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Eugene Zelenkof27d1612017-10-19 21:21:30 +00001//===- ArgumentPromotion.cpp - Promote by-reference arguments -------------===//
Misha Brukmanb1c93172005-04-21 23:48:37 +00002//
Chris Lattner483ae012004-03-07 21:29:54 +00003// The LLVM Compiler Infrastructure
4//
Chris Lattnerf3ebc3f2007-12-29 20:36:04 +00005// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
Misha Brukmanb1c93172005-04-21 23:48:37 +00007//
Chris Lattner483ae012004-03-07 21:29:54 +00008//===----------------------------------------------------------------------===//
9//
10// This pass promotes "by reference" arguments to be "by value" arguments. In
11// practice, this means looking for internal functions that have pointer
Gordon Henriksen78c63ac2007-10-26 03:03:51 +000012// arguments. If it can prove, through the use of alias analysis, that an
13// argument is *only* loaded, then it can pass the value into the function
Chris Lattner483ae012004-03-07 21:29:54 +000014// instead of the address of the value. This can cause recursive simplification
Chris Lattner254f8f82004-05-23 21:21:17 +000015// of code and lead to the elimination of allocas (especially in C++ template
16// code like the STL).
Chris Lattner483ae012004-03-07 21:29:54 +000017//
Chris Lattnerfe6f2e32004-03-08 01:04:36 +000018// This pass also handles aggregate arguments that are passed into a function,
19// scalarizing them if the elements of the aggregate are only loaded. Note that
Matthijs Kooijmanfd307042008-07-29 10:00:13 +000020// by default it refuses to scalarize aggregates which would require passing in
21// more than three operands to the function, because passing thousands of
Duncan Sands1ea0d2e2008-09-07 09:54:09 +000022// operands for a large array or structure is unprofitable! This limit can be
Matthijs Kooijmanfd307042008-07-29 10:00:13 +000023// configured or disabled, however.
Chris Lattnerfe6f2e32004-03-08 01:04:36 +000024//
Chris Lattner483ae012004-03-07 21:29:54 +000025// Note that this transformation could also be done for arguments that are only
Gordon Henriksen78c63ac2007-10-26 03:03:51 +000026// stored to (returning the value instead), but does not currently. This case
27// would be best handled when and if LLVM begins supporting multiple return
28// values from functions.
Chris Lattner483ae012004-03-07 21:29:54 +000029//
30//===----------------------------------------------------------------------===//
31
Chandler Carruthaddcda42017-02-09 23:46:27 +000032#include "llvm/Transforms/IPO/ArgumentPromotion.h"
Reid Spencer7c16caa2004-09-01 22:55:40 +000033#include "llvm/ADT/DepthFirstIterator.h"
Eugene Zelenkof27d1612017-10-19 21:21:30 +000034#include "llvm/ADT/None.h"
Chandler Carruthaddcda42017-02-09 23:46:27 +000035#include "llvm/ADT/Optional.h"
Eugene Zelenkof27d1612017-10-19 21:21:30 +000036#include "llvm/ADT/STLExtras.h"
37#include "llvm/ADT/SmallPtrSet.h"
38#include "llvm/ADT/SmallVector.h"
Reid Spencer7c16caa2004-09-01 22:55:40 +000039#include "llvm/ADT/Statistic.h"
Chris Lattner06fa1762009-08-24 03:52:50 +000040#include "llvm/ADT/StringExtras.h"
Eugene Zelenkof27d1612017-10-19 21:21:30 +000041#include "llvm/ADT/Twine.h"
Chandler Carruthed0881b2012-12-03 16:50:05 +000042#include "llvm/Analysis/AliasAnalysis.h"
Daniel Jasperaec2fa32016-12-19 08:22:17 +000043#include "llvm/Analysis/AssumptionCache.h"
Chandler Carruth7b560d42015-09-09 17:55:00 +000044#include "llvm/Analysis/BasicAliasAnalysis.h"
Eugene Zelenkof27d1612017-10-19 21:21:30 +000045#include "llvm/Analysis/CGSCCPassManager.h"
Chandler Carruthed0881b2012-12-03 16:50:05 +000046#include "llvm/Analysis/CallGraph.h"
Chandler Carruth839a98e2013-01-07 15:26:48 +000047#include "llvm/Analysis/CallGraphSCCPass.h"
Chandler Carruthaddcda42017-02-09 23:46:27 +000048#include "llvm/Analysis/LazyCallGraph.h"
Artur Pilipenko31bcca42016-02-24 12:49:04 +000049#include "llvm/Analysis/Loads.h"
Eugene Zelenkof27d1612017-10-19 21:21:30 +000050#include "llvm/Analysis/MemoryLocation.h"
Chandler Carruth7b560d42015-09-09 17:55:00 +000051#include "llvm/Analysis/TargetLibraryInfo.h"
Tom Stellard3d36e5c2019-01-16 05:15:31 +000052#include "llvm/Analysis/TargetTransformInfo.h"
Eugene Zelenkof27d1612017-10-19 21:21:30 +000053#include "llvm/IR/Argument.h"
54#include "llvm/IR/Attributes.h"
55#include "llvm/IR/BasicBlock.h"
Chandler Carruth1305dc32014-03-04 11:45:46 +000056#include "llvm/IR/CFG.h"
Chandler Carruth219b89b2014-03-04 11:01:28 +000057#include "llvm/IR/CallSite.h"
Chandler Carruth9fb823b2013-01-02 11:36:10 +000058#include "llvm/IR/Constants.h"
Hal Finkel2e42c342014-07-10 05:27:53 +000059#include "llvm/IR/DataLayout.h"
Chandler Carruth9fb823b2013-01-02 11:36:10 +000060#include "llvm/IR/DerivedTypes.h"
Eugene Zelenkof27d1612017-10-19 21:21:30 +000061#include "llvm/IR/Function.h"
62#include "llvm/IR/InstrTypes.h"
63#include "llvm/IR/Instruction.h"
Chandler Carruth9fb823b2013-01-02 11:36:10 +000064#include "llvm/IR/Instructions.h"
Eugene Zelenkof27d1612017-10-19 21:21:30 +000065#include "llvm/IR/Metadata.h"
Chandler Carruth9fb823b2013-01-02 11:36:10 +000066#include "llvm/IR/Module.h"
Eugene Zelenkof27d1612017-10-19 21:21:30 +000067#include "llvm/IR/PassManager.h"
68#include "llvm/IR/Type.h"
69#include "llvm/IR/Use.h"
70#include "llvm/IR/User.h"
71#include "llvm/IR/Value.h"
72#include "llvm/Pass.h"
73#include "llvm/Support/Casting.h"
Chandler Carruthed0881b2012-12-03 16:50:05 +000074#include "llvm/Support/Debug.h"
75#include "llvm/Support/raw_ostream.h"
Chandler Carruthae9ce3d2017-01-29 08:03:19 +000076#include "llvm/Transforms/IPO.h"
Eugene Zelenkof27d1612017-10-19 21:21:30 +000077#include <algorithm>
78#include <cassert>
79#include <cstdint>
80#include <functional>
81#include <iterator>
82#include <map>
Chris Lattner483ae012004-03-07 21:29:54 +000083#include <set>
Eugene Zelenkof27d1612017-10-19 21:21:30 +000084#include <string>
85#include <utility>
86#include <vector>
87
Chris Lattner483ae012004-03-07 21:29:54 +000088using namespace llvm;
89
Chandler Carruth964daaa2014-04-22 02:55:47 +000090#define DEBUG_TYPE "argpromotion"
91
Chandler Carruthae9ce3d2017-01-29 08:03:19 +000092STATISTIC(NumArgumentsPromoted, "Number of pointer arguments promoted");
Chris Lattner1631bcb2006-12-19 22:09:18 +000093STATISTIC(NumAggregatesPromoted, "Number of aggregate arguments promoted");
Chandler Carruthae9ce3d2017-01-29 08:03:19 +000094STATISTIC(NumByValArgsPromoted, "Number of byval arguments promoted");
95STATISTIC(NumArgumentsDead, "Number of dead pointer args eliminated");
Chris Lattner483ae012004-03-07 21:29:54 +000096
Sean Silvae2133e72016-07-02 18:59:51 +000097/// A vector used to hold the indices of a single GEP instruction
Eugene Zelenkof27d1612017-10-19 21:21:30 +000098using IndicesVector = std::vector<uint64_t>;
Sean Silvae2133e72016-07-02 18:59:51 +000099
Chris Lattner254f8f82004-05-23 21:21:17 +0000100/// DoPromotion - This method actually performs the promotion of the specified
Chris Lattner37b6c4f2004-09-18 00:34:13 +0000101/// arguments, and returns the new function. At this point, we know that it's
102/// safe to do so.
