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Chris Lattner6420f1c2003-09-15 04:56:27 +00001//===- LowerSetJmp.cpp - Code pertaining to lowering set/long jumps -------===//
Misha Brukmanfd939082005-04-21 23:48:37 +00002//
John Criswellb576c942003-10-20 19:43:21 +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//
John Criswellb576c942003-10-20 19:43:21 +00008//===----------------------------------------------------------------------===//
Chris Lattner6420f1c2003-09-15 04:56:27 +00009//
10// This file implements the lowering of setjmp and longjmp to use the
Chris Lattner77b398c2003-09-15 05:43:05 +000011// LLVM invoke and unwind instructions as necessary.
Chris Lattner6420f1c2003-09-15 04:56:27 +000012//
13// Lowering of longjmp is fairly trivial. We replace the call with a
14// call to the LLVM library function "__llvm_sjljeh_throw_longjmp()".
15// This unwinds the stack for us calling all of the destructors for
16// objects allocated on the stack.
17//
18// At a setjmp call, the basic block is split and the setjmp removed.
19// The calls in a function that have a setjmp are converted to invoke
20// where the except part checks to see if it's a longjmp exception and,
21// if so, if it's handled in the function. If it is, then it gets the
22// value returned by the longjmp and goes to where the basic block was
23// split. Invoke instructions are handled in a similar fashion with the
24// original except block being executed if it isn't a longjmp except
25// that is handled by that function.
26//
27//===----------------------------------------------------------------------===//
28
29//===----------------------------------------------------------------------===//
30// FIXME: This pass doesn't deal with PHI statements just yet. That is,
31// we expect this to occur before SSAification is done. This would seem
32// to make sense, but in general, it might be a good idea to make this
33// pass invokable via the "opt" command at will.
34//===----------------------------------------------------------------------===//
35
Chris Lattner86453c52006-12-19 22:09:18 +000036#define DEBUG_TYPE "lowersetjmp"
Chris Lattner1e2385b2003-11-21 21:54:22 +000037#include "llvm/Transforms/IPO.h"
Chris Lattner6420f1c2003-09-15 04:56:27 +000038#include "llvm/Constants.h"
39#include "llvm/DerivedTypes.h"
40#include "llvm/Instructions.h"
41#include "llvm/Intrinsics.h"
Owen Anderson14ce9ef2009-07-06 01:34:54 +000042#include "llvm/LLVMContext.h"
Chris Lattner6420f1c2003-09-15 04:56:27 +000043#include "llvm/Module.h"
44#include "llvm/Pass.h"
Gabor Greiffef8c4e2010-06-24 14:13:36 +000045#include "llvm/Support/CallSite.h"
Chris Lattnerbb2d4de2003-10-13 00:57:16 +000046#include "llvm/Support/CFG.h"
Chris Lattner6420f1c2003-09-15 04:56:27 +000047#include "llvm/Support/InstVisitor.h"
Chris Lattnera2dc7272004-03-14 02:13:38 +000048#include "llvm/Transforms/Utils/Local.h"
Reid Spencer551ccae2004-09-01 22:55:40 +000049#include "llvm/ADT/DepthFirstIterator.h"
50#include "llvm/ADT/Statistic.h"
Dan Gohmanc9235d22008-03-21 23:51:57 +000051#include <map>
Chris Lattner1e2385b2003-11-21 21:54:22 +000052using namespace llvm;
Brian Gaeked0fde302003-11-11 22:41:34 +000053
Chris Lattner86453c52006-12-19 22:09:18 +000054STATISTIC(LongJmpsTransformed, "Number of longjmps transformed");
55STATISTIC(SetJmpsTransformed , "Number of setjmps transformed");
56STATISTIC(CallsTransformed , "Number of calls invokified");
57STATISTIC(InvokesTransformed , "Number of invokes modified");
Chris Lattner6420f1c2003-09-15 04:56:27 +000058
Chris Lattner86453c52006-12-19 22:09:18 +000059namespace {
Chris Lattner6420f1c2003-09-15 04:56:27 +000060 //===--------------------------------------------------------------------===//
Chris Lattnerbc53e5e2004-10-07 06:00:24 +000061 // LowerSetJmp pass implementation.
Nick Lewycky6726b6d2009-10-25 06:33:48 +000062 class LowerSetJmp : public ModulePass, public InstVisitor<LowerSetJmp> {
Chris Lattner6420f1c2003-09-15 04:56:27 +000063 // LLVM library functions...
