15 21:11:48 +0000239 GS.HasNonInstructionUser = true;
240 // Otherwise must be some other user.
Chris Lattner079236d2004-02-25 21:34:36 +0000241 return true;
242 }
243
244 return false;
245}
246
Chris Lattner670c8892004-10-08 17:32:09 +0000247static Constant *getAggregateConstantElement(Constant *Agg, Constant *Idx) {
248 ConstantInt *CI = dyn_cast<ConstantInt>(Idx);
249 if (!CI) return 0;
Reid Spencerb83eb642006-10-20 07:07:24 +0000250 unsigned IdxV = CI->getZExtValue();
Chris Lattner7a90b682004-10-07 04:16:33 +0000251
Chris Lattner670c8892004-10-08 17:32:09 +0000252 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(Agg)) {
253 if (IdxV < CS->getNumOperands()) return CS->getOperand(IdxV);
254 } else if (ConstantArray *CA = dyn_cast<ConstantArray>(Agg)) {
255 if (IdxV < CA->getNumOperands()) return CA->getOperand(IdxV);
Reid Spencer9d6565a2007-02-15 02:26:10 +0000256 } else if (ConstantVector *CP = dyn_cast<ConstantVector>(Agg)) {
Chris Lattner670c8892004-10-08 17:32:09 +0000257 if (IdxV < CP->getNumOperands()) return CP->getOperand(IdxV);
Chris Lattner7a7ed022004-10-16 18:09:00 +0000258 } else if (isa<ConstantAggregateZero>(Agg)) {
Chris Lattner670c8892004-10-08 17:32:09 +0000259 if (const StructType *STy = dyn_cast<StructType>(Agg->getType())) {
260 if (IdxV < STy->getNumElements())
261 return Constant::getNullValue(STy->getElementType(IdxV));
262 } else if (const SequentialType *STy =
263 dyn_cast<SequentialType>(Agg->getType())) {
264 return Constant::getNullValue(STy->getElementType());
265 }
Chris Lattner7a7ed022004-10-16 18:09:00 +0000266 } else if (isa<UndefValue>(Agg)) {
267 if (const StructType *STy = dyn_cast<StructType>(Agg->getType())) {
268 if (IdxV < STy->getNumElements())
269 return UndefValue::get(STy->getElementType(IdxV));
270 } else if (const SequentialType *STy =
271 dyn_cast<SequentialType>(Agg->getType())) {
272 return UndefValue::get(STy->getElementType());
273 }
Chris Lattner670c8892004-10-08 17:32:09 +0000274 }
275 return 0;
276}
Chris Lattner7a90b682004-10-07 04:16:33 +0000277
Chris Lattner7a90b682004-10-07 04:16:33 +0000278
Chris Lattnere47ba742004-10-06 20:57:02 +0000279/// CleanupConstantGlobalUsers - We just marked GV constant. Loop over all
280/// users of the global, cleaning up the obvious ones. This is largely just a
Chris Lattner031955d2004-10-10 16:43:46 +0000281/// quick scan over the use list to clean up the easy and obvious cruft. This
282/// returns true if it made a change.
283static bool CleanupConstantGlobalUsers(Value *V, Constant *Init) {
284 bool Changed = false;
Chris Lattner7a90b682004-10-07 04:16:33 +0000285 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;) {
286 User *U = *UI++;
Misha Brukmanfd939082005-04-21 23:48:37 +0000287
Chris Lattner7a90b682004-10-07 04:16:33 +0000288 if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
Chris Lattner35c81b02005-02-27 18:58:52 +0000289 if (Init) {
290 // Replace the load with the initializer.
291 LI->replaceAllUsesWith(Init);
292 LI->eraseFromParent();
293 Changed = true;
294 }
Chris Lattner7a90b682004-10-07 04:16:33 +0000295 } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
Chris Lattnere47ba742004-10-06 20:57:02 +0000296 // Store must be unreachable or storing Init into the global.
Chris Lattner7a7ed022004-10-16 18:09:00 +0000297 SI->eraseFromParent();
Chris Lattner031955d2004-10-10 16:43:46 +0000298 Changed = true;
Chris Lattner7a90b682004-10-07 04:16:33 +0000299 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
300 if (CE->getOpcode() == Instruction::GetElementPtr) {
Chris Lattneraae4a1c2005-09-26 07:34:35 +0000301 Constant *SubInit = 0;
302 if (Init)
303 SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
Chris Lattner35c81b02005-02-27 18:58:52 +0000304 Changed |= CleanupConstantGlobalUsers(CE, SubInit);
Reid Spencer3da59db2006-11-27 01:05:10 +0000305 } else if (CE->getOpcode() == Instruction::BitCast &&
Chris Lattner35c81b02005-02-27 18:58:52 +0000306 isa<PointerType>(CE->getType())) {
307 // Pointer cast, delete any stores and memsets to the global.
308 Changed |= CleanupConstantGlobalUsers(CE, 0);
309 }
310
311 if (CE->use_empty()) {
312 CE->destroyConstant();
313 Changed = true;
Chris Lattner7a90b682004-10-07 04:16:33 +0000314 }
315 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
Chris Lattner7b52fe72007-11-09 17:33:02 +0000316 // Do not transform "gepinst (gep constexpr (GV))" here, because forming
317 // "gepconstexpr (gep constexpr (GV))" will cause the two gep's to fold
318 // and will invalidate our notion of what Init is.
Chris Lattner19450242007-11-13 21:46:23 +0000319 Constant *SubInit = 0;
Chris Lattner7b52fe72007-11-09 17:33:02 +0000320 if (!isa<ConstantExpr>(GEP->getOperand(0))) {
321 ConstantExpr *CE =
322 dyn_cast_or_null<ConstantExpr>(ConstantFoldInstruction(GEP));
323 if (Init && CE && CE->getOpcode() == Instruction::GetElementPtr)
Chris Lattner19450242007-11-13 21:46:23 +0000324 SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
Chris Lattner7b52fe72007-11-09 17:33:02 +0000325 }
Chris Lattner19450242007-11-13 21:46:23 +0000326 Changed |= CleanupConstantGlobalUsers(GEP, SubInit);
Chris Lattnerc4d81b02004-10-10 16:47:33 +0000327
Chris Lattner031955d2004-10-10 16:43:46 +0000328 if (GEP->use_empty()) {
Chris Lattner7a7ed022004-10-16 18:09:00 +0000329 GEP->eraseFromParent();
Chris Lattner031955d2004-10-10 16:43:46 +0000330 Changed = true;
331 }
Chris Lattner35c81b02005-02-27 18:58:52 +0000332 } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U)) { // memset/cpy/mv
333 if (MI->getRawDest() == V) {
334 MI->eraseFromParent();
335 Changed = true;
336 }
337
Chris Lattnera4be1dc2004-10-08 20:59:28 +0000338 } else if (Constant *C = dyn_cast<Constant>(U)) {
339 // If we have a chain of dead constantexprs or other things dangling from
340 // us, and if they are all dead, nuke them without remorse.
Devang Patel743cdf82009-03-06 01:37:41 +0000341 if (ConstantIsDead(C)) {
342 C->destroyConstant();
Chris Lattner35c81b02005-02-27 18:58:52 +0000343 // This could have invalidated UI, start over from scratch.
Chris Lattnera4be1dc2004-10-08 20:59:28 +0000344 CleanupConstantGlobalUsers(V, Init);
Chris Lattner031955d2004-10-10 16:43:46 +0000345 return true;
Chris Lattnera4be1dc2004-10-08 20:59:28 +0000346 }
Chris Lattnere47ba742004-10-06 20:57:02 +0000347 }
348 }
Chris Lattner031955d2004-10-10 16:43:46 +0000349 return Changed;
Chris Lattnere47ba742004-10-06 20:57:02 +0000350}
351
Chris Lattner941db492008-01-14 02:09:12 +0000352/// isSafeSROAElementUse - Return true if the specified instruction is a safe
353/// user of a derived expression from a global that we want to SROA.
354static bool isSafeSROAElementUse(Value *V) {
355 // We might have a dead and dangling constant hanging off of here.
356 if (Constant *C = dyn_cast<Constant>(V))
357 return ConstantIsDead(C);
Chris Lattner727c2102008-01-14 01:31:05 +0000358
Chris Lattner941db492008-01-14 02:09:12 +0000359 Instruction *I = dyn_cast<Instruction>(V);
360 if (!I) return false;
361
362 // Loads are ok.
363 if (isa<LoadInst>(I)) return true;
364
365 // Stores *to* the pointer are ok.
366 if (StoreInst *SI = dyn_cast<StoreInst>(I))
367 return SI->getOperand(0) != V;
368
369 // Otherwise, it must be a GEP.
370 GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I);
371 if (GEPI == 0) return false;
372
373 if (GEPI->getNumOperands() < 3 || !isa<Constant>(GEPI->getOperand(1)) ||
374 !cast<Constant>(GEPI->getOperand(1))->isNullValue())
375 return false;
376
377 for (Value::use_iterator I = GEPI->use_begin(), E = GEPI->use_end();
378 I != E; ++I)
379 if (!isSafeSROAElementUse(*I))
380 return false;
Chris Lattner727c2102008-01-14 01:31:05 +0000381 return true;
382}
383
Chris Lattner941db492008-01-14 02:09:12 +0000384
385/// IsUserOfGlobalSafeForSRA - U is a direct user of the specified global value.
386/// Look at it and its uses and decide whether it is safe to SROA this global.
387///
388static bool IsUserOfGlobalSafeForSRA(User *U, GlobalValue *GV) {
389 // The user of the global must be a GEP Inst or a ConstantExpr GEP.
390 if (!isa<GetElementPtrInst>(U) &&
391 (!isa<ConstantExpr>(U) ||
392 cast<ConstantExpr>(U)->getOpcode() != Instruction::GetElementPtr))
393 return false;
394
395 // Check to see if this ConstantExpr GEP is SRA'able. In particular, we
396 // don't like < 3 operand CE's, and we don't like non-constant integer
397 // indices. This enforces that all uses are 'gep GV, 0, C, ...' for some
398 // value of C.
399 if (U->getNumOperands() < 3 || !isa<Constant>(U->getOperand(1)) ||
400 !cast<Constant>(U->getOperand(1))->isNullValue() ||
401 !isa<ConstantInt>(U->getOperand(2)))
402 return false;
403
404 gep_type_iterator GEPI = gep_type_begin(U), E = gep_type_end(U);
405 ++GEPI; // Skip over the pointer index.
406
407 // If this is a use of an array allocation, do a bit more checking for sanity.
408 if (const ArrayType *AT = dyn_cast<ArrayType>(*GEPI)) {
409 uint64_t NumElements = AT->getNumElements();
410 ConstantInt *Idx = cast<ConstantInt>(U->getOperand(2));
411
412 // Check to make sure that index falls within the array. If not,
413 // something funny is going on, so we won't do the optimization.
414 //
415 if (Idx->getZExtValue() >= NumElements)
416 return false;
417
418 // We cannot scalar repl this level of the array unless any array
419 // sub-indices are in-range constants. In particular, consider:
420 // A[0][i]. We cannot know that the user isn't doing invalid things like
421 // allowing i to index an out-of-range subscript that accesses A[1].
422 //
423 // Scalar replacing *just* the outer index of the array is probably not
424 // going to be a win anyway, so just give up.
425 for (++GEPI; // Skip array index.
426 GEPI != E && (isa<ArrayType>(*GEPI) || isa<VectorType>(*GEPI));
427 ++GEPI) {
428 uint64_t NumElements;
429 if (const ArrayType *SubArrayTy = dyn_cast<ArrayType>(*GEPI))
430 NumElements = SubArrayTy->getNumElements();
431 else
432 NumElements = cast<VectorType>(*GEPI)->getNumElements();
433
434 ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPI.getOperand());
435 if (!IdxVal || IdxVal->getZExtValue() >= NumElements)
436 return false;
437 }
438 }
439
440 for (Value::use_iterator I = U->use_begin(), E = U->use_end(); I != E; ++I)
441 if (!isSafeSROAElementUse(*I))
442 return false;
443 return true;
444}
445
446/// GlobalUsersSafeToSRA - Look at all uses of the global and decide whether it
447/// is safe for us to perform this transformation.
448///
449static bool GlobalUsersSafeToSRA(GlobalValue *GV) {
450 for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end();
451 UI != E; ++UI) {
452 if (!IsUserOfGlobalSafeForSRA(*UI, GV))
453 return false;
454 }
455 return true;
456}
457
458
Chris Lattner670c8892004-10-08 17:32:09 +0000459/// SRAGlobal - Perform scalar replacement of aggregates on the specified global
460/// variable. This opens the door for other optimizations by exposing the
461/// behavior of the program in a more fine-grained way. We have determined that
462/// this transformation is safe already. We return the first global variable we
463/// insert so that the caller can reprocess it.
Chris Lattner998182b2008-04-26 07:40:11 +0000464static GlobalVariable *SRAGlobal(GlobalVariable *GV, const TargetData &TD) {
Chris Lattner727c2102008-01-14 01:31:05 +0000465 // Make sure this global only has simple uses that we can SRA.
Chris Lattner941db492008-01-14 02:09:12 +0000466 if (!GlobalUsersSafeToSRA(GV))
Chris Lattner727c2102008-01-14 01:31:05 +0000467 return 0;
468
Rafael Espindolabb46f522009-01-15 20:18:42 +0000469 assert(GV->hasLocalLinkage() && !GV->isConstant());
Chris Lattner670c8892004-10-08 17:32:09 +0000470 Constant *Init = GV->getInitializer();
471 const Type *Ty = Init->getType();
Misha Brukmanfd939082005-04-21 23:48:37 +0000472
Chris Lattner670c8892004-10-08 17:32:09 +0000473 std::vector<GlobalVariable*> NewGlobals;
474 Module::GlobalListType &Globals = GV->getParent()->getGlobalList();
475
Chris Lattner998182b2008-04-26 07:40:11 +0000476 // Get the alignment of the global, either explicit or target-specific.
477 unsigned StartAlignment = GV->getAlignment();
478 if (StartAlignment == 0)
479 StartAlignment = TD.getABITypeAlignment(GV->getType());
480
Chris Lattner670c8892004-10-08 17:32:09 +0000481 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
482 NewGlobals.reserve(STy->getNumElements());
Chris Lattner998182b2008-04-26 07:40:11 +0000483 const StructLayout &Layout = *TD.getStructLayout(STy);
Chris Lattner670c8892004-10-08 17:32:09 +0000484 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
485 Constant *In = getAggregateConstantElement(Init,
Reid Spencerc5b206b2006-12-31 05:48:39 +0000486 ConstantInt::get(Type::Int32Ty, i));
Chris Lattner670c8892004-10-08 17:32:09 +0000487 assert(In && "Couldn't get element of initializer?");
488 GlobalVariable *NGV = new GlobalVariable(STy->getElementType(i), false,
489 GlobalVariable::InternalLinkage,
Lauro Ramos Venancioc7635522007-04-12 18:32:50 +0000490 In, GV->getName()+"."+utostr(i),
491 (Module *)NULL,
Matthijs Kooijmanbc1f9892008-07-17 11:59:53 +0000492 GV->isThreadLocal(),
493 GV->getType()->getAddressSpace());
Chris Lattner670c8892004-10-08 17:32:09 +0000494 Globals.insert(GV, NGV);
495 NewGlobals.push_back(NGV);
Chris Lattner998182b2008-04-26 07:40:11 +0000496
497 // Calculate the known alignment of the field. If the original aggregate
498 // had 256 byte alignment for example, something might depend on that:
499 // propagate info to each field.
500 uint64_t FieldOffset = Layout.getElementOffset(i);
501 unsigned NewAlign = (unsigned)MinAlign(StartAlignment, FieldOffset);
502 if (NewAlign > TD.getABITypeAlignment(STy->getElementType(i)))
503 NGV->setAlignment(NewAlign);
Chris Lattner670c8892004-10-08 17:32:09 +0000504 }
505 } else if (const SequentialType *STy = dyn_cast<SequentialType>(Ty)) {
506 unsigned NumElements = 0;
507 if (const ArrayType *ATy = dyn_cast<ArrayType>(STy))
508 NumElements = ATy->getNumElements();
Chris Lattner670c8892004-10-08 17:32:09 +0000509 else
Chris Lattner998182b2008-04-26 07:40:11 +0000510 NumElements = cast<VectorType>(STy)->getNumElements();
Chris Lattner670c8892004-10-08 17:32:09 +0000511
Chris Lattner1f21ef12005-02-23 16:53:04 +0000512 if (NumElements > 16 && GV->hasNUsesOrMore(16))
Chris Lattnerd514d822005-02-01 01:23:31 +0000513 return 0; // It's not worth it.
Chris Lattner670c8892004-10-08 17:32:09 +0000514 NewGlobals.reserve(NumElements);
Chris Lattner998182b2008-04-26 07:40:11 +0000515
Duncan Sands777d2302009-05-09 07:06:46 +0000516 uint64_t EltSize = TD.getTypeAllocSize(STy->getElementType());
Chris Lattner998182b2008-04-26 07:40:11 +0000517 unsigned EltAlign = TD.getABITypeAlignment(STy->getElementType());
Chris Lattner670c8892004-10-08 17:32:09 +0000518 for (unsigned i = 0, e = NumElements; i != e; ++i) {
519 Constant *In = getAggregateConstantElement(Init,
Reid Spencerc5b206b2006-12-31 05:48:39 +0000520 ConstantInt::get(Type::Int32Ty, i));
Chris Lattner670c8892004-10-08 17:32:09 +0000521 assert(In && "Couldn't get element of initializer?");
522
523 GlobalVariable *NGV = new GlobalVariable(STy->getElementType(), false,
524 GlobalVariable::InternalLinkage,
Lauro Ramos Venancioc7635522007-04-12 18:32:50 +0000525 In, GV->getName()+"."+utostr(i),
526 (Module *)NULL,
Matthijs Kooijmanbc1f9892008-07-17 11:59:53 +0000527 GV->isThreadLocal(),
528 GV->getType()->getAddressSpace());
Chris Lattner670c8892004-10-08 17:32:09 +0000529 Globals.insert(GV, NGV);
530 NewGlobals.push_back(NGV);
Chris Lattner998182b2008-04-26 07:40:11 +0000531
532 // Calculate the known alignment of the field. If the original aggregate
533 // had 256 byte alignment for example, something might depend on that:
534 // propagate info to each field.
