llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: Zahira Ammarguellat (zahiraam) <details> <summary>Changes</summary> Check for comparisons to INF and NaN when in ffast-math mode and generate a warning. --- Full diff: https://github.com/llvm/llvm-project/pull/76873.diff 5 Files Affected: - (modified) clang/include/clang/Basic/DiagnosticSemaKinds.td (+3) - (modified) clang/include/clang/Sema/Sema.h (+7-2) - (modified) clang/lib/Sema/SemaChecking.cpp (+74-6) - (modified) clang/lib/Sema/SemaExpr.cpp (+5-2) - (added) clang/test/Sema/warn-fp-fast-compare.cpp (+245) ``````````diff diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index e54f969c19039d..d19be567a1bf66 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -6771,6 +6771,9 @@ def warn_pointer_sub_null_ptr : Warning< def warn_floatingpoint_eq : Warning< "comparing floating point with == or != is unsafe">, InGroup<DiagGroup<"float-equal">>, DefaultIgnore; +def warn_fast_floatingpoint_eq : Warning< + "explicit comparison with %0 when the program is assumed to not use or produce %0">, + InGroup<TautologicalConstantCompare>; def err_setting_eval_method_used_in_unsafe_context : Error < "%select{'#pragma clang fp eval_method'|option 'ffp-eval-method'}0 cannot be used with " diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h index 5e3b57ea33220b..b19ce6312e83bc 100644 --- a/clang/include/clang/Sema/Sema.h +++ b/clang/include/clang/Sema/Sema.h @@ -13893,8 +13893,9 @@ class Sema final { bool SemaBuiltinVAStart(unsigned BuiltinID, CallExpr *TheCall); bool SemaBuiltinVAStartARMMicrosoft(CallExpr *Call); - bool SemaBuiltinUnorderedCompare(CallExpr *TheCall); - bool SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs); + bool SemaBuiltinUnorderedCompare(CallExpr *TheCall, unsigned BuiltinID); + bool SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs, + unsigned BuiltinID); bool SemaBuiltinComplex(CallExpr *TheCall); bool SemaBuiltinVSX(CallExpr *TheCall); bool SemaBuiltinOSLogFormat(CallExpr *TheCall); @@ -13998,6 +13999,8 @@ class Sema final { SourceRange range, llvm::SmallBitVector &CheckedVarArgs); + void CheckInfNaNFunction(const CallExpr *Call, const FunctionDecl *FDecl); + void CheckAbsoluteValueFunction(const CallExpr *Call, const FunctionDecl *FDecl); @@ -14024,6 +14027,8 @@ class Sema final { public: void CheckFloatComparison(SourceLocation Loc, Expr *LHS, Expr *RHS, BinaryOperatorKind Opcode); + void CheckInfNaNFloatComparison(SourceLocation Loc, Expr *LHS, Expr *RHS, + BinaryOperatorKind Opcode); private: void CheckImplicitConversions(Expr *E, SourceLocation CC = SourceLocation()); diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp index 3168d38dd66c36..2c4d628ab160d2 100644 --- a/clang/lib/Sema/SemaChecking.cpp +++ b/clang/lib/Sema/SemaChecking.cpp @@ -2169,6 +2169,7 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID, ICEArguments &= ~(1 << ArgNo); } + FPOptions FPO; switch (BuiltinID) { case Builtin::BI__builtin___CFStringMakeConstantString: // CFStringMakeConstantString is currently not implemented for GOFF (i.e., @@ -2245,15 +2246,15 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID, case Builtin::BI__builtin_islessequal: case Builtin::BI__builtin_islessgreater: case Builtin::BI__builtin_isunordered: - if (SemaBuiltinUnorderedCompare(TheCall)) + if (SemaBuiltinUnorderedCompare(TheCall, BuiltinID)) return ExprError(); break; case Builtin::BI__builtin_fpclassify: - if (SemaBuiltinFPClassification(TheCall, 6)) + if (SemaBuiltinFPClassification(TheCall, 6, BuiltinID)) return ExprError(); break; case Builtin::BI__builtin_isfpclass: - if (SemaBuiltinFPClassification(TheCall, 2)) + if (SemaBuiltinFPClassification(TheCall, 2, BuiltinID)) return ExprError(); break; case Builtin::BI__builtin_isfinite: @@ -2267,7 +2268,7 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID, case Builtin::BI__builtin_signbit: case Builtin::BI__builtin_signbitf: case Builtin::BI__builtin_signbitl: - if (SemaBuiltinFPClassification(TheCall, 1)) + if (SemaBuiltinFPClassification(TheCall, 1, BuiltinID)) return