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| 1 //===- LowerEmExceptions - Lower exceptions for Emscripten/JS -----------===// | |
| 2 // | |
| 3 // The LLVM Compiler Infrastructure | |
| 4 // | |
| 5 // This file is distributed under the University of Illinois Open Source | |
| 6 // License. See LICENSE.TXT for details. | |
| 7 // | |
| 8 //===----------------------------------------------------------------------===// | |
| 9 // | |
| 10 // This is based off the 'cheap' version of LowerInvoke. It does two things: | |
| 11 // | |
| 12 // 1) Lower | |
| 13 // invoke() to l1 unwind l2 | |
| 14 // into | |
| 15 // preinvoke(); // (will clear __THREW__) | |
| 16 // call(); | |
| 17 // threw = postinvoke(); (check __THREW__) | |
| 18 // br threw, l1, l2 | |
| 19 // | |
| 20 // We do this to avoid introducing a new LLVM IR type, or to try to reuse | |
| 21 // invoke-landingpad for our special purposes (as they are checked very | |
| 22 // carefully by llvm) | |
| 23 // | |
| 24 // 2) Lower landingpads to a call to emscripten_landingpad | |
| 25 // | |
| 26 // 3) Lower resume to emscripten_resume which receives non-aggregate inputs | |
| 27 // | |
| 28 //===----------------------------------------------------------------------===// | |
| 29 | |
| 30 #include "llvm/Transforms/Scalar.h" | |
| 31 #include "llvm/ADT/SmallVector.h" | |
| 32 #include "llvm/ADT/Statistic.h" | |
| 33 #include "llvm/IR/Constants.h" | |
| 34 #include "llvm/IR/DerivedTypes.h" | |
| 35 #include "llvm/IR/Instructions.h" | |
| 36 #include "llvm/IR/Intrinsics.h" | |
| 37 #include "llvm/IR/LLVMContext.h" | |
| 38 #include "llvm/IR/Module.h" | |
| 39 #include "llvm/Pass.h" | |
| 40 #include "llvm/Support/CommandLine.h" | |
| 41 #include "llvm/Target/TargetLowering.h" | |
| 42 #include "llvm/Transforms/Utils/BasicBlockUtils.h" | |
| 43 #include "llvm/Transforms/Utils/Local.h" | |
| 44 #include "llvm/Transforms/NaCl.h" | |
| 45 #include "llvm/Support/raw_ostream.h" | |
| 46 | |
| 47 #include <vector> | |
| 48 #include <set> | |
| 49 | |
| 50 #ifdef NDEBUG | |
| 51 #undef assert | |
| 52 #define assert(x) { if (!(x)) report_fatal_error(#x); } | |
| 53 #endif | |
| 54 | |
| 55 using namespace llvm; | |
| 56 | |
| 57 static cl::list<std::string> | |
| 58 Whitelist("emscripten-cxx-exceptions-whitelist", | |
| 59 cl::desc("Enables C++ exceptions in emscripten (see emscripten EXCEPTI
ON_CATCHING_WHITELIST option)"), | |
| 60 cl::CommaSeparated); | |
| 61 | |
| 62 namespace { | |
| 63 class LowerEmExceptions : public ModulePass { | |
| 64 Function *GetHigh, *PreInvoke, *PostInvoke, *LandingPad, *Resume; | |
| 65 Module *TheModule; | |
| 66 | |
| 67 public: | |
| 68 static char ID; // Pass identification, replacement for typeid | |
| 69 explicit LowerEmExceptions() : ModulePass(ID), GetHigh(NULL), PreInvoke(NULL
), PostInvoke(NULL), LandingPad(NULL), Resume(NULL), TheModule(NULL) { | |
| 70 initializeLowerEmExceptionsPass(*PassRegistry::getPassRegistry()); | |
| 71 } | |
| 72 bool runOnModule(Module &M); | |
| 73 }; | |
| 74 } | |
| 75 | |
