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//===- LowerEmExceptions - Lower exceptions for Emscripten/JS -----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This is based off the 'cheap' version of LowerInvoke. It does two things:
//
// 1) Lower
// invoke() to l1 unwind l2
// into
// preinvoke(); // (will clear __THREW__)
// call();
// threw = postinvoke(); (check __THREW__)
// br threw, l1, l2
//
// 2) Lower landingpads to return a single i8*, avoid the structural type
// which is unneeded anyhow.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/NaCl.h"
using namespace llvm;
namespace {
class LowerEmExceptions : public ModulePass {
Function *PreInvoke, *PostInvoke;
Module *TheModule;
public:
static char ID; // Pass identification, replacement for typeid
explicit LowerEmExceptions() : ModulePass(ID), PreInvoke(NULL), PostInvoke(NULL), TheModule(NULL) {
initializeLowerEmExceptionsPass(*PassRegistry::getPassRegistry());
}
bool runOnModule(Module &M);
};
}
char LowerEmExceptions::ID = 0;
INITIALIZE_PASS(LowerEmExceptions, "loweremexceptions",
"Lower invoke and unwind for js/emscripten",
false, false)
Instruction *getSingleUse(Instruction *I) {
Instruction *Ret = NULL;
for (Instruction::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE; ++UI) {
assert(Ret == NULL);
Ret = cast<ExtractElementInst>(*UI);
}
assert(Ret != NULL);
return Ret;
}
bool LowerEmExceptions::runOnModule(Module &M) {
TheModule = &M;
Type *Void = Type::getVoidTy(M.getContext());
Type *i32 = Type::getInt32Ty(M.getContext());
SmallVector<Type*, 0> ArgTypes;
FunctionType *VoidFunc = FunctionType::get(Void, ArgTypes, false);
FunctionType *IntFunc = FunctionType::get(i32, ArgTypes, false);
PreInvoke = Function::Create(VoidFunc, GlobalValue::ExternalLinkage, "preInvoke", TheModule);
PostInvoke = Function::Create(IntFunc, GlobalValue::ExternalLinkage, "postInvoke", TheModule);
bool Changed = false;
for (Module::iterator Iter = M.begin(), E = M.end(); Iter != E; ) {
Function *F = Iter++;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
// Fix up the landingpad. First, make a copy returning just an integer
LandingPadInst *LP = II->getLandingPadInst();
unsigned Num = LP->getNumClauses();
LandingPadInst *NewLP = LandingPadInst::Create(i32, LP->getPersonalityFn(), Num, "", LP);
NewLP->setCleanup(LP->isCleanup());
for (unsigned i = 0; i < Num; i++) NewLP->addClause(LP->getClause(i));
// Next, replace the old LP's single use, which is an extractelement, to eliminate the ee's and use the value directly
ExtractElementInst *EE = cast<ExtractElementInst>(getSingleUse(LP));
EE->replaceAllUsesWith(NewLP);
EE->eraseFromParent();
// Finish the LP by replacing it
LP->replaceAllUsesWith(NewLP);
LP->eraseFromParent();
Changed = true;
}
}
}
return Changed;
}
ModulePass *llvm::createLowerEmExceptionsPass() {
return new LowerEmExceptions();
}
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