Chris Lattner35057c22007-01-07 06:59:47 +000064 Constant *InitSJMap; // __llvm_sjljeh_init_setjmpmap
65 Constant *DestroySJMap; // __llvm_sjljeh_destroy_setjmpmap
66 Constant *AddSJToMap; // __llvm_sjljeh_add_setjmp_to_map
67 Constant *ThrowLongJmp; // __llvm_sjljeh_throw_longjmp
68 Constant *TryCatchLJ; // __llvm_sjljeh_try_catching_longjmp_exception
69 Constant *IsLJException; // __llvm_sjljeh_is_longjmp_exception
70 Constant *GetLJValue; // __llvm_sjljeh_get_longjmp_value
Chris Lattner6420f1c2003-09-15 04:56:27 +000071
72 typedef std::pair<SwitchInst*, CallInst*> SwitchValuePair;
73
Chris Lattnerbb2d4de2003-10-13 00:57:16 +000074 // Keep track of those basic blocks reachable via a depth-first search of
75 // the CFG from a setjmp call. We only need to transform those "call" and
76 // "invoke" instructions that are reachable from the setjmp call site.
77 std::set<BasicBlock*> DFSBlocks;
78
Chris Lattner6420f1c2003-09-15 04:56:27 +000079 // The setjmp map is going to hold information about which setjmps
80 // were called (each setjmp gets its own number) and with which
81 // buffer it was called.
82 std::map<Function*, AllocaInst*> SJMap;
83
84 // The rethrow basic block map holds the basic block to branch to if
85 // the exception isn't handled in the current function and needs to
86 // be rethrown.
87 std::map<const Function*, BasicBlock*> RethrowBBMap;
88
89 // The preliminary basic block map holds a basic block that grabs the
90 // exception and determines if it's handled by the current function.
91 std::map<const Function*, BasicBlock*> PrelimBBMap;
92
93 // The switch/value map holds a switch inst/call inst pair. The
94 // switch inst controls which handler (if any) gets called and the
95 // value is the value returned to that handler by the call to
96 // __llvm_sjljeh_get_longjmp_value.
97 std::map<const Function*, SwitchValuePair> SwitchValMap;
98
99 // A map of which setjmps we've seen so far in a function.
100 std::map<const Function*, unsigned> SetJmpIDMap;
101
102 AllocaInst* GetSetJmpMap(Function* Func);
103 BasicBlock* GetRethrowBB(Function* Func);
104 SwitchValuePair GetSJSwitch(Function* Func, BasicBlock* Rethrow);
105
106 void TransformLongJmpCall(CallInst* Inst);
107 void TransformSetJmpCall(CallInst* Inst);
108
Benjamin Kramer419e44e2009-11-03 12:52:50 +0000109 bool IsTransformableFunction(StringRef Name);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000110 public:
Nick Lewyckyecd94c82007-05-06 13:37:16 +0000111 static char ID; // Pass identification, replacement for typeid
Owen Anderson90c579d2010-08-06 18:33:48 +0000112 LowerSetJmp() : ModulePass(ID) {}
Devang Patel794fd752007-05-01 21:15:47 +0000113
Chris Lattner6420f1c2003-09-15 04:56:27 +0000114 void visitCallInst(CallInst& CI);
115 void visitInvokeInst(InvokeInst& II);
116 void visitReturnInst(ReturnInst& RI);
117 void visitUnwindInst(UnwindInst& UI);
118
Chris Lattnerb12914b2004-09-20 04:48:05 +0000119 bool runOnModule(Module& M);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000120 bool doInitialization(Module& M);
121 };
Chris Lattner6420f1c2003-09-15 04:56:27 +0000122} // end anonymous namespace
123
Dan Gohman844731a2008-05-13 00:00:25 +0000124char LowerSetJmp::ID = 0;
Owen Andersond13db2c2010-07-21 22:09:45 +0000125INITIALIZE_PASS(LowerSetJmp, "lowersetjmp", "Lower Set Jump", false, false);
Dan Gohman844731a2008-05-13 00:00:25 +0000126
Chris Lattner6420f1c2003-09-15 04:56:27 +0000127// run - Run the transformation on the program. We grab the function
128// prototypes for longjmp and setjmp. If they are used in the program,
129// then we can go directly to the places they're at and transform them.
Chris Lattnerb12914b2004-09-20 04:48:05 +0000130bool LowerSetJmp::runOnModule(Module& M) {
Chris Lattner6420f1c2003-09-15 04:56:27 +0000131 bool Changed = false;
132
133 // These are what the functions are called.
