diff options
Diffstat (limited to 'gnu/llvm/lib/Target/WebAssembly/WebAssemblyLowerGlobalDtors.cpp')
| -rw-r--r-- | gnu/llvm/lib/Target/WebAssembly/WebAssemblyLowerGlobalDtors.cpp | 190 |
1 files changed, 0 insertions, 190 deletions
diff --git a/gnu/llvm/lib/Target/WebAssembly/WebAssemblyLowerGlobalDtors.cpp b/gnu/llvm/lib/Target/WebAssembly/WebAssemblyLowerGlobalDtors.cpp deleted file mode 100644 index 84c877cb8d0..00000000000 --- a/gnu/llvm/lib/Target/WebAssembly/WebAssemblyLowerGlobalDtors.cpp +++ /dev/null @@ -1,190 +0,0 @@ -//===-- WebAssemblyLowerGlobalDtors.cpp - Lower @llvm.global_dtors --------===// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -/// -/// \file -/// Lower @llvm.global_dtors. -/// -/// WebAssembly doesn't have a builtin way to invoke static destructors. -/// Implement @llvm.global_dtors by creating wrapper functions that are -/// registered in @llvm.global_ctors and which contain a call to -/// `__cxa_atexit` to register their destructor functions. -/// -//===----------------------------------------------------------------------===// - -#include "WebAssembly.h" -#include "llvm/ADT/MapVector.h" -#include "llvm/IR/Constants.h" -#include "llvm/IR/Instructions.h" -#include "llvm/IR/Intrinsics.h" -#include "llvm/IR/Module.h" -#include "llvm/Pass.h" -#include "llvm/Support/Debug.h" -#include "llvm/Support/raw_ostream.h" -#include "llvm/Transforms/Utils/ModuleUtils.h" -using namespace llvm; - -#define DEBUG_TYPE "wasm-lower-global-dtors" - -namespace { -class LowerGlobalDtors final : public ModulePass { - StringRef getPassName() const override { - return "WebAssembly Lower @llvm.global_dtors"; - } - - void getAnalysisUsage(AnalysisUsage &AU) const override { - AU.setPreservesCFG(); - ModulePass::getAnalysisUsage(AU); - } - - bool runOnModule(Module &M) override; - -public: - static char ID; - LowerGlobalDtors() : ModulePass(ID) {} -}; -} // End anonymous namespace - -char LowerGlobalDtors::ID = 0; -INITIALIZE_PASS(LowerGlobalDtors, DEBUG_TYPE, - "Lower @llvm.global_dtors for WebAssembly", false, false) - -ModulePass *llvm::createWebAssemblyLowerGlobalDtors() { - return new LowerGlobalDtors(); -} - -bool LowerGlobalDtors::runOnModule(Module &M) { - LLVM_DEBUG(dbgs() << "********** Lower Global Destructors **********\n"); - - GlobalVariable *GV = M.getGlobalVariable("llvm.global_dtors"); - if (!GV) - return false; - - const ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer()); - if (!InitList) - return false; - - // Sanity-check @llvm.global_dtor's type. - StructType *ETy = dyn_cast<StructType>(InitList->getType()->getElementType()); - if (!ETy || ETy->getNumElements() != 3 || - !ETy->getTypeAtIndex(0U)->isIntegerTy() || - !ETy->getTypeAtIndex(1U)->isPointerTy() || - !ETy->getTypeAtIndex(2U)->isPointerTy()) - return false; // Not (int, ptr, ptr). - - // Collect the contents of @llvm.global_dtors, collated by priority and - // associated symbol. - std::map<uint16_t, MapVector<Constant *, std::vector<Constant *>>> DtorFuncs; - for (Value *O : InitList->operands()) { - ConstantStruct *CS = dyn_cast<ConstantStruct>(O); - if (!CS) - continue; // Malformed. - - ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0)); - if (!Priority) - continue; // Malformed. - uint16_t PriorityValue = Priority->getLimitedValue(UINT16_MAX); - - Constant *DtorFunc = CS->getOperand(1); - if (DtorFunc->isNullValue()) - break; // Found a null terminator, skip the rest. - - Constant *Associated = CS->getOperand(2); - Associated = cast<Constant>(Associated->stripPointerCastsNoFollowAliases()); - - DtorFuncs[PriorityValue][Associated].push_back(DtorFunc); - } - if (DtorFuncs.empty()) - return false; - - // extern "C" int __cxa_atexit(void (*f)(void *), void *p, void *d); - LLVMContext &C = M.getContext(); - PointerType *VoidStar = Type::getInt8PtrTy(C); - Type *AtExitFuncArgs[] = {VoidStar}; - FunctionType *AtExitFuncTy = - FunctionType::get(Type::getVoidTy(C), AtExitFuncArgs, - /*isVarArg=*/false); - - Type *AtExitArgs[] = {PointerType::get(AtExitFuncTy, 0), VoidStar, VoidStar}; - FunctionType *AtExitTy = FunctionType::get(Type::getInt32Ty(C), AtExitArgs, - /*isVarArg=*/false); - Constant *AtExit = M.getOrInsertFunction("__cxa_atexit", AtExitTy); - - // Declare __dso_local. - Constant *DsoHandle = M.getNamedValue("__dso_handle"); - if (!DsoHandle) { - Type *DsoHandleTy = Type::getInt8Ty(C); - GlobalVariable *Handle = new GlobalVariable( - M, DsoHandleTy, /*isConstant=*/true, - GlobalVariable::ExternalWeakLinkage, nullptr, "__dso_handle"); - Handle->setVisibility(GlobalVariable::HiddenVisibility); - DsoHandle = Handle; - } - - // For each unique priority level and associated symbol, generate a function - // to call all the destructors at that level, and a function to register the - // first function with __cxa_atexit. - for (auto &PriorityAndMore : DtorFuncs) { - uint16_t Priority = PriorityAndMore.first; - for (auto &AssociatedAndMore : PriorityAndMore.second) { - Constant *Associated = AssociatedAndMore.first; - - Function *CallDtors = Function::Create( - AtExitFuncTy, Function::PrivateLinkage, - "call_dtors" + - (Priority != UINT16_MAX ? (Twine(".") + Twine(Priority)) - : Twine()) + - (!Associated->isNullValue() ? (Twine(".") + Associated->getName()) - : Twine()), - &M); - BasicBlock *BB = BasicBlock::Create(C, "body", CallDtors); - - for (auto Dtor : AssociatedAndMore.second) - CallInst::Create(Dtor, "", BB); - ReturnInst::Create(C, BB); - - FunctionType *VoidVoid = FunctionType::get(Type::getVoidTy(C), - /*isVarArg=*/false); - Function *RegisterCallDtors = Function::Create( - VoidVoid, Function::PrivateLinkage, - "register_call_dtors" + - (Priority != UINT16_MAX ? (Twine(".") + Twine(Priority)) - : Twine()) + - (!Associated->isNullValue() ? (Twine(".") + Associated->getName()) - : Twine()), - &M); - BasicBlock *EntryBB = BasicBlock::Create(C, "entry", RegisterCallDtors); - BasicBlock *FailBB = BasicBlock::Create(C, "fail", RegisterCallDtors); - BasicBlock *RetBB = BasicBlock::Create(C, "return", RegisterCallDtors); - - Value *Null = ConstantPointerNull::get(VoidStar); - Value *Args[] = {CallDtors, Null, DsoHandle}; - Value *Res = CallInst::Create(AtExit, Args, "call", EntryBB); - Value *Cmp = new ICmpInst(*EntryBB, ICmpInst::ICMP_NE, Res, - Constant::getNullValue(Res->getType())); - BranchInst::Create(FailBB, RetBB, Cmp, EntryBB); - - // If `__cxa_atexit` hits out-of-memory, trap, so that we don't misbehave. - // This should be very rare, because if the process is running out of - // memory before main has even started, something is wrong. - CallInst::Create(Intrinsic::getDeclaration(&M, Intrinsic::trap), "", - FailBB); - new UnreachableInst(C, FailBB); - - ReturnInst::Create(C, RetBB); - - // Now register the registration function with @llvm.global_ctors. - appendToGlobalCtors(M, RegisterCallDtors, Priority, Associated); - } - } - - // Now that we've lowered everything, remove @llvm.global_dtors. - GV->eraseFromParent(); - - return true; -} |