Chandler Carruthaddcda42017-02-09 23:46:27 +0000103static Function *
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000104doPromotion(Function *F, SmallPtrSetImpl<Argument *> &ArgsToPromote,
Chandler Carruthaddcda42017-02-09 23:46:27 +0000105 SmallPtrSetImpl<Argument *> &ByValArgsToTransform,
106 Optional<function_ref<void(CallSite OldCS, CallSite NewCS)>>
107 ReplaceCallSite) {
Chris Lattner483ae012004-03-07 21:29:54 +0000108 // Start by computing a new prototype for the function, which is the same as
109 // the old function, but has modified arguments.
Chris Lattner229907c2011-07-18 04:54:35 +0000110 FunctionType *FTy = F->getFunctionType();
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000111 std::vector<Type *> Params;
Chris Lattner483ae012004-03-07 21:29:54 +0000112
Eugene Zelenkof27d1612017-10-19 21:21:30 +0000113 using ScalarizeTable = std::set<std::pair<Type *, IndicesVector>>;
Chris Lattner1c676f72004-06-21 00:07:58 +0000114
Chris Lattnerfe6f2e32004-03-08 01:04:36 +0000115 // ScalarizedElements - If we are promoting a pointer that has elements
116 // accessed out of it, keep track of which elements are accessed so that we
117 // can add one argument for each.
118 //
119 // Arguments that are directly loaded will have a zero element value here, to
120 // handle cases where there are both a direct load and GEP accesses.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000121 std::map<Argument *, ScalarizeTable> ScalarizedElements;
Chris Lattnerfe6f2e32004-03-08 01:04:36 +0000122
Chris Lattner254f8f82004-05-23 21:21:17 +0000123 // OriginalLoads - Keep track of a representative load instruction from the
124 // original function so that we can tell the alias analysis implementation
125 // what the new GEP/Load instructions we are inserting look like.
Manman Renbc376582013-11-15 20:41:15 +0000126 // We need to keep the original loads for each argument and the elements
127 // of the argument that are accessed.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000128 std::map<std::pair<Argument *, IndicesVector>, LoadInst *> OriginalLoads;
Chris Lattner254f8f82004-05-23 21:21:17 +0000129
Bill Wendling3d7b0b82012-12-19 07:18:57 +0000130 // Attribute - Keep track of the parameter attributes for the arguments
Duncan Sandsad0ea2d2007-11-27 13:23:08 +0000131 // that we are *not* promoting. For the ones that we do promote, the parameter
132 // attributes are lost
Reid Kleckner7f720332017-04-13 00:58:09 +0000133 SmallVector<AttributeSet, 8> ArgAttrVec;
134 AttributeList PAL = F->getAttributes();
Duncan Sands1ea0d2e2008-09-07 09:54:09 +0000135
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000136 // First, determine the new argument list
Reid Kleckner6652a522017-04-28 18:37:16 +0000137 unsigned ArgNo = 0;
Duncan Sandsad0ea2d2007-11-27 13:23:08 +0000138 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E;
Reid Kleckner6652a522017-04-28 18:37:16 +0000139 ++I, ++ArgNo) {
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000140 if (ByValArgsToTransform.count(&*I)) {
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000141 // Simple byval argument? Just add all the struct element types.
Chris Lattner229907c2011-07-18 04:54:35 +0000142 Type *AgTy = cast<PointerType>(I->getType())->getElementType();
143 StructType *STy = cast<StructType>(AgTy);
Benjamin Kramer5fbfe2f2015-02-28 13:20:15 +0000144 Params.insert(Params.end(), STy->element_begin(), STy->element_end());
Reid Kleckner7f720332017-04-13 00:58:09 +0000145 ArgAttrVec.insert(ArgAttrVec.end(), STy->getNumElements(),
146 AttributeSet());
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000147 ++NumByValArgsPromoted;
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000148 } else if (!ArgsToPromote.count(&*I)) {
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000149 // Unchanged argument
Chris Lattner483ae012004-03-07 21:29:54 +0000150 Params.push_back(I->getType());
Reid Kleckner6652a522017-04-28 18:37:16 +0000151 ArgAttrVec.push_back(PAL.getParamAttributes(ArgNo));
Chris Lattner254f8f82004-05-23 21:21:17 +0000152 } else if (I->use_empty()) {
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000153 // Dead argument (which are always marked as promotable)
Chris Lattner254f8f82004-05-23 21:21:17 +0000154 ++NumArgumentsDead;
Mikael Holmene0ced142017-07-10 06:07:24 +0000155
156 // There may be remaining metadata uses of the argument for things like
157 // llvm.dbg.value. Replace them with undef.
158 I->replaceAllUsesWith(UndefValue::get(I->getType()));
Chris Lattner254f8f82004-05-23 21:21:17 +0000159 } else {
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000160 // Okay, this is being promoted. This means that the only uses are loads
161 // or GEPs which are only used by loads
162
163 // In this table, we will track which indices are loaded from the argument
164 // (where direct loads are tracked as no indices).
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000165 ScalarizeTable &ArgIndices = ScalarizedElements[&*I];
Chandler Carruthcdf47882014-03-09 03:16:01 +0000166 for (User *U : I->users()) {
167 Instruction *UI = cast<Instruction>(U);
David Blaikie76826632015-03-14 21:11:26 +0000168 Type *SrcTy;
169 if (LoadInst *L = dyn_cast<LoadInst>(UI))
170 SrcTy = L->getType();
171 else
172 SrcTy = cast<GetElementPtrInst>(UI)->getSourceElementType();
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000173 IndicesVector Indices;
Chandler Carruthcdf47882014-03-09 03:16:01 +0000174 Indices.reserve(UI->getNumOperands() - 1);
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000175 // Since loads will only have a single operand, and GEPs only a single
176 // non-index operand, this will record direct loads without any indices,
177 // and gep+loads with the GEP indices.
Chandler Carruthcdf47882014-03-09 03:16:01 +0000178 for (User::op_iterator II = UI->op_begin() + 1, IE = UI->op_end();
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000179 II != IE; ++II)
180 Indices.push_back(cast<ConstantInt>(*II)->getSExtValue());
181 // GEPs with a single 0 index can be merged with direct loads
182 if (Indices.size() == 1 && Indices.front() == 0)
183 Indices.clear();
David Blaikie76826632015-03-14 21:11:26 +0000184 ArgIndices.insert(std::make_pair(SrcTy, Indices));
Owen Andersonedadd3f2006-09-15 05:22:51 +0000185 LoadInst *OrigLoad;
Chandler Carruthcdf47882014-03-09 03:16:01 +0000186 if (LoadInst *L = dyn_cast<LoadInst>(UI))
Owen Andersonedadd3f2006-09-15 05:22:51 +0000187 OrigLoad = L;
188 else
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000189 // Take any load, we will use it only to update Alias Analysis
Chandler Carruthcdf47882014-03-09 03:16:01 +0000190 OrigLoad = cast<LoadInst>(UI->user_back());
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000191 OriginalLoads[std::make_pair(&*I, Indices)] = OrigLoad;
Chris Lattnerfe6f2e32004-03-08 01:04:36 +0000192 }
193
194 // Add a parameter to the function for each element passed in.
Benjamin Kramer135f7352016-06-26 12:28:59 +0000195 for (const auto &ArgIndex : ArgIndices) {
Torok Edwin026259f2008-11-16 17:21:25 +0000196 // not allowed to dereference ->begin() if size() is 0
David Blaikied288fb82015-03-30 21:41:43 +0000197 Params.push_back(GetElementPtrInst::getIndexedType(
198 cast<PointerType>(I->getType()->getScalarType())->getElementType(),
Benjamin Kramer135f7352016-06-26 12:28:59 +0000199 ArgIndex.second));
Reid Kleckner7f720332017-04-13 00:58:09 +0000200 ArgAttrVec.push_back(AttributeSet());
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000201 assert(Params.back());
202 }
Chris Lattnerfe6f2e32004-03-08 01:04:36 +0000203
David Blaikie76826632015-03-14 21:11:26 +0000204 if (ArgIndices.size() == 1 && ArgIndices.begin()->second.empty())
Chris Lattnerfe6f2e32004-03-08 01:04:36 +0000205 ++NumArgumentsPromoted;
206 else
207 ++NumAggregatesPromoted;
Chris Lattner483ae012004-03-07 21:29:54 +0000208 }
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000209 }
Chris Lattner483ae012004-03-07 21:29:54 +0000210
Chris Lattner229907c2011-07-18 04:54:35 +0000211 Type *RetTy = FTy->getReturnType();
Chris Lattner483ae012004-03-07 21:29:54 +0000212
Duncan Sandsad0ea2d2007-11-27 13:23:08 +0000213 // Construct the new function type using the new arguments.