Reid Spencer688b0492007-02-05 21:19:13 +0000134 Function* SetJmp = M.getFunction("llvm.setjmp");
135 Function* LongJmp = M.getFunction("llvm.longjmp");
Chris Lattner6420f1c2003-09-15 04:56:27 +0000136
137 // This program doesn't have longjmp and setjmp calls.
138 if ((!LongJmp || LongJmp->use_empty()) &&
139 (!SetJmp || SetJmp->use_empty())) return false;
140
141 // Initialize some values and functions we'll need to transform the
142 // setjmp/longjmp functions.
143 doInitialization(M);
144
Chris Lattnerbb2d4de2003-10-13 00:57:16 +0000145 if (SetJmp) {
Chris Lattnerbb2d4de2003-10-13 00:57:16 +0000146 for (Value::use_iterator B = SetJmp->use_begin(), E = SetJmp->use_end();
147 B != E; ++B) {
Chris Lattner6d3906b2003-10-13 01:02:33 +0000148 BasicBlock* BB = cast<Instruction>(*B)->getParent();
Chris Lattner8b716f62003-10-13 16:49:21 +0000149 for (df_ext_iterator<BasicBlock*> I = df_ext_begin(BB, DFSBlocks),
150 E = df_ext_end(BB, DFSBlocks); I != E; ++I)
Chris Lattner46e033d2003-10-13 16:44:50 +0000151 /* empty */;
Chris Lattnerbb2d4de2003-10-13 00:57:16 +0000152 }
153
Chris Lattner6420f1c2003-09-15 04:56:27 +0000154 while (!SetJmp->use_empty()) {
155 assert(isa<CallInst>(SetJmp->use_back()) &&
156 "User of setjmp intrinsic not a call?");
157 TransformSetJmpCall(cast<CallInst>(SetJmp->use_back()));
158 Changed = true;
159 }
Chris Lattnerbb2d4de2003-10-13 00:57:16 +0000160 }
Chris Lattner6420f1c2003-09-15 04:56:27 +0000161
162 if (LongJmp)
163 while (!LongJmp->use_empty()) {
164 assert(isa<CallInst>(LongJmp->use_back()) &&
165 "User of longjmp intrinsic not a call?");
166 TransformLongJmpCall(cast<CallInst>(LongJmp->use_back()));
167 Changed = true;
168 }
169
170 // Now go through the affected functions and convert calls and invokes
171 // to new invokes...
172 for (std::map<Function*, AllocaInst*>::iterator
173 B = SJMap.begin(), E = SJMap.end(); B != E; ++B) {
174 Function* F = B->first;
175 for (Function::iterator BB = F->begin(), BE = F->end(); BB != BE; ++BB)
176 for (BasicBlock::iterator IB = BB->begin(), IE = BB->end(); IB != IE; ) {
177 visit(*IB++);
178 if (IB != BB->end() && IB->getParent() != BB)
179 break; // The next instruction got moved to a different block!
180 }
181 }
182
Chris Lattnerbb2d4de2003-10-13 00:57:16 +0000183 DFSBlocks.clear();
Chris Lattner6420f1c2003-09-15 04:56:27 +0000184 SJMap.clear();
185 RethrowBBMap.clear();
186 PrelimBBMap.clear();
187 SwitchValMap.clear();
188 SetJmpIDMap.clear();
189
190 return Changed;
191}
192
193// doInitialization - For the lower long/setjmp pass, this ensures that a
194// module contains a declaration for the intrisic functions we are going
195// to call to convert longjmp and setjmp calls.
196//
197// This function is always successful, unless it isn't.
198bool LowerSetJmp::doInitialization(Module& M)
199{
Duncan Sandsac53a0b2009-10-06 15:40:36 +0000200 const Type *SBPTy = Type::getInt8PtrTy(M.getContext());
Owen Andersondebcb012009-07-29 22:17:13 +0000201 const Type *SBPPTy = PointerType::getUnqual(SBPTy);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000202
203 // N.B. See llvm/runtime/GCCLibraries/libexception/SJLJ-Exception.h for
204 // a description of the following library functions.