ExprError(); break; case Builtin::BI__builtin_shufflevector: @@ -7621,6 +7622,7 @@ bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall, CheckAbsoluteValueFunction(TheCall, FDecl); CheckMaxUnsignedZero(TheCall, FDecl); + CheckInfNaNFunction(TheCall, FDecl); if (getLangOpts().ObjC) DiagnoseCStringFormatDirectiveInCFAPI(*this, FDecl, Args, NumArgs); @@ -9090,10 +9092,16 @@ bool Sema::SemaBuiltinVAStartARMMicrosoft(CallExpr *Call) { /// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and /// friends. This is declared to take (...), so we have to check everything. -bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { +bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall, unsigned BuiltinID) { if (checkArgCount(*this, TheCall, 2)) return true; + if (BuiltinID == Builtin::BI__builtin_isunordered) { + if (TheCall->getFPFeaturesInEffect(getLangOpts()).getNoHonorNaNs()) + Diag(TheCall->getBeginLoc(), diag::warn_fast_floatingpoint_eq) + << "NaN" << TheCall->getSourceRange(); + } + ExprResult OrigArg0 = TheCall->getArg(0); ExprResult OrigArg1 = TheCall->getArg(1); @@ -9128,10 +9136,22 @@ bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { /// SemaBuiltinSemaBuiltinFPClassification - Handle functions like /// __builtin_isnan and friends. This is declared to take (...), so we have /// to check everything. -bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { +bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs, + unsigned BuiltinID) { if (checkArgCount(*this, TheCall, NumArgs)) return true; + FPOptions FPO = TheCall->getFPFeaturesInEffect(getLangOpts()); + if (FPO.getNoHonorInfs() && (BuiltinID == Builtin::BI__builtin_isfinite || + BuiltinID == Builtin::BI__builtin_isinf || + BuiltinID == Builtin::BI__builtin_isinf_sign)) + Diag(TheCall->getBeginLoc(), diag::warn_fast_floatingpoint_eq) + << "infinity" << TheCall->getSourceRange(); + if (FPO.getNoHonorNaNs() && (BuiltinID == Builtin::BI__builtin_isnan || + BuiltinID == Builtin::BI__builtin_isunordered)) + Diag(TheCall->getBeginLoc(), diag::warn_fast_floatingpoint_eq) + << "NaN" << TheCall->getSourceRange(); + bool IsFPClass = NumArgs == 2; // Find out position of floating-point argument. @@ -12878,6 +12898,22 @@ static bool IsStdFunction(const FunctionDecl *FDecl, return true; } +void Sema::CheckInfNaNFunction(const CallExpr *Call, + const FunctionDecl *FDecl) { + FPOptions FPO = Call->getFPFeaturesInEffect(getLangOpts()); + if ((IsStdFunction(FDecl, "isnan") || IsStdFunction(FDecl, "isunordered") || + (Call->getBuiltinCallee() == Builtin::BI__builtin_nanf)) && + FPO.getNoHonorNaNs()) + Diag(Call->getBeginLoc(), diag::warn_fast_floatingpoint_eq) + << "NaN" << Call->getSourceRange(); + else if ((IsStdFunction(FDecl, "isinf") || + (IsStdFunction(FDecl, "isfinite") || + (Call->getBuiltinCallee() == Builtin::BI__builtin_inff))) && + FPO.getNoHonorInfs()) + Diag(Call->getBeginLoc(), diag::warn_fast_floatingpoint_eq) + << "infinity" << Call->getSourceRange(); +} + // Warn when using the wrong abs() function. void Sema::CheckAbsoluteValueFunction(const CallExpr *Call, const FunctionDecl *FDecl) { @@ -13846,6 +13882,38 @@ Sema::CheckReturnValExpr(Expr *RetValExp, QualType lhsType, CheckPPCMMAType(RetValExp->getType(), ReturnLoc); } +/// Diagnose comparison to NAN or INFINITY in fast math modes. +/// The comparison to NaN or INFINITY is always false in +/// fast modes: float evaluation will not result in inf or nan. +void Sema::CheckInfNaNFloatComparison(SourceLocation Loc, Expr *LHS, Expr *RHS, + BinaryOperatorKind Opcode) { + Expr *LeftExprSansParen = LHS->IgnoreParenImpCasts(); + Expr *RightExprSansParen = RHS->IgnoreParenImpCasts(); + + FPOptions FPO = LHS->getFPFeaturesInEffect(getLangOpts()); + bool NoHonorNaNs = FPO.getNoHonorNaNs(); + bool NoHonorInfs = FPO.getNoHonorInfs(); + llvm::APFloat Value(0.0); + + auto IsConstant = [&Value](Expr *E, Expr *ESansParen, ASTContext &Context) { + return !E->isValueDependent() && + ESansParen->EvaluateAsFloat(Value, Context, + Expr::SE_AllowSideEffects); + }; + + if (IsConstant(LHS, LeftExprSansParen, Context) && + ((NoHonorNaNs && Value.isNaN()) || (NoHonorInfs && Value.isInfinity()))) + Diag(Loc, diag::warn_fast_floatingpoint_eq) + << (Value.isNaN() ? "NaN" : "infinity") << LHS->getSourceRange() + << RHS->getSourceRange(); + + if (IsConstant(RHS, RightExprSansParen, Context) && + ((NoHonorNaNs && Value.isNaN()) || (NoHonorInfs && Value.isInfinity()))) + Diag(Loc, diag::warn_fast_floatingpoint_eq) + << (Value.isNaN() ? "NaN" : "infinity") << LHS->getSourceRange() + << RHS->getSourceRange(); +} + /// Check for comparisons of floating-point values using == and !=. Issue a /// warning if the comparison is not likely to do what the programmer intended. void Sema::CheckFloatComparison(SourceLocation Loc, Expr *LHS, Expr *RHS, diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index 960f513d1111b2..005ddfa882195d 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -13044,9 +13044,12 @@ static QualType checkArithmeticOrEnumeralCompare(Sema &S, ExprResult &LHS, if (Type->isAnyComplexType() && BinaryOperator::isRelationalOp(Opc)) return S.InvalidOperands(Loc, LHS, RHS); - // Check for comparisons of floating point operands using != and ==. - if (Type->hasFloatingRepresentation()) + if (Type->hasFloatingRepresentation()) { + // Check for comparisons to NAN or INFINITY in fast math mode. + S.CheckInfNaNFloatComparison(Loc, LHS.get(), RHS.get(), Opc); + // Check for comparisons of floating point operands using != and ==. S.CheckFloatComparison(Loc, LHS.get(), RHS.get(), Opc); + } // The result of comparisons is 'bool' in C++, 'int' in C. return S.Context.getLogicalOperationType(); diff --git a/clang/test/Sema/warn-fp-fast-compare.cpp b/clang/test/Sema/warn-fp-fast-compare.cpp new file mode 100644 index 00000000000000..df8c8145f538ad --- /dev/null +++ b/clang/test/Sema/warn-fp-fast-compare.cpp @@ -0,0 +1,245 @@ +// RUN: %clang_cc1 -x c++ -verify -triple powerpc64le-unknown-unknown %s \ +// RUN: -menable-no-infs -menable-no-nans -DFAST=1 + +// RUN: %clang_cc1 -x c++ -verify -triple powerpc64le-unknown-unknown %s \ +// RUN: -DNOFAST=1 + +// RUN: %clang_cc1 -x c++ -verify -triple powerpc64le-unknown-unknown %s \ +// RUN: -menable-no-infs -DNO_INFS=1 + +// RUN: %clang_cc1 -x c++ -verify -triple powerpc64le-unknown-unknown %s \ +// RUN: -menable-no-nans -DNO_NANS=1 + +int isunorderedf (float x, float y); +#if NOFAST +// expected-no-diagnostics +#endif +extern "C++" { +namespace std __attribute__((__visibility__("default"))) { + bool + isinf(float __x); + bool + isinf(double __x); + bool + isinf(long double __x); + bool + isnan(float __x); + bool + isnan(double __x); + bool + isnan(long double __x); +bool + isfinite(float __x); + bool + isfinite(double __x); + bool + isfinte(long double __x); + bool + isunordered(float __x, float __y); + bool + isunordered(double __x, double __y); + bool + isunordered(long double __x, long double __y); +} // namespace ) +} +#define NAN (__builtin_nanf("")) +#define INFINITY (__builtin_inff()) + +int compareit(float a, float b) { + volatile int i, j, k, l, m, n, o, p; +#if FAST +// expected-warning@+11 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if FAST +// expected-warning@+8 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+5 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+2 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif + i = a == INFINITY; +#if FAST +// expected-warning@+11 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if FAST +// expected-warning@+8 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+5 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+2 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif + j = INFINITY == a; +#if FAST +// expected-warning@+11 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if FAST +// expected-warning@+8 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+5 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+2 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif + i = a == NAN; +#if FAST +// expected-warning@+11 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if FAST +// expected-warning@+8 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+5 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+2 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif + j = NAN == a; +#if FAST +// expected-warning@+11 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if FAST +// expected-warning@+8 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+5 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+2 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif + j = INFINITY <= a; +#if FAST +// expected-warning@+11 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if FAST +// expected-warning@+8 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS + // expected-warning@+5 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+2 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif + j = INFINITY < a; +#if FAST +// expected-warning@+11 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if FAST +// expected-warning@+8 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+5 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS + // expected-warning@+2 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif + j = a > NAN; +#if FAST +// expected-warning@+11 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if FAST +// expected-warning@+8 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+5 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+2 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif + j = a >= NAN; +#if FAST +// expected-warning@+5 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+2 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +k = std::isinf(a); +#if FAST +// expected-warning@+5 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+2 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif + l = std::isnan(a); +#if FAST +// expected-warning@+5 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+2 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif + o = std::isfinite(a); +#if FAST +// expected-warning@+5 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+2 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif + m = __builtin_isinf(a); +#if FAST +// expected-warning@+5 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+2 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif + n = __builtin_isnan(a); +#if FAST +// expected-warning@+5 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+2 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif + p = __builtin_isfinite(a); + + // These should NOT warn, since they are not comparing with NaN or infinity. + j = a > 1.1; + j = b < 1.1; + j = a >= 1.1; + j = b <= 1.1; + j = isunorderedf(a, b); + +#if FAST +// expected-warning@+5 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+2 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif + j = isunorderedf(a, NAN); +#if FAST +// expected-warning@+5 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if NO_INFS +// expected-warning@+2 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif + j = isunorderedf(a, INFINITY); +#if FAST +// expected-warning@+11 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if FAST +// expected-warning@+8 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+5 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+2 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif + i = std::isunordered(a, NAN); +#if FAST +// expected-warning@+11 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif +#if FAST +// expected-warning@+8 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_NANS +// expected-warning@+5 {{explicit comparison with NaN when the program is assumed to not use or produce NaN}} +#endif +#if NO_INFS +// expected-warning@+2 {{explicit comparison with infinity when the program is assumed to not use or produce infinity}} +#endif + i = std::isunordered(a, INFINITY); + return 0; +} `````````` </details> https://github.com/llvm/llvm-project/pull/76873 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
