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move FoldBitCast earlier in the file, and use it instead of
ConstantExpr::getBitCast in various places. llvm-svn: 85039
This commit is contained in:
Chris Lattner
parent
f6cb8d6b90
commit
d80c1f61d2
@ -39,6 +39,129 @@ using namespace llvm;
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// Constant Folding internal helper functions
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//===----------------------------------------------------------------------===//
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/// FoldBitCast - Constant fold bitcast, symbolically evaluating it with
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/// TargetData. This always returns a non-null constant, but it may be a
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/// ConstantExpr if unfoldable.
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static Constant *FoldBitCast(Constant *C, const Type *DestTy,
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const TargetData &TD) {
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// If this is a bitcast from constant vector -> vector, fold it.
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ConstantVector *CV = dyn_cast<ConstantVector>(C);
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if (CV == 0)
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return ConstantExpr::getBitCast(C, DestTy);
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const VectorType *DestVTy = dyn_cast<VectorType>(DestTy);
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if (DestVTy == 0)
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return ConstantExpr::getBitCast(C, DestTy);
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// If the element types match, VMCore can fold it.
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unsigned NumDstElt = DestVTy->getNumElements();
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unsigned NumSrcElt = CV->getNumOperands();
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if (NumDstElt == NumSrcElt)
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return ConstantExpr::getBitCast(C, DestTy);
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const Type *SrcEltTy = CV->getType()->getElementType();
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const Type *DstEltTy = DestVTy->getElementType();
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// Otherwise, we're changing the number of elements in a vector, which
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// requires endianness information to do the right thing. For example,
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// bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
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// folds to (little endian):
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// <4 x i32> <i32 0, i32 0, i32 1, i32 0>
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// and to (big endian):
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// <4 x i32> <i32 0, i32 0, i32 0, i32 1>
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// First thing is first. We only want to think about integer here, so if
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// we have something in FP form, recast it as integer.
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if (DstEltTy->isFloatingPoint()) {
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// Fold to an vector of integers with same size as our FP type.
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unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits();
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const Type *DestIVTy =
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VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumDstElt);
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// Recursively handle this integer conversion, if possible.
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C = FoldBitCast(C, DestIVTy, TD);
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if (!C) return ConstantExpr::getBitCast(C, DestTy);
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// Finally, VMCore can handle this now that #elts line up.
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return ConstantExpr::getBitCast(C, DestTy);
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}
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// Okay, we know the destination is integer, if the input is FP, convert
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// it to integer first.
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if (SrcEltTy->isFloatingPoint()) {
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unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
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const Type *SrcIVTy =
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VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumSrcElt);
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// Ask VMCore to do the conversion now that #elts line up.
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C = ConstantExpr::getBitCast(C, SrcIVTy);
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CV = dyn_cast<ConstantVector>(C);
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if (!CV) // If VMCore wasn't able to fold it, bail out.
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return C;
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}
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// Now we know that the input and output vectors are both integer vectors
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// of the same size, and that their #elements is not the same. Do the
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// conversion here, which depends on whether the input or output has
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// more elements.
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bool isLittleEndian = TD.isLittleEndian();
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SmallVector<Constant*, 32> Result;
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if (NumDstElt < NumSrcElt) {
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// Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>)
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Constant *Zero = Constant::getNullValue(DstEltTy);
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unsigned Ratio = NumSrcElt/NumDstElt;
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unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits();
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unsigned SrcElt = 0;
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for (unsigned i = 0; i != NumDstElt; ++i) {
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// Build each element of the result.
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Constant *Elt = Zero;
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unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1);
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for (unsigned j = 0; j != Ratio; ++j) {
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Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(SrcElt++));
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if (!Src) // Reject constantexpr elements.
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return ConstantExpr::getBitCast(C, DestTy);
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// Zero extend the element to the right size.
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Src = ConstantExpr::getZExt(Src, Elt->getType());
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// Shift it to the right place, depending on endianness.
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Src = ConstantExpr::getShl(Src,
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ConstantInt::get(Src->getType(), ShiftAmt));
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ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize;
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// Mix it in.
