From a5c7472726578c0884a6e69a4f808e4aa9a5d8ed Mon Sep 17 00:00:00 2001 From: Reid Spencer Date: Tue, 27 Feb 2007 19:29:54 +0000 Subject: [PATCH 1/1] 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 --- lib/VMCore/ConstantFold.cpp | 19 +++++-------------- 1 file changed, 5 insertions(+), 14 deletions(-) diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp index d9f32158e5f..d4b02d99155 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(V)) { - APInt Val(APIntOps::RoundDoubleToAPInt(FPC->getValue())); uint32_t DestBitWidth = cast(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(V)) { - APInt Val(APIntOps::RoundDoubleToAPInt(FPC->getValue())); uint32_t DestBitWidth = cast(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(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(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 -- 2.34.1