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move FoldBitCast earlier in the file, and use it instead of

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ConstantExpr::getBitCast in various places.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85039 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2009-10-25 06:08:26 +00:00
parent ea9d57bc9a
commit 6333c3959b
1 changed files with 132 additions and 132 deletions
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264
lib/Analysis/ConstantFolding.cpp
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@@ -39,6 +39,129 @@ using namespace llvm;
// Constant Folding internal helper functions // Constant Folding internal helper functions
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
/// FoldBitCast - Constant fold bitcast, symbolically evaluating it with
/// TargetData. This always returns a non-null constant, but it may be a
/// ConstantExpr if unfoldable.
static Constant *FoldBitCast(Constant *C, const Type *DestTy,
const TargetData &TD) {
// If this is a bitcast from constant vector -> vector, fold it.
ConstantVector *CV = dyn_cast<ConstantVector>(C);
if (CV == 0)
return ConstantExpr::getBitCast(C, DestTy);
const VectorType *DestVTy = dyn_cast<VectorType>(DestTy);
if (DestVTy == 0)
return ConstantExpr::getBitCast(C, DestTy);
// If the element types match, VMCore can fold it.
unsigned NumDstElt = DestVTy->getNumElements();
unsigned NumSrcElt = CV->getNumOperands();
if (NumDstElt == NumSrcElt)
return ConstantExpr::getBitCast(C, DestTy);
const Type *SrcEltTy = CV->getType()->getElementType();
const Type *DstEltTy = DestVTy->getElementType();
// Otherwise, we're changing the number of elements in a vector, which
// requires endianness information to do the right thing. For example,
// bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
// folds to (little endian):
// <4 x i32> <i32 0, i32 0, i32 1, i32 0>
// and to (big endian):
// <4 x i32> <i32 0, i32 0, i32 0, i32 1>
// First thing is first. We only want to think about integer here, so if
// we have something in FP form, recast it as integer.
if (DstEltTy->isFloatingPoint()) {
// Fold to an vector of integers with same size as our FP type.
unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits();
const Type *DestIVTy =
VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumDstElt);
// Recursively handle this integer conversion, if possible.
C = FoldBitCast(C, DestIVTy, TD);
if (!C) return ConstantExpr::getBitCast(C, DestTy);
// Finally, VMCore can handle this now that #elts line up.
return ConstantExpr::getBitCast(C, DestTy);
}
// Okay, we know the destination is integer, if the input is FP, convert
// it to integer first.
if (SrcEltTy->isFloatingPoint()) {
unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
const Type *SrcIVTy =
VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumSrcElt);
// Ask VMCore to do the conversion now that #elts line up.
C = ConstantExpr::getBitCast(C, SrcIVTy);
CV = dyn_cast<ConstantVector>(C);
if (!CV) // If VMCore wasn't able to fold it, bail out.
return C;
}
// Now we know that the input and output vectors are both integer vectors
// of the same size, and that their #elements is not the same. Do the
// conversion here, which depends on whether the input or output has
// more elements.
bool isLittleEndian = TD.isLittleEndian();
SmallVector<Constant*, 32> Result;
if (NumDstElt < NumSrcElt) {
// Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>)
Constant *Zero = Constant::getNullValue(DstEltTy);
unsigned Ratio = NumSrcElt/NumDstElt;
unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits();
unsigned SrcElt = 0;
for (unsigned i = 0; i != NumDstElt; ++i) {
// Build each element of the result.
Constant *Elt = Zero;
unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1);
for (unsigned j = 0; j != Ratio; ++j) {
Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(SrcElt++));
if (!Src) // Reject constantexpr elements.
return ConstantExpr::getBitCast(C, DestTy);
// Zero extend the element to the right size.
Src = ConstantExpr::getZExt(Src, Elt->getType());
// Shift it to the right place, depending on endianness.
Src = ConstantExpr::getShl(Src,
ConstantInt::get(Src->getType(), ShiftAmt));
ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize;
// Mix it in.
Elt = ConstantExpr::getOr(Elt, Src);
}
Result.push_back(Elt);
}
} else {
// Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
unsigned Ratio = NumDstElt/NumSrcElt;
unsigned DstBitSize = DstEltTy->getPrimitiveSizeInBits();
// Loop over each source value, expanding into multiple results.
for (unsigned i = 0; i != NumSrcElt; ++i) {
Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(i));
if (!Src) // Reject constantexpr elements.
return ConstantExpr::getBitCast(C, DestTy);
unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1);
for (unsigned j = 0; j != Ratio; ++j) {
// Shift the piece of the value into the right place, depending on
// endianness.