535 unsigned NewAlign = (unsigned)MinAlign(StartAlignment, EltSize*i);
536 if (NewAlign > EltAlign)
537 NGV->setAlignment(NewAlign);
Chris Lattner670c8892004-10-08 17:32:09 +0000538 }
539 }
540
541 if (NewGlobals.empty())
542 return 0;
543
Bill Wendling0a81aac2006-11-26 10:02:32 +0000544 DOUT << "PERFORMING GLOBAL SRA ON: " << *GV;
Chris Lattner30ba5692004-10-11 05:54:41 +0000545
Reid Spencerc5b206b2006-12-31 05:48:39 +0000546 Constant *NullInt = Constant::getNullValue(Type::Int32Ty);
Chris Lattner670c8892004-10-08 17:32:09 +0000547
548 // Loop over all of the uses of the global, replacing the constantexpr geps,
549 // with smaller constantexpr geps or direct references.
550 while (!GV->use_empty()) {
Chris Lattner30ba5692004-10-11 05:54:41 +0000551 User *GEP = GV->use_back();
552 assert(((isa<ConstantExpr>(GEP) &&
553 cast<ConstantExpr>(GEP)->getOpcode()==Instruction::GetElementPtr)||
554 isa<GetElementPtrInst>(GEP)) && "NonGEP CE's are not SRAable!");
Misha Brukmanfd939082005-04-21 23:48:37 +0000555
Chris Lattner670c8892004-10-08 17:32:09 +0000556 // Ignore the 1th operand, which has to be zero or else the program is quite
557 // broken (undefined). Get the 2nd operand, which is the structure or array
558 // index.
Reid Spencerb83eb642006-10-20 07:07:24 +0000559 unsigned Val = cast<ConstantInt>(GEP->getOperand(2))->getZExtValue();
Chris Lattner670c8892004-10-08 17:32:09 +0000560 if (Val >= NewGlobals.size()) Val = 0; // Out of bound array access.
561
Chris Lattner30ba5692004-10-11 05:54:41 +0000562 Value *NewPtr = NewGlobals[Val];
Chris Lattner670c8892004-10-08 17:32:09 +0000563
564 // Form a shorter GEP if needed.
Anton Korobeynikov07e6e562008-02-20 11:26:25 +0000565 if (GEP->getNumOperands() > 3) {
Chris Lattner30ba5692004-10-11 05:54:41 +0000566 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEP)) {
Chris Lattner55eb1c42007-01-31 04:40:53 +0000567 SmallVector<Constant*, 8> Idxs;
Chris Lattner30ba5692004-10-11 05:54:41 +0000568 Idxs.push_back(NullInt);
569 for (unsigned i = 3, e = CE->getNumOperands(); i != e; ++i)
570 Idxs.push_back(CE->getOperand(i));
Chris Lattner55eb1c42007-01-31 04:40:53 +0000571 NewPtr = ConstantExpr::getGetElementPtr(cast<Constant>(NewPtr),
572 &Idxs[0], Idxs.size());
Chris Lattner30ba5692004-10-11 05:54:41 +0000573 } else {
574 GetElementPtrInst *GEPI = cast<GetElementPtrInst>(GEP);
Chris Lattner699d1442007-01-31 19:59:55 +0000575 SmallVector<Value*, 8> Idxs;
Chris Lattner30ba5692004-10-11 05:54:41 +0000576 Idxs.push_back(NullInt);
577 for (unsigned i = 3, e = GEPI->getNumOperands(); i != e; ++i)
578 Idxs.push_back(GEPI->getOperand(i));
Gabor Greif051a9502008-04-06 20:25:17 +0000579 NewPtr = GetElementPtrInst::Create(NewPtr, Idxs.begin(), Idxs.end(),
580 GEPI->getName()+"."+utostr(Val), GEPI);
Chris Lattner30ba5692004-10-11 05:54:41 +0000581 }
Anton Korobeynikov07e6e562008-02-20 11:26:25 +0000582 }
Chris Lattner30ba5692004-10-11 05:54:41 +0000583 GEP->replaceAllUsesWith(NewPtr);
584
585 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(GEP))
Chris Lattner7a7ed022004-10-16 18:09:00 +0000586 GEPI->eraseFromParent();
Chris Lattner30ba5692004-10-11 05:54:41 +0000587 else
588 cast<ConstantExpr>(GEP)->destroyConstant();
Chris Lattner670c8892004-10-08 17:32:09 +0000589 }
590
Chris Lattnere40e2d12004-10-08 20:25:55 +0000591 // Delete the old global, now that it is dead.
592 Globals.erase(GV);
Chris Lattner670c8892004-10-08 17:32:09 +0000593 ++NumSRA;
Chris Lattner30ba5692004-10-11 05:54:41 +0000594
595 // Loop over the new globals array deleting any globals that are obviously
596 // dead. This can arise due to scalarization of a structure or an array that
597 // has elements that are dead.
598 unsigned FirstGlobal = 0;
599 for (unsigned i = 0, e = NewGlobals.size(); i != e; ++i)
600 if (NewGlobals[i]->use_empty()) {
601 Globals.erase(NewGlobals[i]);
602 if (FirstGlobal == i) ++FirstGlobal;
603 }
604
605 return FirstGlobal != NewGlobals.size() ? NewGlobals[FirstGlobal] : 0;
Chris Lattner670c8892004-10-08 17:32:09 +0000606}
607
Chris Lattner9b34a612004-10-09 21:48:45 +0000608/// AllUsesOfValueWillTrapIfNull - Return true if all users of the specified
Chris Lattner81686182007-09-13 16:30:19 +0000609/// value will trap if the value is dynamically null. PHIs keeps track of any
610/// phi nodes we've seen to avoid reprocessing them.
611static bool AllUsesOfValueWillTrapIfNull(Value *V,
612 SmallPtrSet<PHINode*, 8> &PHIs) {
Chris Lattner9b34a612004-10-09 21:48:45 +0000613 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
614 if (isa<LoadInst>(*UI)) {
615 // Will trap.
616 } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
617 if (SI->getOperand(0) == V) {
Bill Wendlinge8156192006-12-07 01:30:32 +0000618 //cerr << "NONTRAPPING USE: " << **UI;
Chris Lattner9b34a612004-10-09 21:48:45 +0000619 return false; // Storing the value.
620 }
621 } else if (CallInst *CI = dyn_cast<CallInst>(*UI)) {
622 if (CI->getOperand(0) != V) {
Bill Wendlinge8156192006-12-07 01:30:32 +0000623 //cerr << "NONTRAPPING USE: " << **UI;
Chris Lattner9b34a612004-10-09 21:48:45 +0000624 return false; // Not calling the ptr
625 }
626 } else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) {
627 if (II->getOperand(0) != V) {
Bill Wendlinge8156192006-12-07 01:30:32 +0000628 //cerr << "NONTRAPPING USE: " << **UI;
Chris Lattner9b34a612004-10-09 21:48:45 +0000629 return false; // Not calling the ptr
630 }
Chris Lattner81686182007-09-13 16:30:19 +0000631 } else if (BitCastInst *CI = dyn_cast<BitCastInst>(*UI)) {
632 if (!AllUsesOfValueWillTrapIfNull(CI, PHIs)) return false;
Chris Lattner9b34a612004-10-09 21:48:45 +0000633 } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI)) {
Chris Lattner81686182007-09-13 16:30:19 +0000634 if (!AllUsesOfValueWillTrapIfNull(GEPI, PHIs)) return false;
635 } else if (PHINode *PN = dyn_cast<PHINode>(*UI)) {
636 // If we've already seen this phi node, ignore it, it has already been
637 // checked.
638 if (PHIs.insert(PN))
639 return AllUsesOfValueWillTrapIfNull(PN, PHIs);
Reid Spencere4d87aa2006-12-23 06:05:41 +0000640 } else if (isa<ICmpInst>(*UI) &&
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000641 isa<ConstantPointerNull>(UI->getOperand(1))) {
642 // Ignore setcc X, null
Chris Lattner9b34a612004-10-09 21:48:45 +0000643 } else {
Bill Wendlinge8156192006-12-07 01:30:32 +0000644 //cerr << "NONTRAPPING USE: " << **UI;
Chris Lattner9b34a612004-10-09 21:48:45 +0000645 return false;
646 }
647 return true;
648}
649
650/// AllUsesOfLoadedValueWillTrapIfNull - Return true if all uses of any loads
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000651/// from GV will trap if the loaded value is null. Note that this also permits
652/// comparisons of the loaded value against null, as a special case.
Chris Lattner9b34a612004-10-09 21:48:45 +0000653static bool AllUsesOfLoadedValueWillTrapIfNull(GlobalVariable *GV) {
654 for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI!=E; ++UI)
655 if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
Chris Lattner81686182007-09-13 16:30:19 +0000656 SmallPtrSet<PHINode*, 8> PHIs;
657 if (!AllUsesOfValueWillTrapIfNull(LI, PHIs))
Chris Lattner9b34a612004-10-09 21:48:45 +0000658 return false;
659 } else if (isa<StoreInst>(*UI)) {
660 // Ignore stores to the global.
661 } else {
662 // We don't know or understand this user, bail out.
Bill Wendlinge8156192006-12-07 01:30:32 +0000663 //cerr << "UNKNOWN USER OF GLOBAL!: " << **UI;
Chris Lattner9b34a612004-10-09 21:48:45 +0000664 return false;
665 }
666
667 return true;
668}
669
Chris Lattner708148e2004-10-10 23:14:11 +0000670static bool OptimizeAwayTrappingUsesOfValue(Value *V, Constant *NewV) {
671 bool Changed = false;
672 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ) {
673 Instruction *I = cast<Instruction>(*UI++);
674 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
675 LI->setOperand(0, NewV);
676 Changed = true;
677 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
678 if (SI->getOperand(1) == V) {
679 SI->setOperand(1, NewV);
680 Changed = true;
681 }
682 } else if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
683 if (I->getOperand(0) == V) {
684 // Calling through the pointer! Turn into a direct call, but be careful
685 // that the pointer is not also being passed as an argument.
686 I->setOperand(0, NewV);
687 Changed = true;
688 bool PassedAsArg = false;
689 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
690 if (I->getOperand(i) == V) {
691 PassedAsArg = true;
692 I->setOperand(i, NewV);
693 }
694
695 if (PassedAsArg) {
696 // Being passed as an argument also. Be careful to not invalidate UI!
697 UI = V->use_begin();
698 }
699 }
700 } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
701 Changed |= OptimizeAwayTrappingUsesOfValue(CI,
Chris Lattner6e8fbad2006-11-30 17:32:29 +0000702 ConstantExpr::getCast(CI->getOpcode(),
703 NewV, CI->getType()));
Chris Lattner708148e2004-10-10 23:14:11 +0000704 if (CI->use_empty()) {
705 Changed = true;
Chris Lattner7a7ed022004-10-16 18:09:00 +0000706 CI->eraseFromParent();
Chris Lattner708148e2004-10-10 23:14:11 +0000707 }
708 } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
709 // Should handle GEP here.
Chris Lattner55eb1c42007-01-31 04:40:53 +0000710 SmallVector<Constant*, 8> Idxs;
711 Idxs.reserve(GEPI->getNumOperands()-1);
Gabor Greif5e463212008-05-29 01:59:18 +0000712 for (User::op_iterator i = GEPI->op_begin() + 1, e = GEPI->op_end();
713 i != e; ++i)
714 if (Constant *C = dyn_cast<Constant>(*i))
Chris Lattner55eb1c42007-01-31 04:40:53 +0000715 Idxs.push_back(C);
Chris Lattner708148e2004-10-10 23:14:11 +0000716 else
717 break;
Chris Lattner55eb1c42007-01-31 04:40:53 +0000718 if (Idxs.size() == GEPI->getNumOperands()-1)
Chris Lattner708148e2004-10-10 23:14:11 +0000719 Changed |= OptimizeAwayTrappingUsesOfValue(GEPI,
Chris Lattner55eb1c42007-01-31 04:40:53 +0000720 ConstantExpr::getGetElementPtr(NewV, &Idxs[0],
721 Idxs.size()));
Chris Lattner708148e2004-10-10 23:14:11 +0000722 if (GEPI->use_empty()) {
723 Changed = true;
Chris Lattner7a7ed022004-10-16 18:09:00 +0000724 GEPI->eraseFromParent();
Chris Lattner708148e2004-10-10 23:14:11 +0000725 }
726 }
727 }
728
729 return Changed;
730}
731
732
733/// OptimizeAwayTrappingUsesOfLoads - The specified global has only one non-null
734/// value stored into it. If there are uses of the loaded value that would trap
735/// if the loaded value is dynamically null, then we know that they cannot be
736/// reachable with a null optimize away the load.
737static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV) {
Chris Lattner708148e2004-10-10 23:14:11 +0000738 bool Changed = false;
739
Chris Lattner92c6bd22009-01-14 00:12:58 +0000740 // Keep track of whether we are able to remove all the uses of the global
741 // other than the store that defines it.
742 bool AllNonStoreUsesGone = true;
743
Chris Lattner708148e2004-10-10 23:14:11 +0000744 // Replace all uses of loads with uses of uses of the stored value.
Chris Lattner92c6bd22009-01-14 00:12:58 +0000745 for (Value::use_iterator GUI = GV->use_begin(), E = GV->use_end(); GUI != E;){
746 User *GlobalUser = *GUI++;
747 if (LoadInst *LI = dyn_cast<LoadInst>(GlobalUser)) {
Chris Lattner708148e2004-10-10 23:14:11 +0000748 Changed |= OptimizeAwayTrappingUsesOfValue(LI, LV);
Chris Lattner92c6bd22009-01-14 00:12:58 +0000749 // If we were able to delete all uses of the loads
750 if (LI->use_empty()) {
751 LI->eraseFromParent();
752 Changed = true;
753 } else {
754 AllNonStoreUsesGone = false;
755 }
756 } else if (isa<StoreInst>(GlobalUser)) {
757 // Ignore the store that stores "LV" to the global.
758 assert(GlobalUser->getOperand(1) == GV &&
759 "Must be storing *to* the global");
Chris Lattner708148e2004-10-10 23:14:11 +0000760 } else {
Chris Lattner92c6bd22009-01-14 00:12:58 +0000761 AllNonStoreUsesGone = false;
762
763 // If we get here we could have other crazy uses that are transitively
764 // loaded.
765 assert((isa<PHINode>(GlobalUser) || isa<SelectInst>(GlobalUser) ||
766 isa<ConstantExpr>(GlobalUser)) && "Only expect load and stores!");
Chris Lattner708148e2004-10-10 23:14:11 +0000767 }
Chris Lattner92c6bd22009-01-14 00:12:58 +0000768 }
Chris Lattner708148e2004-10-10 23:14:11 +0000769
770 if (Changed) {
Bill Wendling0a81aac2006-11-26 10:02:32 +0000771 DOUT << "OPTIMIZED LOADS FROM STORED ONCE POINTER: " << *GV;
Chris Lattner708148e2004-10-10 23:14:11 +0000772 ++NumGlobUses;
773 }
774
Chris Lattner708148e2004-10-10 23:14:11 +0000775 // If we nuked all of the loads, then none of the stores are needed either,
776 // nor is the global.
Chris Lattner92c6bd22009-01-14 00:12:58 +0000777 if (AllNonStoreUsesGone) {
Bill Wendling0a81aac2006-11-26 10:02:32 +0000778 DOUT << " *** GLOBAL NOW DEAD!\n";
Chris Lattner708148e2004-10-10 23:14:11 +0000779 CleanupConstantGlobalUsers(GV, 0);
780 if (GV->use_empty()) {
Chris Lattner7a7ed022004-10-16 18:09:00 +0000781 GV->eraseFromParent();
Chris Lattner708148e2004-10-10 23:14:11 +0000782 ++NumDeleted;
783 }
784 Changed = true;
785 }
786 return Changed;
787}
788
Chris Lattner30ba5692004-10-11 05:54:41 +0000789/// ConstantPropUsersOf - Walk the use list of V, constant folding all of the
790/// instructions that are foldable.
791static void ConstantPropUsersOf(Value *V) {
792 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; )
793 if (Instruction *I = dyn_cast<Instruction>(*UI++))
794 if (Constant *NewC = ConstantFoldInstruction(I)) {
795 I->replaceAllUsesWith(NewC);
796
Chris Lattnerd514d822005-02-01 01:23:31 +0000797 // Advance UI to the next non-I use to avoid invalidating it!
798 // Instructions could multiply use V.
799 while (UI != E && *UI == I)
Chris Lattner30ba5692004-10-11 05:54:41 +0000800 ++UI;
Chris Lattnerd514d822005-02-01 01:23:31 +0000801 I->eraseFromParent();
Chris Lattner30ba5692004-10-11 05:54:41 +0000802 }
803}
804
805/// OptimizeGlobalAddressOfMalloc - This function takes the specified global
806/// variable, and transforms the program as if it always contained the result of
807/// the specified malloc. Because it is always the result of the specified
808/// malloc, there is no reason to actually DO the malloc. Instead, turn the
Chris Lattner6e8fbad2006-11-30 17:32:29 +0000809/// malloc into a global, and any loads of GV as uses of the new global.
