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ConstantFolding: Factor code into helper function

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llvm-svn: 288459
This commit is contained in:
Matt Arsenault 2016-12-02 02:26:02 +00:00
parent ab85225be4
commit 47a4b39646
1 changed files with 34 additions and 23 deletions
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57
llvm/lib/Analysis/ConstantFolding.cpp
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@ -58,7 +58,37 @@ namespace {
// Constant Folding internal helper functions
//===----------------------------------------------------------------------===//
/// Constant fold bitcast, symbolically evaluating it with DataLayout.
static Constant *foldConstVectorToAPInt(APInt &Result, Type *DestTy,
Constant *C, Type *SrcEltTy,
unsigned NumSrcElts,
const DataLayout &DL) {
// Now that we know that the input value is a vector of integers, just shift
// and insert them into our result.
unsigned BitShift = DL.getTypeSizeInBits(SrcEltTy);
for (unsigned i = 0; i != NumSrcElts; ++i) {
Constant *Element;
if (DL.isLittleEndian())
Element = C->getAggregateElement(NumSrcElts - i - 1);
else
Element = C->getAggregateElement(i);
if (Element && isa<UndefValue>(Element)) {
Result <<= BitShift;
continue;
}
auto *ElementCI = dyn_cast_or_null<ConstantInt>(Element);
if (!ElementCI)
return ConstantExpr::getBitCast(C, DestTy);
Result <<= BitShift;
Result |= ElementCI->getValue().zextOrSelf(Result.getBitWidth());
}
return nullptr;
}
// Constant fold bitcast, symbolically evaluating it with DataLayout.
/// This always returns a non-null constant, but it may be a
/// ConstantExpr if unfoldable.
Constant *FoldBitCast(Constant *C, Type *DestTy, const DataLayout &DL) {
@ -88,29 +118,10 @@ Constant *FoldBitCast(Constant *C, Type *DestTy, const DataLayout &DL) {
C = ConstantExpr::getBitCast(C, SrcIVTy);
}
// Now that we know that the input value is a vector of integers, just shift
// and insert them into our result.
unsigned BitShift = DL.getTypeSizeInBits(SrcEltTy);
APInt Result(IT->getBitWidth(), 0);
for (unsigned i = 0; i != NumSrcElts; ++i) {
Constant *Element;
if (DL.isLittleEndian())
Element = C->getAggregateElement(NumSrcElts-i-1);
else
Element = C->getAggregateElement(i);
if (Element && isa<UndefValue>(Element)) {
Result <<= BitShift;
continue;
}
auto *ElementCI = dyn_cast_or_null<ConstantInt>(Element);
if (!ElementCI)
return ConstantExpr::getBitCast(C, DestTy);
Result <<= BitShift;
Result |= ElementCI->getValue().zextOrSelf(IT->getBitWidth());
}
if (Constant *CE = foldConstVectorToAPInt(Result, DestTy, C,
SrcEltTy, NumSrcElts, DL))
return CE;
return ConstantInt::get(IT, Result);
}