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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
//
// We do this to avoid introducing a new LLVM IR type, or to try to reuse
// invoke-landingpad for our special purposes (as they are checked very
// carefully by llvm)
//
// 2) Lower landingpads to a call to emscripten_landingpad
//
// 3) Lower resume to emscripten_resume which receives non-aggregate inputs
//
//===----------------------------------------------------------------------===//
#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"
#include <vector>
#include <set>
#include "llvm/Support/raw_ostream.h"
#include <stdio.h>
#define dump(x) fprintf(stderr, x "\n")
#define dumpv(x, ...) fprintf(stderr, x "\n", __VA_ARGS__)
#define dumpfail(x) { fprintf(stderr, x "\n"); fprintf(stderr, "%s : %d\n", __FILE__, __LINE__); report_fatal_error("fail"); }
#define dumpfailv(x, ...) { fprintf(stderr, x "\n", __VA_ARGS__); fprintf(stderr, "%s : %d\n", __FILE__, __LINE__); report_fatal_error("fail"); }
#define dumpIR(value) { \
std::string temp; \
raw_string_ostream stream(temp); \
stream << *(value); \
fprintf(stderr, "%s\n", temp.c_str()); \
}
#undef assert
#define assert(x) { if (!(x)) dumpfail(#x); }
using namespace llvm;
namespace {
class LowerEmExceptions : public ModulePass {
Function *GetHigh, *PreInvoke, *PostInvoke, *LandingPad, *Resume;
Module *TheModule;
public:
static char ID; // Pass identification, replacement for typeid
explicit LowerEmExceptions() : ModulePass(ID), GetHigh(NULL), PreInvoke(NULL), PostInvoke(NULL), LandingPad(NULL), Resume(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)
bool LowerEmExceptions::runOnModule(Module &M) {
TheModule = &M;
// Add functions
Type *i32 = Type::getInt32Ty(M.getContext());
Type *i8 = Type::getInt8Ty(M.getContext());
Type *i1 = Type::getInt1Ty(M.getContext());
Type *i8P = i8->getPointerTo();
Type *Void = Type::getVoidTy(M.getContext());
if (!TheModule->getFunction("getHigh32")) {
FunctionType *GetHighFunc = FunctionType::get(i32, false);
GetHigh = Function::Create(GetHighFunc, GlobalValue::ExternalLinkage,
"getHigh32", TheModule);
}
FunctionType *VoidFunc = FunctionType::get(Void, false);
PreInvoke = Function::Create(VoidFunc, GlobalValue::ExternalLinkage, "emscripten_preinvoke", TheModule);
FunctionType *Int1Func = FunctionType::get(i1, false);
PostInvoke = Function::Create(Int1Func, GlobalValue::ExternalLinkage, "emscripten_postinvoke", TheModule);
FunctionType *LandingPadFunc = FunctionType::get(i8P, true);
LandingPad = Function::Create(LandingPadFunc, GlobalValue::ExternalLinkage, "emscripten_landingpad", TheModule);
FunctionType *ResumeFunc = FunctionType::get(Void, true);
Resume = Function::Create(ResumeFunc, GlobalValue::ExternalLinkage, "emscripten_resume", TheModule);
// Process
bool Changed = false;
for (Module::iterator Iter = M.begin(), E = M.end(); Iter != E; ) {
Function *F = Iter++;
std::vector<Instruction*> ToErase;
std::set<LandingPadInst*> LandingPads;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
// check terminator for invokes
if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
// Insert a normal call instruction folded in between pre- and post-invoke
CallInst *Pre = CallInst::Create(PreInvoke, "", II);
SmallVector<Value*,16> CallArgs(II->op_begin(), II->op_end() - 3);
CallInst *NewCall = CallInst::Create(II->getCalledValue(),
CallArgs, "", II);
NewCall->takeName(II);
NewCall->setCallingConv(II->getCallingConv());
NewCall->setAttributes(II->getAttributes());
NewCall->setDebugLoc(II->getDebugLoc());
II->replaceAllUsesWith(NewCall);
ToErase.push_back(II);
CallInst *Post = CallInst::Create(PostInvoke, "", II);
// Insert a branch based on the postInvoke
BranchInst::Create(II->getUnwindDest(), II->getNormalDest(), Post, II);
LandingPads.insert(II->getLandingPadInst());
Changed = true;
}
// scan the body of the basic block for resumes
for (BasicBlock::iterator Iter = BB->begin(), E = BB->end();
Iter != E; ) {
Instruction *I = Iter++;
if (ResumeInst *R = dyn_cast<ResumeInst>(I)) {
// split the input into legal values
Value *Input = R->getValue();
ExtractValueInst *Low = ExtractValueInst::Create(Input, 0, "", R);
ExtractValueInst *High = ExtractValueInst::Create(Input, 1, "", R);
// create a resume call
SmallVector<Value*,2> CallArgs;
CallArgs.push_back(Low);
CallArgs.push_back(High);
CallInst *NewR = CallInst::Create(Resume, CallArgs, "", R);
UnreachableInst *U = new UnreachableInst(TheModule->getContext(), R); // add a terminator to the block
ToErase.push_back(R);
}
}
}
// Handle all the landingpad for this function together, as multiple invokes may share a single lp
for (std::set<LandingPadInst*>::iterator I = LandingPads.begin(); I != LandingPads.end(); I++) {
// Replace the landingpad with a landingpad call to get the low part, and a getHigh for the high
LandingPadInst *LP = *I;
unsigned Num = LP->getNumClauses();
SmallVector<Value*,16> NewLPArgs;
NewLPArgs.push_back(LP->getPersonalityFn());
for (unsigned i = 0; i < Num; i++) NewLPArgs.push_back(LP->getClause(i));
NewLPArgs.push_back(LP->isCleanup() ? ConstantInt::getTrue(i1) : ConstantInt::getFalse(i1));
CallInst *NewLP = CallInst::Create(LandingPad, NewLPArgs, "", LP);
Instruction *High = CallInst::Create(GetHigh, "", LP);
// New recreate an aggregate for them, which will be all simplified later (simplification cannot handle landingpad, hence all this)
InsertValueInst *IVA = InsertValueInst::Create(UndefValue::get(LP->getType()), NewLP, 0, "", LP);
InsertValueInst *IVB = InsertValueInst::Create(IVA, High, 1, "", LP);
LP->replaceAllUsesWith(IVB);
ToErase.push_back(LP);
}
// erase everything we no longer need in this function
for (unsigned i = 0; i < ToErase.size(); i++) ToErase[i]->eraseFromParent();
}
return Changed;
}
ModulePass *llvm::createLowerEmExceptionsPass() {
return new LowerEmExceptions();
}
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