Constant *Elt = ConstantExpr::getLShr(Src,
ConstantInt::get(Src->getType(), ShiftAmt));
ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
// Truncate and remember this piece.
Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
}
}
}
return ConstantVector::get(Result.data(), Result.size());
}
/// IsConstantOffsetFromGlobal - If this constant is actually a constant offset /// IsConstantOffsetFromGlobal - If this constant is actually a constant offset
/// from a global, return the global and the constant. Because of /// from a global, return the global and the constant. Because of
/// constantexprs, this function is recursive. /// constantexprs, this function is recursive.
@@ -125,11 +248,11 @@ static bool ReadDataFromGlobal(Constant *C, uint64_t ByteOffset,
if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) { if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
if (CFP->getType()->isDoubleTy()) { if (CFP->getType()->isDoubleTy()) {
C = ConstantExpr::getBitCast(C, Type::getInt64Ty(C->getContext())); C = FoldBitCast(C, Type::getInt64Ty(C->getContext()), TD);
return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD); return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
} }
if (CFP->getType()->isFloatTy()){ if (CFP->getType()->isFloatTy()){
C = ConstantExpr::getBitCast(C, Type::getInt32Ty(C->getContext())); C = FoldBitCast(C, Type::getInt32Ty(C->getContext()), TD);
return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD); return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
} }
return false; return false;
@@ -235,9 +358,9 @@ static Constant *FoldReinterpretLoadFromConstPtr(Constant *C,
} else } else
return 0; return 0;
C = ConstantExpr::getBitCast(C, MapTy); C = FoldBitCast(C, MapTy, TD);
if (Constant *Res = FoldReinterpretLoadFromConstPtr(C, TD)) if (Constant *Res = FoldReinterpretLoadFromConstPtr(C, TD))
return ConstantExpr::getBitCast(Res, LoadTy); return FoldBitCast(Res, LoadTy, TD);
return 0; return 0;
} }
@@ -479,132 +602,11 @@ static Constant *SymbolicallyEvaluateGEP(Constant* const* Ops, unsigned NumOps,
// If we ended up indexing a member with a type that doesn't match // If we ended up indexing a member with a type that doesn't match
// the type of what the original indices indexed, add a cast. // the type of what the original indices indexed, add a cast.
if (Ty != cast<PointerType>(ResultTy)->getElementType()) if (Ty != cast<PointerType>(ResultTy)->getElementType())
C = ConstantExpr::getBitCast(C, ResultTy); C = FoldBitCast(C, ResultTy, *TD);
return C; return C;
} }
/// FoldBitCast - Constant fold bitcast, symbolically evaluating it with
/// TargetData. This always returns a non-null constant, but it may be a
/// ConstantExpr if unfoldable.
static Constant *FoldBitCast(Constant *C, const Type *DestTy,
const TargetData &TD, LLVMContext &Context) {
// If this is a bitcast from constant vector -> vector, fold it.
ConstantVector *CV = dyn_cast<ConstantVector>(C);
if (CV == 0)
return ConstantExpr::getBitCast(C, DestTy);
const VectorType *DestVTy = dyn_cast<VectorType>(DestTy);
if (DestVTy == 0)
return ConstantExpr::getBitCast(C, DestTy);
// If the element types match, VMCore can fold it.
unsigned NumDstElt = DestVTy->getNumElements();
unsigned NumSrcElt = CV->getNumOperands();
if (NumDstElt == NumSrcElt)
return ConstantExpr::getBitCast(C, DestTy);
const Type *SrcEltTy = CV->getType()->getElementType();
const Type *DstEltTy = DestVTy->getElementType();
// Otherwise, we're changing the number of elements in a vector, which
// requires endianness information to do the right thing. For example,
// bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
// folds to (little endian):
// <4 x i32> <i32 0, i32 0, i32 1, i32 0>
// and to (big endian):
// <4 x i32> <i32 0, i32 0, i32 0, i32 1>
// First thing is first. We only want to think about integer here, so if
// we have something in FP form, recast it as integer.
if (DstEltTy->isFloatingPoint()) {
// Fold to an vector of integers with same size as our FP type.
unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits();
const Type *DestIVTy = VectorType::get(
IntegerType::get(Context, FPWidth), NumDstElt);
// Recursively handle this integer conversion, if possible.