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Elt = ConstantExpr::getOr(Elt, Src);
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}
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Result.push_back(Elt);
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}
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} else {
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// Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
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unsigned Ratio = NumDstElt/NumSrcElt;
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unsigned DstBitSize = DstEltTy->getPrimitiveSizeInBits();
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// Loop over each source value, expanding into multiple results.
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for (unsigned i = 0; i != NumSrcElt; ++i) {
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Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(i));
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if (!Src) // Reject constantexpr elements.
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return ConstantExpr::getBitCast(C, DestTy);
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unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1);
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for (unsigned j = 0; j != Ratio; ++j) {
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// Shift the piece of the value into the right place, depending on
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// endianness.
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Constant *Elt = ConstantExpr::getLShr(Src,
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ConstantInt::get(Src->getType(), ShiftAmt));
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ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
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// Truncate and remember this piece.
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Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
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}
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}
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}
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return ConstantVector::get(Result.data(), Result.size());
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}
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/// IsConstantOffsetFromGlobal - If this constant is actually a constant offset
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/// from a global, return the global and the constant. Because of
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/// constantexprs, this function is recursive.
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@ -125,11 +248,11 @@ static bool ReadDataFromGlobal(Constant *C, uint64_t ByteOffset,
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if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
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if (CFP->getType()->isDoubleTy()) {
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C = ConstantExpr::getBitCast(C, Type::getInt64Ty(C->getContext()));
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C = FoldBitCast(C, Type::getInt64Ty(C->getContext()), TD);
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return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
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}
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if (CFP->getType()->isFloatTy()){
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C = ConstantExpr::getBitCast(C, Type::getInt32Ty(C->getContext()));
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C = FoldBitCast(C, Type::getInt32Ty(C->getContext()), TD);
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return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
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}
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return false;
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@ -235,9 +358,9 @@ static Constant *FoldReinterpretLoadFromConstPtr(Constant *C,
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} else
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return 0;
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C = ConstantExpr::getBitCast(C, MapTy);
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C = FoldBitCast(C, MapTy, TD);
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if (Constant *Res = FoldReinterpretLoadFromConstPtr(C, TD))
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return ConstantExpr::getBitCast(Res, LoadTy);
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return FoldBitCast(Res, LoadTy, TD);
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return 0;
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}
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@ -479,132 +602,11 @@ static Constant *SymbolicallyEvaluateGEP(Constant* const* Ops, unsigned NumOps,
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// If we ended up indexing a member with a type that doesn't match
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// the type of what the original indices indexed, add a cast.
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if (Ty != cast<PointerType>(ResultTy)->getElementType())
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C = ConstantExpr::getBitCast(C, ResultTy);
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C = FoldBitCast(C, ResultTy, *TD);
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return C;
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}
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/// FoldBitCast - Constant fold bitcast, symbolically evaluating it with
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/// TargetData. This always returns a non-null constant, but it may be a
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/// ConstantExpr if unfoldable.
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static Constant *FoldBitCast(Constant *C, const Type *DestTy,
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const TargetData &TD, LLVMContext &Context) {
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// If this is a bitcast from constant vector -> vector, fold it.
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ConstantVector *CV = dyn_cast<ConstantVector>(C);
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if (CV == 0)
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return ConstantExpr::getBitCast(C, DestTy);
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const VectorType *DestVTy = dyn_cast<VectorType>(DestTy);
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if (DestVTy == 0)
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return ConstantExpr::getBitCast(C, DestTy);
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// If the element types match, VMCore can fold it.
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unsigned NumDstElt = DestVTy->getNumElements();
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unsigned NumSrcElt = CV->getNumOperands();
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if (NumDstElt == NumSrcElt)
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return ConstantExpr::getBitCast(C, DestTy);
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const Type *SrcEltTy = CV->getType()->getElementType();
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const Type *DstEltTy = DestVTy->getElementType();
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// Otherwise, we're changing the number of elements in a vector, which
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// requires endianness information to do the right thing. For example,
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// bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
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// folds to (little endian):
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// <4 x i32> <i32 0, i32 0, i32 1, i32 0>
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// and to (big endian):
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// <4 x i32> <i32 0, i32 0, i32 0, i32 1>
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// First thing is first. We only want to think about integer here, so if
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// we have something in FP form, recast it as integer.
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if (DstEltTy->isFloatingPoint()) {
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// Fold to an vector of integers with same size as our FP type.