205
206 // void __llvm_sjljeh_init_setjmpmap(void**)
207 InitSJMap = M.getOrInsertFunction("__llvm_sjljeh_init_setjmpmap",
Owen Anderson1d0be152009-08-13 21:58:54 +0000208 Type::getVoidTy(M.getContext()),
209 SBPPTy, (Type *)0);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000210 // void __llvm_sjljeh_destroy_setjmpmap(void**)
211 DestroySJMap = M.getOrInsertFunction("__llvm_sjljeh_destroy_setjmpmap",
Owen Anderson1d0be152009-08-13 21:58:54 +0000212 Type::getVoidTy(M.getContext()),
213 SBPPTy, (Type *)0);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000214
215 // void __llvm_sjljeh_add_setjmp_to_map(void**, void*, unsigned)
216 AddSJToMap = M.getOrInsertFunction("__llvm_sjljeh_add_setjmp_to_map",
Owen Anderson1d0be152009-08-13 21:58:54 +0000217 Type::getVoidTy(M.getContext()),
218 SBPPTy, SBPTy,
219 Type::getInt32Ty(M.getContext()),
220 (Type *)0);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000221
222 // void __llvm_sjljeh_throw_longjmp(int*, int)
223 ThrowLongJmp = M.getOrInsertFunction("__llvm_sjljeh_throw_longjmp",
Owen Anderson1d0be152009-08-13 21:58:54 +0000224 Type::getVoidTy(M.getContext()), SBPTy,
225 Type::getInt32Ty(M.getContext()),
Jeff Cohen66c5fd62005-10-23 04:37:20 +0000226 (Type *)0);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000227
228 // unsigned __llvm_sjljeh_try_catching_longjmp_exception(void **)
229 TryCatchLJ =
230 M.getOrInsertFunction("__llvm_sjljeh_try_catching_longjmp_exception",
Owen Anderson1d0be152009-08-13 21:58:54 +0000231 Type::getInt32Ty(M.getContext()), SBPPTy, (Type *)0);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000232
233 // bool __llvm_sjljeh_is_longjmp_exception()
234 IsLJException = M.getOrInsertFunction("__llvm_sjljeh_is_longjmp_exception",
Owen Anderson1d0be152009-08-13 21:58:54 +0000235 Type::getInt1Ty(M.getContext()),
236 (Type *)0);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000237
238 // int __llvm_sjljeh_get_longjmp_value()
239 GetLJValue = M.getOrInsertFunction("__llvm_sjljeh_get_longjmp_value",
Owen Anderson1d0be152009-08-13 21:58:54 +0000240 Type::getInt32Ty(M.getContext()),
241 (Type *)0);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000242 return true;
243}
244
245// IsTransformableFunction - Return true if the function name isn't one
246// of the ones we don't want transformed. Currently, don't transform any
247// "llvm.{setjmp,longjmp}" functions and none of the setjmp/longjmp error
248// handling functions (beginning with __llvm_sjljeh_...they don't throw
249// exceptions).
Benjamin Kramer419e44e2009-11-03 12:52:50 +0000250bool LowerSetJmp::IsTransformableFunction(StringRef Name) {
251 return !Name.startswith("__llvm_sjljeh_");
Chris Lattner6420f1c2003-09-15 04:56:27 +0000252}
253
254// TransformLongJmpCall - Transform a longjmp call into a call to the
255// internal __llvm_sjljeh_throw_longjmp function. It then takes care of
256// throwing the exception for us.
257void LowerSetJmp::TransformLongJmpCall(CallInst* Inst)
258{
Benjamin Kramer419e44e2009-11-03 12:52:50 +0000259 const Type* SBPTy = Type::getInt8PtrTy(Inst->getContext());
Chris Lattner6420f1c2003-09-15 04:56:27 +0000260
261 // Create the call to "__llvm_sjljeh_throw_longjmp". This takes the
262 // same parameters as "longjmp", except that the buffer is cast to a
263 // char*. It returns "void", so it doesn't need to replace any of
264 // Inst's uses and doesn't get a name.
Reid Spencer3da59db2006-11-27 01:05:10 +0000265 CastInst* CI =
Gabor Greiffef8c4e2010-06-24 14:13:36 +0000266 new BitCastInst(Inst->getArgOperand(0), SBPTy, "LJBuf", Inst);
267 Value *Args[] = { CI, Inst->getArgOperand(1) };
Benjamin Kramer419e44e2009-11-03 12:52:50 +0000268 CallInst::Create(ThrowLongJmp, Args, Args + 2, "", Inst);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000269
270 SwitchValuePair& SVP = SwitchValMap[Inst->getParent()->getParent()];
271
272 // If the function has a setjmp call in it (they are transformed first)
273 // we should branch to the basic block that determines if this longjmp
274 // is applicable here. Otherwise, issue an unwind.