Owen Anderson4056ca92009-07-29 22:17:13 +0000214 FunctionType *NFTy = FunctionType::get(RetTy, Params, FTy->isVarArg());
Misha Brukmanb1c93172005-04-21 23:48:37 +0000215
Chris Lattnere0987212009-09-15 05:40:35 +0000216 // Create the new function body and insert it into the module.
Dylan McKayf920da02018-12-18 09:52:52 +0000217 Function *NF = Function::Create(NFTy, F->getLinkage(), F->getAddressSpace(),
218 F->getName());
Duncan Sandsdd7daee2008-05-26 19:58:59 +0000219 NF->copyAttributesFrom(F);
Chris Lattner5630c4f2008-01-17 01:17:03 +0000220
David Blaikiee844cd52014-07-01 21:13:37 +0000221 // Patch the pointer to LLVM function in debug info descriptor.
Peter Collingbourned4bff302015-11-05 22:03:56 +0000222 NF->setSubprogram(F->getSubprogram());
223 F->setSubprogram(nullptr);
David Blaikie8e9cfa52014-07-23 22:09:29 +0000224
Nicola Zaghend34e60c2018-05-14 12:53:11 +0000225 LLVM_DEBUG(dbgs() << "ARG PROMOTION: Promoting to:" << *NF << "\n"
226 << "From: " << *F);
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000227
Chris Lattner5630c4f2008-01-17 01:17:03 +0000228 // Recompute the parameter attributes list based on the new arguments for
229 // the function.
Reid Kleckner7f720332017-04-13 00:58:09 +0000230 NF->setAttributes(AttributeList::get(F->getContext(), PAL.getFnAttributes(),
231 PAL.getRetAttributes(), ArgAttrVec));
232 ArgAttrVec.clear();
Duncan Sandsdd7daee2008-05-26 19:58:59 +0000233
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000234 F->getParent()->getFunctionList().insert(F->getIterator(), NF);
Zhou Shenga30cdb92008-03-20 08:05:05 +0000235 NF->takeName(F);
Chris Lattner254f8f82004-05-23 21:21:17 +0000236
Chris Lattner483ae012004-03-07 21:29:54 +0000237 // Loop over all of the callers of the function, transforming the call sites
238 // to pass in the loaded pointers.
239 //
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000240 SmallVector<Value *, 16> Args;
Chris Lattner483ae012004-03-07 21:29:54 +0000241 while (!F->use_empty()) {
Chandler Carruthcdf47882014-03-09 03:16:01 +0000242 CallSite CS(F->user_back());
Gabor Greif161cb042010-03-23 14:40:20 +0000243 assert(CS.getCalledFunction() == F);
Chris Lattner483ae012004-03-07 21:29:54 +0000244 Instruction *Call = CS.getInstruction();
Reid Klecknerb5180542017-03-21 16:57:19 +0000245 const AttributeList &CallPAL = CS.getAttributes();
Duncan Sands1ea0d2e2008-09-07 09:54:09 +0000246
Chris Lattner254f8f82004-05-23 21:21:17 +0000247 // Loop over the operands, inserting GEP and loads in the caller as
248 // appropriate.
Chris Lattner483ae012004-03-07 21:29:54 +0000249 CallSite::arg_iterator AI = CS.arg_begin();
Reid Kleckner6652a522017-04-28 18:37:16 +0000250 ArgNo = 0;
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000251 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E;
Reid Kleckner6652a522017-04-28 18:37:16 +0000252 ++I, ++AI, ++ArgNo)
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000253 if (!ArgsToPromote.count(&*I) && !ByValArgsToTransform.count(&*I)) {
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000254 Args.push_back(*AI); // Unmodified argument
Reid Kleckner6652a522017-04-28 18:37:16 +0000255 ArgAttrVec.push_back(CallPAL.getParamAttributes(ArgNo));
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000256 } else if (ByValArgsToTransform.count(&*I)) {
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000257 // Emit a GEP and load for each element of the struct.
Chris Lattner229907c2011-07-18 04:54:35 +0000258 Type *AgTy = cast<PointerType>(I->getType())->getElementType();
259 StructType *STy = cast<StructType>(AgTy);
Owen Anderson55f1c092009-08-13 21:58:54 +0000260 Value *Idxs[2] = {
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000261 ConstantInt::get(Type::getInt32Ty(F->getContext()), 0), nullptr};
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000262 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
Owen Anderson55f1c092009-08-13 21:58:54 +0000263 Idxs[1] = ConstantInt::get(Type::getInt32Ty(F->getContext()), i);
David Blaikie76826632015-03-14 21:11:26 +0000264 Value *Idx = GetElementPtrInst::Create(
Benjamin Kramerdba7ee92015-05-28 11:24:24 +0000265 STy, *AI, Idxs, (*AI)->getName() + "." + Twine(i), Call);
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000266 // TODO: Tell AA about the new values?
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000267 Args.push_back(new LoadInst(Idx, Idx->getName() + ".val", Call));
Reid Kleckner7f720332017-04-13 00:58:09 +0000268 ArgAttrVec.push_back(AttributeSet());
Duncan Sands1ea0d2e2008-09-07 09:54:09 +0000269 }
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000270 } else if (!I->use_empty()) {
Chris Lattner254f8f82004-05-23 21:21:17 +0000271 // Non-dead argument: insert GEPs and loads as appropriate.
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000272 ScalarizeTable &ArgIndices = ScalarizedElements[&*I];
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000273 // Store the Value* version of the indices in here, but declare it now
Gabor Greif161cb042010-03-23 14:40:20 +0000274 // for reuse.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000275 std::vector<Value *> Ops;
Benjamin Kramer135f7352016-06-26 12:28:59 +0000276 for (const auto &ArgIndex : ArgIndices) {
Chris Lattnerfe6f2e32004-03-08 01:04:36 +0000277 Value *V = *AI;
Benjamin Kramer135f7352016-06-26 12:28:59 +0000278 LoadInst *OrigLoad =
279 OriginalLoads[std::make_pair(&*I, ArgIndex.second)];
280 if (!ArgIndex.second.empty()) {
281 Ops.reserve(ArgIndex.second.size());
Chris Lattner229907c2011-07-18 04:54:35 +0000282 Type *ElTy = V->getType();
Martin Storsjoe81233d2017-05-04 10:54:35 +0000283 for (auto II : ArgIndex.second) {
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000284 // Use i32 to index structs, and i64 for others (pointers/arrays).
285 // This satisfies GEP constraints.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000286 Type *IdxTy =
287 (ElTy->isStructTy() ? Type::getInt32Ty(F->getContext())
288 : Type::getInt64Ty(F->getContext()));
Benjamin Kramer135f7352016-06-26 12:28:59 +0000289 Ops.push_back(ConstantInt::get(IdxTy, II));
Gabor Greif161cb042010-03-23 14:40:20 +0000290 // Keep track of the type we're currently indexing.
Peter Collingbourne45681582016-12-02 03:05:41 +0000291 if (auto *ElPTy = dyn_cast<PointerType>(ElTy))
292 ElTy = ElPTy->getElementType();
293 else
294 ElTy = cast<CompositeType>(ElTy)->getTypeAtIndex(II);
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000295 }
Gabor Greif161cb042010-03-23 14:40:20 +0000296 // And create a GEP to extract those indices.
Benjamin Kramer135f7352016-06-26 12:28:59 +0000297 V = GetElementPtrInst::Create(ArgIndex.first, V, Ops,
David Blaikie72edd882015-03-14 21:40:12 +0000298 V->getName() + ".idx", Call);
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000299 Ops.clear();
Chris Lattner254f8f82004-05-23 21:21:17 +0000300 }
Eric Christopher81c03442010-03-27 01:54:00 +0000301 // Since we're replacing a load make sure we take the alignment
302 // of the previous load.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000303 LoadInst *newLoad = new LoadInst(V, V->getName() + ".val", Call);
Eric Christopher81c03442010-03-27 01:54:00 +0000304 newLoad->setAlignment(OrigLoad->getAlignment());
Hal Finkelcc39b672014-07-24 12:16:19 +0000305 // Transfer the AA info too.
