On Thu, May 19, 2016 at 6:11 PM, Justin Lebar via cfe-commits < cfe-commits@lists.llvm.org> wrote:
> jlebar created this revision. > jlebar added a reviewer: rsmith. > jlebar added a subscriber: cfe-commits. > > http://reviews.llvm.org/D20457 > > Files: > include/clang/Basic/LangOptions.def > include/clang/Driver/Options.td > > Index: include/clang/Driver/Options.td > =================================================================== > --- include/clang/Driver/Options.td > +++ include/clang/Driver/Options.td > @@ -592,9 +592,13 @@ > def : Flag<["-"], "fno-extended-identifiers">, Group<f_Group>, > Flags<[Unsupported]>; > def fhosted : Flag<["-"], "fhosted">, Group<f_Group>; > def ffast_math : Flag<["-"], "ffast-math">, Group<f_Group>, > Flags<[CC1Option]>, > - HelpText<"Enable the *frontend*'s 'fast-math' mode. This has no effect > on " > - "optimizations, but provides a preprocessor macro > __FAST_MATH__ the " > - "same as GCC's -ffast-math flag">; > + HelpText<"Enable fast-math mode. This defines the __FAST_MATH__ > preprocessor " > + "macro, and lets the compiler make aggressive, potentially > unsafe " > + "assumptions about floating-point math. These include: " > + "Floating-point math obeys regular algebraic rules for real " > + "numbers (e.g. + and * are associative, and x/y == x * (1/y)), > " > + "operands to fp operations are not equal to NaN and Inf, and > +0 " > + "and -0 are interchangeable.">; > This is significantly too long for HelpText. The current help text for this flag is already too long: $ clang --help [...] -fembed-bitcode Embed LLVM IR bitcode as data -femit-all-decls Emit all declarations, even if unused -femulated-tls Use emutls functions to access thread_local variables -fexceptions Enable support for exception handling -ffast-math Enable the *frontend*'s 'fast-math' mode. This has no effect on optimizations, but provides a preprocessor macro __FAST_MATH__ the same as GCC's -ffast-math flag -ffixed-r9 Reserve the r9 register (ARM only) -ffixed-x18 Reserve the x18 register (AArch64 only) [...] Can you move this to UsersManual.rst instead, and put something short here instead, like "Allow aggressive, lossy floating-point optimizations"? def fno_fast_math : Flag<["-"], "fno-fast-math">, Group<f_Group>; > def fmath_errno : Flag<["-"], "fmath-errno">, Group<f_Group>, > Flags<[CC1Option]>, > HelpText<"Require math functions to indicate errors by setting errno">; > Index: include/clang/Basic/LangOptions.def > =================================================================== > --- include/clang/Basic/LangOptions.def > +++ include/clang/Basic/LangOptions.def > @@ -162,7 +162,7 @@ > COMPATIBLE_LANGOPT(GNUInline , 1, 0, "GNU inline semantics") > COMPATIBLE_LANGOPT(NoInlineDefine , 1, 0, "__NO_INLINE__ predefined > macro") > COMPATIBLE_LANGOPT(Deprecated , 1, 0, "__DEPRECATED predefined > macro") > -COMPATIBLE_LANGOPT(FastMath , 1, 0, "__FAST_MATH__ predefined > macro") > +COMPATIBLE_LANGOPT(FastMath , 1, 0, "Fast fp math optimizations, > and __FAST_MATH__ predefined macro") > Something like "fast FP math [...]" would fit better into the diagnostics where this appears. > COMPATIBLE_LANGOPT(FiniteMathOnly , 1, 0, "__FINITE_MATH_ONLY__ > predefined macro") > COMPATIBLE_LANGOPT(UnsafeFPMath , 1, 0, "Unsafe Floating Point Math") > > > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits > >
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