Chris Lattner30ba5692004-10-11 05:54:41 +0000810static GlobalVariable *OptimizeGlobalAddressOfMalloc(GlobalVariable *GV,
811 MallocInst *MI) {
Bill Wendling0a81aac2006-11-26 10:02:32 +0000812 DOUT << "PROMOTING MALLOC GLOBAL: " << *GV << " MALLOC = " << *MI;
Chris Lattner30ba5692004-10-11 05:54:41 +0000813 ConstantInt *NElements = cast<ConstantInt>(MI->getArraySize());
814
Reid Spencerb83eb642006-10-20 07:07:24 +0000815 if (NElements->getZExtValue() != 1) {
Chris Lattner30ba5692004-10-11 05:54:41 +0000816 // If we have an array allocation, transform it to a single element
817 // allocation to make the code below simpler.
818 Type *NewTy = ArrayType::get(MI->getAllocatedType(),
Reid Spencerb83eb642006-10-20 07:07:24 +0000819 NElements->getZExtValue());
Chris Lattner30ba5692004-10-11 05:54:41 +0000820 MallocInst *NewMI =
Reid Spencerc5b206b2006-12-31 05:48:39 +0000821 new MallocInst(NewTy, Constant::getNullValue(Type::Int32Ty),
Nate Begeman14b05292005-11-05 09:21:28 +0000822 MI->getAlignment(), MI->getName(), MI);
Chris Lattner699d1442007-01-31 19:59:55 +0000823 Value* Indices[2];
824 Indices[0] = Indices[1] = Constant::getNullValue(Type::Int32Ty);
Gabor Greif051a9502008-04-06 20:25:17 +0000825 Value *NewGEP = GetElementPtrInst::Create(NewMI, Indices, Indices + 2,
826 NewMI->getName()+".el0", MI);
Chris Lattner30ba5692004-10-11 05:54:41 +0000827 MI->replaceAllUsesWith(NewGEP);
Chris Lattner7a7ed022004-10-16 18:09:00 +0000828 MI->eraseFromParent();
Chris Lattner30ba5692004-10-11 05:54:41 +0000829 MI = NewMI;
830 }
Misha Brukmanfd939082005-04-21 23:48:37 +0000831
Chris Lattner7a7ed022004-10-16 18:09:00 +0000832 // Create the new global variable. The contents of the malloc'd memory is
833 // undefined, so initialize with an undef value.
834 Constant *Init = UndefValue::get(MI->getAllocatedType());
Chris Lattner30ba5692004-10-11 05:54:41 +0000835 GlobalVariable *NewGV = new GlobalVariable(MI->getAllocatedType(), false,
836 GlobalValue::InternalLinkage, Init,
Lauro Ramos Venancioc7635522007-04-12 18:32:50 +0000837 GV->getName()+".body",
838 (Module *)NULL,
839 GV->isThreadLocal());
Chris Lattner998182b2008-04-26 07:40:11 +0000840 // FIXME: This new global should have the alignment returned by malloc. Code
841 // could depend on malloc returning large alignment (on the mac, 16 bytes) but
842 // this would only guarantee some lower alignment.
Chris Lattner30ba5692004-10-11 05:54:41 +0000843 GV->getParent()->getGlobalList().insert(GV, NewGV);
Misha Brukmanfd939082005-04-21 23:48:37 +0000844
Chris Lattner30ba5692004-10-11 05:54:41 +0000845 // Anything that used the malloc now uses the global directly.
846 MI->replaceAllUsesWith(NewGV);
Chris Lattner30ba5692004-10-11 05:54:41 +0000847
848 Constant *RepValue = NewGV;
849 if (NewGV->getType() != GV->getType()->getElementType())
Reid Spencerd977d862006-12-12 23:36:14 +0000850 RepValue = ConstantExpr::getBitCast(RepValue,
851 GV->getType()->getElementType());
Chris Lattner30ba5692004-10-11 05:54:41 +0000852
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000853 // If there is a comparison against null, we will insert a global bool to
854 // keep track of whether the global was initialized yet or not.
Misha Brukmanfd939082005-04-21 23:48:37 +0000855 GlobalVariable *InitBool =
Reid Spencer4fe16d62007-01-11 18:21:29 +0000856 new GlobalVariable(Type::Int1Ty, false, GlobalValue::InternalLinkage,
Lauro Ramos Venancioc7635522007-04-12 18:32:50 +0000857 ConstantInt::getFalse(), GV->getName()+".init",
858 (Module *)NULL, GV->isThreadLocal());
Chris Lattnerbc965b92004-12-02 06:25:58 +0000859 bool InitBoolUsed = false;
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000860
Chris Lattner30ba5692004-10-11 05:54:41 +0000861 // Loop over all uses of GV, processing them in turn.
Chris Lattnerbc965b92004-12-02 06:25:58 +0000862 std::vector<StoreInst*> Stores;
Chris Lattner30ba5692004-10-11 05:54:41 +0000863 while (!GV->use_empty())
864 if (LoadInst *LI = dyn_cast<LoadInst>(GV->use_back())) {
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000865 while (!LI->use_empty()) {
Chris Lattnerd514d822005-02-01 01:23:31 +0000866 Use &LoadUse = LI->use_begin().getUse();
Reid Spencere4d87aa2006-12-23 06:05:41 +0000867 if (!isa<ICmpInst>(LoadUse.getUser()))
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000868 LoadUse = RepValue;
869 else {
Reid Spencere4d87aa2006-12-23 06:05:41 +0000870 ICmpInst *CI = cast<ICmpInst>(LoadUse.getUser());
871 // Replace the cmp X, 0 with a use of the bool value.
872 Value *LV = new LoadInst(InitBool, InitBool->getName()+".val", CI);
Chris Lattnerbc965b92004-12-02 06:25:58 +0000873 InitBoolUsed = true;
Reid Spencere4d87aa2006-12-23 06:05:41 +0000874 switch (CI->getPredicate()) {
875 default: assert(0 && "Unknown ICmp Predicate!");
876 case ICmpInst::ICMP_ULT:
877 case ICmpInst::ICMP_SLT:
Zhou Sheng6b6b6ef2007-01-11 12:24:14 +0000878 LV = ConstantInt::getFalse(); // X < null -> always false
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000879 break;
Reid Spencere4d87aa2006-12-23 06:05:41 +0000880 case ICmpInst::ICMP_ULE:
881 case ICmpInst::ICMP_SLE:
882 case ICmpInst::ICMP_EQ:
Gabor Greif7cbd8a32008-05-16 19:29:10 +0000883 LV = BinaryOperator::CreateNot(LV, "notinit", CI);
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000884 break;
Reid Spencere4d87aa2006-12-23 06:05:41 +0000885 case ICmpInst::ICMP_NE:
886 case ICmpInst::ICMP_UGE:
887 case ICmpInst::ICMP_SGE:
888 case ICmpInst::ICMP_UGT:
889 case ICmpInst::ICMP_SGT:
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000890 break; // no change.
891 }
Reid Spencere4d87aa2006-12-23 06:05:41 +0000892 CI->replaceAllUsesWith(LV);
893 CI->eraseFromParent();
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000894 }
895 }
Chris Lattner7a7ed022004-10-16 18:09:00 +0000896 LI->eraseFromParent();
Chris Lattner30ba5692004-10-11 05:54:41 +0000897 } else {
898 StoreInst *SI = cast<StoreInst>(GV->use_back());
Chris Lattnerbc965b92004-12-02 06:25:58 +0000899 // The global is initialized when the store to it occurs.
Zhou Sheng6b6b6ef2007-01-11 12:24:14 +0000900 new StoreInst(ConstantInt::getTrue(), InitBool, SI);
Chris Lattner7a7ed022004-10-16 18:09:00 +0000901 SI->eraseFromParent();
Chris Lattner30ba5692004-10-11 05:54:41 +0000902 }
903
Chris Lattnerbc965b92004-12-02 06:25:58 +0000904 // If the initialization boolean was used, insert it, otherwise delete it.
905 if (!InitBoolUsed) {
906 while (!InitBool->use_empty()) // Delete initializations
907 cast<Instruction>(InitBool->use_back())->eraseFromParent();
908 delete InitBool;
909 } else
910 GV->getParent()->getGlobalList().insert(GV, InitBool);
911
912
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000913 // Now the GV is dead, nuke it and the malloc.
Chris Lattner7a7ed022004-10-16 18:09:00 +0000914 GV->eraseFromParent();
Chris Lattnere9ece2a2004-10-22 06:43:28 +0000915 MI->eraseFromParent();
Chris Lattner30ba5692004-10-11 05:54:41 +0000916
917 // To further other optimizations, loop over all users of NewGV and try to
918 // constant prop them. This will promote GEP instructions with constant
919 // indices into GEP constant-exprs, which will allow global-opt to hack on it.
920 ConstantPropUsersOf(NewGV);
921 if (RepValue != NewGV)
922 ConstantPropUsersOf(RepValue);
923
924 return NewGV;
925}
Chris Lattner708148e2004-10-10 23:14:11 +0000926
Chris Lattnerfa07e4f2004-12-02 07:11:07 +0000927/// ValueIsOnlyUsedLocallyOrStoredToOneGlobal - Scan the use-list of V checking
928/// to make sure that there are no complex uses of V. We permit simple things
929/// like dereferencing the pointer, but not storing through the address, unless
930/// it is to the specified global.
931static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Instruction *V,
Chris Lattnerc451f9c2007-09-13 16:37:20 +0000932 GlobalVariable *GV,
933 SmallPtrSet<PHINode*, 8> &PHIs) {
Chris Lattner49b6d4a2008-12-15 21:08:54 +0000934 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
935 Instruction *Inst = dyn_cast<Instruction>(*UI);
936 if (Inst == 0) return false;
937
938 if (isa<LoadInst>(Inst) || isa<CmpInst>(Inst)) {
939 continue; // Fine, ignore.
940 }
941
942 if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
Chris Lattnerfa07e4f2004-12-02 07:11:07 +0000943 if (SI->getOperand(0) == V && SI->getOperand(1) != GV)
944 return false; // Storing the pointer itself... bad.
Chris Lattner49b6d4a2008-12-15 21:08:54 +0000945 continue; // Otherwise, storing through it, or storing into GV... fine.
946 }
947
948 if (isa<GetElementPtrInst>(Inst)) {
949 if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Inst, GV, PHIs))
Chris Lattnerfa07e4f2004-12-02 07:11:07 +0000950 return false;
Chris Lattner49b6d4a2008-12-15 21:08:54 +0000951 continue;
952 }
953
954 if (PHINode *PN = dyn_cast<PHINode>(Inst)) {
Chris Lattnerc451f9c2007-09-13 16:37:20 +0000955 // PHIs are ok if all uses are ok. Don't infinitely recurse through PHI
956 // cycles.
957 if (PHIs.insert(PN))
Chris Lattner5e6e4942007-09-14 03:41:21 +0000958 if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(PN, GV, PHIs))
959 return false;
Chris Lattner49b6d4a2008-12-15 21:08:54 +0000960 continue;
Chris Lattnerfa07e4f2004-12-02 07:11:07 +0000961 }
Chris Lattner49b6d4a2008-12-15 21:08:54 +0000962
963 if (BitCastInst *BCI = dyn_cast<BitCastInst>(Inst)) {
964 if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(BCI, GV, PHIs))
965 return false;
966 continue;
967 }
968
969 return false;
970 }
Chris Lattnerfa07e4f2004-12-02 07:11:07 +0000971 return true;
Chris Lattnerfa07e4f2004-12-02 07:11:07 +0000972}
973
Chris Lattner86395032006-09-30 23:32:09 +0000974/// ReplaceUsesOfMallocWithGlobal - The Alloc pointer is stored into GV
975/// somewhere. Transform all uses of the allocation into loads from the
976/// global and uses of the resultant pointer. Further, delete the store into
977/// GV. This assumes that these value pass the
978/// 'ValueIsOnlyUsedLocallyOrStoredToOneGlobal' predicate.
979static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc,
980 GlobalVariable *GV) {
981 while (!Alloc->use_empty()) {
Chris Lattnera637a8b2007-09-13 18:00:31 +0000982 Instruction *U = cast<Instruction>(*Alloc->use_begin());
983 Instruction *InsertPt = U;
Chris Lattner86395032006-09-30 23:32:09 +0000984 if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
985 // If this is the store of the allocation into the global, remove it.
986 if (SI->getOperand(1) == GV) {
987 SI->eraseFromParent();
988 continue;
989 }
Chris Lattnera637a8b2007-09-13 18:00:31 +0000990 } else if (PHINode *PN = dyn_cast<PHINode>(U)) {
991 // Insert the load in the corresponding predecessor, not right before the
992 // PHI.
Gabor Greifa36791d2009-01-23 19:40:15 +0000993 InsertPt = PN->getIncomingBlock(Alloc->use_begin())->getTerminator();
Chris Lattner101f44e2008-12-15 21:44:34 +0000994 } else if (isa<BitCastInst>(U)) {
995 // Must be bitcast between the malloc and store to initialize the global.
996 ReplaceUsesOfMallocWithGlobal(U, GV);
997 U->eraseFromParent();
998 continue;
999 } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U)) {
1000 // If this is a "GEP bitcast" and the user is a store to the global, then
1001 // just process it as a bitcast.
1002 if (GEPI->hasAllZeroIndices() && GEPI->hasOneUse())
1003 if (StoreInst *SI = dyn_cast<StoreInst>(GEPI->use_back()))
1004 if (SI->getOperand(1) == GV) {
1005 // Must be bitcast GEP between the malloc and store to initialize
1006 // the global.
1007 ReplaceUsesOfMallocWithGlobal(GEPI, GV);
1008 GEPI->eraseFromParent();
1009 continue;
1010 }
Chris Lattner86395032006-09-30 23:32:09 +00001011 }
Chris Lattner101f44e2008-12-15 21:44:34 +00001012
Chris Lattner86395032006-09-30 23:32:09 +00001013 // Insert a load from the global, and use it instead of the malloc.
Chris Lattnera637a8b2007-09-13 18:00:31 +00001014 Value *NL = new LoadInst(GV, GV->getName()+".val", InsertPt);
Chris Lattner86395032006-09-30 23:32:09 +00001015 U->replaceUsesOfWith(Alloc, NL);
1016 }
1017}
1018
Chris Lattner85d3d4f2008-12-16 21:24:51 +00001019/// LoadUsesSimpleEnoughForHeapSRA - Verify that all uses of V (a load, or a phi
1020/// of a load) are simple enough to perform heap SRA on. This permits GEP's
1021/// that index through the array and struct field, icmps of null, and PHIs.
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001022static bool LoadUsesSimpleEnoughForHeapSRA(Value *V,
Evan Cheng5d163962009-06-02 00:56:07 +00001023 SmallPtrSet<PHINode*, 32> &LoadUsingPHIs,
1024 SmallPtrSet<PHINode*, 32> &LoadUsingPHIsPerLoad) {
Chris Lattner85d3d4f2008-12-16 21:24:51 +00001025 // We permit two users of the load: setcc comparing against the null
1026 // pointer, and a getelementptr of a specific form.
1027 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
1028 Instruction *User = cast<Instruction>(*UI);
1029
1030 // Comparison against null is ok.
1031 if (ICmpInst *ICI = dyn_cast<ICmpInst>(User)) {
1032 if (!isa<ConstantPointerNull>(ICI->getOperand(1)))
1033 return false;
1034 continue;
1035 }
1036
1037 // getelementptr is also ok, but only a simple form.
1038 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
1039 // Must index into the array and into the struct.
1040 if (GEPI->getNumOperands() < 3)
1041 return false;
1042
1043 // Otherwise the GEP is ok.
1044 continue;
1045 }
1046
1047 if (PHINode *PN = dyn_cast<PHINode>(User)) {
Evan Cheng5d163962009-06-02 00:56:07 +00001048 if (!LoadUsingPHIsPerLoad.insert(PN))
1049 // This means some phi nodes are dependent on each other.
1050 // Avoid infinite looping!
1051 return false;
1052 if (!LoadUsingPHIs.insert(PN))
1053 // If we have already analyzed this PHI, then it is safe.
Chris Lattner85d3d4f2008-12-16 21:24:51 +00001054 continue;
1055
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001056 // Make sure all uses of the PHI are simple enough to transform.
Evan Cheng5d163962009-06-02 00:56:07 +00001057 if (!LoadUsesSimpleEnoughForHeapSRA(PN,
1058 LoadUsingPHIs, LoadUsingPHIsPerLoad))
Chris Lattner85d3d4f2008-12-16 21:24:51 +00001059 return false;
1060
1061 continue;
Chris Lattner86395032006-09-30 23:32:09 +00001062 }
Chris Lattner85d3d4f2008-12-16 21:24:51 +00001063
1064 // Otherwise we don't know what this is, not ok.
1065 return false;
1066 }
1067
1068 return true;
1069}
1070
1071
1072/// AllGlobalLoadUsesSimpleEnoughForHeapSRA - If all users of values loaded from
1073/// GV are simple enough to perform HeapSRA, return true.
