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https://github.com/c64scene-ar/llvm-6502.git
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75 lines
2.6 KiB
C++
75 lines
2.6 KiB
C++
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//===- LowerInvoke.cpp - Eliminate Invoke & Unwind instructions -----------===//
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//
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// This transformation is designed for use by code generators which do not yet
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// support stack unwinding. This pass gives them the ability to execute any
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// program which does not throw an exception, by turning 'invoke' instructions
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// into calls and by turning 'unwind' instructions into calls to abort().
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Pass.h"
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#include "llvm/iTerminators.h"
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#include "llvm/iOther.h"
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#include "llvm/Module.h"
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#include "llvm/Type.h"
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#include "llvm/Constant.h"
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#include "Support/Statistic.h"
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namespace {
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Statistic<> NumLowered("lowerinvoke", "Number of invoke & unwinds replaced");
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class LowerInvoke : public FunctionPass {
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Function *AbortFn;
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public:
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bool doInitialization(Module &M);
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bool runOnFunction(Function &F);
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};
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RegisterOpt<LowerInvoke>
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X("lowerinvoke", "Lower invoke and unwind, for unwindless code generators");
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}
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FunctionPass *createLowerInvokePass() { return new LowerInvoke(); }
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// doInitialization - Make sure that there is a prototype for abort in the
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// current module.
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bool LowerInvoke::doInitialization(Module &M) {
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AbortFn = M.getOrInsertFunction("abort", Type::VoidTy, 0);
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return true;
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}
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bool LowerInvoke::runOnFunction(Function &F) {
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bool Changed = false;
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for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
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if (InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) {
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// Insert a normal call instruction...
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std::string Name = II->getName(); II->setName("");
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Value *NewCall = new CallInst(II->getCalledValue(),
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std::vector<Value*>(II->op_begin()+3,
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II->op_end()), Name,II);
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II->replaceAllUsesWith(NewCall);
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// Insert an unconditional branch to the normal destination
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new BranchInst(II->getNormalDest(), II);
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// Remove the invoke instruction now.
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I->getInstList().erase(II);
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++NumLowered; Changed = true;
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} else if (UnwindInst *UI = dyn_cast<UnwindInst>(I->getTerminator())) {
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// Insert a call to abort()
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new CallInst(AbortFn, std::vector<Value*>(), "", UI);
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// Insert a return instruction.
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new ReturnInst(F.getReturnType() == Type::VoidTy ? 0 :
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Constant::getNullValue(F.getReturnType()), UI);
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// Remove the unwind instruction now.
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I->getInstList().erase(UI);
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++NumLowered; Changed = true;
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}
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return Changed;
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}
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