306 AAMDNodes AAInfo;
307 OrigLoad->getAAMetadata(AAInfo);
308 newLoad->setAAMetadata(AAInfo);
309
Eric Christopher81c03442010-03-27 01:54:00 +0000310 Args.push_back(newLoad);
Reid Kleckner7f720332017-04-13 00:58:09 +0000311 ArgAttrVec.push_back(AttributeSet());
Chris Lattnerfe6f2e32004-03-08 01:04:36 +0000312 }
Chris Lattner483ae012004-03-07 21:29:54 +0000313 }
314
Gabor Greif161cb042010-03-23 14:40:20 +0000315 // Push any varargs arguments on the list.
Reid Kleckner6652a522017-04-28 18:37:16 +0000316 for (; AI != CS.arg_end(); ++AI, ++ArgNo) {
Chris Lattner483ae012004-03-07 21:29:54 +0000317 Args.push_back(*AI);
Reid Kleckner6652a522017-04-28 18:37:16 +0000318 ArgAttrVec.push_back(CallPAL.getParamAttributes(ArgNo));
Chris Lattner5630c4f2008-01-17 01:17:03 +0000319 }
Chris Lattner483ae012004-03-07 21:29:54 +0000320
David Majnemercd24bb12016-04-29 04:56:12 +0000321 SmallVector<OperandBundleDef, 1> OpBundles;
322 CS.getOperandBundlesAsDefs(OpBundles);
323
Reid Kleckner7f720332017-04-13 00:58:09 +0000324 CallSite NewCS;
Chris Lattner483ae012004-03-07 21:29:54 +0000325 if (InvokeInst *II = dyn_cast<InvokeInst>(Call)) {
Reid Kleckner7f720332017-04-13 00:58:09 +0000326 NewCS = InvokeInst::Create(NF, II->getNormalDest(), II->getUnwindDest(),
Reid Kleckner3a115032017-04-13 18:10:30 +0000327 Args, OpBundles, "", Call);
Chris Lattner483ae012004-03-07 21:29:54 +0000328 } else {
Reid Kleckner7f720332017-04-13 00:58:09 +0000329 auto *NewCall = CallInst::Create(NF, Args, OpBundles, "", Call);
330 NewCall->setTailCallKind(cast<CallInst>(Call)->getTailCallKind());
331 NewCS = NewCall;
Chris Lattner483ae012004-03-07 21:29:54 +0000332 }
Reid Kleckner7f720332017-04-13 00:58:09 +0000333 NewCS.setCallingConv(CS.getCallingConv());
334 NewCS.setAttributes(
335 AttributeList::get(F->getContext(), CallPAL.getFnAttributes(),
336 CallPAL.getRetAttributes(), ArgAttrVec));
337 NewCS->setDebugLoc(Call->getDebugLoc());
Reid Kleckner3a115032017-04-13 18:10:30 +0000338 uint64_t W;
339 if (Call->extractProfTotalWeight(W))
340 NewCS->setProfWeight(W);
Chris Lattner483ae012004-03-07 21:29:54 +0000341 Args.clear();
Reid Kleckner7f720332017-04-13 00:58:09 +0000342 ArgAttrVec.clear();
Chris Lattner483ae012004-03-07 21:29:54 +0000343
Duncan Sands3cf7d862008-09-08 11:07:35 +0000344 // Update the callgraph to know that the callsite has been transformed.
Chandler Carruthaddcda42017-02-09 23:46:27 +0000345 if (ReplaceCallSite)
Reid Kleckner7f720332017-04-13 00:58:09 +0000346 (*ReplaceCallSite)(CS, NewCS);
Duncan Sands3cf7d862008-09-08 11:07:35 +0000347
Chris Lattner483ae012004-03-07 21:29:54 +0000348 if (!Call->use_empty()) {
Reid Kleckner7f720332017-04-13 00:58:09 +0000349 Call->replaceAllUsesWith(NewCS.getInstruction());
350 NewCS->takeName(Call);
Chris Lattner483ae012004-03-07 21:29:54 +0000351 }
Misha Brukmanb1c93172005-04-21 23:48:37 +0000352
Chris Lattner483ae012004-03-07 21:29:54 +0000353 // Finally, remove the old call from the program, reducing the use-count of
354 // F.
Chris Lattner4062a622008-01-11 19:20:39 +0000355 Call->eraseFromParent();
Chris Lattner483ae012004-03-07 21:29:54 +0000356 }
357
Matt Arsenault3c1fc762017-04-10 22:27:50 +0000358 const DataLayout &DL = F->getParent()->getDataLayout();
359
Chris Lattner483ae012004-03-07 21:29:54 +0000360 // Since we have now created the new function, splice the body of the old
361 // function right into the new function, leaving the old rotting hulk of the
362 // function empty.
363 NF->getBasicBlockList().splice(NF->begin(), F->getBasicBlockList());
364
Chris Lattner0ab5e2c2011-04-15 05:18:47 +0000365 // Loop over the argument list, transferring uses of the old arguments over to
366 // the new arguments, also transferring over the names as well.
Chris Lattnera06a8fd2007-02-13 02:10:56 +0000367 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(),
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000368 I2 = NF->arg_begin();
369 I != E; ++I) {
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000370 if (!ArgsToPromote.count(&*I) && !ByValArgsToTransform.count(&*I)) {
Chris Lattner483ae012004-03-07 21:29:54 +0000371 // If this is an unmodified argument, move the name and users over to the
372 // new version.
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000373 I->replaceAllUsesWith(&*I2);
374 I2->takeName(&*I);
Chris Lattner483ae012004-03-07 21:29:54 +0000375 ++I2;
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000376 continue;
Chris Lattner483ae012004-03-07 21:29:54 +0000377 }
Duncan Sands1ea0d2e2008-09-07 09:54:09 +0000378
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000379 if (ByValArgsToTransform.count(&*I)) {
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000380 // In the callee, we create an alloca, and store each of the new incoming
381 // arguments into the alloca.
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000382 Instruction *InsertPt = &NF->begin()->front();
Duncan Sands1ea0d2e2008-09-07 09:54:09 +0000383
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000384 // Just add all the struct element types.
Chris Lattner229907c2011-07-18 04:54:35 +0000385 Type *AgTy = cast<PointerType>(I->getType())->getElementType();
Matt Arsenault3c1fc762017-04-10 22:27:50 +0000386 Value *TheAlloca = new AllocaInst(AgTy, DL.getAllocaAddrSpace(), nullptr,
Reid Klecknerda748f12017-08-04 17:09:11 +0000387 I->getParamAlignment(), "", InsertPt);
Chris Lattner229907c2011-07-18 04:54:35 +0000388 StructType *STy = cast<StructType>(AgTy);
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000389 Value *Idxs[2] = {ConstantInt::get(Type::getInt32Ty(F->getContext()), 0),
390 nullptr};
Duncan Sands1ea0d2e2008-09-07 09:54:09 +0000391
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000392 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
Owen Anderson55f1c092009-08-13 21:58:54 +0000393 Idxs[1] = ConstantInt::get(Type::getInt32Ty(F->getContext()), i);
David Blaikie096b1da2015-03-14 19:53:33 +0000394 Value *Idx = GetElementPtrInst::Create(
395 AgTy, TheAlloca, Idxs, TheAlloca->getName() + "." + Twine(i),
396 InsertPt);
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000397 I2->setName(I->getName() + "." + Twine(i));
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000398 new StoreInst(&*I2++, Idx, InsertPt);
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000399 }
Duncan Sands1ea0d2e2008-09-07 09:54:09 +0000400
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000401 // Anything that used the arg should now use the alloca.
402 I->replaceAllUsesWith(TheAlloca);
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000403 TheAlloca->takeName(&*I);
Rafael Espindola2a05ea52014-01-23 17:19:42 +0000404
405 // If the alloca is used in a call, we must clear the tail flag since
406 // the callee now uses an alloca from the caller.
Chandler Carruthcdf47882014-03-09 03:16:01 +0000407 for (User *U : TheAlloca->users()) {
408 CallInst *Call = dyn_cast<CallInst>(U);
Rafael Espindola2a05ea52014-01-23 17:19:42 +0000409 if (!Call)
410 continue;
411 Call->setTailCall(false);
412 }
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000413 continue;
Duncan Sands1ea0d2e2008-09-07 09:54:09 +0000414 }
415
Chandler Carrutha1032a02015-07-22 09:49:59 +0000416 if (I->use_empty())
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000417 continue;
Duncan Sands1ea0d2e2008-09-07 09:54:09 +0000418
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000419 // Otherwise, if we promoted this argument, then all users are load
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000420 // instructions (or GEPs with only load users), and all loads should be
421 // using the new argument that we added.
