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| author | Wolfgang Bangerth <bangerth@dealii.org> | 2007-03-31 09:22:51 -0600 |
|---|---|---|
| committer | Manuel López-Ibáñez <manu@gcc.gnu.org> | 2007-03-31 15:22:51 +0000 |
| commit | c9516c38e3ea4a028efafe349142638800e0212e (patch) | |
| tree | d8f787bddc709588a9114f0bb34501758081d4c1 /gcc/doc | |
| parent | 6be42dd4a21f046a05ccbb5c27cda488bd1c5113 (diff) | |
| download | gcc-c9516c38e3ea4a028efafe349142638800e0212e.zip gcc-c9516c38e3ea4a028efafe349142638800e0212e.tar.gz gcc-c9516c38e3ea4a028efafe349142638800e0212e.tar.bz2 | |
re PR rtl-optimization/14737 (Purge political statement from -ffast-math docs)
2007-03-31 Wolfgang Bangerth <bangerth@dealii.org>
Manuel Lopez-Ibanez <manu@gcc.gnu.org>
PR 14737
* doc/invoke.texi: (optimization options): Reword description
of -ffast-math. Document its primary purpose.
Co-Authored-By: Manuel López-Ibáñez <manu@gcc.gnu.org>
From-SVN: r123382
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/invoke.texi | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 38552b7..db0b743 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -5909,10 +5909,11 @@ Sets @option{-fno-math-errno}, @option{-funsafe-math-optimizations}, @* This option causes the preprocessor macro @code{__FAST_MATH__} to be defined. -This option should never be turned on by any @option{-O} option since +This option is not turned on by any @option{-O} option since it can result in incorrect output for programs which depend on an exact implementation of IEEE or ISO rules/specifications for -math functions. +math functions. It may, however, yield faster code for programs +that do not require the guarantees of these specifications. @item -fno-math-errno @opindex fno-math-errno @@ -5921,10 +5922,11 @@ with a single instruction, e.g., sqrt. A program that relies on IEEE exceptions for math error handling may want to use this flag for speed while maintaining IEEE arithmetic compatibility. -This option should never be turned on by any @option{-O} option since +This option is not turned on by any @option{-O} option since it can result in incorrect output for programs which depend on an exact implementation of IEEE or ISO rules/specifications for -math functions. +math functions. It may, however, yield faster code for programs +that do not require the guarantees of these specifications. The default is @option{-fmath-errno}. @@ -5940,10 +5942,11 @@ ANSI standards. When used at link-time, it may include libraries or startup files that change the default FPU control word or other similar optimizations. -This option should never be turned on by any @option{-O} option since +This option is not turned on by any @option{-O} option since it can result in incorrect output for programs which depend on an exact implementation of IEEE or ISO rules/specifications for -math functions. +math functions. It may, however, yield faster code for programs +that do not require the guarantees of these specifications. The default is @option{-fno-unsafe-math-optimizations}. @@ -5952,9 +5955,11 @@ The default is @option{-fno-unsafe-math-optimizations}. Allow optimizations for floating-point arithmetic that assume that arguments and results are not NaNs or +-Infs. -This option should never be turned on by any @option{-O} option since +This option is not turned on by any @option{-O} option since it can result in incorrect output for programs which depend on -an exact implementation of IEEE or ISO rules/specifications. +an exact implementation of IEEE or ISO rules/specifications for +math functions. It may, however, yield faster code for programs +that do not require the guarantees of these specifications. The default is @option{-fno-finite-math-only}. |