1074static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA(GlobalVariable *GV,
1075 MallocInst *MI) {
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001076 SmallPtrSet<PHINode*, 32> LoadUsingPHIs;
Evan Cheng5d163962009-06-02 00:56:07 +00001077 SmallPtrSet<PHINode*, 32> LoadUsingPHIsPerLoad;
Chris Lattner85d3d4f2008-12-16 21:24:51 +00001078 for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI != E;
1079 ++UI)
Evan Cheng5d163962009-06-02 00:56:07 +00001080 if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
1081 if (!LoadUsesSimpleEnoughForHeapSRA(LI, LoadUsingPHIs,
1082 LoadUsingPHIsPerLoad))
Chris Lattner85d3d4f2008-12-16 21:24:51 +00001083 return false;
Evan Cheng5d163962009-06-02 00:56:07 +00001084 LoadUsingPHIsPerLoad.clear();
1085 }
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001086
1087 // If we reach here, we know that all uses of the loads and transitive uses
1088 // (through PHI nodes) are simple enough to transform. However, we don't know
1089 // that all inputs the to the PHI nodes are in the same equivalence sets.
1090 // Check to verify that all operands of the PHIs are either PHIS that can be
1091 // transformed, loads from GV, or MI itself.
1092 for (SmallPtrSet<PHINode*, 32>::iterator I = LoadUsingPHIs.begin(),
1093 E = LoadUsingPHIs.end(); I != E; ++I) {
1094 PHINode *PN = *I;
1095 for (unsigned op = 0, e = PN->getNumIncomingValues(); op != e; ++op) {
1096 Value *InVal = PN->getIncomingValue(op);
1097
1098 // PHI of the stored value itself is ok.
1099 if (InVal == MI) continue;
1100
1101 if (PHINode *InPN = dyn_cast<PHINode>(InVal)) {
1102 // One of the PHIs in our set is (optimistically) ok.
1103 if (LoadUsingPHIs.count(InPN))
1104 continue;
1105 return false;
1106 }
1107
1108 // Load from GV is ok.
1109 if (LoadInst *LI = dyn_cast<LoadInst>(InVal))
1110 if (LI->getOperand(0) == GV)
1111 continue;
1112
1113 // UNDEF? NULL?
1114
1115 // Anything else is rejected.
1116 return false;
1117 }
1118 }
1119
Chris Lattner86395032006-09-30 23:32:09 +00001120 return true;
1121}
1122
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001123static Value *GetHeapSROAValue(Value *V, unsigned FieldNo,
1124 DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues,
1125 std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) {
1126 std::vector<Value*> &FieldVals = InsertedScalarizedValues[V];
1127
1128 if (FieldNo >= FieldVals.size())
1129 FieldVals.resize(FieldNo+1);
1130
1131 // If we already have this value, just reuse the previously scalarized
1132 // version.
1133 if (Value *FieldVal = FieldVals[FieldNo])
1134 return FieldVal;
1135
1136 // Depending on what instruction this is, we have several cases.
1137 Value *Result;
1138 if (LoadInst *LI = dyn_cast<LoadInst>(V)) {
1139 // This is a scalarized version of the load from the global. Just create
1140 // a new Load of the scalarized global.
1141 Result = new LoadInst(GetHeapSROAValue(LI->getOperand(0), FieldNo,
1142 InsertedScalarizedValues,
1143 PHIsToRewrite),
1144 LI->getName()+".f" + utostr(FieldNo), LI);
1145 } else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1146 // PN's type is pointer to struct. Make a new PHI of pointer to struct
1147 // field.
1148 const StructType *ST =
1149 cast<StructType>(cast<PointerType>(PN->getType())->getElementType());
1150
1151 Result =PHINode::Create(PointerType::getUnqual(ST->getElementType(FieldNo)),
1152 PN->getName()+".f"+utostr(FieldNo), PN);
1153 PHIsToRewrite.push_back(std::make_pair(PN, FieldNo));
1154 } else {
1155 assert(0 && "Unknown usable value");
1156 Result = 0;
1157 }
1158
1159 return FieldVals[FieldNo] = Result;
Chris Lattnera637a8b2007-09-13 18:00:31 +00001160}
1161
Chris Lattner330245e2007-09-13 17:29:05 +00001162/// RewriteHeapSROALoadUser - Given a load instruction and a value derived from
1163/// the load, rewrite the derived value to use the HeapSRoA'd load.
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001164static void RewriteHeapSROALoadUser(Instruction *LoadUser,
1165 DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues,
1166 std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) {
Chris Lattner330245e2007-09-13 17:29:05 +00001167 // If this is a comparison against null, handle it.
1168 if (ICmpInst *SCI = dyn_cast<ICmpInst>(LoadUser)) {
1169 assert(isa<ConstantPointerNull>(SCI->getOperand(1)));
1170 // If we have a setcc of the loaded pointer, we can use a setcc of any
1171 // field.
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001172 Value *NPtr = GetHeapSROAValue(SCI->getOperand(0), 0,
1173 InsertedScalarizedValues, PHIsToRewrite);
Chris Lattner330245e2007-09-13 17:29:05 +00001174
1175 Value *New = new ICmpInst(SCI->getPredicate(), NPtr,
1176 Constant::getNullValue(NPtr->getType()),
1177 SCI->getName(), SCI);
1178 SCI->replaceAllUsesWith(New);
1179 SCI->eraseFromParent();
1180 return;
1181 }
1182
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001183 // Handle 'getelementptr Ptr, Idx, i32 FieldNo ...'
Chris Lattnera637a8b2007-09-13 18:00:31 +00001184 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(LoadUser)) {
1185 assert(GEPI->getNumOperands() >= 3 && isa<ConstantInt>(GEPI->getOperand(2))
1186 && "Unexpected GEPI!");
Chris Lattner330245e2007-09-13 17:29:05 +00001187
Chris Lattnera637a8b2007-09-13 18:00:31 +00001188 // Load the pointer for this field.
1189 unsigned FieldNo = cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue();
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001190 Value *NewPtr = GetHeapSROAValue(GEPI->getOperand(0), FieldNo,
1191 InsertedScalarizedValues, PHIsToRewrite);
Chris Lattnera637a8b2007-09-13 18:00:31 +00001192
1193 // Create the new GEP idx vector.
1194 SmallVector<Value*, 8> GEPIdx;
1195 GEPIdx.push_back(GEPI->getOperand(1));
1196 GEPIdx.append(GEPI->op_begin()+3, GEPI->op_end());
1197
Gabor Greifb1dbcd82008-05-15 10:04:30 +00001198 Value *NGEPI = GetElementPtrInst::Create(NewPtr,
1199 GEPIdx.begin(), GEPIdx.end(),
Gabor Greif051a9502008-04-06 20:25:17 +00001200 GEPI->getName(), GEPI);
Chris Lattnera637a8b2007-09-13 18:00:31 +00001201 GEPI->replaceAllUsesWith(NGEPI);
1202 GEPI->eraseFromParent();
1203 return;
1204 }
Chris Lattner309f20f2007-09-13 21:31:36 +00001205
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001206 // Recursively transform the users of PHI nodes. This will lazily create the
1207 // PHIs that are needed for individual elements. Keep track of what PHIs we
1208 // see in InsertedScalarizedValues so that we don't get infinite loops (very
1209 // antisocial). If the PHI is already in InsertedScalarizedValues, it has
1210 // already been seen first by another load, so its uses have already been
1211 // processed.
1212 PHINode *PN = cast<PHINode>(LoadUser);
1213 bool Inserted;
1214 DenseMap<Value*, std::vector<Value*> >::iterator InsertPos;
1215 tie(InsertPos, Inserted) =
1216 InsertedScalarizedValues.insert(std::make_pair(PN, std::vector<Value*>()));
1217 if (!Inserted) return;
Chris Lattner309f20f2007-09-13 21:31:36 +00001218
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001219 // If this is the first time we've seen this PHI, recursively process all
1220 // users.
Chris Lattnerf49a28c2008-12-17 05:42:08 +00001221 for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end(); UI != E; ) {
1222 Instruction *User = cast<Instruction>(*UI++);
1223 RewriteHeapSROALoadUser(User, InsertedScalarizedValues, PHIsToRewrite);
1224 }
Chris Lattner330245e2007-09-13 17:29:05 +00001225}
1226
Chris Lattner86395032006-09-30 23:32:09 +00001227/// RewriteUsesOfLoadForHeapSRoA - We are performing Heap SRoA on a global. Ptr
1228/// is a value loaded from the global. Eliminate all uses of Ptr, making them
1229/// use FieldGlobals instead. All uses of loaded values satisfy
Chris Lattner85d3d4f2008-12-16 21:24:51 +00001230/// AllGlobalLoadUsesSimpleEnoughForHeapSRA.
Chris Lattner330245e2007-09-13 17:29:05 +00001231static void RewriteUsesOfLoadForHeapSRoA(LoadInst *Load,
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001232 DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues,
1233 std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) {
1234 for (Value::use_iterator UI = Load->use_begin(), E = Load->use_end();
Chris Lattnerf49a28c2008-12-17 05:42:08 +00001235 UI != E; ) {
1236 Instruction *User = cast<Instruction>(*UI++);
1237 RewriteHeapSROALoadUser(User, InsertedScalarizedValues, PHIsToRewrite);
1238 }
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001239
1240 if (Load->use_empty()) {
1241 Load->eraseFromParent();
1242 InsertedScalarizedValues.erase(Load);
1243 }
Chris Lattner86395032006-09-30 23:32:09 +00001244}
1245
1246/// PerformHeapAllocSRoA - MI is an allocation of an array of structures. Break
1247/// it up into multiple allocations of arrays of the fields.
1248static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, MallocInst *MI){
Bill Wendling0a81aac2006-11-26 10:02:32 +00001249 DOUT << "SROA HEAP ALLOC: " << *GV << " MALLOC = " << *MI;
Chris Lattner86395032006-09-30 23:32:09 +00001250 const StructType *STy = cast<StructType>(MI->getAllocatedType());
1251
1252 // There is guaranteed to be at least one use of the malloc (storing
1253 // it into GV). If there are other uses, change them to be uses of
1254 // the global to simplify later code. This also deletes the store
1255 // into GV.
1256 ReplaceUsesOfMallocWithGlobal(MI, GV);
1257
1258 // Okay, at this point, there are no users of the malloc. Insert N
1259 // new mallocs at the same place as MI, and N globals.
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001260 std::vector<Value*> FieldGlobals;
Chris Lattner86395032006-09-30 23:32:09 +00001261 std::vector<MallocInst*> FieldMallocs;
1262
1263 for (unsigned FieldNo = 0, e = STy->getNumElements(); FieldNo != e;++FieldNo){
1264 const Type *FieldTy = STy->getElementType(FieldNo);
Christopher Lamb43ad6b32007-12-17 01:12:55 +00001265 const Type *PFieldTy = PointerType::getUnqual(FieldTy);
Chris Lattner86395032006-09-30 23:32:09 +00001266
1267 GlobalVariable *NGV =
1268 new GlobalVariable(PFieldTy, false, GlobalValue::InternalLinkage,
1269 Constant::getNullValue(PFieldTy),
Lauro Ramos Venancioc7635522007-04-12 18:32:50 +00001270 GV->getName() + ".f" + utostr(FieldNo), GV,
1271 GV->isThreadLocal());
Chris Lattner86395032006-09-30 23:32:09 +00001272 FieldGlobals.push_back(NGV);
1273
1274 MallocInst *NMI = new MallocInst(FieldTy, MI->getArraySize(),
1275 MI->getName() + ".f" + utostr(FieldNo),MI);
1276 FieldMallocs.push_back(NMI);
1277 new StoreInst(NMI, NGV, MI);
1278 }
1279
1280 // The tricky aspect of this transformation is handling the case when malloc
1281 // fails. In the original code, malloc failing would set the result pointer
1282 // of malloc to null. In this case, some mallocs could succeed and others
1283 // could fail. As such, we emit code that looks like this:
1284 // F0 = malloc(field0)
1285 // F1 = malloc(field1)
1286 // F2 = malloc(field2)
1287 // if (F0 == 0 || F1 == 0 || F2 == 0) {
1288 // if (F0) { free(F0); F0 = 0; }
1289 // if (F1) { free(F1); F1 = 0; }
1290 // if (F2) { free(F2); F2 = 0; }
1291 // }
1292 Value *RunningOr = 0;
1293 for (unsigned i = 0, e = FieldMallocs.size(); i != e; ++i) {
Reid Spencere4d87aa2006-12-23 06:05:41 +00001294 Value *Cond = new ICmpInst(ICmpInst::ICMP_EQ, FieldMallocs[i],
Chris Lattner86395032006-09-30 23:32:09 +00001295 Constant::getNullValue(FieldMallocs[i]->getType()),
1296 "isnull", MI);
1297 if (!RunningOr)
1298 RunningOr = Cond; // First seteq
1299 else
Gabor Greif7cbd8a32008-05-16 19:29:10 +00001300 RunningOr = BinaryOperator::CreateOr(RunningOr, Cond, "tmp", MI);
Chris Lattner86395032006-09-30 23:32:09 +00001301 }
1302
1303 // Split the basic block at the old malloc.
1304 BasicBlock *OrigBB = MI->getParent();
1305 BasicBlock *ContBB = OrigBB->splitBasicBlock(MI, "malloc_cont");
1306
1307 // Create the block to check the first condition. Put all these blocks at the
1308 // end of the function as they are unlikely to be executed.
Gabor Greif051a9502008-04-06 20:25:17 +00001309 BasicBlock *NullPtrBlock = BasicBlock::Create("malloc_ret_null",
1310 OrigBB->getParent());
Chris Lattner86395032006-09-30 23:32:09 +00001311
1312 // Remove the uncond branch from OrigBB to ContBB, turning it into a cond
1313 // branch on RunningOr.
1314 OrigBB->getTerminator()->eraseFromParent();
Gabor Greif051a9502008-04-06 20:25:17 +00001315 BranchInst::Create(NullPtrBlock, ContBB, RunningOr, OrigBB);
Chris Lattner86395032006-09-30 23:32:09 +00001316
1317 // Within the NullPtrBlock, we need to emit a comparison and branch for each
1318 // pointer, because some may be null while others are not.
1319 for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) {
1320 Value *GVVal = new LoadInst(FieldGlobals[i], "tmp", NullPtrBlock);
Reid Spencere4d87aa2006-12-23 06:05:41 +00001321 Value *Cmp = new ICmpInst(ICmpInst::ICMP_NE, GVVal,
1322 Constant::getNullValue(GVVal->getType()),
1323 "tmp", NullPtrBlock);
Gabor Greif051a9502008-04-06 20:25:17 +00001324 BasicBlock *FreeBlock = BasicBlock::Create("free_it", OrigBB->getParent());
1325 BasicBlock *NextBlock = BasicBlock::Create("next", OrigBB->getParent());
1326 BranchInst::Create(FreeBlock, NextBlock, Cmp, NullPtrBlock);
Chris Lattner86395032006-09-30 23:32:09 +00001327
1328 // Fill in FreeBlock.
1329 new FreeInst(GVVal, FreeBlock);
1330 new StoreInst(Constant::getNullValue(GVVal->getType()), FieldGlobals[i],
1331 FreeBlock);
Gabor Greif051a9502008-04-06 20:25:17 +00001332 BranchInst::Create(NextBlock, FreeBlock);
Chris Lattner86395032006-09-30 23:32:09 +00001333
1334 NullPtrBlock = NextBlock;
1335 }
1336
Gabor Greif051a9502008-04-06 20:25:17 +00001337 BranchInst::Create(ContBB, NullPtrBlock);
Chris Lattner86395032006-09-30 23:32:09 +00001338
1339 // MI is no longer needed, remove it.
1340 MI->eraseFromParent();
1341
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001342 /// InsertedScalarizedLoads - As we process loads, if we can't immediately
1343 /// update all uses of the load, keep track of what scalarized loads are
1344 /// inserted for a given load.
1345 DenseMap<Value*, std::vector<Value*> > InsertedScalarizedValues;
1346 InsertedScalarizedValues[GV] = FieldGlobals;
1347
1348 std::vector<std::pair<PHINode*, unsigned> > PHIsToRewrite;
Chris Lattner86395032006-09-30 23:32:09 +00001349
1350 // Okay, the malloc site is completely handled. All of the uses of GV are now
1351 // loads, and all uses of those loads are simple. Rewrite them to use loads
1352 // of the per-field globals instead.
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001353 for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI != E;) {
1354 Instruction *User = cast<Instruction>(*UI++);
1355
1356 if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
1357 RewriteUsesOfLoadForHeapSRoA(LI, InsertedScalarizedValues, PHIsToRewrite);
1358 continue;
Chris Lattner39ff1e22007-01-09 23:29:37 +00001359 }
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001360
1361 // Must be a store of null.
1362 StoreInst *SI = cast<StoreInst>(User);
1363 assert(isa<ConstantPointerNull>(SI->getOperand(0)) &&
1364 "Unexpected heap-sra user!");
1365
1366 // Insert a store of null into each global.
1367 for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) {
1368 const PointerType *PT = cast<PointerType>(FieldGlobals[i]->getType());
1369 Constant *Null = Constant::getNullValue(PT->getElementType());
1370 new StoreInst(Null, FieldGlobals[i], SI);
1371 }
1372 // Erase the original store.
1373 SI->eraseFromParent();
Chris Lattner86395032006-09-30 23:32:09 +00001374 }
1375
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001376 // While we have PHIs that are interesting to rewrite, do it.
1377 while (!PHIsToRewrite.empty()) {
1378 PHINode *PN = PHIsToRewrite.back().first;
1379 unsigned FieldNo = PHIsToRewrite.back().second;
1380 PHIsToRewrite.pop_back();
1381 PHINode *FieldPN = cast<PHINode>(InsertedScalarizedValues[PN][FieldNo]);
1382 assert(FieldPN->getNumIncomingValues() == 0 &&"Already processed this phi");
1383
1384 // Add all the incoming values. This can materialize more phis.