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000422 ScalarizeTable &ArgIndices = ScalarizedElements[&*I];
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000423
424 while (!I->use_empty()) {
Chandler Carruthcdf47882014-03-09 03:16:01 +0000425 if (LoadInst *LI = dyn_cast<LoadInst>(I->user_back())) {
David Blaikie76826632015-03-14 21:11:26 +0000426 assert(ArgIndices.begin()->second.empty() &&
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000427 "Load element should sort to front!");
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000428 I2->setName(I->getName() + ".val");
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000429 LI->replaceAllUsesWith(&*I2);
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000430 LI->eraseFromParent();
Nicola Zaghend34e60c2018-05-14 12:53:11 +0000431 LLVM_DEBUG(dbgs() << "*** Promoted load of argument '" << I->getName()
432 << "' in function '" << F->getName() << "'\n");
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000433 } else {
Chandler Carruthcdf47882014-03-09 03:16:01 +0000434 GetElementPtrInst *GEP = cast<GetElementPtrInst>(I->user_back());
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000435 IndicesVector Operands;
436 Operands.reserve(GEP->getNumIndices());
437 for (User::op_iterator II = GEP->idx_begin(), IE = GEP->idx_end();
438 II != IE; ++II)
439 Operands.push_back(cast<ConstantInt>(*II)->getSExtValue());
440
441 // GEPs with a single 0 index can be merged with direct loads
442 if (Operands.size() == 1 && Operands.front() == 0)
443 Operands.clear();
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000444
445 Function::arg_iterator TheArg = I2;
446 for (ScalarizeTable::iterator It = ArgIndices.begin();
David Blaikie76826632015-03-14 21:11:26 +0000447 It->second != Operands; ++It, ++TheArg) {
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000448 assert(It != ArgIndices.end() && "GEP not handled??");
449 }
450
451 std::string NewName = I->getName();
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000452 for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000453 NewName += "." + utostr(Operands[i]);
Matthijs Kooijmanfd307042008-07-29 10:00:13 +0000454 }
455 NewName += ".val";
456 TheArg->setName(NewName);
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000457
Nicola Zaghend34e60c2018-05-14 12:53:11 +0000458 LLVM_DEBUG(dbgs() << "*** Promoted agg argument '" << TheArg->getName()
459 << "' of function '" << NF->getName() << "'\n");
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000460
461 // All of the uses must be load instructions. Replace them all with
462 // the argument specified by ArgNo.
463 while (!GEP->use_empty()) {
Chandler Carruthcdf47882014-03-09 03:16:01 +0000464 LoadInst *L = cast<LoadInst>(GEP->user_back());
Duncan P. N. Exon Smith17323402015-10-13 17:51:03 +0000465 L->replaceAllUsesWith(&*TheArg);
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000466 L->eraseFromParent();
467 }
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000468 GEP->eraseFromParent();
469 }
470 }
471
472 // Increment I2 past all of the arguments added for this promoted pointer.
Benjamin Kramer84036252012-09-30 17:31:56 +0000473 std::advance(I2, ArgIndices.size());
Chris Lattnerb5bd9242008-01-11 22:31:41 +0000474 }
Chris Lattner483ae012004-03-07 21:29:54 +0000475
Chandler Carruthaddcda42017-02-09 23:46:27 +0000476 return NF;
Chris Lattner483ae012004-03-07 21:29:54 +0000477}
David Blaikiee844cd52014-07-01 21:13:37 +0000478
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000479/// AllCallersPassInValidPointerForArgument - Return true if we can prove that
480/// all callees pass in a valid pointer for the specified function argument.
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000481static bool allCallersPassInValidPointerForArgument(Argument *Arg) {
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000482 Function *Callee = Arg->getParent();
483 const DataLayout &DL = Callee->getParent()->getDataLayout();
484
485 unsigned ArgNo = Arg->getArgNo();
486
487 // Look at all call sites of the function. At this point we know we only have
488 // direct callees.
489 for (User *U : Callee->users()) {
490 CallSite CS(U);
491 assert(CS && "Should only have direct calls!");
492
493 if (!isDereferenceablePointer(CS.getArgument(ArgNo), DL))
494 return false;
495 }
496 return true;
497}
498
499/// Returns true if Prefix is a prefix of longer. That means, Longer has a size
500/// that is greater than or equal to the size of prefix, and each of the
501/// elements in Prefix is the same as the corresponding elements in Longer.
502///
503/// This means it also returns true when Prefix and Longer are equal!
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000504static bool isPrefix(const IndicesVector &Prefix, const IndicesVector &Longer) {
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000505 if (Prefix.size() > Longer.size())
506 return false;
507 return std::equal(Prefix.begin(), Prefix.end(), Longer.begin());
508}
509
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000510/// Checks if Indices, or a prefix of Indices, is in Set.
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000511static bool prefixIn(const IndicesVector &Indices,
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000512 std::set<IndicesVector> &Set) {
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000513 std::set<IndicesVector>::iterator Low;
514 Low = Set.upper_bound(Indices);
515 if (Low != Set.begin())
516 Low--;
517 // Low is now the last element smaller than or equal to Indices. This means
518 // it points to a prefix of Indices (possibly Indices itself), if such
519 // prefix exists.
520 //
521 // This load is safe if any prefix of its operands is safe to load.
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000522 return Low != Set.end() && isPrefix(*Low, Indices);
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000523}
524
525/// Mark the given indices (ToMark) as safe in the given set of indices
526/// (Safe). Marking safe usually means adding ToMark to Safe. However, if there
527/// is already a prefix of Indices in Safe, Indices are implicitely marked safe
528/// already. Furthermore, any indices that Indices is itself a prefix of, are
529/// removed from Safe (since they are implicitely safe because of Indices now).
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000530static void markIndicesSafe(const IndicesVector &ToMark,
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000531 std::set<IndicesVector> &Safe) {
532 std::set<IndicesVector>::iterator Low;
533 Low = Safe.upper_bound(ToMark);
534 // Guard against the case where Safe is empty
535 if (Low != Safe.begin())
536 Low--;
537 // Low is now the last element smaller than or equal to Indices. This
538 // means it points to a prefix of Indices (possibly Indices itself), if
539 // such prefix exists.
540 if (Low != Safe.end()) {
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000541 if (isPrefix(*Low, ToMark))
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000542 // If there is already a prefix of these indices (or exactly these
543 // indices) marked a safe, don't bother adding these indices
544 return;
545
546 // Increment Low, so we can use it as a "insert before" hint
547 ++Low;
548 }
549 // Insert
550 Low = Safe.insert(Low, ToMark);
551 ++Low;
552 // If there we're a prefix of longer index list(s), remove those
553 std::set<IndicesVector>::iterator End = Safe.end();
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000554 while (Low != End && isPrefix(ToMark, *Low)) {
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000555 std::set<IndicesVector>::iterator Remove = Low;
556 ++Low;
557 Safe.erase(Remove);
558 }
559}
560
561/// isSafeToPromoteArgument - As you might guess from the name of this method,
562/// it checks to see if it is both safe and useful to promote the argument.
563/// This method limits promotion of aggregates to only promote up to three
564/// elements of the aggregate in order to avoid exploding the number of
565/// arguments passed in.
566static bool isSafeToPromoteArgument(Argument *Arg, bool isByValOrInAlloca,
567 AAResults &AAR, unsigned MaxElements) {
Eugene Zelenkof27d1612017-10-19 21:21:30 +0000568 using GEPIndicesSet = std::set<IndicesVector>;
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000569
570 // Quick exit for unused arguments
571 if (Arg->use_empty())
572 return true;
573
574 // We can only promote this argument if all of the uses are loads, or are GEP
575 // instructions (with constant indices) that are subsequently loaded.
576 //
577 // Promoting the argument causes it to be loaded in the caller
578 // unconditionally. This is only safe if we can prove that either the load
579 // would have happened in the callee anyway (ie, there is a load in the entry
580 // block) or the pointer passed in at every call site is guaranteed to be
581 // valid.
582 // In the former case, invalid loads can happen, but would have happened
583 // anyway, in the latter case, invalid loads won't happen. This prevents us
584 // from introducing an invalid load that wouldn't have happened in the
585 // original code.
586 //
587 // This set will contain all sets of indices that are loaded in the entry
588 // block, and thus are safe to unconditionally load in the caller.
589 //
590 // This optimization is also safe for InAlloca parameters, because it verifies
591 // that the address isn't captured.
592 GEPIndicesSet SafeToUnconditionallyLoad;
593
594 // This set contains all the sets of indices that we are planning to promote.
595 // This makes it possible to limit the number of arguments added.
596 GEPIndicesSet ToPromote;
597
598 // If the pointer is always valid, any load with first index 0 is valid.
