[PATCH] D20457: Update -ffast-math documentation to match reality.
Justin Lebar via cfe-commits
cfe-commits at lists.llvm.org
Thu May 19 18:11:57 PDT 2016
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.">;
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")
COMPATIBLE_LANGOPT(FiniteMathOnly , 1, 0, "__FINITE_MATH_ONLY__ predefined macro")
COMPATIBLE_LANGOPT(UnsafeFPMath , 1, 0, "Unsafe Floating Point Math")
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