| 76 char LowerEmExceptions::ID = 0; | |
| 77 INITIALIZE_PASS(LowerEmExceptions, "loweremexceptions", | |
| 78 "Lower invoke and unwind for js/emscripten", | |
| 79 false, false) | |
| 80 | |
| 81 bool canThrow(Value *V) { | |
| 82 if (Function *F = dyn_cast<Function>(V)) { | |
| 83 // intrinsics and some emscripten builtins cannot throw | |
| 84 if (F->isIntrinsic()) return false; | |
| 85 StringRef Name = F->getName(); | |
| 86 if (Name.startswith("emscripten_asm_")) return false; | |
| 87 if (Name == "setjmp" || Name == "longjmp") return false; // leave setjmp and
longjmp (mostly) alone, we process them properly later | |
| 88 return true; | |
| 89 } | |
| 90 return true; // not a function, so an indirect call - can throw, we can't tell | |
| 91 } | |
| 92 | |
| 93 bool LowerEmExceptions::runOnModule(Module &M) { | |
| 94 TheModule = &M; | |
| 95 | |
| 96 // Add functions | |
| 97 | |
| 98 Type *i32 = Type::getInt32Ty(M.getContext()); | |
| 99 Type *i8 = Type::getInt8Ty(M.getContext()); | |
| 100 Type *i1 = Type::getInt1Ty(M.getContext()); | |
| 101 Type *i8P = i8->getPointerTo(); | |
| 102 Type *Void = Type::getVoidTy(M.getContext()); | |
| 103 | |
| 104 if (!(GetHigh = TheModule->getFunction("getHigh32"))) { | |
| 105 FunctionType *GetHighFunc = FunctionType::get(i32, false); | |
| 106 GetHigh = Function::Create(GetHighFunc, GlobalValue::ExternalLinkage, | |
| 107 "getHigh32", TheModule); | |
| 108 } | |
| 109 | |
| 110 if (!(PreInvoke = TheModule->getFunction("emscripten_preinvoke"))) { | |
| 111 FunctionType *VoidFunc = FunctionType::get(Void, false); | |
| 112 PreInvoke = Function::Create(VoidFunc, GlobalValue::ExternalLinkage, "emscri
pten_preinvoke", TheModule); | |
| 113 } | |
| 114 | |
| 115 if (!(PostInvoke = TheModule->getFunction("emscripten_postinvoke"))) { | |
| 116 FunctionType *IntFunc = FunctionType::get(i32, false); | |
| 117 PostInvoke = Function::Create(IntFunc, GlobalValue::ExternalLinkage, "emscri
pten_postinvoke", TheModule); | |
| 118 } | |
| 119 | |
| 120 FunctionType *LandingPadFunc = FunctionType::get(i8P, true); | |
| 121 LandingPad = Function::Create(LandingPadFunc, GlobalValue::ExternalLinkage, "e
mscripten_landingpad", TheModule); | |
| 122 | |
| 123 FunctionType *ResumeFunc = FunctionType::get(Void, true); | |
| 124 Resume = Function::Create(ResumeFunc, GlobalValue::ExternalLinkage, "emscripte
n_resume", TheModule); | |
| 125 | |
| 126 // Process | |
| 127 | |
| 128 std::set<std::string> WhitelistSet(Whitelist.begin(), Whitelist.end()); | |
| 129 | |
| 130 bool Changed = false; | |
| 131 | |
| 132 for (Module::iterator Iter = M.begin(), E = M.end(); Iter != E; ) { | |
| 133 Function *F = Iter++; | |
| 134 | |
| 135 std::vector<Instruction*> ToErase; | |
| 136 std::set<LandingPadInst*> LandingPads; | |
| 137 | |
| 138 bool AllowExceptionsInFunc = WhitelistSet.empty() || (WhitelistSet.count("_"
+ F->getName().str()) != 0); | |
| 139 | |
| 140 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { | |
| 141 // check terminator for invokes | |
| 142 if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) { | |
| 143 LandingPads.insert(II->getLandingPadInst()); | |
| 144 | |
| 145 bool NeedInvoke = AllowExceptionsInFunc && canThrow(II->getCalledValue()
); | |
| 146 | |
| 147 if (NeedInvoke) { | |
| 148 // If we are calling a function that is noreturn, we must remove that
attribute. The code we | |
| 149 // insert here does expect it to return, after we catch the exception. | |
| 150 if (II->doesNotReturn()) { | |
| 151 if (Function *F = dyn_cast<Function>(II->getCalledValue())) { | |
| 152 F->removeFnAttr(Attribute::NoReturn); | |
| 153 } | |
| 154 II->setAttributes(II->getAttributes().removeAttribute(TheModule->get
Context(), AttributeSet::FunctionIndex, Attribute::NoReturn)); | |
| 155 assert(!II->doesNotReturn()); | |
| 156 } | |
| 157 | |
| 158 // Insert a normal call instruction folded in between pre- and post-in
voke | |
| 159 CallInst::Create(PreInvoke, "", II); | |
| 160 | |
| 161 SmallVector<Value*,16> CallArgs(II->op_begin(), II->op_end() - 3); | |
| 162 CallInst *NewCall = CallInst::Create(II->getCalledValue(), | |
| 163 CallArgs, "", II); | |
| 164 NewCall->takeName(II); | |
| 165 NewCall->setCallingConv(II->getCallingConv()); | |
| 166 NewCall->setAttributes(II->getAttributes()); | |
| 167 NewCall->setDebugLoc(II->getDebugLoc()); | |
| 168 II->replaceAllUsesWith(NewCall); | |
| 169 ToErase.push_back(II); | |
| 170 | |
| 171 CallInst *Post = CallInst::Create(PostInvoke, "", II); | |
| 172 Instruction *Post1 = new TruncInst(Post, i1, "", II); | |
| 173 | |
| 174 // Insert a branch based on the postInvoke | |
| 175 BranchInst::Create(II->getUnwindDest(), II->getNormalDest(), Post1, II
); | |
| 176 } else { | |
| 177 // This can't throw, and we don't need this invoke, just replace it wi
th a call+branch | |
| 178 SmallVector<Value*,16> CallArgs(II->op_begin(), II->op_end() - 3); | |
| 179 CallInst *NewCall = CallInst::Create(II->getCalledValue(), | |
| 180 CallArgs, "", II); | |
| 181 NewCall->takeName(II); | |
| 182 NewCall->setCallingConv(II->getCallingConv()); | |
| 183 NewCall->setAttributes(II->getAttributes()); | |
| 184 NewCall->setDebugLoc(II->getDebugLoc()); | |
| 185 II->replaceAllUsesWith(NewCall); | |
| 186 ToErase.push_back(II); | |
| 187 | |
| 188 BranchInst::Create(II->getNormalDest(), II); | |
| 189 | |
| 190 // Remove any PHI node entries from the exception destination. | |
| 191 II->getUnwindDest()->removePredecessor(BB); | |
| 192 } | |
| 193 | |
| 194 Changed = true; | |
| 195 } | |
| 196 // scan the body of the basic block for resumes | |
| 197 for (BasicBlock::iterator Iter = BB->begin(), E = BB->end(); | |
| 198 Iter != E; ) { | |
| 199 Instruction *I = Iter++; | |
| 200 if (ResumeInst *R = dyn_cast<ResumeInst>(I)) { | |
| 201 // split the input into legal values | |
| 202 Value *Input = R->getValue(); | |
| 203 ExtractValueInst *Low = ExtractValueInst::Create(Input, 0, "", R); | |
| 204 ExtractValueInst *High = ExtractValueInst::Create(Input, 1, "", R); | |
| 205 | |
| 206 // create a resume call | |
| 207 SmallVector<Value*,2> CallArgs; | |
| 208 CallArgs.push_back(Low); | |