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000599 if (isByValOrInAlloca || allCallersPassInValidPointerForArgument(Arg))
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000600 SafeToUnconditionallyLoad.insert(IndicesVector(1, 0));
601
602 // First, iterate the entry block and mark loads of (geps of) arguments as
603 // safe.
604 BasicBlock &EntryBlock = Arg->getParent()->front();
605 // Declare this here so we can reuse it
606 IndicesVector Indices;
607 for (Instruction &I : EntryBlock)
608 if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
609 Value *V = LI->getPointerOperand();
610 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) {
611 V = GEP->getPointerOperand();
612 if (V == Arg) {
613 // This load actually loads (part of) Arg? Check the indices then.
614 Indices.reserve(GEP->getNumIndices());
615 for (User::op_iterator II = GEP->idx_begin(), IE = GEP->idx_end();
616 II != IE; ++II)
617 if (ConstantInt *CI = dyn_cast<ConstantInt>(*II))
618 Indices.push_back(CI->getSExtValue());
619 else
620 // We found a non-constant GEP index for this argument? Bail out
621 // right away, can't promote this argument at all.
622 return false;
623
624 // Indices checked out, mark them as safe
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000625 markIndicesSafe(Indices, SafeToUnconditionallyLoad);
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000626 Indices.clear();
627 }
628 } else if (V == Arg) {
629 // Direct loads are equivalent to a GEP with a single 0 index.
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000630 markIndicesSafe(IndicesVector(1, 0), SafeToUnconditionallyLoad);
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000631 }
632 }
633
634 // Now, iterate all uses of the argument to see if there are any uses that are
635 // not (GEP+)loads, or any (GEP+)loads that are not safe to promote.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000636 SmallVector<LoadInst *, 16> Loads;
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000637 IndicesVector Operands;
638 for (Use &U : Arg->uses()) {
639 User *UR = U.getUser();
640 Operands.clear();
641 if (LoadInst *LI = dyn_cast<LoadInst>(UR)) {
642 // Don't hack volatile/atomic loads
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000643 if (!LI->isSimple())
644 return false;
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000645 Loads.push_back(LI);
646 // Direct loads are equivalent to a GEP with a zero index and then a load.
647 Operands.push_back(0);
648 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(UR)) {
649 if (GEP->use_empty()) {
650 // Dead GEP's cause trouble later. Just remove them if we run into
651 // them.
652 GEP->eraseFromParent();
653 // TODO: This runs the above loop over and over again for dead GEPs
654 // Couldn't we just do increment the UI iterator earlier and erase the
655 // use?
656 return isSafeToPromoteArgument(Arg, isByValOrInAlloca, AAR,
657 MaxElements);
658 }
659
660 // Ensure that all of the indices are constants.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000661 for (User::op_iterator i = GEP->idx_begin(), e = GEP->idx_end(); i != e;
662 ++i)
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000663 if (ConstantInt *C = dyn_cast<ConstantInt>(*i))
664 Operands.push_back(C->getSExtValue());
665 else
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000666 return false; // Not a constant operand GEP!
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000667
668 // Ensure that the only users of the GEP are load instructions.
669 for (User *GEPU : GEP->users())
670 if (LoadInst *LI = dyn_cast<LoadInst>(GEPU)) {
671 // Don't hack volatile/atomic loads
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000672 if (!LI->isSimple())
673 return false;
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000674 Loads.push_back(LI);
675 } else {
676 // Other uses than load?
677 return false;
678 }
679 } else {
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000680 return false; // Not a load or a GEP.
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000681 }
682
683 // Now, see if it is safe to promote this load / loads of this GEP. Loading
684 // is safe if Operands, or a prefix of Operands, is marked as safe.
Chandler Carruth8e9c0a82017-01-29 08:03:21 +0000685 if (!prefixIn(Operands, SafeToUnconditionallyLoad))
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000686 return false;
687
688 // See if we are already promoting a load with these indices. If not, check
689 // to make sure that we aren't promoting too many elements. If so, nothing
690 // to do.
691 if (ToPromote.find(Operands) == ToPromote.end()) {
692 if (MaxElements > 0 && ToPromote.size() == MaxElements) {
Nicola Zaghend34e60c2018-05-14 12:53:11 +0000693 LLVM_DEBUG(dbgs() << "argpromotion not promoting argument '"
694 << Arg->getName()
695 << "' because it would require adding more "
696 << "than " << MaxElements
697 << " arguments to the function.\n");
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000698 // We limit aggregate promotion to only promoting up to a fixed number
699 // of elements of the aggregate.
700 return false;
701 }
702 ToPromote.insert(std::move(Operands));
703 }
704 }
705
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000706 if (Loads.empty())
707 return true; // No users, this is a dead argument.
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000708
709 // Okay, now we know that the argument is only used by load instructions and
710 // it is safe to unconditionally perform all of them. Use alias analysis to
711 // check to see if the pointer is guaranteed to not be modified from entry of
712 // the function to each of the load instructions.
713
714 // Because there could be several/many load instructions, remember which
715 // blocks we know to be transparent to the load.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000716 df_iterator_default_set<BasicBlock *, 16> TranspBlocks;
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000717
718 for (LoadInst *Load : Loads) {
719 // Check to see if the load is invalidated from the start of the block to
720 // the load itself.
721 BasicBlock *BB = Load->getParent();
722
723 MemoryLocation Loc = MemoryLocation::get(Load);
Alina Sbirlea193429f2017-12-07 22:41:34 +0000724 if (AAR.canInstructionRangeModRef(BB->front(), *Load, Loc, ModRefInfo::Mod))
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000725 return false; // Pointer is invalidated!
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000726
727 // Now check every path from the entry block to the load for transparency.
728 // To do this, we perform a depth first search on the inverse CFG from the
729 // loading block.
730 for (BasicBlock *P : predecessors(BB)) {
731 for (BasicBlock *TranspBB : inverse_depth_first_ext(P, TranspBlocks))
732 if (AAR.canBasicBlockModify(*TranspBB, Loc))
733 return false;
734 }
735 }
736
737 // If the path from the entry of the function to each load is free of
738 // instructions that potentially invalidate the load, we can make the
739 // transformation!
740 return true;
741}
742
Adrian Prantl5f8f34e42018-05-01 15:54:18 +0000743/// Checks if a type could have padding bytes.
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000744static bool isDenselyPacked(Type *type, const DataLayout &DL) {
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000745 // There is no size information, so be conservative.
746 if (!type->isSized())
747 return false;
748
749 // If the alloc size is not equal to the storage size, then there are padding
750 // bytes. For x86_fp80 on x86-64, size: 80 alloc size: 128.
751 if (DL.getTypeSizeInBits(type) != DL.getTypeAllocSizeInBits(type))
752 return false;
753
754 if (!isa<CompositeType>(type))
755 return true;
756
757 // For homogenous sequential types, check for padding within members.
758 if (SequentialType *seqTy = dyn_cast<SequentialType>(type))
759 return isDenselyPacked(seqTy->getElementType(), DL);
760
761 // Check for padding within and between elements of a struct.
762 StructType *StructTy = cast<StructType>(type);
763 const StructLayout *Layout = DL.getStructLayout(StructTy);
764 uint64_t StartPos = 0;
765 for (unsigned i = 0, E = StructTy->getNumElements(); i < E; ++i) {
766 Type *ElTy = StructTy->getElementType(i);
767 if (!isDenselyPacked(ElTy, DL))
768 return false;
769 if (StartPos != Layout->getElementOffsetInBits(i))
770 return false;
771 StartPos += DL.getTypeAllocSizeInBits(ElTy);
772 }
773
774 return true;
775}
776
Adrian Prantl5f8f34e42018-05-01 15:54:18 +0000777/// Checks if the padding bytes of an argument could be accessed.
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000778static bool canPaddingBeAccessed(Argument *arg) {
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000779 assert(arg->hasByValAttr());
780
781 // Track all the pointers to the argument to make sure they are not captured.
782 SmallPtrSet<Value *, 16> PtrValues;
783 PtrValues.insert(arg);
784
785 // Track all of the stores.
786 SmallVector<StoreInst *, 16> Stores;
787
788 // Scan through the uses recursively to make sure the pointer is always used
789 // sanely.
