[PATCH] D20457: Update -ffast-math documentation to match reality.
Justin Lebar via cfe-commits
cfe-commits at lists.llvm.org
Fri May 20 11:17:27 PDT 2016
jlebar updated this revision to Diff 57958.
jlebar added a comment.
Update per Richard's review.
http://reviews.llvm.org/D20457
Files:
docs/UsersManual.rst
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 +592,7 @@
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">;
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")
Index: docs/UsersManual.rst
===================================================================
--- docs/UsersManual.rst
+++ docs/UsersManual.rst
@@ -1055,6 +1055,18 @@
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 fp 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
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D20457.57958.patch
Type: text/x-patch
Size: 2659 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20160520/b82794ea/attachment.bin>
More information about the cfe-commits
mailing list