275 if (SVP.first)
Gabor Greif051a9502008-04-06 20:25:17 +0000276 BranchInst::Create(SVP.first->getParent(), Inst);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000277 else
Owen Anderson1d0be152009-08-13 21:58:54 +0000278 new UnwindInst(Inst->getContext(), Inst);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000279
Chris Lattner3987abd2005-05-05 15:47:43 +0000280 // Remove all insts after the branch/unwind inst. Go from back to front to
281 // avoid replaceAllUsesWith if possible.
282 BasicBlock *BB = Inst->getParent();
283 Instruction *Removed;
284 do {
285 Removed = &BB->back();
286 // If the removed instructions have any users, replace them now.
287 if (!Removed->use_empty())
Owen Anderson9e9a0d52009-07-30 23:03:37 +0000288 Removed->replaceAllUsesWith(UndefValue::get(Removed->getType()));
Chris Lattner3987abd2005-05-05 15:47:43 +0000289 Removed->eraseFromParent();
290 } while (Removed != Inst);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000291
292 ++LongJmpsTransformed;
293}
294
295// GetSetJmpMap - Retrieve (create and initialize, if necessary) the
296// setjmp map. This map is going to hold information about which setjmps
297// were called (each setjmp gets its own number) and with which buffer it
298// was called. There can be only one!
299AllocaInst* LowerSetJmp::GetSetJmpMap(Function* Func)
300{
301 if (SJMap[Func]) return SJMap[Func];
302
303 // Insert the setjmp map initialization before the first instruction in
304 // the function.
Chris Lattner02a3be02003-09-20 14:39:18 +0000305 Instruction* Inst = Func->getEntryBlock().begin();
Chris Lattner6420f1c2003-09-15 04:56:27 +0000306 assert(Inst && "Couldn't find even ONE instruction in entry block!");
307
308 // Fill in the alloca and call to initialize the SJ map.
Owen Anderson1d0be152009-08-13 21:58:54 +0000309 const Type *SBPTy =
Duncan Sandsac53a0b2009-10-06 15:40:36 +0000310 Type::getInt8PtrTy(Func->getContext());
Owen Anderson50dead02009-07-15 23:53:25 +0000311 AllocaInst* Map = new AllocaInst(SBPTy, 0, "SJMap", Inst);
Gabor Greif051a9502008-04-06 20:25:17 +0000312 CallInst::Create(InitSJMap, Map, "", Inst);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000313 return SJMap[Func] = Map;
314}
315
316// GetRethrowBB - Only one rethrow basic block is needed per function.
317// If this is a longjmp exception but not handled in this block, this BB
318// performs the rethrow.
319BasicBlock* LowerSetJmp::GetRethrowBB(Function* Func)
320{
321 if (RethrowBBMap[Func]) return RethrowBBMap[Func];
322
323 // The basic block we're going to jump to if we need to rethrow the
324 // exception.
Owen Anderson1d0be152009-08-13 21:58:54 +0000325 BasicBlock* Rethrow =
326 BasicBlock::Create(Func->getContext(), "RethrowExcept", Func);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000327
328 // Fill in the "Rethrow" BB with a call to rethrow the exception. This
329 // is the last instruction in the BB since at this point the runtime
330 // should exit this function and go to the next function.
Owen Anderson1d0be152009-08-13 21:58:54 +0000331 new UnwindInst(Func->getContext(), Rethrow);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000332 return RethrowBBMap[Func] = Rethrow;
333}
334
335// GetSJSwitch - Return the switch statement that controls which handler
336// (if any) gets called and the value returned to that handler.
337LowerSetJmp::SwitchValuePair LowerSetJmp::GetSJSwitch(Function* Func,
338 BasicBlock* Rethrow)
339{
340 if (SwitchValMap[Func].first) return SwitchValMap[Func];
341
Owen Anderson1d0be152009-08-13 21:58:54 +0000342 BasicBlock* LongJmpPre =
343 BasicBlock::Create(Func->getContext(), "LongJmpBlkPre", Func);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000344
345 // Keep track of the preliminary basic block for some of the other
346 // transformations.
347 PrelimBBMap[Func] = LongJmpPre;
348
349 // Grab the exception.