C = FoldBitCast(C, DestIVTy, TD, Context);
if (!C) return ConstantExpr::getBitCast(C, DestTy);
// Finally, VMCore can handle this now that #elts line up.
return ConstantExpr::getBitCast(C, DestTy);
}
// Okay, we know the destination is integer, if the input is FP, convert
// it to integer first.
if (SrcEltTy->isFloatingPoint()) {
unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
const Type *SrcIVTy = VectorType::get(
IntegerType::get(Context, FPWidth), NumSrcElt);
// Ask VMCore to do the conversion now that #elts line up.
C = ConstantExpr::getBitCast(C, SrcIVTy);
CV = dyn_cast<ConstantVector>(C);
if (!CV) // If VMCore wasn't able to fold it, bail out.
return C;
}
// Now we know that the input and output vectors are both integer vectors
// of the same size, and that their #elements is not the same. Do the
// conversion here, which depends on whether the input or output has
// more elements.
bool isLittleEndian = TD.isLittleEndian();
SmallVector<Constant*, 32> Result;
if (NumDstElt < NumSrcElt) {
// Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>)
Constant *Zero = Constant::getNullValue(DstEltTy);
unsigned Ratio = NumSrcElt/NumDstElt;
unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits();
unsigned SrcElt = 0;
for (unsigned i = 0; i != NumDstElt; ++i) {
// Build each element of the result.
Constant *Elt = Zero;
unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1);
for (unsigned j = 0; j != Ratio; ++j) {
Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(SrcElt++));
if (!Src) // Reject constantexpr elements.
return ConstantExpr::getBitCast(C, DestTy);
// Zero extend the element to the right size.
Src = ConstantExpr::getZExt(Src, Elt->getType());
// Shift it to the right place, depending on endianness.
Src = ConstantExpr::getShl(Src,
ConstantInt::get(Src->getType(), ShiftAmt));
ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize;
// Mix it in.
Elt = ConstantExpr::getOr(Elt, Src);
}
Result.push_back(Elt);
}
} else {
// Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
unsigned Ratio = NumDstElt/NumSrcElt;
unsigned DstBitSize = DstEltTy->getPrimitiveSizeInBits();
// Loop over each source value, expanding into multiple results.
for (unsigned i = 0; i != NumSrcElt; ++i) {
Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(i));
if (!Src) // Reject constantexpr elements.
return ConstantExpr::getBitCast(C, DestTy);
unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1);
for (unsigned j = 0; j != Ratio; ++j) {
// Shift the piece of the value into the right place, depending on
// endianness.
Constant *Elt = ConstantExpr::getLShr(Src,
ConstantInt::get(Src->getType(), ShiftAmt));
ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
// Truncate and remember this piece.
Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
}
}
}
return ConstantVector::get(Result.data(), Result.size());
}
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
@@ -730,11 +732,9 @@ Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
if (TD && if (TD &&
TD->getPointerSizeInBits() <= TD->getPointerSizeInBits() <=
CE->getType()->getScalarSizeInBits()) { CE->getType()->getScalarSizeInBits()) {
if (CE->getOpcode() == Instruction::PtrToInt) { if (CE->getOpcode() == Instruction::PtrToInt)
Constant *Input = CE->getOperand(0); return FoldBitCast(CE->getOperand(0), DestTy, *TD);
Constant *C = FoldBitCast(Input, DestTy, *TD, Context);
return C ? C : ConstantExpr::getBitCast(Input, DestTy);
}
// If there's a constant offset added to the integer value before // If there's a constant offset added to the integer value before
// it is casted back to a pointer, see if the expression can be // it is casted back to a pointer, see if the expression can be
// converted into a GEP. // converted into a GEP.
@@ -780,7 +780,7 @@ Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
return ConstantExpr::getCast(Opcode, Ops[0], DestTy); return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
case Instruction::BitCast: case Instruction::BitCast:
if (TD) if (TD)
return FoldBitCast(Ops[0], DestTy, *TD, Context); return FoldBitCast(Ops[0], DestTy, *TD);
return ConstantExpr::getBitCast(Ops[0], DestTy); return ConstantExpr::getBitCast(Ops[0], DestTy);
case Instruction::Select: case Instruction::Select:
return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]); return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);