1385 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1386 Value *InVal = PN->getIncomingValue(i);
1387 InVal = GetHeapSROAValue(InVal, FieldNo, InsertedScalarizedValues,
1388 PHIsToRewrite);
1389 FieldPN->addIncoming(InVal, PN->getIncomingBlock(i));
1390 }
1391 }
1392
1393 // Drop all inter-phi links and any loads that made it this far.
1394 for (DenseMap<Value*, std::vector<Value*> >::iterator
1395 I = InsertedScalarizedValues.begin(), E = InsertedScalarizedValues.end();
1396 I != E; ++I) {
1397 if (PHINode *PN = dyn_cast<PHINode>(I->first))
1398 PN->dropAllReferences();
1399 else if (LoadInst *LI = dyn_cast<LoadInst>(I->first))
1400 LI->dropAllReferences();
1401 }
1402
1403 // Delete all the phis and loads now that inter-references are dead.
1404 for (DenseMap<Value*, std::vector<Value*> >::iterator
1405 I = InsertedScalarizedValues.begin(), E = InsertedScalarizedValues.end();
1406 I != E; ++I) {
1407 if (PHINode *PN = dyn_cast<PHINode>(I->first))
1408 PN->eraseFromParent();
1409 else if (LoadInst *LI = dyn_cast<LoadInst>(I->first))
1410 LI->eraseFromParent();
1411 }
1412
Chris Lattner86395032006-09-30 23:32:09 +00001413 // The old global is now dead, remove it.
1414 GV->eraseFromParent();
1415
1416 ++NumHeapSRA;
Chris Lattnerbce4afe2008-12-17 05:28:49 +00001417 return cast<GlobalVariable>(FieldGlobals[0]);
Chris Lattner86395032006-09-30 23:32:09 +00001418}
1419
Chris Lattnere61d0a62008-12-15 21:02:25 +00001420/// TryToOptimizeStoreOfMallocToGlobal - This function is called when we see a
1421/// pointer global variable with a single value stored it that is a malloc or
1422/// cast of malloc.
1423static bool TryToOptimizeStoreOfMallocToGlobal(GlobalVariable *GV,
1424 MallocInst *MI,
1425 Module::global_iterator &GVI,
1426 TargetData &TD) {
1427 // If this is a malloc of an abstract type, don't touch it.
1428 if (!MI->getAllocatedType()->isSized())
1429 return false;
1430
1431 // We can't optimize this global unless all uses of it are *known* to be
1432 // of the malloc value, not of the null initializer value (consider a use
1433 // that compares the global's value against zero to see if the malloc has
1434 // been reached). To do this, we check to see if all uses of the global
1435 // would trap if the global were null: this proves that they must all
1436 // happen after the malloc.
1437 if (!AllUsesOfLoadedValueWillTrapIfNull(GV))
1438 return false;
1439
1440 // We can't optimize this if the malloc itself is used in a complex way,
1441 // for example, being stored into multiple globals. This allows the
1442 // malloc to be stored into the specified global, loaded setcc'd, and
1443 // GEP'd. These are all things we could transform to using the global
1444 // for.
1445 {
1446 SmallPtrSet<PHINode*, 8> PHIs;
1447 if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(MI, GV, PHIs))
1448 return false;
1449 }
1450
1451
1452 // If we have a global that is only initialized with a fixed size malloc,
1453 // transform the program to use global memory instead of malloc'd memory.
1454 // This eliminates dynamic allocation, avoids an indirection accessing the
1455 // data, and exposes the resultant global to further GlobalOpt.
1456 if (ConstantInt *NElements = dyn_cast<ConstantInt>(MI->getArraySize())) {
1457 // Restrict this transformation to only working on small allocations
1458 // (2048 bytes currently), as we don't want to introduce a 16M global or
1459 // something.
1460 if (NElements->getZExtValue()*
Duncan Sands777d2302009-05-09 07:06:46 +00001461 TD.getTypeAllocSize(MI->getAllocatedType()) < 2048) {
Chris Lattnere61d0a62008-12-15 21:02:25 +00001462 GVI = OptimizeGlobalAddressOfMalloc(GV, MI);
1463 return true;
1464 }
1465 }
1466
1467 // If the allocation is an array of structures, consider transforming this
1468 // into multiple malloc'd arrays, one for each field. This is basically
1469 // SRoA for malloc'd memory.
Chris Lattner101f44e2008-12-15 21:44:34 +00001470 const Type *AllocTy = MI->getAllocatedType();
1471
1472 // If this is an allocation of a fixed size array of structs, analyze as a
1473 // variable size array. malloc [100 x struct],1 -> malloc struct, 100
1474 if (!MI->isArrayAllocation())
1475 if (const ArrayType *AT = dyn_cast<ArrayType>(AllocTy))
1476 AllocTy = AT->getElementType();
1477
1478 if (const StructType *AllocSTy = dyn_cast<StructType>(AllocTy)) {
Chris Lattnere61d0a62008-12-15 21:02:25 +00001479 // This the structure has an unreasonable number of fields, leave it
1480 // alone.
Chris Lattner101f44e2008-12-15 21:44:34 +00001481 if (AllocSTy->getNumElements() <= 16 && AllocSTy->getNumElements() != 0 &&
Chris Lattner85d3d4f2008-12-16 21:24:51 +00001482 AllGlobalLoadUsesSimpleEnoughForHeapSRA(GV, MI)) {
Chris Lattner101f44e2008-12-15 21:44:34 +00001483
1484 // If this is a fixed size array, transform the Malloc to be an alloc of
1485 // structs. malloc [100 x struct],1 -> malloc struct, 100
1486 if (const ArrayType *AT = dyn_cast<ArrayType>(MI->getAllocatedType())) {
1487 MallocInst *NewMI =
1488 new MallocInst(AllocSTy,
1489 ConstantInt::get(Type::Int32Ty, AT->getNumElements()),
1490 "", MI);
1491 NewMI->takeName(MI);
1492 Value *Cast = new BitCastInst(NewMI, MI->getType(), "tmp", MI);
1493 MI->replaceAllUsesWith(Cast);
1494 MI->eraseFromParent();
1495 MI = NewMI;
1496 }
1497
Chris Lattnere61d0a62008-12-15 21:02:25 +00001498 GVI = PerformHeapAllocSRoA(GV, MI);
1499 return true;
1500 }
1501 }
1502
1503 return false;
1504}
Chris Lattner86395032006-09-30 23:32:09 +00001505
Chris Lattner9b34a612004-10-09 21:48:45 +00001506// OptimizeOnceStoredGlobal - Try to optimize globals based on the knowledge
1507// that only one value (besides its initializer) is ever stored to the global.
Chris Lattner30ba5692004-10-11 05:54:41 +00001508static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal,
Chris Lattner7f8897f2006-08-27 22:42:52 +00001509 Module::global_iterator &GVI,
1510 TargetData &TD) {
Chris Lattner344b41c2008-12-15 21:20:32 +00001511 // Ignore no-op GEPs and bitcasts.
1512 StoredOnceVal = StoredOnceVal->stripPointerCasts();
Chris Lattner9b34a612004-10-09 21:48:45 +00001513
Chris Lattner708148e2004-10-10 23:14:11 +00001514 // If we are dealing with a pointer global that is initialized to null and
1515 // only has one (non-null) value stored into it, then we can optimize any
1516 // users of the loaded value (often calls and loads) that would trap if the
1517 // value was null.
Chris Lattner9b34a612004-10-09 21:48:45 +00001518 if (isa<PointerType>(GV->getInitializer()->getType()) &&
1519 GV->getInitializer()->isNullValue()) {
Chris Lattner708148e2004-10-10 23:14:11 +00001520 if (Constant *SOVC = dyn_cast<Constant>(StoredOnceVal)) {
1521 if (GV->getInitializer()->getType() != SOVC->getType())
Reid Spencerd977d862006-12-12 23:36:14 +00001522 SOVC = ConstantExpr::getBitCast(SOVC, GV->getInitializer()->getType());
Misha Brukmanfd939082005-04-21 23:48:37 +00001523
Chris Lattner708148e2004-10-10 23:14:11 +00001524 // Optimize away any trapping uses of the loaded value.
1525 if (OptimizeAwayTrappingUsesOfLoads(GV, SOVC))
Chris Lattner8be80122004-10-10 17:07:12 +00001526 return true;
Chris Lattner30ba5692004-10-11 05:54:41 +00001527 } else if (MallocInst *MI = dyn_cast<MallocInst>(StoredOnceVal)) {
Chris Lattnere61d0a62008-12-15 21:02:25 +00001528 if (TryToOptimizeStoreOfMallocToGlobal(GV, MI, GVI, TD))
1529 return true;
Chris Lattner708148e2004-10-10 23:14:11 +00001530 }
Chris Lattner9b34a612004-10-09 21:48:45 +00001531 }
Chris Lattner30ba5692004-10-11 05:54:41 +00001532
Chris Lattner9b34a612004-10-09 21:48:45 +00001533 return false;
1534}
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001535
Chris Lattner58e44f42008-01-14 01:17:44 +00001536/// TryToShrinkGlobalToBoolean - At this point, we have learned that the only
1537/// two values ever stored into GV are its initializer and OtherVal. See if we
1538/// can shrink the global into a boolean and select between the two values
1539/// whenever it is used. This exposes the values to other scalar optimizations.
1540static bool TryToShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) {
1541 const Type *GVElType = GV->getType()->getElementType();
1542
1543 // If GVElType is already i1, it is already shrunk. If the type of the GV is
Chris Lattner6f6923f2009-03-07 23:32:02 +00001544 // an FP value, pointer or vector, don't do this optimization because a select
1545 // between them is very expensive and unlikely to lead to later
1546 // simplification. In these cases, we typically end up with "cond ? v1 : v2"
1547 // where v1 and v2 both require constant pool loads, a big loss.
Chris Lattner58e44f42008-01-14 01:17:44 +00001548 if (GVElType == Type::Int1Ty || GVElType->isFloatingPoint() ||
Chris Lattner6f6923f2009-03-07 23:32:02 +00001549 isa<PointerType>(GVElType) || isa<VectorType>(GVElType))
Chris Lattner58e44f42008-01-14 01:17:44 +00001550 return false;
1551
1552 // Walk the use list of the global seeing if all the uses are load or store.
1553 // If there is anything else, bail out.
1554 for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I)
Devang Patel771281f2009-03-06 01:39:36 +00001555 if (!isa<LoadInst>(I) && !isa<StoreInst>(I))
Chris Lattner58e44f42008-01-14 01:17:44 +00001556 return false;
1557
1558 DOUT << " *** SHRINKING TO BOOL: " << *GV;
1559
Chris Lattner96a86b22004-12-12 05:53:50 +00001560 // Create the new global, initializing it to false.
Reid Spencer4fe16d62007-01-11 18:21:29 +00001561 GlobalVariable *NewGV = new GlobalVariable(Type::Int1Ty, false,
Nick Lewycky0e670df2009-05-03 03:49:08 +00001562 GlobalValue::InternalLinkage, ConstantInt::getFalse(),
1563 GV->getName()+".b",
Lauro Ramos Venancioc7635522007-04-12 18:32:50 +00001564 (Module *)NULL,
1565 GV->isThreadLocal());
Chris Lattner96a86b22004-12-12 05:53:50 +00001566 GV->getParent()->getGlobalList().insert(GV, NewGV);
1567
1568 Constant *InitVal = GV->getInitializer();
Reid Spencer4fe16d62007-01-11 18:21:29 +00001569 assert(InitVal->getType() != Type::Int1Ty && "No reason to shrink to bool!");
Chris Lattner96a86b22004-12-12 05:53:50 +00001570
1571 // If initialized to zero and storing one into the global, we can use a cast
1572 // instead of a select to synthesize the desired value.
1573 bool IsOneZero = false;
1574 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal))
Reid Spencercae57542007-03-02 00:28:52 +00001575 IsOneZero = InitVal->isNullValue() && CI->isOne();
Chris Lattner96a86b22004-12-12 05:53:50 +00001576
1577 while (!GV->use_empty()) {
Devang Patel771281f2009-03-06 01:39:36 +00001578 Instruction *UI = cast<Instruction>(GV->use_back());
1579 if (StoreInst *SI = dyn_cast<StoreInst>(UI)) {
Chris Lattner96a86b22004-12-12 05:53:50 +00001580 // Change the store into a boolean store.
1581 bool StoringOther = SI->getOperand(0) == OtherVal;
1582 // Only do this if we weren't storing a loaded value.
Chris Lattner38c25562004-12-12 19:34:41 +00001583 Value *StoreVal;
Chris Lattner96a86b22004-12-12 05:53:50 +00001584 if (StoringOther || SI->getOperand(0) == InitVal)
Reid Spencer579dca12007-01-12 04:24:46 +00001585 StoreVal = ConstantInt::get(Type::Int1Ty, StoringOther);
Chris Lattner38c25562004-12-12 19:34:41 +00001586 else {
1587 // Otherwise, we are storing a previously loaded copy. To do this,
1588 // change the copy from copying the original value to just copying the
1589 // bool.
1590 Instruction *StoredVal = cast<Instruction>(SI->getOperand(0));
1591
1592 // If we're already replaced the input, StoredVal will be a cast or
1593 // select instruction. If not, it will be a load of the original
1594 // global.
1595 if (LoadInst *LI = dyn_cast<LoadInst>(StoredVal)) {
1596 assert(LI->getOperand(0) == GV && "Not a copy!");
1597 // Insert a new load, to preserve the saved value.
1598 StoreVal = new LoadInst(NewGV, LI->getName()+".b", LI);
1599 } else {
1600 assert((isa<CastInst>(StoredVal) || isa<SelectInst>(StoredVal)) &&
1601 "This is not a form that we understand!");
1602 StoreVal = StoredVal->getOperand(0);
1603 assert(isa<LoadInst>(StoreVal) && "Not a load of NewGV!");
1604 }
1605 }
1606 new StoreInst(StoreVal, NewGV, SI);
Devang Patel771281f2009-03-06 01:39:36 +00001607 } else {
Chris Lattner96a86b22004-12-12 05:53:50 +00001608 // Change the load into a load of bool then a select.
Devang Patel771281f2009-03-06 01:39:36 +00001609 LoadInst *LI = cast<LoadInst>(UI);
Chris Lattner046800a2007-02-11 01:08:35 +00001610 LoadInst *NLI = new LoadInst(NewGV, LI->getName()+".b", LI);
Chris Lattner96a86b22004-12-12 05:53:50 +00001611 Value *NSI;
1612 if (IsOneZero)
Chris Lattner046800a2007-02-11 01:08:35 +00001613 NSI = new ZExtInst(NLI, LI->getType(), "", LI);
Misha Brukmanfd939082005-04-21 23:48:37 +00001614 else
Gabor Greif051a9502008-04-06 20:25:17 +00001615 NSI = SelectInst::Create(NLI, OtherVal, InitVal, "", LI);
Chris Lattner046800a2007-02-11 01:08:35 +00001616 NSI->takeName(LI);
Chris Lattner96a86b22004-12-12 05:53:50 +00001617 LI->replaceAllUsesWith(NSI);
Devang Patel771281f2009-03-06 01:39:36 +00001618 }
1619 UI->eraseFromParent();
Chris Lattner96a86b22004-12-12 05:53:50 +00001620 }
1621
1622 GV->eraseFromParent();
Chris Lattner58e44f42008-01-14 01:17:44 +00001623 return true;
Chris Lattner96a86b22004-12-12 05:53:50 +00001624}
1625
1626
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001627/// ProcessInternalGlobal - Analyze the specified global variable and optimize
1628/// it if possible. If we make a change, return true.
Chris Lattner30ba5692004-10-11 05:54:41 +00001629bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
Chris Lattnere4d5c442005-03-15 04:54:21 +00001630 Module::global_iterator &GVI) {
Chris Lattner5a6bb6a2008-12-16 07:34:30 +00001631 SmallPtrSet<PHINode*, 16> PHIUsers;
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001632 GlobalStatus GS;
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001633 GV->removeDeadConstantUsers();
1634
1635 if (GV->use_empty()) {
Bill Wendling0a81aac2006-11-26 10:02:32 +00001636 DOUT << "GLOBAL DEAD: " << *GV;
Chris Lattner7a7ed022004-10-16 18:09:00 +00001637 GV->eraseFromParent();
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001638 ++NumDeleted;
1639 return true;
1640 }
1641
1642 if (!AnalyzeGlobal(GV, GS, PHIUsers)) {
Chris Lattnercff16732006-09-30 19:40:30 +00001643#if 0
Bill Wendlinge8156192006-12-07 01:30:32 +00001644 cerr << "Global: " << *GV;
1645 cerr << " isLoaded = " << GS.isLoaded << "\n";
1646 cerr << " StoredType = ";
Chris Lattnercff16732006-09-30 19:40:30 +00001647 switch (GS.StoredType) {
Bill Wendlinge8156192006-12-07 01:30:32 +00001648 case GlobalStatus::NotStored: cerr << "NEVER STORED\n"; break;
1649 case GlobalStatus::isInitializerStored: cerr << "INIT STORED\n"; break;
1650 case GlobalStatus::isStoredOnce: cerr << "STORED ONCE\n"; break;
1651 case GlobalStatus::isStored: cerr << "stored\n"; break;
Chris Lattnercff16732006-09-30 19:40:30 +00001652 }
1653 if (GS.StoredType == GlobalStatus::isStoredOnce && GS.StoredOnceValue)
Bill Wendlinge8156192006-12-07 01:30:32 +00001654 cerr << " StoredOnceValue = " << *GS.StoredOnceValue << "\n";
Chris Lattnercff16732006-09-30 19:40:30 +00001655 if (GS.AccessingFunction && !GS.HasMultipleAccessingFunctions)
Bill Wendlinge8156192006-12-07 01:30:32 +00001656 cerr << " AccessingFunction = " << GS.AccessingFunction->getName()
Chris Lattnercff16732006-09-30 19:40:30 +00001657 << "\n";
Bill Wendlinge8156192006-12-07 01:30:32 +00001658 cerr << " HasMultipleAccessingFunctions = "
Chris Lattnercff16732006-09-30 19:40:30 +00001659 << GS.HasMultipleAccessingFunctions << "\n";
Bill Wendlinge8156192006-12-07 01:30:32 +00001660 cerr << " HasNonInstructionUser = " << GS.HasNonInstructionUser<<"\n";
Bill Wendlinge8156192006-12-07 01:30:32 +00001661 cerr << "\n";
Chris Lattnercff16732006-09-30 19:40:30 +00001662#endif
1663
Alkis Evlogimenosf64ea9d2005-02-10 18:36:30 +00001664 // If this is a first class global and has only one accessing function
1665 // and this function is main (which we know is not recursive we can make
1666 // this global a local variable) we replace the global with a local alloca
1667 // in this function.