Dan Gohman52d36e62008-06-19 17:53:32 +0000350 CallInst* Cond = CallInst::Create(IsLJException, "IsLJExcept", LongJmpPre);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000351
352 // The "decision basic block" gets the number associated with the
353 // setjmp call returning to switch on and the value returned by
354 // longjmp.
Owen Anderson1d0be152009-08-13 21:58:54 +0000355 BasicBlock* DecisionBB =
356 BasicBlock::Create(Func->getContext(), "LJDecisionBB", Func);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000357
Gabor Greif051a9502008-04-06 20:25:17 +0000358 BranchInst::Create(DecisionBB, Rethrow, Cond, LongJmpPre);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000359
360 // Fill in the "decision" basic block.
Dan Gohman52d36e62008-06-19 17:53:32 +0000361 CallInst* LJVal = CallInst::Create(GetLJValue, "LJVal", DecisionBB);
362 CallInst* SJNum = CallInst::Create(TryCatchLJ, GetSetJmpMap(Func), "SJNum",
363 DecisionBB);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000364
Gabor Greif051a9502008-04-06 20:25:17 +0000365 SwitchInst* SI = SwitchInst::Create(SJNum, Rethrow, 0, DecisionBB);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000366 return SwitchValMap[Func] = SwitchValuePair(SI, LJVal);
367}
368
369// TransformSetJmpCall - The setjmp call is a bit trickier to transform.
370// We're going to convert all setjmp calls to nops. Then all "call" and
371// "invoke" instructions in the function are converted to "invoke" where
372// the "except" branch is used when returning from a longjmp call.
373void LowerSetJmp::TransformSetJmpCall(CallInst* Inst)
374{
375 BasicBlock* ABlock = Inst->getParent();
376 Function* Func = ABlock->getParent();
377
378 // Add this setjmp to the setjmp map.
Owen Anderson1d0be152009-08-13 21:58:54 +0000379 const Type* SBPTy =
Duncan Sandsac53a0b2009-10-06 15:40:36 +0000380 Type::getInt8PtrTy(Inst->getContext());
Reid Spencer3da59db2006-11-27 01:05:10 +0000381 CastInst* BufPtr =
Gabor Greiffef8c4e2010-06-24 14:13:36 +0000382 new BitCastInst(Inst->getArgOperand(0), SBPTy, "SBJmpBuf", Inst);
Benjamin Kramer419e44e2009-11-03 12:52:50 +0000383 Value *Args[] = {
384 GetSetJmpMap(Func), BufPtr,
385 ConstantInt::get(Type::getInt32Ty(Inst->getContext()), SetJmpIDMap[Func]++)
386 };
387 CallInst::Create(AddSJToMap, Args, Args + 3, "", Inst);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000388
Chris Lattnerd7222ec2003-11-06 19:18:49 +0000389 // We are guaranteed that there are no values live across basic blocks
390 // (because we are "not in SSA form" yet), but there can still be values live
391 // in basic blocks. Because of this, splitting the setjmp block can cause
392 // values above the setjmp to not dominate uses which are after the setjmp
393 // call. For all of these occasions, we must spill the value to the stack.
394 //
395 std::set<Instruction*> InstrsAfterCall;
396
397 // The call is probably very close to the end of the basic block, for the
398 // common usage pattern of: 'if (setjmp(...))', so keep track of the
399 // instructions after the call.
400 for (BasicBlock::iterator I = ++BasicBlock::iterator(Inst), E = ABlock->end();
401 I != E; ++I)
Misha Brukmanfd939082005-04-21 23:48:37 +0000402 InstrsAfterCall.insert(I);
Chris Lattnerd7222ec2003-11-06 19:18:49 +0000403
404 for (BasicBlock::iterator II = ABlock->begin();
405 II != BasicBlock::iterator(Inst); ++II)
406 // Loop over all of the uses of instruction. If any of them are after the
407 // call, "spill" the value to the stack.
408 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
Gabor Greifb7df5002010-07-12 14:12:11 +0000409 UI != E; ++UI) {
410 User *U = *UI;
411 if (cast<Instruction>(U)->getParent() != ABlock ||
412 InstrsAfterCall.count(cast<Instruction>(U))) {
Owen Anderson50dead02009-07-15 23:53:25 +0000413 DemoteRegToStack(*II);
Chris Lattnerd7222ec2003-11-06 19:18:49 +0000414 break;
415 }
Gabor Greifb7df5002010-07-12 14:12:11 +0000416 }
Chris Lattnerd7222ec2003-11-06 19:18:49 +0000417 InstrsAfterCall.clear();
418
Chris Lattner6420f1c2003-09-15 04:56:27 +0000419 // Change the setjmp call into a branch statement. We'll remove the
420 // setjmp call in a little bit. No worries.
