From 0edc47ad7b3fb5ad5f9dcd4139f3074dd11ff457 Mon Sep 17 00:00:00 2001 From: Dale Johannesen Date: Tue, 25 Sep 2007 23:07:07 +0000 Subject: [PATCH] Make APFloat->int conversions deterministic even in cases with undefined behavior. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42328 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Support/APFloat.cpp | 38 ++++++++++++++++++++++++++++++++----- lib/VMCore/ConstantFold.cpp | 2 -- 2 files changed, 33 insertions(+), 7 deletions(-) diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp index b3705f5058f..348b8ab1cd9 100644 --- a/lib/Support/APFloat.cpp +++ b/lib/Support/APFloat.cpp @@ -1399,13 +1399,28 @@ APFloat::convertToInteger(integerPart *parts, unsigned int width, unsigned int msb, partsCount; int bits; - /* Handle the three special cases first. */ - if(category == fcInfinity || category == fcNaN) - return opInvalidOp; - partsCount = partCountForBits(width); - if(category == fcZero) { + /* Handle the three special cases first. We produce + a deterministic result even for the Invalid cases. */ + if (category == fcNaN) { + // Neither sign nor isSigned affects this. + APInt::tcSet(parts, 0, partsCount); + return opInvalidOp; + } + if (category == fcInfinity) { + if (!sign && isSigned) + APInt::tcSetLeastSignificantBits(parts, partsCount, width-1); + else if (!sign && !isSigned) + APInt::tcSetLeastSignificantBits(parts, partsCount, width); + else if (sign && isSigned) { + APInt::tcSetLeastSignificantBits(parts, partsCount, 1); + APInt::tcShiftLeft(parts, partsCount, width-1); + } else // sign && !isSigned + APInt::tcSet(parts, 0, partsCount); + return opInvalidOp; + } + if (category == fcZero) { APInt::tcSet(parts, 0, partsCount); return opOK; } @@ -1418,6 +1433,19 @@ APFloat::convertToInteger(integerPart *parts, unsigned int width, if(bits > 0) { lost_fraction = tmp.shiftSignificandRight(bits); } else { + if (-bits >= semantics->precision) { + // Unrepresentably large. + if (!sign && isSigned) + APInt::tcSetLeastSignificantBits(parts, partsCount, width-1); + else if (!sign && !isSigned) + APInt::tcSetLeastSignificantBits(parts, partsCount, width); + else if (sign && isSigned) { + APInt::tcSetLeastSignificantBits(parts, partsCount, 1); + APInt::tcShiftLeft(parts, partsCount, width-1); + } else // sign && !isSigned + APInt::tcSet(parts, 0, partsCount); + return (opStatus)(opOverflow | opInexact); + } tmp.shiftSignificandLeft(-bits); lost_fraction = lfExactlyZero; } diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp index d8b8566193a..7154afb1833 100644 --- a/lib/VMCore/ConstantFold.cpp +++ b/lib/VMCore/ConstantFold.cpp @@ -197,8 +197,6 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V, APFloat::opStatus status = V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI, APFloat::rmTowardZero); - if (status!=APFloat::opOK && status!=APFloat::opInexact) - return 0; // give up APInt Val(DestBitWidth, 2, x); return ConstantInt::get(Val); } -- 2.34.1