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unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits();
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const Type *DestIVTy = VectorType::get(
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IntegerType::get(Context, FPWidth), NumDstElt);
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// Recursively handle this integer conversion, if possible.
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C = FoldBitCast(C, DestIVTy, TD, Context);
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if (!C) return ConstantExpr::getBitCast(C, DestTy);
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// Finally, VMCore can handle this now that #elts line up.
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return ConstantExpr::getBitCast(C, DestTy);
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}
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// Okay, we know the destination is integer, if the input is FP, convert
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// it to integer first.
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if (SrcEltTy->isFloatingPoint()) {
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unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
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const Type *SrcIVTy = VectorType::get(
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IntegerType::get(Context, FPWidth), NumSrcElt);
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// Ask VMCore to do the conversion now that #elts line up.
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C = ConstantExpr::getBitCast(C, SrcIVTy);
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CV = dyn_cast<ConstantVector>(C);
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if (!CV) // If VMCore wasn't able to fold it, bail out.
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return C;
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}
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// Now we know that the input and output vectors are both integer vectors
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// of the same size, and that their #elements is not the same. Do the
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// conversion here, which depends on whether the input or output has
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// more elements.
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bool isLittleEndian = TD.isLittleEndian();
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SmallVector<Constant*, 32> Result;
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if (NumDstElt < NumSrcElt) {
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// Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>)
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Constant *Zero = Constant::getNullValue(DstEltTy);
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unsigned Ratio = NumSrcElt/NumDstElt;
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unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits();
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unsigned SrcElt = 0;
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for (unsigned i = 0; i != NumDstElt; ++i) {
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// Build each element of the result.
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Constant *Elt = Zero;
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unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1);
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for (unsigned j = 0; j != Ratio; ++j) {
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Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(SrcElt++));
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if (!Src) // Reject constantexpr elements.
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return ConstantExpr::getBitCast(C, DestTy);
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// Zero extend the element to the right size.
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Src = ConstantExpr::getZExt(Src, Elt->getType());
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// Shift it to the right place, depending on endianness.
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Src = ConstantExpr::getShl(Src,
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ConstantInt::get(Src->getType(), ShiftAmt));
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ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize;
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// Mix it in.
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Elt = ConstantExpr::getOr(Elt, Src);
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}
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Result.push_back(Elt);
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}
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} else {
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// Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
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unsigned Ratio = NumDstElt/NumSrcElt;
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unsigned DstBitSize = DstEltTy->getPrimitiveSizeInBits();
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// Loop over each source value, expanding into multiple results.
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for (unsigned i = 0; i != NumSrcElt; ++i) {
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Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(i));
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if (!Src) // Reject constantexpr elements.
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return ConstantExpr::getBitCast(C, DestTy);
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unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1);
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for (unsigned j = 0; j != Ratio; ++j) {
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// Shift the piece of the value into the right place, depending on
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// endianness.
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Constant *Elt = ConstantExpr::getLShr(Src,
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ConstantInt::get(Src->getType(), ShiftAmt));
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ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
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// Truncate and remember this piece.
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Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
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}
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}
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}
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return ConstantVector::get(Result.data(), Result.size());
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}
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//===----------------------------------------------------------------------===//
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@ -730,11 +732,9 @@ Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
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if (TD &&
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TD->getPointerSizeInBits() <=
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CE->getType()->getScalarSizeInBits()) {
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if (CE->getOpcode() == Instruction::PtrToInt) {
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Constant *Input = CE->getOperand(0);
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Constant *C = FoldBitCast(Input, DestTy, *TD, Context);
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return C ? C : ConstantExpr::getBitCast(Input, DestTy);
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}
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if (CE->getOpcode() == Instruction::PtrToInt)
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return FoldBitCast(CE->getOperand(0), DestTy, *TD);
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// If there's a constant offset added to the integer value before
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// it is casted back to a pointer, see if the expression can be
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// converted into a GEP.
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@ -780,7 +780,7 @@ Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
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return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
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case Instruction::BitCast:
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if (TD)
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return FoldBitCast(Ops[0], DestTy, *TD, Context);
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return FoldBitCast(Ops[0], DestTy, *TD);
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return ConstantExpr::getBitCast(Ops[0], DestTy);
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case Instruction::Select:
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return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
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