421 BasicBlock* SetJmpContBlock = ABlock->splitBasicBlock(Inst);
422 assert(SetJmpContBlock && "Couldn't split setjmp BB!!");
423
Chris Lattnercb2d1a22005-04-21 16:46:46 +0000424 SetJmpContBlock->setName(ABlock->getName()+"SetJmpCont");
425
426 // Add the SetJmpContBlock to the set of blocks reachable from a setjmp.
427 DFSBlocks.insert(SetJmpContBlock);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000428
Chris Lattner6420f1c2003-09-15 04:56:27 +0000429 // This PHI node will be in the new block created from the
430 // splitBasicBlock call.
Owen Anderson1d0be152009-08-13 21:58:54 +0000431 PHINode* PHI = PHINode::Create(Type::getInt32Ty(Inst->getContext()),
432 "SetJmpReturn", Inst);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000433
434 // Coming from a call to setjmp, the return is 0.
Owen Anderson1d0be152009-08-13 21:58:54 +0000435 PHI->addIncoming(Constant::getNullValue(Type::getInt32Ty(Inst->getContext())),
436 ABlock);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000437
438 // Add the case for this setjmp's number...
439 SwitchValuePair SVP = GetSJSwitch(Func, GetRethrowBB(Func));
Owen Anderson1d0be152009-08-13 21:58:54 +0000440 SVP.first->addCase(ConstantInt::get(Type::getInt32Ty(Inst->getContext()),
441 SetJmpIDMap[Func] - 1),
Owen Andersoneed707b2009-07-24 23:12:02 +0000442 SetJmpContBlock);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000443
444 // Value coming from the handling of the exception.
445 PHI->addIncoming(SVP.second, SVP.second->getParent());
446
447 // Replace all uses of this instruction with the PHI node created by
448 // the eradication of setjmp.
449 Inst->replaceAllUsesWith(PHI);
Dan Gohman1adec832008-06-21 22:08:46 +0000450 Inst->eraseFromParent();
Chris Lattner6420f1c2003-09-15 04:56:27 +0000451
452 ++SetJmpsTransformed;
453}
454
455// visitCallInst - This converts all LLVM call instructions into invoke
456// instructions. The except part of the invoke goes to the "LongJmpBlkPre"
457// that grabs the exception and proceeds to determine if it's a longjmp
458// exception or not.
459void LowerSetJmp::visitCallInst(CallInst& CI)
460{
461 if (CI.getCalledFunction())
462 if (!IsTransformableFunction(CI.getCalledFunction()->getName()) ||
463 CI.getCalledFunction()->isIntrinsic()) return;
464
465 BasicBlock* OldBB = CI.getParent();
Chris Lattnerbb2d4de2003-10-13 00:57:16 +0000466
467 // If not reachable from a setjmp call, don't transform.
468 if (!DFSBlocks.count(OldBB)) return;
469
Chris Lattner6420f1c2003-09-15 04:56:27 +0000470 BasicBlock* NewBB = OldBB->splitBasicBlock(CI);
471 assert(NewBB && "Couldn't split BB of \"call\" instruction!!");
Chris Lattnerd286b242005-06-15 22:49:30 +0000472 DFSBlocks.insert(NewBB);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000473 NewBB->setName("Call2Invoke");
474
Chris Lattner6d3906b2003-10-13 01:02:33 +0000475 Function* Func = OldBB->getParent();
Chris Lattner6420f1c2003-09-15 04:56:27 +0000476
477 // Construct the new "invoke" instruction.
478 TerminatorInst* Term = OldBB->getTerminator();
Gabor Greiffef8c4e2010-06-24 14:13:36 +0000479 CallSite CS(&CI);
480 std::vector<Value*> Params(CS.arg_begin(), CS.arg_end());
Gabor Greif051a9502008-04-06 20:25:17 +0000481 InvokeInst* II =
482 InvokeInst::Create(CI.getCalledValue(), NewBB, PrelimBBMap[Func],
483 Params.begin(), Params.end(), CI.getName(), Term);
Duncan Sandsdc024672007-11-27 13:23:08 +0000484 II->setCallingConv(CI.getCallingConv());
Devang Patel05988662008-09-25 21:00:45 +0000485 II->setAttributes(CI.getAttributes());
Chris Lattner6420f1c2003-09-15 04:56:27 +0000486
487 // Replace the old call inst with the invoke inst and remove the call.