790 SmallVector<Value *, 16> WorkList;
791 WorkList.insert(WorkList.end(), arg->user_begin(), arg->user_end());
792 while (!WorkList.empty()) {
793 Value *V = WorkList.back();
794 WorkList.pop_back();
795 if (isa<GetElementPtrInst>(V) || isa<PHINode>(V)) {
796 if (PtrValues.insert(V).second)
797 WorkList.insert(WorkList.end(), V->user_begin(), V->user_end());
798 } else if (StoreInst *Store = dyn_cast<StoreInst>(V)) {
799 Stores.push_back(Store);
800 } else if (!isa<LoadInst>(V)) {
801 return true;
802 }
803 }
804
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000805 // Check to make sure the pointers aren't captured
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000806 for (StoreInst *Store : Stores)
807 if (PtrValues.count(Store->getValueOperand()))
808 return true;
809
810 return false;
811}
812
Tom Stellard3d36e5c2019-01-16 05:15:31 +0000813static bool areFunctionArgsABICompatible(
814 const Function &F, const TargetTransformInfo &TTI,
815 SmallPtrSetImpl<Argument *> &ArgsToPromote,
816 SmallPtrSetImpl<Argument *> &ByValArgsToTransform) {
817 for (const Use &U : F.uses()) {
818 CallSite CS(U.getUser());
819 const Function *Caller = CS.getCaller();
820 const Function *Callee = CS.getCalledFunction();
821 if (!TTI.areFunctionArgsABICompatible(Caller, Callee, ArgsToPromote) ||
822 !TTI.areFunctionArgsABICompatible(Caller, Callee, ByValArgsToTransform))
823 return false;
824 }
825 return true;
826}
827
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000828/// PromoteArguments - This method checks the specified function to see if there
829/// are any promotable arguments and if it is safe to promote the function (for
830/// example, all callers are direct). If safe to promote some arguments, it
831/// calls the DoPromotion method.
Chandler Carruthaddcda42017-02-09 23:46:27 +0000832static Function *
833promoteArguments(Function *F, function_ref<AAResults &(Function &F)> AARGetter,
834 unsigned MaxElements,
835 Optional<function_ref<void(CallSite OldCS, CallSite NewCS)>>
Tom Stellard3d36e5c2019-01-16 05:15:31 +0000836 ReplaceCallSite,
837 const TargetTransformInfo &TTI) {
Luke Cheeseman6c1e6bb2018-02-22 14:42:08 +0000838 // Don't perform argument promotion for naked functions; otherwise we can end
839 // up removing parameters that are seemingly 'not used' as they are referred
840 // to in the assembly.
841 if(F->hasFnAttribute(Attribute::Naked))
842 return nullptr;
843
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000844 // Make sure that it is local to this module.
Chandler Carruthaddcda42017-02-09 23:46:27 +0000845 if (!F->hasLocalLinkage())
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000846 return nullptr;
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000847
848 // Don't promote arguments for variadic functions. Adding, removing, or
849 // changing non-pack parameters can change the classification of pack
850 // parameters. Frontends encode that classification at the call site in the
851 // IR, while in the callee the classification is determined dynamically based
852 // on the number of registers consumed so far.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000853 if (F->isVarArg())
854 return nullptr;
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000855
856 // First check: see if there are any pointer arguments! If not, quick exit.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000857 SmallVector<Argument *, 16> PointerArgs;
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000858 for (Argument &I : F->args())
859 if (I.getType()->isPointerTy())
860 PointerArgs.push_back(&I);
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000861 if (PointerArgs.empty())
862 return nullptr;
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000863
864 // Second check: make sure that all callers are direct callers. We can't
865 // transform functions that have indirect callers. Also see if the function
Tom Stellard3d36e5c2019-01-16 05:15:31 +0000866 // is self-recursive and check that target features are compatible.
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000867 bool isSelfRecursive = false;
868 for (Use &U : F->uses()) {
869 CallSite CS(U.getUser());
870 // Must be a direct call.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000871 if (CS.getInstruction() == nullptr || !CS.isCallee(&U))
872 return nullptr;
873
Fedor Indutny1571b122018-03-02 00:59:27 +0000874 // Can't change signature of musttail callee
875 if (CS.isMustTailCall())
876 return nullptr;
877
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000878 if (CS.getInstruction()->getParent()->getParent() == F)
879 isSelfRecursive = true;
880 }
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000881
Fedor Indutny1571b122018-03-02 00:59:27 +0000882 // Can't change signature of musttail caller
883 // FIXME: Support promoting whole chain of musttail functions
884 for (BasicBlock &BB : *F)
885 if (BB.getTerminatingMustTailCall())
886 return nullptr;
887
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000888 const DataLayout &DL = F->getParent()->getDataLayout();
889
890 AAResults &AAR = AARGetter(*F);
891
892 // Check to see which arguments are promotable. If an argument is promotable,
893 // add it to ArgsToPromote.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000894 SmallPtrSet<Argument *, 8> ArgsToPromote;
895 SmallPtrSet<Argument *, 8> ByValArgsToTransform;
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000896 for (Argument *PtrArg : PointerArgs) {
897 Type *AgTy = cast<PointerType>(PtrArg->getType())->getElementType();
898
899 // Replace sret attribute with noalias. This reduces register pressure by
900 // avoiding a register copy.
901 if (PtrArg->hasStructRetAttr()) {
902 unsigned ArgNo = PtrArg->getArgNo();
Reid Klecknera0b45f42017-05-03 18:17:31 +0000903 F->removeParamAttr(ArgNo, Attribute::StructRet);
904 F->addParamAttr(ArgNo, Attribute::NoAlias);
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000905 for (Use &U : F->uses()) {
906 CallSite CS(U.getUser());
Reid Klecknera0b45f42017-05-03 18:17:31 +0000907 CS.removeParamAttr(ArgNo, Attribute::StructRet);
908 CS.addParamAttr(ArgNo, Attribute::NoAlias);
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000909 }
910 }
911
912 // If this is a byval argument, and if the aggregate type is small, just
913 // pass the elements, which is always safe, if the passed value is densely
914 // packed or if we can prove the padding bytes are never accessed. This does
915 // not apply to inalloca.
916 bool isSafeToPromote =
917 PtrArg->hasByValAttr() &&
918 (isDenselyPacked(AgTy, DL) || !canPaddingBeAccessed(PtrArg));
919 if (isSafeToPromote) {
920 if (StructType *STy = dyn_cast<StructType>(AgTy)) {
921 if (MaxElements > 0 && STy->getNumElements() > MaxElements) {
Nicola Zaghend34e60c2018-05-14 12:53:11 +0000922 LLVM_DEBUG(dbgs() << "argpromotion disable promoting argument '"
923 << PtrArg->getName()
924 << "' because it would require adding more"
925 << " than " << MaxElements
926 << " arguments to the function.\n");
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000927 continue;
928 }
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000929
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000930 // If all the elements are single-value types, we can promote it.
931 bool AllSimple = true;
932 for (const auto *EltTy : STy->elements()) {
933 if (!EltTy->isSingleValueType()) {
934 AllSimple = false;
935 break;
936 }
937 }
938
939 // Safe to transform, don't even bother trying to "promote" it.
940 // Passing the elements as a scalar will allow sroa to hack on
941 // the new alloca we introduce.
942 if (AllSimple) {
943 ByValArgsToTransform.insert(PtrArg);
944 continue;
945 }
946 }
947 }
948
949 // If the argument is a recursive type and we're in a recursive
950 // function, we could end up infinitely peeling the function argument.
951 if (isSelfRecursive) {
952 if (StructType *STy = dyn_cast<StructType>(AgTy)) {
953 bool RecursiveType = false;
954 for (const auto *EltTy : STy->elements()) {
955 if (EltTy == PtrArg->getType()) {
956 RecursiveType = true;
957 break;
958 }
959 }
960 if (RecursiveType)
961 continue;
962 }
963 }
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000964
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000965 // Otherwise, see if we can promote the pointer to its value.
966 if (isSafeToPromoteArgument(PtrArg, PtrArg->hasByValOrInAllocaAttr(), AAR,
967 MaxElements))
968 ArgsToPromote.insert(PtrArg);
969 }
970
971 // No promotable pointer arguments.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +0000972 if (ArgsToPromote.empty() && ByValArgsToTransform.empty())
Chandler Carruthcd836cd2017-01-29 08:03:16 +0000973 return nullptr;
974
Tom Stellard3d36e5c2019-01-16 05:15:31 +0000975 if (!areFunctionArgsABICompatible(*F, TTI, ArgsToPromote,
976 ByValArgsToTransform))
977 return nullptr;
978
Chandler Carruthaddcda42017-02-09 23:46:27 +0000979 return doPromotion(F, ArgsToPromote, ByValArgsToTransform, ReplaceCallSite);
980}
981
982PreservedAnalyses ArgumentPromotionPass::run(LazyCallGraph::SCC &C,
983 CGSCCAnalysisManager &AM,
984 LazyCallGraph &CG,
985 CGSCCUpdateResult &UR) {
986 bool Changed = false, LocalChange;
987
988 // Iterate until we stop promoting from this SCC.
