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Implement Transforms/InstCombine/IntPtrCast.ll
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15029 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1966,7 +1966,7 @@ static CastType getCastType(const Type *Src, const Type *Dest) {
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// instruction.
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//
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static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
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const Type *DstTy) {
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const Type *DstTy, TargetData *TD) {
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// It is legal to eliminate the instruction if casting A->B->A if the sizes
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// are identical and the bits don't get reinterpreted (for example
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@ -1974,6 +1974,15 @@ static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
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if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
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return true;
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// If the source and destination types are pointer types, and the intermediate
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// is an integer type bigger than a pointer, eliminate the casts.
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if (isa<PointerType>(SrcTy) && isa<PointerType>(DstTy)) {
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if (isa<PointerType>(MidTy)) return true;
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if (MidTy->isInteger() && MidTy->getPrimitiveSize() >= TD->getPointerSize())
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return true;
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}
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// Allow free casting and conversion of sizes as long as the sign doesn't
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// change...
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if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
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@ -2010,18 +2019,14 @@ static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
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return true;
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}
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}
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// Otherwise, we cannot succeed. Specifically we do not want to allow things
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// like: short -> ushort -> uint, because this can create wrong results if
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// the input short is negative!
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//
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return false;
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}
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static bool ValueRequiresCast(const Value *V, const Type *Ty) {
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static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
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if (V->getType() == Ty || isa<Constant>(V)) return false;
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if (const CastInst *CI = dyn_cast<CastInst>(V))
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if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty))
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if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
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TD))
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return false;
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return true;
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}
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@ -2056,7 +2061,7 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
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//
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if (CastInst *CSrc = dyn_cast<CastInst>(Src)) {
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if (isEliminableCastOfCast(CSrc->getOperand(0)->getType(),
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CSrc->getType(), CI.getType())) {
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CSrc->getType(), CI.getType(), TD)) {
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// This instruction now refers directly to the cast's src operand. This
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// has a good chance of making CSrc dead.
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CI.setOperand(0, CSrc->getOperand(0));
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@ -2153,8 +2158,8 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
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// Don't insert two casts if they cannot be eliminated. We allow two
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// casts to be inserted if the sizes are the same. This could only be
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// converting signedness, which is a noop.
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if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy) ||
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!ValueRequiresCast(Op0, DestTy)) {
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if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
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!ValueRequiresCast(Op0, DestTy, TD)) {
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Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
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Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
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return BinaryOperator::create(cast<BinaryOperator>(SrcI)
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