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instcombine: Migrate fwrite optimizations

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This patch migrates the fwrite optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168892 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Meador Inge
2012-11-29 15:45:39 +00:00
parent 28d52913ab
commit c2e331275b
4 changed files with 93 additions and 51 deletions
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35
lib/Transforms/Utils/SimplifyLibCalls.cpp
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@@ -1577,6 +1577,39 @@ struct FPrintFOpt : public LibCallOptimization {
}
};
struct FWriteOpt : public LibCallOptimization {
virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Require a pointer, an integer, an integer, a pointer, returning integer.
FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 4 || !FT->getParamType(0)->isPointerTy() ||
!FT->getParamType(1)->isIntegerTy() ||
!FT->getParamType(2)->isIntegerTy() ||
!FT->getParamType(3)->isPointerTy() ||
!FT->getReturnType()->isIntegerTy())
return 0;
// Get the element size and count.
ConstantInt *SizeC = dyn_cast<ConstantInt>(CI->getArgOperand(1));
ConstantInt *CountC = dyn_cast<ConstantInt>(CI->getArgOperand(2));
if (!SizeC || !CountC) return 0;
uint64_t Bytes = SizeC->getZExtValue()*CountC->getZExtValue();
// If this is writing zero records, remove the call (it's a noop).
if (Bytes == 0)
return ConstantInt::get(CI->getType(), 0);
// If this is writing one byte, turn it into fputc.
// This optimisation is only valid, if the return value is unused.
if (Bytes == 1 && CI->use_empty()) { // fwrite(S,1,1,F) -> fputc(S[0],F)
Value *Char = B.CreateLoad(CastToCStr(CI->getArgOperand(0), B), "char");
Value *NewCI = EmitFPutC(Char, CI->getArgOperand(3), B, TD, TLI);
return NewCI ? ConstantInt::get(CI->getType(), 1) : 0;
}
return 0;
}
};
} // End anonymous namespace.
namespace llvm {
@@ -1634,6 +1667,7 @@ class LibCallSimplifierImpl {
PrintFOpt PrintF;
SPrintFOpt SPrintF;
FPrintFOpt FPrintF;
FWriteOpt FWrite;
void initOptimizations();
void addOpt(LibFunc::Func F, LibCallOptimization* Opt);
@@ -1760,6 +1794,7 @@ void LibCallSimplifierImpl::initOptimizations() {
addOpt(LibFunc::printf, &PrintF);
addOpt(LibFunc::sprintf, &SPrintF);
addOpt(LibFunc::fprintf, &FPrintF);
addOpt(LibFunc::fwrite, &FWrite);
}
Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {