зеркало из https://github.com/microsoft/clang-1.git
UBSan: Don't diagnose inf/nan conversions between floating-point types. It's far from clear whether these have undefined behavior, and these checks are helping no-one. Keep the double->float overflow warnings, though, since those are useful in practice, even though it's unclear whether such operations have defined behavior.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178194 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Richard Smith
Родитель
87d2a37bde
Коммит
508764518d
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@ -583,19 +583,17 @@ void ScalarExprEmitter::EmitFloatConversionCheck(Value *OrigSrc,
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Check = Builder.CreateAnd(GE, LE);
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}
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} else {
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// Floating-point to integer or floating-point to floating-point. This has
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// undefined behavior if the source is +-Inf, NaN, or doesn't fit into the
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// destination type (after truncation to an integer for float-to-integer).
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const llvm::fltSemantics &SrcSema =
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CGF.getContext().getFloatTypeSemantics(OrigSrcType);
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APFloat MaxSrc(SrcSema, APFloat::uninitialized);
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APFloat MinSrc(SrcSema, APFloat::uninitialized);
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if (isa<llvm::IntegerType>(DstTy)) {
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// Floating-point to integer. This has undefined behavior if the source is
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// +-Inf, NaN, or doesn't fit into the destination type (after truncation
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// to an integer).
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unsigned Width = CGF.getContext().getIntWidth(DstType);
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bool Unsigned = DstType->isUnsignedIntegerOrEnumerationType();
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APSInt Min = APSInt::getMinValue(Width, Unsigned);
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APFloat MinSrc(SrcSema, APFloat::uninitialized);
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if (MinSrc.convertFromAPInt(Min, !Unsigned, APFloat::rmTowardZero) &
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APFloat::opOverflow)
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// Don't need an overflow check for lower bound. Just check for
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@ -607,6 +605,7 @@ void ScalarExprEmitter::EmitFloatConversionCheck(Value *OrigSrc,
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MinSrc.subtract(APFloat(SrcSema, 1), APFloat::rmTowardNegative);
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APSInt Max = APSInt::getMaxValue(Width, Unsigned);
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APFloat MaxSrc(SrcSema, APFloat::uninitialized);
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if (MaxSrc.convertFromAPInt(Max, !Unsigned, APFloat::rmTowardZero) &
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APFloat::opOverflow)
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// Don't need an overflow check for upper bound. Just check for
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@ -616,44 +615,60 @@ void ScalarExprEmitter::EmitFloatConversionCheck(Value *OrigSrc,
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// Find the smallest value which is too large to represent (before
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// truncation toward zero).
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MaxSrc.add(APFloat(SrcSema, 1), APFloat::rmTowardPositive);
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} else {
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const llvm::fltSemantics &DstSema =
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CGF.getContext().getFloatTypeSemantics(DstType);
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bool IsInexact;
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MinSrc = APFloat::getLargest(DstSema, true);
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if (MinSrc.convert(SrcSema, APFloat::rmTowardZero, &IsInexact) &
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APFloat::opOverflow)
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MinSrc = APFloat::getLargest(SrcSema, true);
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// If we're converting from __half, convert the range to float to match
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// the type of src.
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if (OrigSrcType->isHalfType()) {
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const llvm::fltSemantics &Sema =
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CGF.getContext().getFloatTypeSemantics(SrcType);
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bool IsInexact;
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MinSrc.convert(Sema, APFloat::rmTowardZero, &IsInexact);
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MaxSrc.convert(Sema, APFloat::rmTowardZero, &IsInexact);
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}
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MaxSrc = APFloat::getLargest(DstSema, false);
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if (MaxSrc.convert(SrcSema, APFloat::rmTowardZero, &IsInexact) &
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APFloat::opOverflow)
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MaxSrc = APFloat::getLargest(SrcSema, false);
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}
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// If we're converting from __half, convert the range to float to match
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// the type of src.
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if (OrigSrcType->isHalfType()) {
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const llvm::fltSemantics &Sema =
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CGF.getContext().getFloatTypeSemantics(SrcType);
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bool IsInexact;
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MinSrc.convert(Sema, APFloat::rmTowardZero, &IsInexact);
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MaxSrc.convert(Sema, APFloat::rmTowardZero, &IsInexact);
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}
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if (isa<llvm::IntegerType>(DstTy)) {
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llvm::Value *GE =
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Builder.CreateFCmpOGT(Src, llvm::ConstantFP::get(VMContext, MinSrc));
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llvm::Value *LE =
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Builder.CreateFCmpOLT(Src, llvm::ConstantFP::get(VMContext, MaxSrc));
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Check = Builder.CreateAnd(GE, LE);
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} else {
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// FIXME: Maybe split this sanitizer out from float-cast-overflow.
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//
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// Floating-point to floating-point. This has undefined behavior if the
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// source is not in the range of representable values of the destination
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// type. The C and C++ standards are spectacularly unclear here. We
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// diagnose finite out-of-range conversions, but allow infinities and NaNs
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// to convert to the corresponding value in the smaller type.
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//
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// C11 Annex F gives all such conversions defined behavior for IEC 60559
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// conforming implementations. Unfortunately, LLVM's fptrunc instruction
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// does not.
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// Converting from a lower rank to a higher rank can never have
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// undefined behavior, since higher-rank types must have a superset
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// of values of lower-rank types.
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if (CGF.getContext().getFloatingTypeOrder(OrigSrcType, DstType) != 1)
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return;
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assert(!OrigSrcType->isHalfType() &&
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"should not check conversion from __half, it has the lowest rank");
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const llvm::fltSemantics &DstSema =
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CGF.getContext().getFloatTypeSemantics(DstType);
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APFloat MinBad = APFloat::getLargest(DstSema, false);
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APFloat MaxBad = APFloat::getInf(DstSema, false);
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bool IsInexact;
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MinBad.convert(SrcSema, APFloat::rmTowardZero, &IsInexact);
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MaxBad.convert(SrcSema, APFloat::rmTowardZero, &IsInexact);
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Value *AbsSrc = CGF.EmitNounwindRuntimeCall(
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CGF.CGM.getIntrinsic(llvm::Intrinsic::fabs, Src->getType()), Src);
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llvm::Value *GE =
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Builder.CreateFCmpOGE(Src, llvm::ConstantFP::get(VMContext, MinSrc));
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Builder.CreateFCmpOGT(AbsSrc, llvm::ConstantFP::get(VMContext, MinBad));
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llvm::Value *LE =
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Builder.CreateFCmpOLE(Src, llvm::ConstantFP::get(VMContext, MaxSrc));
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Check = Builder.CreateAnd(GE, LE);
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Builder.CreateFCmpOLT(AbsSrc, llvm::ConstantFP::get(VMContext, MaxBad));
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Check = Builder.CreateNot(Builder.CreateAnd(GE, LE));
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}
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}
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@ -364,14 +364,17 @@ signed char fp16_char_overflow(__fp16 *p) {
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// CHECK: @float_float_overflow
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// CHECK-TRAP: @float_float_overflow
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float float_float_overflow(double f) {
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// CHECK: %[[GE:.*]] = fcmp oge double %[[F:.*]], 0xC7EFFFFFE0000000
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// CHECK: %[[LE:.*]] = fcmp ole double %[[F]], 0x47EFFFFFE0000000
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// CHECK: %[[F:.*]] = call double @llvm.fabs.f64(
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// CHECK: %[[GE:.*]] = fcmp ogt double %[[F]], 0x47EFFFFFE0000000
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// CHECK: %[[LE:.*]] = fcmp olt double %[[F]], 0x7FF0000000000000
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// CHECK: and i1 %[[GE]], %[[LE]]
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// CHECK: call void @__ubsan_handle_float_cast_overflow(
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// CHECK-TRAP: %[[GE:.*]] = fcmp oge double %[[F:.*]], 0xC7EFFFFFE0000000
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// CHECK-TRAP: %[[LE:.*]] = fcmp ole double %[[F]], 0x47EFFFFFE0000000
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// CHECK-TRAP: %[[INBOUNDS:.*]] = and i1 %[[GE]], %[[LE]]
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// CHECK-TRAP: %[[F:.*]] = call double @llvm.fabs.f64(
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// CHECK-TRAP: %[[GE:.*]] = fcmp ogt double %[[F]], 0x47EFFFFFE0000000
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// CHECK-TRAP: %[[LE:.*]] = fcmp olt double %[[F]], 0x7FF0000000000000
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// CHECK-TRAP: %[[OUTOFBOUNDS:.*]] = and i1 %[[GE]], %[[LE]]
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// CHECK-TRAP: %[[INBOUNDS:.*]] = xor i1 %[[OUTOFBOUNDS]], true
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// CHECK-TRAP-NEXT: br i1 %[[INBOUNDS]]
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// CHECK-TRAP: call void @llvm.trap() [[NR_NUW]]
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