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| author | Reid Spencer <rspencer@reidspencer.com> | 2007-02-27 19:29:54 +0000 |
|---|---|---|
| committer | Reid Spencer <rspencer@reidspencer.com> | 2007-02-27 19:29:54 +0000 |
| commit | a5c7472726578c0884a6e69a4f808e4aa9a5d8ed (patch) | |
| tree | 207cdaf307e4b0bd575628f7bd5c4c959a8a5834 /lib/VMCore/ConstantFold.cpp | |
| parent | 55fc8a43ee60fdfcc59a7fdc74c2479b84d25f28 (diff) | |
| download | llvm-a5c7472726578c0884a6e69a4f808e4aa9a5d8ed.tar.gz llvm-a5c7472726578c0884a6e69a4f808e4aa9a5d8ed.tar.bz2 llvm-a5c7472726578c0884a6e69a4f808e4aa9a5d8ed.tar.xz | |
For PR1205:
Implement review feedback:
1. Use new APInt::RoundDoubleToAPInt interface to specify the bit width so
that we don't have to truncate or extend in constant folding.
2. Fix a pasteo in SDiv that prevented a check for overflow.
3. Fix the shift operators: undef happens when the shift amount is equal
to the bitwidth.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34677 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/VMCore/ConstantFold.cpp')
| -rw-r--r-- | lib/VMCore/ConstantFold.cpp | 19 |
1 files changed, 5 insertions, 14 deletions
diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp index d9f32158e5..d4b02d9915 100644 --- a/lib/VMCore/ConstantFold.cpp +++ b/lib/VMCore/ConstantFold.cpp @@ -176,23 +176,15 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V, return 0; // Can't fold. case Instruction::FPToUI: if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { - APInt Val(APIntOps::RoundDoubleToAPInt(FPC->getValue())); uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); - if (Val.getBitWidth() > DestBitWidth) - Val.trunc(DestBitWidth); - else if (Val.getBitWidth() < DestBitWidth) - Val.zext(DestBitWidth); + APInt Val(APIntOps::RoundDoubleToAPInt(FPC->getValue(), DestBitWidth)); return ConstantInt::get(DestTy, Val); } return 0; // Can't fold. case Instruction::FPToSI: if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { - APInt Val(APIntOps::RoundDoubleToAPInt(FPC->getValue())); uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); - if (Val.getBitWidth() > DestBitWidth) - Val.trunc(DestBitWidth); - else if (Val.getBitWidth() < DestBitWidth) - Val.sext(DestBitWidth); + APInt Val(APIntOps::RoundDoubleToAPInt(FPC->getValue(), DestBitWidth)); return ConstantInt::get(DestTy, Val); } return 0; // Can't fold. @@ -604,7 +596,6 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, case Instruction::SDiv: if (CI2->isNullValue()) return 0; // X / 0 -> can't fold - return ConstantInt::get(C1->getType(), C1V.sdiv(C2V)); if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) return 0; // MIN_INT / -1 -> overflow return ConstantInt::get(C1->getType(), C1V.sdiv(C2V)); @@ -626,21 +617,21 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, return ConstantInt::get(C1->getType(), C1V ^ C2V); case Instruction::Shl: if (uint32_t shiftAmt = C2V.getZExtValue()) - if (shiftAmt <= C1V.getBitWidth()) + if (shiftAmt < C1V.getBitWidth()) return ConstantInt::get(C1->getType(), C1V.shl(shiftAmt)); else return UndefValue::get(C1->getType()); // too big shift is undef return const_cast<ConstantInt*>(CI1); // Zero shift is identity case Instruction::LShr: if (uint32_t shiftAmt = C2V.getZExtValue()) - if (shiftAmt <= C1V.getBitWidth()) + if (shiftAmt < C1V.getBitWidth()) return ConstantInt::get(C1->getType(), C1V.lshr(shiftAmt)); else return UndefValue::get(C1->getType()); // too big shift is undef return const_cast<ConstantInt*>(CI1); // Zero shift is identity case Instruction::AShr: if (uint32_t shiftAmt = C2V.getZExtValue()) - if (shiftAmt <= C1V.getBitWidth()) + if (shiftAmt < C1V.getBitWidth()) return ConstantInt::get(C1->getType(), C1V.ashr(shiftAmt)); else return UndefValue::get(C1->getType()); // too big shift is undef |