diff options
Diffstat (limited to 'contrib/llvm/lib/Target/WebAssembly')
4 files changed, 166 insertions, 2 deletions
diff --git a/contrib/llvm/lib/Target/WebAssembly/WebAssembly.h b/contrib/llvm/lib/Target/WebAssembly/WebAssembly.h index 09c35b4825fc..8738263ad847 100644 --- a/contrib/llvm/lib/Target/WebAssembly/WebAssembly.h +++ b/contrib/llvm/lib/Target/WebAssembly/WebAssembly.h @@ -28,6 +28,7 @@ class FunctionPass; // LLVM IR passes. ModulePass *createWebAssemblyLowerEmscriptenEHSjLj(bool DoEH, bool DoSjLj); void initializeWebAssemblyLowerEmscriptenEHSjLjPass(PassRegistry &); +ModulePass *createWebAssemblyFixFunctionBitcasts(); FunctionPass *createWebAssemblyOptimizeReturned(); // ISel and immediate followup passes. diff --git a/contrib/llvm/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp b/contrib/llvm/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp new file mode 100644 index 000000000000..d5474a02ce01 --- /dev/null +++ b/contrib/llvm/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp @@ -0,0 +1,159 @@ +//===-- WebAssemblyFixFunctionBitcasts.cpp - Fix function bitcasts --------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +/// +/// \file +/// \brief Fix bitcasted functions. +/// +/// WebAssembly requires caller and callee signatures to match, however in LLVM, +/// some amount of slop is vaguely permitted. Detect mismatch by looking for +/// bitcasts of functions and rewrite them to use wrapper functions instead. +/// +/// This doesn't catch all cases, such as when a function's address is taken in +/// one place and casted in another, but it works for many common cases. +/// +/// Note that LLVM already optimizes away function bitcasts in common cases by +/// dropping arguments as needed, so this pass only ends up getting used in less +/// common cases. +/// +//===----------------------------------------------------------------------===// + +#include "WebAssembly.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/Operator.h" +#include "llvm/Pass.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +using namespace llvm; + +#define DEBUG_TYPE "wasm-fix-function-bitcasts" + +namespace { +class FixFunctionBitcasts final : public ModulePass { + StringRef getPassName() const override { + return "WebAssembly Fix Function Bitcasts"; + } + + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.setPreservesCFG(); + ModulePass::getAnalysisUsage(AU); + } + + bool runOnModule(Module &M) override; + +public: + static char ID; + FixFunctionBitcasts() : ModulePass(ID) {} +}; +} // End anonymous namespace + +char FixFunctionBitcasts::ID = 0; +ModulePass *llvm::createWebAssemblyFixFunctionBitcasts() { + return new FixFunctionBitcasts(); +} + +// Recursively descend the def-use lists from V to find non-bitcast users of +// bitcasts of V. +static void FindUses(Value *V, Function &F, + SmallVectorImpl<std::pair<Use *, Function *>> &Uses) { + for (Use &U : V->uses()) { + if (BitCastOperator *BC = dyn_cast<BitCastOperator>(U.getUser())) + FindUses(BC, F, Uses); + else if (U.get()->getType() != F.getType()) + Uses.push_back(std::make_pair(&U, &F)); + } +} + +// Create a wrapper function with type Ty that calls F (which may have a +// different type). Attempt to support common bitcasted function idioms: +// - Call with more arguments than needed: arguments are dropped +// - Call with fewer arguments than needed: arguments are filled in with undef +// - Return value is not needed: drop it +// - Return value needed but not present: supply an undef +// +// For now, return nullptr without creating a wrapper if the wrapper cannot +// be generated due to incompatible types. +static Function *CreateWrapper(Function *F, FunctionType *Ty) { + Module *M = F->getParent(); + + Function *Wrapper = + Function::Create(Ty, Function::PrivateLinkage, "bitcast", M); + BasicBlock *BB = BasicBlock::Create(M->getContext(), "body", Wrapper); + + // Determine what arguments to pass. + SmallVector<Value *, 4> Args; + Function::arg_iterator AI = Wrapper->arg_begin(); + FunctionType::param_iterator PI = F->getFunctionType()->param_begin(); + FunctionType::param_iterator PE = F->getFunctionType()->param_end(); + for (; AI != Wrapper->arg_end() && PI != PE; ++AI, ++PI) { + if (AI->getType() != *PI) { + Wrapper->eraseFromParent(); + return nullptr; + } + Args.push_back(&*AI); + } + for (; PI != PE; ++PI) + Args.push_back(UndefValue::get(*PI)); + + CallInst *Call = CallInst::Create(F, Args, "", BB); + + // Determine what value to return. + if (Ty->getReturnType()->isVoidTy()) + ReturnInst::Create(M->getContext(), BB); + else if (F->getFunctionType()->getReturnType()->isVoidTy()) + ReturnInst::Create(M->getContext(), UndefValue::get(Ty->getReturnType()), + BB); + else if (F->getFunctionType()->getReturnType() == Ty->getReturnType()) + ReturnInst::Create(M->getContext(), Call, BB); + else { + Wrapper->eraseFromParent(); + return nullptr; + } + + return Wrapper; +} + +bool FixFunctionBitcasts::runOnModule(Module &M) { + SmallVector<std::pair<Use *, Function *>, 0> Uses; + + // Collect all the places that need wrappers. + for (Function &F : M) + FindUses(&F, F, Uses); + + DenseMap<std::pair<Function *, FunctionType *>, Function *> Wrappers; + + for (auto &UseFunc : Uses) { + Use *U = UseFunc.first; + Function *F = UseFunc.second; + PointerType *PTy = cast<PointerType>(U->get()->getType()); + FunctionType *Ty = dyn_cast<FunctionType>(PTy->getElementType()); + + // If the function is casted to something like i8* as a "generic pointer" + // to be later casted to something else, we can't generate a wrapper for it. + // Just ignore such casts for now. + if (!Ty) + continue; + + auto Pair = Wrappers.insert(std::make_pair(std::make_pair(F, Ty), nullptr)); + if (Pair.second) + Pair.first->second = CreateWrapper(F, Ty); + + Function *Wrapper = Pair.first->second; + if (!Wrapper) + continue; + + if (isa<Constant>(U->get())) + U->get()->replaceAllUsesWith(Wrapper); + else + U->set(Wrapper); + } + + return true; +} diff --git a/contrib/llvm/lib/Target/WebAssembly/WebAssemblyInstrInteger.td b/contrib/llvm/lib/Target/WebAssembly/WebAssemblyInstrInteger.td index 8a3248ee669e..e872dc219846 100644 --- a/contrib/llvm/lib/Target/WebAssembly/WebAssemblyInstrInteger.td +++ b/contrib/llvm/lib/Target/WebAssembly/WebAssemblyInstrInteger.td @@ -40,8 +40,8 @@ defm ROTL : BinaryInt<rotl, "rotl", 0x77, 0x89>; defm ROTR : BinaryInt<rotr, "rotr", 0x78, 0x8a>; let isCommutable = 1 in { -defm EQ : ComparisonInt<SETEQ, "eq ", 0x46, 0x68>; -defm NE : ComparisonInt<SETNE, "ne ", 0x47, 0x69>; +defm EQ : ComparisonInt<SETEQ, "eq ", 0x46, 0x51>; +defm NE : ComparisonInt<SETNE, "ne ", 0x47, 0x52>; } // isCommutable = 1 defm LT_S : ComparisonInt<SETLT, "lt_s", 0x48, 0x53>; defm LT_U : ComparisonInt<SETULT, "lt_u", 0x49, 0x54>; diff --git a/contrib/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/contrib/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp index b61bc0a08143..f5ef35a2ad40 100644 --- a/contrib/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp +++ b/contrib/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp @@ -163,6 +163,10 @@ void WebAssemblyPassConfig::addIRPasses() { // control specifically what gets lowered. addPass(createAtomicExpandPass(TM)); + // Fix function bitcasts, as WebAssembly requires caller and callee signatures + // to match. + addPass(createWebAssemblyFixFunctionBitcasts()); + // Optimize "returned" function attributes. if (getOptLevel() != CodeGenOpt::None) addPass(createWebAssemblyOptimizeReturned()); |