| 209 CallArgs.push_back(High); | |
| 210 CallInst::Create(Resume, CallArgs, "", R); | |
| 211 | |
| 212 new UnreachableInst(TheModule->getContext(), R); // add a terminator t
o the block | |
| 213 | |
| 214 ToErase.push_back(R); | |
| 215 } | |
| 216 } | |
| 217 } | |
| 218 | |
| 219 // Look for orphan landingpads, can occur in blocks with no predecesors | |
| 220 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { | |
| 221 Instruction *I = BB->getFirstNonPHI(); | |
| 222 if (LandingPadInst *LP = dyn_cast<LandingPadInst>(I)) { | |
| 223 LandingPads.insert(LP); | |
| 224 } | |
| 225 } | |
| 226 | |
| 227 // Handle all the landingpad for this function together, as multiple invokes
may share a single lp | |
| 228 for (std::set<LandingPadInst*>::iterator I = LandingPads.begin(); I != Landi
ngPads.end(); I++) { | |
| 229 // Replace the landingpad with a landingpad call to get the low part, and
a getHigh for the high | |
| 230 LandingPadInst *LP = *I; | |
| 231 unsigned Num = LP->getNumClauses(); | |
| 232 SmallVector<Value*,16> NewLPArgs; | |
| 233 NewLPArgs.push_back(LP->getPersonalityFn()); | |
| 234 for (unsigned i = 0; i < Num; i++) { | |
| 235 Value *Arg = LP->getClause(i); | |
| 236 // As a temporary workaround for the lack of aggregate varargs support | |
| 237 // in the varargs lowering code, break out filter operands into their | |
| 238 // component elements. | |
| 239 if (LP->isFilter(i)) { | |
| 240 ArrayType *ATy = cast<ArrayType>(Arg->getType()); | |
| 241 for (unsigned elem = 0, elemEnd = ATy->getNumElements(); elem != elemE
nd; ++elem) { | |
| 242 Instruction *EE = ExtractValueInst::Create(Arg, makeArrayRef(elem),
"", LP); | |
| 243 NewLPArgs.push_back(EE); | |
| 244 } | |
| 245 } else { | |
| 246 NewLPArgs.push_back(Arg); | |
| 247 } | |
| 248 } | |
| 249 NewLPArgs.push_back(LP->isCleanup() ? ConstantInt::getTrue(i1) : ConstantI
nt::getFalse(i1)); | |
| 250 CallInst *NewLP = CallInst::Create(LandingPad, NewLPArgs, "", LP); | |
| 251 | |
| 252 Instruction *High = CallInst::Create(GetHigh, "", LP); | |
| 253 | |
| 254 // New recreate an aggregate for them, which will be all simplified later
(simplification cannot handle landingpad, hence all this) | |
| 255 InsertValueInst *IVA = InsertValueInst::Create(UndefValue::get(LP->getType
()), NewLP, 0, "", LP); | |
| 256 InsertValueInst *IVB = InsertValueInst::Create(IVA, High, 1, "", LP); | |
| 257 | |
| 258 LP->replaceAllUsesWith(IVB); | |
| 259 ToErase.push_back(LP); | |
| 260 } | |
| 261 | |
| 262 // erase everything we no longer need in this function | |
| 263 for (unsigned i = 0; i < ToErase.size(); i++) ToErase[i]->eraseFromParent(); | |
| 264 } | |
| 265 | |
| 266 return Changed; | |
| 267 } | |
| 268 | |
| 269 ModulePass *llvm::createLowerEmExceptionsPass() { | |
| 270 return new LowerEmExceptions(); | |
| 271 } | |
| 272 | |
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Chromium Code Reviews
Issue 1692803002:
Remove Emscripten support (Closed)
Base URL: https://chromium.googlesource.com/a/native_client/pnacl-llvm.git@master