1668 //
Dan Gohman399101a2008-05-23 00:17:26 +00001669 // NOTE: It doesn't make sense to promote non single-value types since we
Alkis Evlogimenosf64ea9d2005-02-10 18:36:30 +00001670 // are just replacing static memory to stack memory.
1671 if (!GS.HasMultipleAccessingFunctions &&
Chris Lattner553ca522005-06-15 21:11:48 +00001672 GS.AccessingFunction && !GS.HasNonInstructionUser &&
Dan Gohman399101a2008-05-23 00:17:26 +00001673 GV->getType()->getElementType()->isSingleValueType() &&
Alkis Evlogimenosf64ea9d2005-02-10 18:36:30 +00001674 GS.AccessingFunction->getName() == "main" &&
1675 GS.AccessingFunction->hasExternalLinkage()) {
Bill Wendling0a81aac2006-11-26 10:02:32 +00001676 DOUT << "LOCALIZING GLOBAL: " << *GV;
Alkis Evlogimenosf64ea9d2005-02-10 18:36:30 +00001677 Instruction* FirstI = GS.AccessingFunction->getEntryBlock().begin();
1678 const Type* ElemTy = GV->getType()->getElementType();
Nate Begeman14b05292005-11-05 09:21:28 +00001679 // FIXME: Pass Global's alignment when globals have alignment
Alkis Evlogimenosf64ea9d2005-02-10 18:36:30 +00001680 AllocaInst* Alloca = new AllocaInst(ElemTy, NULL, GV->getName(), FirstI);
1681 if (!isa<UndefValue>(GV->getInitializer()))
1682 new StoreInst(GV->getInitializer(), Alloca, FirstI);
Misha Brukmanfd939082005-04-21 23:48:37 +00001683
Alkis Evlogimenosf64ea9d2005-02-10 18:36:30 +00001684 GV->replaceAllUsesWith(Alloca);
1685 GV->eraseFromParent();
1686 ++NumLocalized;
1687 return true;
1688 }
Chris Lattnercff16732006-09-30 19:40:30 +00001689
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001690 // If the global is never loaded (but may be stored to), it is dead.
1691 // Delete it now.
1692 if (!GS.isLoaded) {
Bill Wendling0a81aac2006-11-26 10:02:32 +00001693 DOUT << "GLOBAL NEVER LOADED: " << *GV;
Chris Lattner930f4752004-10-09 03:32:52 +00001694
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001695 // Delete any stores we can find to the global. We may not be able to
1696 // make it completely dead though.
Chris Lattner031955d2004-10-10 16:43:46 +00001697 bool Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer());
Chris Lattner930f4752004-10-09 03:32:52 +00001698
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001699 // If the global is dead now, delete it.
1700 if (GV->use_empty()) {
Chris Lattner7a7ed022004-10-16 18:09:00 +00001701 GV->eraseFromParent();
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001702 ++NumDeleted;
Chris Lattner930f4752004-10-09 03:32:52 +00001703 Changed = true;
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001704 }
Chris Lattner930f4752004-10-09 03:32:52 +00001705 return Changed;
Misha Brukmanfd939082005-04-21 23:48:37 +00001706
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001707 } else if (GS.StoredType <= GlobalStatus::isInitializerStored) {
Bill Wendling0a81aac2006-11-26 10:02:32 +00001708 DOUT << "MARKING CONSTANT: " << *GV;
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001709 GV->setConstant(true);
Misha Brukmanfd939082005-04-21 23:48:37 +00001710
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001711 // Clean up any obviously simplifiable users now.
1712 CleanupConstantGlobalUsers(GV, GV->getInitializer());
Misha Brukmanfd939082005-04-21 23:48:37 +00001713
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001714 // If the global is dead now, just nuke it.
1715 if (GV->use_empty()) {
Bill Wendling0a81aac2006-11-26 10:02:32 +00001716 DOUT << " *** Marking constant allowed us to simplify "
1717 << "all users and delete global!\n";
Chris Lattner7a7ed022004-10-16 18:09:00 +00001718 GV->eraseFromParent();
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001719 ++NumDeleted;
1720 }
Misha Brukmanfd939082005-04-21 23:48:37 +00001721
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001722 ++NumMarked;
1723 return true;
Dan Gohman399101a2008-05-23 00:17:26 +00001724 } else if (!GV->getInitializer()->getType()->isSingleValueType()) {
Chris Lattner998182b2008-04-26 07:40:11 +00001725 if (GlobalVariable *FirstNewGV = SRAGlobal(GV,
1726 getAnalysis<TargetData>())) {
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001727 GVI = FirstNewGV; // Don't skip the newly produced globals!
1728 return true;
1729 }
Chris Lattner9b34a612004-10-09 21:48:45 +00001730 } else if (GS.StoredType == GlobalStatus::isStoredOnce) {
Chris Lattner96a86b22004-12-12 05:53:50 +00001731 // If the initial value for the global was an undef value, and if only
1732 // one other value was stored into it, we can just change the
Duncan Sandsb5024402009-01-13 13:48:44 +00001733 // initializer to be the stored value, then delete all stores to the
Chris Lattner96a86b22004-12-12 05:53:50 +00001734 // global. This allows us to mark it constant.
1735 if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue))
1736 if (isa<UndefValue>(GV->getInitializer())) {
1737 // Change the initial value here.
1738 GV->setInitializer(SOVConstant);
Misha Brukmanfd939082005-04-21 23:48:37 +00001739
Chris Lattner96a86b22004-12-12 05:53:50 +00001740 // Clean up any obviously simplifiable users now.
1741 CleanupConstantGlobalUsers(GV, GV->getInitializer());
Misha Brukmanfd939082005-04-21 23:48:37 +00001742
Chris Lattner96a86b22004-12-12 05:53:50 +00001743 if (GV->use_empty()) {
Bill Wendling0a81aac2006-11-26 10:02:32 +00001744 DOUT << " *** Substituting initializer allowed us to "
1745 << "simplify all users and delete global!\n";
Chris Lattner96a86b22004-12-12 05:53:50 +00001746 GV->eraseFromParent();
1747 ++NumDeleted;
1748 } else {
1749 GVI = GV;
1750 }
1751 ++NumSubstitute;
1752 return true;
Chris Lattner7a7ed022004-10-16 18:09:00 +00001753 }
Chris Lattner7a7ed022004-10-16 18:09:00 +00001754
Chris Lattner9b34a612004-10-09 21:48:45 +00001755 // Try to optimize globals based on the knowledge that only one value
1756 // (besides its initializer) is ever stored to the global.
Chris Lattner30ba5692004-10-11 05:54:41 +00001757 if (OptimizeOnceStoredGlobal(GV, GS.StoredOnceValue, GVI,
1758 getAnalysis<TargetData>()))
Chris Lattner9b34a612004-10-09 21:48:45 +00001759 return true;
Chris Lattner96a86b22004-12-12 05:53:50 +00001760
1761 // Otherwise, if the global was not a boolean, we can shrink it to be a
1762 // boolean.
1763 if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue))
Chris Lattner58e44f42008-01-14 01:17:44 +00001764 if (TryToShrinkGlobalToBoolean(GV, SOVConstant)) {
Chris Lattner96a86b22004-12-12 05:53:50 +00001765 ++NumShrunkToBool;
1766 return true;
1767 }
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001768 }
1769 }
1770 return false;
1771}
1772
Chris Lattnerfb217ad2005-05-08 22:18:06 +00001773/// OnlyCalledDirectly - Return true if the specified function is only called
1774/// directly. In other words, its address is never taken.
1775static bool OnlyCalledDirectly(Function *F) {
1776 for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); UI != E;++UI){
1777 Instruction *User = dyn_cast<Instruction>(*UI);
1778 if (!User) return false;
1779 if (!isa<CallInst>(User) && !isa<InvokeInst>(User)) return false;
1780
1781 // See if the function address is passed as an argument.
Gabor Greif5e463212008-05-29 01:59:18 +00001782 for (User::op_iterator i = User->op_begin() + 1, e = User->op_end();
Bill Wendlingf9e67ac2008-08-12 23:15:44 +00001783 i != e; ++i)
Gabor Greif5e463212008-05-29 01:59:18 +00001784 if (*i == F) return false;
Chris Lattnerfb217ad2005-05-08 22:18:06 +00001785 }
1786 return true;
1787}
1788
1789/// ChangeCalleesToFastCall - Walk all of the direct calls of the specified
1790/// function, changing them to FastCC.
1791static void ChangeCalleesToFastCall(Function *F) {
1792 for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); UI != E;++UI){
Duncan Sands548448a2008-02-18 17:32:13 +00001793 CallSite User(cast<Instruction>(*UI));
1794 User.setCallingConv(CallingConv::Fast);
Chris Lattnerfb217ad2005-05-08 22:18:06 +00001795 }
1796}
Chris Lattnera4be1dc2004-10-08 20:59:28 +00001797
Devang Patel05988662008-09-25 21:00:45 +00001798static AttrListPtr StripNest(const AttrListPtr &Attrs) {
Chris Lattner58d74912008-03-12 17:45:29 +00001799 for (unsigned i = 0, e = Attrs.getNumSlots(); i != e; ++i) {
Devang Patel05988662008-09-25 21:00:45 +00001800 if ((Attrs.getSlot(i).Attrs & Attribute::Nest) == 0)
Duncan Sands548448a2008-02-18 17:32:13 +00001801 continue;
1802
Duncan Sands548448a2008-02-18 17:32:13 +00001803 // There can be only one.
Devang Patel05988662008-09-25 21:00:45 +00001804 return Attrs.removeAttr(Attrs.getSlot(i).Index, Attribute::Nest);
Duncan Sands3d5378f2008-02-16 20:56:04 +00001805 }
1806
1807 return Attrs;
1808}
1809
1810static void RemoveNestAttribute(Function *F) {
Devang Patel05988662008-09-25 21:00:45 +00001811 F->setAttributes(StripNest(F->getAttributes()));
Duncan Sands3d5378f2008-02-16 20:56:04 +00001812 for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); UI != E;++UI){
Duncan Sands548448a2008-02-18 17:32:13 +00001813 CallSite User(cast<Instruction>(*UI));
Devang Patel05988662008-09-25 21:00:45 +00001814 User.setAttributes(StripNest(User.getAttributes()));
Duncan Sands3d5378f2008-02-16 20:56:04 +00001815 }
1816}
1817
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001818bool GlobalOpt::OptimizeFunctions(Module &M) {
1819 bool Changed = false;
1820 // Optimize functions.
1821 for (Module::iterator FI = M.begin(), E = M.end(); FI != E; ) {
1822 Function *F = FI++;
Duncan Sandsfc5940d2009-03-06 10:21:56 +00001823 // Functions without names cannot be referenced outside this module.
1824 if (!F->hasName() && !F->isDeclaration())
1825 F->setLinkage(GlobalValue::InternalLinkage);
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001826 F->removeDeadConstantUsers();
Rafael Espindolabb46f522009-01-15 20:18:42 +00001827 if (F->use_empty() && (F->hasLocalLinkage() ||
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001828 F->hasLinkOnceLinkage())) {
1829 M.getFunctionList().erase(F);
1830 Changed = true;
1831 ++NumFnDeleted;
Rafael Espindolabb46f522009-01-15 20:18:42 +00001832 } else if (F->hasLocalLinkage()) {
Duncan Sands3d5378f2008-02-16 20:56:04 +00001833 if (F->getCallingConv() == CallingConv::C && !F->isVarArg() &&
1834 OnlyCalledDirectly(F)) {
1835 // If this function has C calling conventions, is not a varargs
1836 // function, and is only called directly, promote it to use the Fast
1837 // calling convention.
1838 F->setCallingConv(CallingConv::Fast);
1839 ChangeCalleesToFastCall(F);
1840 ++NumFastCallFns;
1841 Changed = true;
1842 }
1843
Devang Patel05988662008-09-25 21:00:45 +00001844 if (F->getAttributes().hasAttrSomewhere(Attribute::Nest) &&
Duncan Sands3d5378f2008-02-16 20:56:04 +00001845 OnlyCalledDirectly(F)) {
1846 // The function is not used by a trampoline intrinsic, so it is safe
1847 // to remove the 'nest' attribute.
1848 RemoveNestAttribute(F);
1849 ++NumNestRemoved;
1850 Changed = true;
1851 }
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001852 }
1853 }
1854 return Changed;
1855}
1856
1857bool GlobalOpt::OptimizeGlobalVars(Module &M) {
1858 bool Changed = false;
1859 for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
1860 GVI != E; ) {
1861 GlobalVariable *GV = GVI++;
Duncan Sandsfc5940d2009-03-06 10:21:56 +00001862 // Global variables without names cannot be referenced outside this module.
1863 if (!GV->hasName() && !GV->isDeclaration())
1864 GV->setLinkage(GlobalValue::InternalLinkage);
Rafael Espindolabb46f522009-01-15 20:18:42 +00001865 if (!GV->isConstant() && GV->hasLocalLinkage() &&
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001866 GV->hasInitializer())
1867 Changed |= ProcessInternalGlobal(GV, GVI);
1868 }
1869 return Changed;
1870}
1871
1872/// FindGlobalCtors - Find the llvm.globalctors list, verifying that all
1873/// initializers have an init priority of 65535.
1874GlobalVariable *GlobalOpt::FindGlobalCtors(Module &M) {
Alkis Evlogimenose9c6d362005-10-25 11:18:06 +00001875 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
1876 I != E; ++I)
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001877 if (I->getName() == "llvm.global_ctors") {
1878 // Found it, verify it's an array of { int, void()* }.
1879 const ArrayType *ATy =dyn_cast<ArrayType>(I->getType()->getElementType());
1880 if (!ATy) return 0;
1881 const StructType *STy = dyn_cast<StructType>(ATy->getElementType());
1882 if (!STy || STy->getNumElements() != 2 ||
Reid Spencerc5b206b2006-12-31 05:48:39 +00001883 STy->getElementType(0) != Type::Int32Ty) return 0;
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001884 const PointerType *PFTy = dyn_cast<PointerType>(STy->getElementType(1));
1885 if (!PFTy) return 0;
1886 const FunctionType *FTy = dyn_cast<FunctionType>(PFTy->getElementType());
1887 if (!FTy || FTy->getReturnType() != Type::VoidTy || FTy->isVarArg() ||
1888 FTy->getNumParams() != 0)
1889 return 0;
1890
1891 // Verify that the initializer is simple enough for us to handle.
1892 if (!I->hasInitializer()) return 0;
1893 ConstantArray *CA = dyn_cast<ConstantArray>(I->getInitializer());
1894 if (!CA) return 0;
Gabor Greif5e463212008-05-29 01:59:18 +00001895 for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i)
1896 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(*i)) {
Chris Lattner7d8e58f2005-09-26 02:19:27 +00001897 if (isa<ConstantPointerNull>(CS->getOperand(1)))
1898 continue;
1899
1900 // Must have a function or null ptr.
1901 if (!isa<Function>(CS->getOperand(1)))
1902 return 0;
1903
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001904 // Init priority must be standard.
1905 ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
Reid Spencerb83eb642006-10-20 07:07:24 +00001906 if (!CI || CI->getZExtValue() != 65535)
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001907 return 0;
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001908 } else {
1909 return 0;
1910 }
1911
1912 return I;
1913 }
1914 return 0;
1915}
1916
Chris Lattnerdb973e62005-09-26 02:31:18 +00001917/// ParseGlobalCtors - Given a llvm.global_ctors list that we can understand,
1918/// return a list of the functions and null terminator as a vector.
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001919static std::vector<Function*> ParseGlobalCtors(GlobalVariable *GV) {
1920 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1921 std::vector<Function*> Result;
1922 Result.reserve(CA->getNumOperands());
Gabor Greif5e463212008-05-29 01:59:18 +00001923 for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i) {
1924 ConstantStruct *CS = cast<ConstantStruct>(*i);
Chris Lattnerb1ab4582005-09-26 01:43:45 +00001925 Result.push_back(dyn_cast<Function>(CS->getOperand(1)));
1926 }
1927 return Result;
1928}
1929
Chris Lattnerdb973e62005-09-26 02:31:18 +00001930/// InstallGlobalCtors - Given a specified llvm.global_ctors list, install the
1931/// specified array, returning the new global to use.
1932static GlobalVariable *InstallGlobalCtors(GlobalVariable *GCL,
1933 const std::vector<Function*> &Ctors) {
1934 // If we made a change, reassemble the initializer list.
