diff options
| -rw-r--r-- | docs/UsersManual.rst | 13 | ||||
| -rw-r--r-- | include/clang/Basic/LangOptions.def | 2 | ||||
| -rw-r--r-- | include/clang/Driver/Options.td | 4 |
3 files changed, 15 insertions, 4 deletions
diff --git a/docs/UsersManual.rst b/docs/UsersManual.rst index 48a85a6ccb..b88a418d89 100644 --- a/docs/UsersManual.rst +++ b/docs/UsersManual.rst @@ -1055,6 +1055,19 @@ are listed below. the behavior of sanitizers in the ``cfi`` group to allow checking of cross-DSO virtual and indirect calls. +.. option:: -ffast-math + + Enable fast-math mode. This defines the ``__FAST_MATH__`` preprocessor + macro, and lets the compiler make aggressive, potentially-lossy assumptions + about floating-point math. These include: + + * Floating-point math obeys regular algebraic rules for real numbers (e.g. + ``+`` and ``*`` are associative, ``x/y == x * (1/y)``, and + ``(a + b) * c == a * c + b * c``), + * operands to floating-point operations are not equal to ``NaN`` and + ``Inf``, and + * ``+0`` and ``-0`` are interchangeable. + .. option:: -fwhole-program-vtables Enable whole-program vtable optimizations, such as single-implementation diff --git a/include/clang/Basic/LangOptions.def b/include/clang/Basic/LangOptions.def index 55b389a148..b19095c3f9 100644 --- a/include/clang/Basic/LangOptions.def +++ b/include/clang/Basic/LangOptions.def @@ -162,7 +162,7 @@ COMPATIBLE_VALUE_LANGOPT(PIELevel , 2, 0, "__PIE__ level") 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") COMPATIBLE_LANGOPT(FiniteMathOnly , 1, 0, "__FINITE_MATH_ONLY__ predefined macro") COMPATIBLE_LANGOPT(UnsafeFPMath , 1, 0, "Unsafe Floating Point Math") diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td index dad070ede9..989a06fa13 100644 --- a/include/clang/Driver/Options.td +++ b/include/clang/Driver/Options.td @@ -592,9 +592,7 @@ def : Flag<["-"], "fextended-identifiers">, Group<clang_ignored_f_Group>; 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<"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">; |