488 CI.replaceAllUsesWith(II);
Dan Gohman1adec832008-06-21 22:08:46 +0000489 CI.eraseFromParent();
Chris Lattner6420f1c2003-09-15 04:56:27 +0000490
491 // The old terminator is useless now that we have the invoke inst.
Dan Gohman1adec832008-06-21 22:08:46 +0000492 Term->eraseFromParent();
Chris Lattnerfe2143d2003-10-28 23:14:59 +0000493 ++CallsTransformed;
Chris Lattner6420f1c2003-09-15 04:56:27 +0000494}
495
496// visitInvokeInst - Converting the "invoke" instruction is fairly
497// straight-forward. The old exception part is replaced by a query asking
498// if this is a longjmp exception. If it is, then it goes to the longjmp
499// exception blocks. Otherwise, control is passed the old exception.
500void LowerSetJmp::visitInvokeInst(InvokeInst& II)
501{
502 if (II.getCalledFunction())
503 if (!IsTransformableFunction(II.getCalledFunction()->getName()) ||
504 II.getCalledFunction()->isIntrinsic()) return;
505
Chris Lattnerbb2d4de2003-10-13 00:57:16 +0000506 BasicBlock* BB = II.getParent();
Chris Lattnerbb2d4de2003-10-13 00:57:16 +0000507
508 // If not reachable from a setjmp call, don't transform.
509 if (!DFSBlocks.count(BB)) return;
Chris Lattner6420f1c2003-09-15 04:56:27 +0000510
Chris Lattneraeb2a1d2004-02-08 21:44:31 +0000511 BasicBlock* ExceptBB = II.getUnwindDest();
Chris Lattner6420f1c2003-09-15 04:56:27 +0000512
Chris Lattner6d3906b2003-10-13 01:02:33 +0000513 Function* Func = BB->getParent();
Owen Anderson1d0be152009-08-13 21:58:54 +0000514 BasicBlock* NewExceptBB = BasicBlock::Create(II.getContext(),
515 "InvokeExcept", Func);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000516
517 // If this is a longjmp exception, then branch to the preliminary BB of
518 // the longjmp exception handling. Otherwise, go to the old exception.
Dan Gohman52d36e62008-06-19 17:53:32 +0000519 CallInst* IsLJExcept = CallInst::Create(IsLJException, "IsLJExcept",
520 NewExceptBB);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000521
Gabor Greif051a9502008-04-06 20:25:17 +0000522 BranchInst::Create(PrelimBBMap[Func], ExceptBB, IsLJExcept, NewExceptBB);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000523
Chris Lattneraeb2a1d2004-02-08 21:44:31 +0000524 II.setUnwindDest(NewExceptBB);
Chris Lattnerfe2143d2003-10-28 23:14:59 +0000525 ++InvokesTransformed;
Chris Lattner6420f1c2003-09-15 04:56:27 +0000526}
527
528// visitReturnInst - We want to destroy the setjmp map upon exit from the
529// function.
Chris Lattnerb12914b2004-09-20 04:48:05 +0000530void LowerSetJmp::visitReturnInst(ReturnInst &RI) {
Chris Lattner6420f1c2003-09-15 04:56:27 +0000531 Function* Func = RI.getParent()->getParent();
Gabor Greif051a9502008-04-06 20:25:17 +0000532 CallInst::Create(DestroySJMap, GetSetJmpMap(Func), "", &RI);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000533}
534
535// visitUnwindInst - We want to destroy the setjmp map upon exit from the
536// function.
Chris Lattnerb12914b2004-09-20 04:48:05 +0000537void LowerSetJmp::visitUnwindInst(UnwindInst &UI) {
Chris Lattner6420f1c2003-09-15 04:56:27 +0000538 Function* Func = UI.getParent()->getParent();
Gabor Greif051a9502008-04-06 20:25:17 +0000539 CallInst::Create(DestroySJMap, GetSetJmpMap(Func), "", &UI);
Chris Lattner6420f1c2003-09-15 04:56:27 +0000540}
541
Chris Lattnerb12914b2004-09-20 04:48:05 +0000542ModulePass *llvm::createLowerSetJmpPass() {
Chris Lattner6420f1c2003-09-15 04:56:27 +0000543 return new LowerSetJmp();
544}
Brian Gaeked0fde302003-11-11 22:41:34 +0000545