989 do {
990 LocalChange = false;
991
992 for (LazyCallGraph::Node &N : C) {
993 Function &OldF = N.getFunction();
994
995 FunctionAnalysisManager &FAM =
996 AM.getResult<FunctionAnalysisManagerCGSCCProxy>(C, CG).getManager();
997 // FIXME: This lambda must only be used with this function. We should
998 // skip the lambda and just get the AA results directly.
999 auto AARGetter = [&](Function &F) -> AAResults & {
1000 assert(&F == &OldF && "Called with an unexpected function!");
1001 return FAM.getResult<AAManager>(F);
1002 };
1003
Tom Stellard3d36e5c2019-01-16 05:15:31 +00001004 const TargetTransformInfo &TTI = FAM.getResult<TargetIRAnalysis>(OldF);
1005 Function *NewF =
1006 promoteArguments(&OldF, AARGetter, MaxElements, None, TTI);
Chandler Carruthaddcda42017-02-09 23:46:27 +00001007 if (!NewF)
1008 continue;
1009 LocalChange = true;
1010
1011 // Directly substitute the functions in the call graph. Note that this
1012 // requires the old function to be completely dead and completely
1013 // replaced by the new function. It does no call graph updates, it merely
1014 // swaps out the particular function mapped to a particular node in the
1015 // graph.
1016 C.getOuterRefSCC().replaceNodeFunction(N, *NewF);
1017 OldF.eraseFromParent();
1018 }
1019
1020 Changed |= LocalChange;
1021 } while (LocalChange);
1022
1023 if (!Changed)
1024 return PreservedAnalyses::all();
1025
1026 return PreservedAnalyses::none();
Chandler Carruthcd836cd2017-01-29 08:03:16 +00001027}
1028
1029namespace {
Eugene Zelenkof27d1612017-10-19 21:21:30 +00001030
Chandler Carruthae9ce3d2017-01-29 08:03:19 +00001031/// ArgPromotion - The 'by reference' to 'by value' argument promotion pass.
Chandler Carruthae9ce3d2017-01-29 08:03:19 +00001032struct ArgPromotion : public CallGraphSCCPass {
Eugene Zelenkof27d1612017-10-19 21:21:30 +00001033 // Pass identification, replacement for typeid
1034 static char ID;
1035
1036 explicit ArgPromotion(unsigned MaxElements = 3)
1037 : CallGraphSCCPass(ID), MaxElements(MaxElements) {
1038 initializeArgPromotionPass(*PassRegistry::getPassRegistry());
1039 }
1040
Chandler Carruthae9ce3d2017-01-29 08:03:19 +00001041 void getAnalysisUsage(AnalysisUsage &AU) const override {
1042 AU.addRequired<AssumptionCacheTracker>();
1043 AU.addRequired<TargetLibraryInfoWrapperPass>();
Tom Stellard3d36e5c2019-01-16 05:15:31 +00001044 AU.addRequired<TargetTransformInfoWrapperPass>();
Chandler Carruthae9ce3d2017-01-29 08:03:19 +00001045 getAAResultsAnalysisUsage(AU);
1046 CallGraphSCCPass::getAnalysisUsage(AU);
1047 }
Chandler Carruthcd836cd2017-01-29 08:03:16 +00001048
Chandler Carruthae9ce3d2017-01-29 08:03:19 +00001049 bool runOnSCC(CallGraphSCC &SCC) override;
Chandler Carruthcd836cd2017-01-29 08:03:16 +00001050
Chandler Carruthae9ce3d2017-01-29 08:03:19 +00001051private:
1052 using llvm::Pass::doInitialization;
Eugene Zelenkof27d1612017-10-19 21:21:30 +00001053
Chandler Carruthae9ce3d2017-01-29 08:03:19 +00001054 bool doInitialization(CallGraph &CG) override;
Eugene Zelenkof27d1612017-10-19 21:21:30 +00001055
Chandler Carruthae9ce3d2017-01-29 08:03:19 +00001056 /// The maximum number of elements to expand, or 0 for unlimited.
1057 unsigned MaxElements;
1058};
Eugene Zelenkof27d1612017-10-19 21:21:30 +00001059
1060} // end anonymous namespace
Chandler Carruthcd836cd2017-01-29 08:03:16 +00001061
1062char ArgPromotion::ID = 0;
Eugene Zelenkof27d1612017-10-19 21:21:30 +00001063
Chandler Carruthcd836cd2017-01-29 08:03:16 +00001064INITIALIZE_PASS_BEGIN(ArgPromotion, "argpromotion",
Chandler Carruthae9ce3d2017-01-29 08:03:19 +00001065 "Promote 'by reference' arguments to scalars", false,
1066 false)
Chandler Carruthcd836cd2017-01-29 08:03:16 +00001067INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
1068INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
1069INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
Tom Stellard3d36e5c2019-01-16 05:15:31 +00001070INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
Chandler Carruthcd836cd2017-01-29 08:03:16 +00001071INITIALIZE_PASS_END(ArgPromotion, "argpromotion",
Chandler Carruthae9ce3d2017-01-29 08:03:19 +00001072 "Promote 'by reference' arguments to scalars", false, false)
Chandler Carruthcd836cd2017-01-29 08:03:16 +00001073
1074Pass *llvm::createArgumentPromotionPass(unsigned MaxElements) {
1075 return new ArgPromotion(MaxElements);
1076}
1077
1078bool ArgPromotion::runOnSCC(CallGraphSCC &SCC) {
1079 if (skipSCC(SCC))
1080 return false;
1081
1082 // Get the callgraph information that we need to update to reflect our
1083 // changes.
1084 CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
1085
Peter Collingbournecea1e4e2017-02-09 23:11:52 +00001086 LegacyAARGetter AARGetter(*this);
Chandler Carruthcd836cd2017-01-29 08:03:16 +00001087
1088 bool Changed = false, LocalChange;
1089
1090 // Iterate until we stop promoting from this SCC.
1091 do {
1092 LocalChange = false;
1093 // Attempt to promote arguments from all functions in this SCC.
1094 for (CallGraphNode *OldNode : SCC) {
Chandler Carruthaddcda42017-02-09 23:46:27 +00001095 Function *OldF = OldNode->getFunction();
1096 if (!OldF)
1097 continue;
1098
1099 auto ReplaceCallSite = [&](CallSite OldCS, CallSite NewCS) {
1100 Function *Caller = OldCS.getInstruction()->getParent()->getParent();
1101 CallGraphNode *NewCalleeNode =
1102 CG.getOrInsertFunction(NewCS.getCalledFunction());
1103 CallGraphNode *CallerNode = CG[Caller];
1104 CallerNode->replaceCallEdge(OldCS, NewCS, NewCalleeNode);
1105 };
1106
Tom Stellard3d36e5c2019-01-16 05:15:31 +00001107 const TargetTransformInfo &TTI =
1108 getAnalysis<TargetTransformInfoWrapperPass>().getTTI(*OldF);
Chandler Carruthaddcda42017-02-09 23:46:27 +00001109 if (Function *NewF = promoteArguments(OldF, AARGetter, MaxElements,
Tom Stellard3d36e5c2019-01-16 05:15:31 +00001110 {ReplaceCallSite}, TTI)) {
Chandler Carruthcd836cd2017-01-29 08:03:16 +00001111 LocalChange = true;
Chandler Carruthaddcda42017-02-09 23:46:27 +00001112
1113 // Update the call graph for the newly promoted function.
1114 CallGraphNode *NewNode = CG.getOrInsertFunction(NewF);
1115 NewNode->stealCalledFunctionsFrom(OldNode);
1116 if (OldNode->getNumReferences() == 0)
1117 delete CG.removeFunctionFromModule(OldNode);
1118 else
1119 OldF->setLinkage(Function::ExternalLinkage);
1120
1121 // And updat ethe SCC we're iterating as well.
Chandler Carruthcd836cd2017-01-29 08:03:16 +00001122 SCC.ReplaceNode(OldNode, NewNode);
1123 }
1124 }
1125 // Remember that we changed something.
1126 Changed |= LocalChange;
1127 } while (LocalChange);
1128
1129 return Changed;
1130}
1131
David Blaikiee844cd52014-07-01 21:13:37 +00001132bool ArgPromotion::doInitialization(CallGraph &CG) {
David Blaikiee844cd52014-07-01 21:13:37 +00001133 return CallGraphSCCPass::doInitialization(CG);
1134}