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move 'loading i32 from string' optimization from instcombine

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to libanalysis.  Instcombine shrinking... does this even 
make sense???


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84840 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2009-10-22 06:38:35 +00:00
parent 878e494670
commit 62d327e241
2 changed files with 35 additions and 40 deletions
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34
lib/Transforms/Scalar/InstructionCombining.cpp
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@@ -11345,40 +11345,6 @@ static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
Value *CastOp = CI->getOperand(0);
LLVMContext *Context = IC.getContext();
if (TD) {
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(CI)) {
// Instead of loading constant c string, use corresponding integer value
// directly if string length is small enough.
std::string Str;
if (GetConstantStringInfo(CE->getOperand(0), Str) && !Str.empty()) {
unsigned len = Str.length();
const Type *Ty = cast<PointerType>(CE->getType())->getElementType();
unsigned numBits = Ty->getPrimitiveSizeInBits();
// Replace LI with immediate integer store.
if ((numBits >> 3) == len + 1) {
APInt StrVal(numBits, 0);
APInt SingleChar(numBits, 0);
if (TD->isLittleEndian()) {
for (signed i = len-1; i >= 0; i--) {
SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
StrVal = (StrVal << 8) | SingleChar;
}
} else {
for (unsigned i = 0; i < len; i++) {
SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
StrVal = (StrVal << 8) | SingleChar;
}
// Append NULL at the end.
SingleChar = 0;
StrVal = (StrVal << 8) | SingleChar;
}
Value *NL = ConstantInt::get(*Context, StrVal);
return IC.ReplaceInstUsesWith(LI, NL);
}
}
}
}
const PointerType *DestTy = cast<PointerType>(CI->getType());
const Type *DestPTy = DestTy->getElementType();
if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {