mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-29 13:29:28 +00:00
While there modernize some loops. NFC. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227436 91177308-0d34-0410-b5e6-96231b3b80d8
173 lines
5.5 KiB
C++
173 lines
5.5 KiB
C++
//===-- DwarfEHPrepare - Prepare exception handling for code generation ---===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This pass mulches exception handling code into a form adapted to code
|
|
// generation. Required if using dwarf exception handling.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/CodeGen/Passes.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/IR/Function.h"
|
|
#include "llvm/IR/Instructions.h"
|
|
#include "llvm/IR/Module.h"
|
|
#include "llvm/Pass.h"
|
|
#include "llvm/Target/TargetLowering.h"
|
|
#include "llvm/Target/TargetSubtargetInfo.h"
|
|
using namespace llvm;
|
|
|
|
#define DEBUG_TYPE "dwarfehprepare"
|
|
|
|
STATISTIC(NumResumesLowered, "Number of resume calls lowered");
|
|
|
|
namespace {
|
|
class DwarfEHPrepare : public FunctionPass {
|
|
const TargetMachine *TM;
|
|
|
|
// RewindFunction - _Unwind_Resume or the target equivalent.
|
|
Constant *RewindFunction;
|
|
|
|
bool InsertUnwindResumeCalls(Function &Fn);
|
|
Value *GetExceptionObject(ResumeInst *RI);
|
|
|
|
public:
|
|
static char ID; // Pass identification, replacement for typeid.
|
|
DwarfEHPrepare(const TargetMachine *TM)
|
|
: FunctionPass(ID), TM(TM), RewindFunction(nullptr) {}
|
|
|
|
bool runOnFunction(Function &Fn) override;
|
|
|
|
bool doFinalization(Module &M) override {
|
|
RewindFunction = nullptr;
|
|
return false;
|
|
}
|
|
|
|
const char *getPassName() const override {
|
|
return "Exception handling preparation";
|
|
}
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
char DwarfEHPrepare::ID = 0;
|
|
|
|
FunctionPass *llvm::createDwarfEHPass(const TargetMachine *TM) {
|
|
return new DwarfEHPrepare(TM);
|
|
}
|
|
|
|
/// GetExceptionObject - Return the exception object from the value passed into
|
|
/// the 'resume' instruction (typically an aggregate). Clean up any dead
|
|
/// instructions, including the 'resume' instruction.
|
|
Value *DwarfEHPrepare::GetExceptionObject(ResumeInst *RI) {
|
|
Value *V = RI->getOperand(0);
|
|
Value *ExnObj = nullptr;
|
|
InsertValueInst *SelIVI = dyn_cast<InsertValueInst>(V);
|
|
LoadInst *SelLoad = nullptr;
|
|
InsertValueInst *ExcIVI = nullptr;
|
|
bool EraseIVIs = false;
|
|
|
|
if (SelIVI) {
|
|
if (SelIVI->getNumIndices() == 1 && *SelIVI->idx_begin() == 1) {
|
|
ExcIVI = dyn_cast<InsertValueInst>(SelIVI->getOperand(0));
|
|
if (ExcIVI && isa<UndefValue>(ExcIVI->getOperand(0)) &&
|
|
ExcIVI->getNumIndices() == 1 && *ExcIVI->idx_begin() == 0) {
|
|
ExnObj = ExcIVI->getOperand(1);
|
|
SelLoad = dyn_cast<LoadInst>(SelIVI->getOperand(1));
|
|
EraseIVIs = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!ExnObj)
|
|
ExnObj = ExtractValueInst::Create(RI->getOperand(0), 0, "exn.obj", RI);
|
|
|
|
RI->eraseFromParent();
|
|
|
|
if (EraseIVIs) {
|
|
if (SelIVI->use_empty())
|
|
SelIVI->eraseFromParent();
|
|
if (ExcIVI->use_empty())
|
|
ExcIVI->eraseFromParent();
|
|
if (SelLoad && SelLoad->use_empty())
|
|
SelLoad->eraseFromParent();
|
|
}
|
|
|
|
return ExnObj;
|
|
}
|
|
|
|
/// InsertUnwindResumeCalls - Convert the ResumeInsts that are still present
|
|
/// into calls to the appropriate _Unwind_Resume function.
|
|
bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) {
|
|
SmallVector<ResumeInst*, 16> Resumes;
|
|
for (BasicBlock &BB : Fn) {
|
|
if (auto *RI = dyn_cast<ResumeInst>(BB.getTerminator()))
|
|
Resumes.push_back(RI);
|
|
}
|
|
|
|
if (Resumes.empty())
|
|
return false;
|
|
|
|
// Find the rewind function if we didn't already.
|
|
const TargetLowering *TLI = TM->getSubtargetImpl(Fn)->getTargetLowering();
|
|
LLVMContext &Ctx = Fn.getContext();
|
|
if (!RewindFunction) {
|
|
FunctionType *FTy = FunctionType::get(Type::getVoidTy(Ctx),
|
|
Type::getInt8PtrTy(Ctx), false);
|
|
const char *RewindName = TLI->getLibcallName(RTLIB::UNWIND_RESUME);
|
|
RewindFunction = Fn.getParent()->getOrInsertFunction(RewindName, FTy);
|
|
}
|
|
|
|
// Create the basic block where the _Unwind_Resume call will live.
|
|
unsigned ResumesSize = Resumes.size();
|
|
|
|
if (ResumesSize == 1) {
|
|
// Instead of creating a new BB and PHI node, just append the call to
|
|
// _Unwind_Resume to the end of the single resume block.
|
|
ResumeInst *RI = Resumes.front();
|
|
BasicBlock *UnwindBB = RI->getParent();
|
|
Value *ExnObj = GetExceptionObject(RI);
|
|
|
|
// Call the _Unwind_Resume function.
|
|
CallInst *CI = CallInst::Create(RewindFunction, ExnObj, "", UnwindBB);
|
|
CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
|
|
|
|
// We never expect _Unwind_Resume to return.
|
|
new UnreachableInst(Ctx, UnwindBB);
|
|
return true;
|
|
}
|
|
|
|
BasicBlock *UnwindBB = BasicBlock::Create(Ctx, "unwind_resume", &Fn);
|
|
PHINode *PN = PHINode::Create(Type::getInt8PtrTy(Ctx), ResumesSize,
|
|
"exn.obj", UnwindBB);
|
|
|
|
// Extract the exception object from the ResumeInst and add it to the PHI node
|
|
// that feeds the _Unwind_Resume call.
|
|
for (ResumeInst *RI : Resumes) {
|
|
BasicBlock *Parent = RI->getParent();
|
|
BranchInst::Create(UnwindBB, Parent);
|
|
|
|
Value *ExnObj = GetExceptionObject(RI);
|
|
PN->addIncoming(ExnObj, Parent);
|
|
|
|
++NumResumesLowered;
|
|
}
|
|
|
|
// Call the function.
|
|
CallInst *CI = CallInst::Create(RewindFunction, PN, "", UnwindBB);
|
|
CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
|
|
|
|
// We never expect _Unwind_Resume to return.
|
|
new UnreachableInst(Ctx, UnwindBB);
|
|
return true;
|
|
}
|
|
|
|
bool DwarfEHPrepare::runOnFunction(Function &Fn) {
|
|
bool Changed = InsertUnwindResumeCalls(Fn);
|
|
return Changed;
|
|
}
|