1935 std::vector<Constant*> CSVals;
Reid Spencerc5b206b2006-12-31 05:48:39 +00001936 CSVals.push_back(ConstantInt::get(Type::Int32Ty, 65535));
Chris Lattnerdb973e62005-09-26 02:31:18 +00001937 CSVals.push_back(0);
1938
1939 // Create the new init list.
1940 std::vector<Constant*> CAList;
1941 for (unsigned i = 0, e = Ctors.size(); i != e; ++i) {
Chris Lattner79c11012005-09-26 04:44:35 +00001942 if (Ctors[i]) {
Chris Lattnerdb973e62005-09-26 02:31:18 +00001943 CSVals[1] = Ctors[i];
Chris Lattner79c11012005-09-26 04:44:35 +00001944 } else {
Chris Lattnerdb973e62005-09-26 02:31:18 +00001945 const Type *FTy = FunctionType::get(Type::VoidTy,
1946 std::vector<const Type*>(), false);
Christopher Lamb43ad6b32007-12-17 01:12:55 +00001947 const PointerType *PFTy = PointerType::getUnqual(FTy);
Chris Lattnerdb973e62005-09-26 02:31:18 +00001948 CSVals[1] = Constant::getNullValue(PFTy);
Reid Spencerc5b206b2006-12-31 05:48:39 +00001949 CSVals[0] = ConstantInt::get(Type::Int32Ty, 2147483647);
Chris Lattnerdb973e62005-09-26 02:31:18 +00001950 }
1951 CAList.push_back(ConstantStruct::get(CSVals));
1952 }
1953
1954 // Create the array initializer.
1955 const Type *StructTy =
1956 cast<ArrayType>(GCL->getType()->getElementType())->getElementType();
1957 Constant *CA = ConstantArray::get(ArrayType::get(StructTy, CAList.size()),
1958 CAList);
1959
1960 // If we didn't change the number of elements, don't create a new GV.
1961 if (CA->getType() == GCL->getInitializer()->getType()) {
1962 GCL->setInitializer(CA);
1963 return GCL;
1964 }
1965
1966 // Create the new global and insert it next to the existing list.
1967 GlobalVariable *NGV = new GlobalVariable(CA->getType(), GCL->isConstant(),
Lauro Ramos Venancioc7635522007-04-12 18:32:50 +00001968 GCL->getLinkage(), CA, "",
1969 (Module *)NULL,
1970 GCL->isThreadLocal());
Chris Lattnerdb973e62005-09-26 02:31:18 +00001971 GCL->getParent()->getGlobalList().insert(GCL, NGV);
Chris Lattner046800a2007-02-11 01:08:35 +00001972 NGV->takeName(GCL);
Chris Lattnerdb973e62005-09-26 02:31:18 +00001973
1974 // Nuke the old list, replacing any uses with the new one.
1975 if (!GCL->use_empty()) {
1976 Constant *V = NGV;
1977 if (V->getType() != GCL->getType())
Reid Spencerd977d862006-12-12 23:36:14 +00001978 V = ConstantExpr::getBitCast(V, GCL->getType());
Chris Lattnerdb973e62005-09-26 02:31:18 +00001979 GCL->replaceAllUsesWith(V);
1980 }
1981 GCL->eraseFromParent();
1982
1983 if (Ctors.size())
1984 return NGV;
1985 else
1986 return 0;
1987}
Chris Lattner79c11012005-09-26 04:44:35 +00001988
1989
Chris Lattner5a6bb6a2008-12-16 07:34:30 +00001990static Constant *getVal(DenseMap<Value*, Constant*> &ComputedValues,
Chris Lattner79c11012005-09-26 04:44:35 +00001991 Value *V) {
1992 if (Constant *CV = dyn_cast<Constant>(V)) return CV;
1993 Constant *R = ComputedValues[V];
1994 assert(R && "Reference to an uncomputed value!");
1995 return R;
1996}
1997
1998/// isSimpleEnoughPointerToCommit - Return true if this constant is simple
1999/// enough for us to understand. In particular, if it is a cast of something,
2000/// we punt. We basically just support direct accesses to globals and GEP's of
2001/// globals. This should be kept up to date with CommitValueTo.
2002static bool isSimpleEnoughPointerToCommit(Constant *C) {
Chris Lattner231308c2005-09-27 04:50:03 +00002003 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
Rafael Espindolabb46f522009-01-15 20:18:42 +00002004 if (!GV->hasExternalLinkage() && !GV->hasLocalLinkage())
Anton Korobeynikovb74ed072006-09-14 18:23:27 +00002005 return false; // do not allow weak/linkonce/dllimport/dllexport linkage.
Reid Spencer5cbf9852007-01-30 20:08:39 +00002006 return !GV->isDeclaration(); // reject external globals.
Chris Lattner231308c2005-09-27 04:50:03 +00002007 }
Chris Lattner798b4d52005-09-26 06:52:44 +00002008 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
2009 // Handle a constantexpr gep.
2010 if (CE->getOpcode() == Instruction::GetElementPtr &&
2011 isa<GlobalVariable>(CE->getOperand(0))) {
2012 GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
Rafael Espindolabb46f522009-01-15 20:18:42 +00002013 if (!GV->hasExternalLinkage() && !GV->hasLocalLinkage())
Anton Korobeynikovb74ed072006-09-14 18:23:27 +00002014 return false; // do not allow weak/linkonce/dllimport/dllexport linkage.
Chris Lattner798b4d52005-09-26 06:52:44 +00002015 return GV->hasInitializer() &&
2016 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE);
2017 }
Chris Lattner79c11012005-09-26 04:44:35 +00002018 return false;
2019}
2020
Chris Lattner798b4d52005-09-26 06:52:44 +00002021/// EvaluateStoreInto - Evaluate a piece of a constantexpr store into a global
2022/// initializer. This returns 'Init' modified to reflect 'Val' stored into it.
2023/// At this point, the GEP operands of Addr [0, OpNo) have been stepped into.
2024static Constant *EvaluateStoreInto(Constant *Init, Constant *Val,
2025 ConstantExpr *Addr, unsigned OpNo) {
2026 // Base case of the recursion.
2027 if (OpNo == Addr->getNumOperands()) {
2028 assert(Val->getType() == Init->getType() && "Type mismatch!");
2029 return Val;
2030 }
2031
2032 if (const StructType *STy = dyn_cast<StructType>(Init->getType())) {
2033 std::vector<Constant*> Elts;
2034
2035 // Break up the constant into its elements.
2036 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(Init)) {
Gabor Greif5e463212008-05-29 01:59:18 +00002037 for (User::op_iterator i = CS->op_begin(), e = CS->op_end(); i != e; ++i)
2038 Elts.push_back(cast<Constant>(*i));
Chris Lattner798b4d52005-09-26 06:52:44 +00002039 } else if (isa<ConstantAggregateZero>(Init)) {
2040 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
2041 Elts.push_back(Constant::getNullValue(STy->getElementType(i)));
2042 } else if (isa<UndefValue>(Init)) {
2043 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
2044 Elts.push_back(UndefValue::get(STy->getElementType(i)));
2045 } else {
2046 assert(0 && "This code is out of sync with "
2047 " ConstantFoldLoadThroughGEPConstantExpr");
2048 }
2049
2050 // Replace the element that we are supposed to.
Reid Spencerb83eb642006-10-20 07:07:24 +00002051 ConstantInt *CU = cast<ConstantInt>(Addr->getOperand(OpNo));
2052 unsigned Idx = CU->getZExtValue();
2053 assert(Idx < STy->getNumElements() && "Struct index out of range!");
Chris Lattner798b4d52005-09-26 06:52:44 +00002054 Elts[Idx] = EvaluateStoreInto(Elts[Idx], Val, Addr, OpNo+1);
2055
2056 // Return the modified struct.
Chris Lattnerf0a9aab2007-06-04 22:23:42 +00002057 return ConstantStruct::get(&Elts[0], Elts.size(), STy->isPacked());
Chris Lattner798b4d52005-09-26 06:52:44 +00002058 } else {
2059 ConstantInt *CI = cast<ConstantInt>(Addr->getOperand(OpNo));
2060 const ArrayType *ATy = cast<ArrayType>(Init->getType());
2061
2062 // Break up the array into elements.
2063 std::vector<Constant*> Elts;
2064 if (ConstantArray *CA = dyn_cast<ConstantArray>(Init)) {
Gabor Greif5e463212008-05-29 01:59:18 +00002065 for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i)
2066 Elts.push_back(cast<Constant>(*i));
Chris Lattner798b4d52005-09-26 06:52:44 +00002067 } else if (isa<ConstantAggregateZero>(Init)) {
2068 Constant *Elt = Constant::getNullValue(ATy->getElementType());
2069 Elts.assign(ATy->getNumElements(), Elt);
2070 } else if (isa<UndefValue>(Init)) {
2071 Constant *Elt = UndefValue::get(ATy->getElementType());
2072 Elts.assign(ATy->getNumElements(), Elt);
2073 } else {
2074 assert(0 && "This code is out of sync with "
2075 " ConstantFoldLoadThroughGEPConstantExpr");
2076 }
2077
Reid Spencerb83eb642006-10-20 07:07:24 +00002078 assert(CI->getZExtValue() < ATy->getNumElements());
2079 Elts[CI->getZExtValue()] =
2080 EvaluateStoreInto(Elts[CI->getZExtValue()], Val, Addr, OpNo+1);
Chris Lattner798b4d52005-09-26 06:52:44 +00002081 return ConstantArray::get(ATy, Elts);
2082 }
2083}
2084
Chris Lattner79c11012005-09-26 04:44:35 +00002085/// CommitValueTo - We have decided that Addr (which satisfies the predicate
2086/// isSimpleEnoughPointerToCommit) should get Val as its value. Make it happen.
2087static void CommitValueTo(Constant *Val, Constant *Addr) {
Chris Lattner798b4d52005-09-26 06:52:44 +00002088 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
2089 assert(GV->hasInitializer());
2090 GV->setInitializer(Val);
2091 return;
2092 }
2093
2094 ConstantExpr *CE = cast<ConstantExpr>(Addr);
2095 GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
2096
2097 Constant *Init = GV->getInitializer();
2098 Init = EvaluateStoreInto(Init, Val, CE, 2);
2099 GV->setInitializer(Init);
Chris Lattner79c11012005-09-26 04:44:35 +00002100}
2101
Chris Lattner562a0552005-09-26 05:16:34 +00002102/// ComputeLoadResult - Return the value that would be computed by a load from
2103/// P after the stores reflected by 'memory' have been performed. If we can't
2104/// decide, return null.
Chris Lattner04de1cf2005-09-26 05:15:37 +00002105static Constant *ComputeLoadResult(Constant *P,
Chris Lattner5a6bb6a2008-12-16 07:34:30 +00002106 const DenseMap<Constant*, Constant*> &Memory) {
Chris Lattner04de1cf2005-09-26 05:15:37 +00002107 // If this memory location has been recently stored, use the stored value: it
2108 // is the most up-to-date.
Chris Lattner5a6bb6a2008-12-16 07:34:30 +00002109 DenseMap<Constant*, Constant*>::const_iterator I = Memory.find(P);
Chris Lattner04de1cf2005-09-26 05:15:37 +00002110 if (I != Memory.end()) return I->second;
2111
2112 // Access it.
2113 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(P)) {
2114 if (GV->hasInitializer())
2115 return GV->getInitializer();
2116 return 0;
Chris Lattner04de1cf2005-09-26 05:15:37 +00002117 }
Chris Lattner798b4d52005-09-26 06:52:44 +00002118
2119 // Handle a constantexpr getelementptr.
2120 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(P))
2121 if (CE->getOpcode() == Instruction::GetElementPtr &&
2122 isa<GlobalVariable>(CE->getOperand(0))) {
2123 GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
2124 if (GV->hasInitializer())
2125 return ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE);
2126 }
2127
2128 return 0; // don't know how to evaluate.
Chris Lattner04de1cf2005-09-26 05:15:37 +00002129}
2130
Chris Lattner8a7cc6e2005-09-27 04:27:01 +00002131/// EvaluateFunction - Evaluate a call to function F, returning true if
2132/// successful, false if we can't evaluate it. ActualArgs contains the formal
2133/// arguments for the function.
Chris Lattnercd271422005-09-27 04:45:34 +00002134static bool EvaluateFunction(Function *F, Constant *&RetVal,
Chris Lattner8a7cc6e2005-09-27 04:27:01 +00002135 const std::vector<Constant*> &ActualArgs,
2136 std::vector<Function*> &CallStack,
Chris Lattner5a6bb6a2008-12-16 07:34:30 +00002137 DenseMap<Constant*, Constant*> &MutatedMemory,
Chris Lattner8a7cc6e2005-09-27 04:27:01 +00002138 std::vector<GlobalVariable*> &AllocaTmps) {
Chris Lattnercd271422005-09-27 04:45:34 +00002139 // Check to see if this function is already executing (recursion). If so,
2140 // bail out. TODO: we might want to accept limited recursion.
2141 if (std::find(CallStack.begin(), CallStack.end(), F) != CallStack.end())
2142 return false;
2143
2144 CallStack.push_back(F);
2145
Chris Lattner79c11012005-09-26 04:44:35 +00002146 /// Values - As we compute SSA register values, we store their contents here.
Chris Lattner5a6bb6a2008-12-16 07:34:30 +00002147 DenseMap<Value*, Constant*> Values;
Chris Lattnercd271422005-09-27 04:45:34 +00002148
2149 // Initialize arguments to the incoming values specified.
2150 unsigned ArgNo = 0;
2151 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); AI != E;
2152 ++AI, ++ArgNo)
2153 Values[AI] = ActualArgs[ArgNo];
Chris Lattner8a7cc6e2005-09-27 04:27:01 +00002154
Chris Lattnercdf98be2005-09-26 04:57:38 +00002155 /// ExecutedBlocks - We only handle non-looping, non-recursive code. As such,
2156 /// we can only evaluate any one basic block at most once. This set keeps
2157 /// track of what we have executed so we can detect recursive cases etc.
Chris Lattner5a6bb6a2008-12-16 07:34:30 +00002158 SmallPtrSet<BasicBlock*, 32> ExecutedBlocks;
Chris Lattnera22fdb02005-09-26 17:07:09 +00002159
Chris Lattner79c11012005-09-26 04:44:35 +00002160 // CurInst - The current instruction we're evaluating.
2161 BasicBlock::iterator CurInst = F->begin()->begin();
2162
2163 // This is the main evaluation loop.
2164 while (1) {
2165 Constant *InstResult = 0;
2166
2167 if (StoreInst *SI = dyn_cast<StoreInst>(CurInst)) {
Chris Lattnercd271422005-09-27 04:45:34 +00002168 if (SI->isVolatile()) return false; // no volatile accesses.
Chris Lattner79c11012005-09-26 04:44:35 +00002169 Constant *Ptr = getVal(Values, SI->getOperand(1));
2170 if (!isSimpleEnoughPointerToCommit(Ptr))
2171 // If this is too complex for us to commit, reject it.
Chris Lattnercd271422005-09-27 04:45:34 +00002172 return false;
Chris Lattner79c11012005-09-26 04:44:35 +00002173 Constant *Val = getVal(Values, SI->getOperand(0));
2174 MutatedMemory[Ptr] = Val;
2175 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(CurInst)) {
2176 InstResult = ConstantExpr::get(BO->getOpcode(),
2177 getVal(Values, BO->getOperand(0)),
2178 getVal(Values, BO->getOperand(1)));
Reid Spencere4d87aa2006-12-23 06:05:41 +00002179 } else if (CmpInst *CI = dyn_cast<CmpInst>(CurInst)) {
2180 InstResult = ConstantExpr::getCompare(CI->getPredicate(),
2181 getVal(Values, CI->getOperand(0)),
2182 getVal(Values, CI->getOperand(1)));
Chris Lattner79c11012005-09-26 04:44:35 +00002183 } else if (CastInst *CI = dyn_cast<CastInst>(CurInst)) {
Chris Lattner9a989f02006-11-30 17:26:08 +00002184 InstResult = ConstantExpr::getCast(CI->getOpcode(),
2185 getVal(Values, CI->getOperand(0)),
Chris Lattner79c11012005-09-26 04:44:35 +00002186 CI->getType());
2187 } else if (SelectInst *SI = dyn_cast<SelectInst>(CurInst)) {
2188 InstResult = ConstantExpr::getSelect(getVal(Values, SI->getOperand(0)),
2189 getVal(Values, SI->getOperand(1)),
2190 getVal(Values, SI->getOperand(2)));
Chris Lattner04de1cf2005-09-26 05:15:37 +00002191 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(CurInst)) {
2192 Constant *P = getVal(Values, GEP->getOperand(0));
Chris Lattner55eb1c42007-01-31 04:40:53 +00002193 SmallVector<Constant*, 8> GEPOps;
Gabor Greif5e463212008-05-29 01:59:18 +00002194 for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end();
2195 i != e; ++i)
2196 GEPOps.push_back(getVal(Values, *i));
Chris Lattner55eb1c42007-01-31 04:40:53 +00002197 InstResult = ConstantExpr::getGetElementPtr(P, &GEPOps[0], GEPOps.size());
Chris Lattner04de1cf2005-09-26 05:15:37 +00002198 } else if (LoadInst *LI = dyn_cast<LoadInst>(CurInst)) {
Chris Lattnercd271422005-09-27 04:45:34 +00002199 if (LI->isVolatile()) return false; // no volatile accesses.
Chris Lattner04de1cf2005-09-26 05:15:37 +00002200 InstResult = ComputeLoadResult(getVal(Values, LI->getOperand(0)),
2201 MutatedMemory);
Chris Lattnercd271422005-09-27 04:45:34 +00002202 if (InstResult == 0) return false; // Could not evaluate load.
Chris Lattnera22fdb02005-09-26 17:07:09 +00002203 } else if (AllocaInst *AI = dyn_cast<AllocaInst>(CurInst)) {
Chris Lattnercd271422005-09-27 04:45:34 +00002204 if (AI->isArrayAllocation()) return false; // Cannot handle array allocs.
Chris Lattnera22fdb02005-09-26 17:07:09 +00002205 const Type *Ty = AI->getType()->getElementType();
2206 AllocaTmps.push_back(new GlobalVariable(Ty, false,
2207 GlobalValue::InternalLinkage,
2208 UndefValue::get(Ty),
2209 AI->getName()));
Chris Lattnercd271422005-09-27 04:45:34 +00002210 InstResult = AllocaTmps.back();
2211 } else if (CallInst *CI = dyn_cast<CallInst>(CurInst)) {
Devang Patel412a4462009-03-09 23:04:12 +00002212
2213 // Debug info can safely be ignored here.
2214 if (isa<DbgInfoIntrinsic>(CI)) {
2215 ++CurInst;
2216 continue;
2217 }
2218
Chris Lattner7cd580f2006-07-07 21:37:01 +00002219 // Cannot handle inline asm.
2220 if (isa<InlineAsm>(CI->getOperand(0))) return false;
2221
Chris Lattnercd271422005-09-27 04:45:34 +00002222 // Resolve function pointers.
2223 Function *Callee = dyn_cast<Function>(getVal(Values, CI->getOperand(0)));
2224 if (!Callee) return false; // Cannot resolve.
Chris Lattnera9ec8ab2005-09-27 05:02:43 +00002225
Chris Lattnercd271422005-09-27 04:45:34 +00002226 std::vector<Constant*> Formals;
Gabor Greif5e463212008-05-29 01:59:18 +00002227 for (User::op_iterator i = CI->op_begin() + 1, e = CI->op_end();
2228 i != e; ++i)
2229 Formals.push_back(getVal(Values, *i));
Chris Lattnercd271422005-09-27 04:45:34 +00002230
Reid Spencer5cbf9852007-01-30 20:08:39 +00002231 if (Callee->isDeclaration()) {
Chris Lattnera9ec8ab2005-09-27 05:02:43 +00002232 // If this is a function we can constant fold, do it.
Chris Lattner6c1f5652007-01-30 23:14:52 +00002233 if (Constant *C = ConstantFoldCall(Callee, &Formals[0],
2234 Formals.size())) {
Chris Lattnera9ec8ab2005-09-27 05:02:43 +00002235 InstResult = C;
2236 } else {
2237 return false;
2238 }
2239 } else {
2240 if (Callee->getFunctionType()->isVarArg())
2241 return false;
2242
2243 Constant *RetVal;
Chris Lattnera9ec8ab2005-09-27 05:02:43 +00002244 // Execute the call, if successful, use the return value.
2245 if (!EvaluateFunction(Callee, RetVal, Formals, CallStack,
2246 MutatedMemory, AllocaTmps))
2247 return false;
2248 InstResult = RetVal;
2249 }
Reid Spencer3ed469c2006-11-02 20:25:50 +00002250 } else if (isa<TerminatorInst>(CurInst)) {
Chris Lattnercdf98be2005-09-26 04:57:38 +00002251 BasicBlock *NewBB = 0;
2252 if (BranchInst *BI = dyn_cast<BranchInst>(CurInst)) {
2253 if (BI->isUnconditional()) {
2254 NewBB = BI->getSuccessor(0);
2255 } else {
Zhou Sheng6b6b6ef2007-01-11 12:24:14 +00002256 ConstantInt *Cond =
2257 dyn_cast<ConstantInt>(getVal(Values, BI->getCondition()));
Chris Lattner97d1fad2007-01-12 18:30:11 +00002258 if (!Cond) return false; // Cannot determine.
Zhou Sheng6b6b6ef2007-01-11 12:24:14 +00002259
Reid Spencer579dca12007-01-12 04:24:46 +00002260 NewBB = BI->getSuccessor(!Cond->getZExtValue());
Chris Lattnercdf98be2005-09-26 04:57:38 +00002261 }
2262 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(CurInst)) {
2263 ConstantInt *Val =
2264 dyn_cast<ConstantInt>(getVal(Values, SI->getCondition()));
Chris Lattnercd271422005-09-27 04:45:34 +00002265 if (!Val) return false; // Cannot determine.
Chris Lattnercdf98be2005-09-26 04:57:38 +00002266 NewBB = SI->getSuccessor(SI->findCaseValue(Val));
2267 } else if (ReturnInst *RI = dyn_cast<ReturnInst>(CurInst)) {
Chris Lattnercd271422005-09-27 04:45:34 +00002268 if (RI->getNumOperands())
2269 RetVal = getVal(Values, RI->getOperand(0));
2270
2271 CallStack.pop_back(); // return from fn.
Chris Lattner8a7cc6e2005-09-27 04:27:01 +00002272 return true; // We succeeded at evaluating this ctor!
Chris Lattnercdf98be2005-09-26 04:57:38 +00002273 } else {
Chris Lattnercd271422005-09-27 04:45:34 +00002274 // invoke, unwind, unreachable.
2275 return false; // Cannot handle this terminator.
Chris Lattnercdf98be2005-09-26 04:57:38 +00002276 }
2277
2278 // Okay, we succeeded in evaluating this control flow. See if we have
Chris Lattnercd271422005-09-27 04:45:34 +00002279 // executed the new block before. If so, we have a looping function,
2280 // which we cannot evaluate in reasonable time.
Chris Lattner5a6bb6a2008-12-16 07:34:30 +00002281 if (!ExecutedBlocks.insert(NewBB))
Chris Lattnercd271422005-09-27 04:45:34 +00002282 return false; // looped!
Chris Lattnercdf98be2005-09-26 04:57:38 +00002283
2284 // Okay, we have never been in this block before. Check to see if there
2285 // are any PHI nodes. If so, evaluate them with information about where
2286 // we came from.
2287 BasicBlock *OldBB = CurInst->getParent();
2288 CurInst = NewBB->begin();
2289 PHINode *PN;
2290 for (; (PN = dyn_cast<PHINode>(CurInst)); ++CurInst)
2291 Values[PN] = getVal(Values, PN->getIncomingValueForBlock(OldBB));
2292
2293 // Do NOT increment CurInst. We know that the terminator had no value.
2294 continue;
Chris Lattner79c11012005-09-26 04:44:35 +00002295 } else {
Chris Lattner79c11012005-09-26 04:44:35 +00002296 // Did not know how to evaluate this!
Chris Lattnercd271422005-09-27 04:45:34 +00002297 return false;
Chris Lattner79c11012005-09-26 04:44:35 +00002298 }
2299
2300 if (!CurInst->use_empty())
2301 Values[CurInst] = InstResult;
2302
2303 // Advance program counter.
2304 ++CurInst;
2305 }
Chris Lattner8a7cc6e2005-09-27 04:27:01 +00002306}
2307
2308/// EvaluateStaticConstructor - Evaluate static constructors in the function, if
2309/// we can. Return true if we can, false otherwise.
2310static bool EvaluateStaticConstructor(Function *F) {
2311 /// MutatedMemory - For each store we execute, we update this map. Loads
2312 /// check this to get the most up-to-date value. If evaluation is successful,
2313 /// this state is committed to the process.
Chris Lattner5a6bb6a2008-12-16 07:34:30 +00002314 DenseMap<Constant*, Constant*> MutatedMemory;
Chris Lattner8a7cc6e2005-09-27 04:27:01 +00002315
2316 /// AllocaTmps - To 'execute' an alloca, we create a temporary global variable
2317 /// to represent its body. This vector is needed so we can delete the
2318 /// temporary globals when we are done.
2319 std::vector<GlobalVariable*> AllocaTmps;
2320
2321 /// CallStack - This is used to detect recursion. In pathological situations
2322 /// we could hit exponential behavior, but at least there is nothing
2323 /// unbounded.
2324 std::vector<Function*> CallStack;
2325
2326 // Call the function.
Chris Lattnercd271422005-09-27 04:45:34 +00002327 Constant *RetValDummy;
2328 bool EvalSuccess = EvaluateFunction(F, RetValDummy, std::vector<Constant*>(),
2329 CallStack, MutatedMemory, AllocaTmps);
Chris Lattner8a7cc6e2005-09-27 04:27:01 +00002330 if (EvalSuccess) {
Chris Lattnera22fdb02005-09-26 17:07:09 +00002331 // We succeeded at evaluation: commit the result.
Bill Wendling0a81aac2006-11-26 10:02:32 +00002332 DOUT << "FULLY EVALUATED GLOBAL CTOR FUNCTION '"
2333 << F->getName() << "' to " << MutatedMemory.size()
2334 << " stores.\n";
Chris Lattner5a6bb6a2008-12-16 07:34:30 +00002335 for (DenseMap<Constant*, Constant*>::iterator I = MutatedMemory.begin(),
Chris Lattnera22fdb02005-09-26 17:07:09 +00002336 E = MutatedMemory.end(); I != E; ++I)
2337 CommitValueTo(I->second, I->first);
2338 }
Chris Lattner79c11012005-09-26 04:44:35 +00002339
Chris Lattnera22fdb02005-09-26 17:07:09 +00002340 // At this point, we are done interpreting. If we created any 'alloca'
2341 // temporaries, release them now.
2342 while (!AllocaTmps.empty()) {
2343 GlobalVariable *Tmp = AllocaTmps.back();
2344 AllocaTmps.pop_back();
Chris Lattner8a7cc6e2005-09-27 04:27:01 +00002345
Chris Lattnera22fdb02005-09-26 17:07:09 +00002346 // If there are still users of the alloca, the program is doing something
2347 // silly, e.g. storing the address of the alloca somewhere and using it
2348 // later. Since this is undefined, we'll just make it be null.
2349 if (!Tmp->use_empty())
2350 Tmp->replaceAllUsesWith(Constant::getNullValue(Tmp->getType()));
2351 delete Tmp;
2352 }
Chris Lattneraae4a1c2005-09-26 07:34:35 +00002353
Chris Lattner8a7cc6e2005-09-27 04:27:01 +00002354 return EvalSuccess;
Chris Lattner79c11012005-09-26 04:44:35 +00002355}
2356
Chris Lattnerdb973e62005-09-26 02:31:18 +00002357
Chris Lattner8a7cc6e2005-09-27 04:27:01 +00002358
Chris Lattnerb1ab4582005-09-26 01:43:45 +00002359/// OptimizeGlobalCtorsList - Simplify and evaluation global ctors if possible.
2360/// Return true if anything changed.
2361bool GlobalOpt::OptimizeGlobalCtorsList(GlobalVariable *&GCL) {
2362 std::vector<Function*> Ctors = ParseGlobalCtors(GCL);
2363 bool MadeChange = false;
2364 if (Ctors.empty()) return false;
2365
2366 // Loop over global ctors, optimizing them when we can.
2367 for (unsigned i = 0; i != Ctors.size(); ++i) {
2368 Function *F = Ctors[i];
2369 // Found a null terminator in the middle of the list, prune off the rest of
2370 // the list.
Chris Lattner7d8e58f2005-09-26 02:19:27 +00002371 if (F == 0) {
2372 if (i != Ctors.size()-1) {
2373 Ctors.resize(i+1);
2374 MadeChange = true;
2375 }
Chris Lattnerb1ab4582005-09-26 01:43:45 +00002376 break;
2377 }
2378
Chris Lattner79c11012005-09-26 04:44:35 +00002379 // We cannot simplify external ctor functions.
2380 if (F->empty()) continue;
2381
2382 // If we can evaluate the ctor at compile time, do.
2383 if (EvaluateStaticConstructor(F)) {
2384 Ctors.erase(Ctors.begin()+i);
2385 MadeChange = true;
2386 --i;
2387 ++NumCtorsEvaluated;
2388 continue;
2389 }
Chris Lattnerb1ab4582005-09-26 01:43:45 +00002390 }
2391
2392 if (!MadeChange) return false;
2393
Chris Lattnerdb973e62005-09-26 02:31:18 +00002394 GCL = InstallGlobalCtors(GCL, Ctors);
Chris Lattnerb1ab4582005-09-26 01:43:45 +00002395 return true;
2396}
2397
Duncan Sandsfc5940d2009-03-06 10:21:56 +00002398bool GlobalOpt::OptimizeGlobalAliases(Module &M) {
Anton Korobeynikove4c6b612008-09-09 19:04:59 +00002399 bool Changed = false;
2400
Duncan Sands177d84e2009-01-07 20:01:06 +00002401 for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
Duncan Sands4782b302009-02-15 09:56:08 +00002402 I != E;) {
2403 Module::alias_iterator J = I++;
Duncan Sandsfc5940d2009-03-06 10:21:56 +00002404 // Aliases without names cannot be referenced outside this module.
2405 if (!J->hasName() && !J->isDeclaration())
2406 J->setLinkage(GlobalValue::InternalLinkage);
Duncan Sands4782b302009-02-15 09:56:08 +00002407 // If the aliasee may change at link time, nothing can be done - bail out.
2408 if (J->mayBeOverridden())
Anton Korobeynikove4c6b612008-09-09 19:04:59 +00002409 continue;
2410
Duncan Sands4782b302009-02-15 09:56:08 +00002411 Constant *Aliasee = J->getAliasee();
2412 GlobalValue *Target = cast<GlobalValue>(Aliasee->stripPointerCasts());
Duncan Sands95c5d0f2009-02-18 17:55:38 +00002413 Target->removeDeadConstantUsers();
Duncan Sands4782b302009-02-15 09:56:08 +00002414 bool hasOneUse = Target->hasOneUse() && Aliasee->hasOneUse();
2415
2416 // Make all users of the alias use the aliasee instead.
2417 if (!J->use_empty()) {
2418 J->replaceAllUsesWith(Aliasee);
2419 ++NumAliasesResolved;
2420 Changed = true;
2421 }
2422
2423 // If the aliasee has internal linkage, give it the name and linkage
2424 // of the alias, and delete the alias. This turns:
2425 // define internal ... @f(...)
2426 // @a = alias ... @f
2427 // into:
2428 // define ... @a(...)
Duncan Sands7ae5b9e2009-02-17 17:50:04 +00002429 if (!Target->hasLocalLinkage())
Duncan Sands4782b302009-02-15 09:56:08 +00002430 continue;
2431
2432 // The transform is only useful if the alias does not have internal linkage.
Duncan Sands7ae5b9e2009-02-17 17:50:04 +00002433 if (J->hasLocalLinkage())
Duncan Sands4782b302009-02-15 09:56:08 +00002434 continue;
2435
Duncan Sandsa37d1192009-02-15 11:54:49 +00002436 // Do not perform the transform if multiple aliases potentially target the
2437 // aliasee. This check also ensures that it is safe to replace the section
2438 // and other attributes of the aliasee with those of the alias.
Duncan Sands4782b302009-02-15 09:56:08 +00002439 if (!hasOneUse)
2440 continue;
2441
Duncan Sandsa37d1192009-02-15 11:54:49 +00002442 // Give the aliasee the name, linkage and other attributes of the alias.
Duncan Sands4782b302009-02-15 09:56:08 +00002443 Target->takeName(J);
2444 Target->setLinkage(J->getLinkage());
Duncan Sandsa37d1192009-02-15 11:54:49 +00002445 Target->GlobalValue::copyAttributesFrom(J);
Duncan Sands4782b302009-02-15 09:56:08 +00002446
2447 // Delete the alias.
2448 M.getAliasList().erase(J);
2449 ++NumAliasesRemoved;
2450 Changed = true;
Anton Korobeynikove4c6b612008-09-09 19:04:59 +00002451 }
2452
2453 return Changed;
2454}
Chris Lattnerb1ab4582005-09-26 01:43:45 +00002455
Chris Lattner7a90b682004-10-07 04:16:33 +00002456bool GlobalOpt::runOnModule(Module &M) {
Chris Lattner079236d2004-02-25 21:34:36 +00002457 bool Changed = false;
Chris Lattnerb1ab4582005-09-26 01:43:45 +00002458
2459 // Try to find the llvm.globalctors list.
2460 GlobalVariable *GlobalCtors = FindGlobalCtors(M);
Chris Lattner7a90b682004-10-07 04:16:33 +00002461
Chris Lattner7a90b682004-10-07 04:16:33 +00002462 bool LocalChange = true;
2463 while (LocalChange) {
2464 LocalChange = false;
Chris Lattnerb1ab4582005-09-26 01:43:45 +00002465
2466 // Delete functions that are trivially dead, ccc -> fastcc
2467 LocalChange |= OptimizeFunctions(M);
2468
2469 // Optimize global_ctors list.
2470 if (GlobalCtors)
2471 LocalChange |= OptimizeGlobalCtorsList(GlobalCtors);
2472
2473 // Optimize non-address-taken globals.
2474 LocalChange |= OptimizeGlobalVars(M);
Anton Korobeynikove4c6b612008-09-09 19:04:59 +00002475
2476 // Resolve aliases, when possible.
Duncan Sandsfc5940d2009-03-06 10:21:56 +00002477 LocalChange |= OptimizeGlobalAliases(M);
Anton Korobeynikove4c6b612008-09-09 19:04:59 +00002478 Changed |= LocalChange;
Chris Lattner7a90b682004-10-07 04:16:33 +00002479 }
Chris Lattnerb1ab4582005-09-26 01:43:45 +00002480
2481 // TODO: Move all global ctors functions to the end of the module for code
2482 // layout.
2483
Chris Lattner079236d2004-02-25 21:34:36 +00002484 return Changed;
2485}