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| author | Roger Sayle <roger@eyesopen.com> | 2007-01-19 19:35:22 +0000 |
|---|---|---|
| committer | Roger Sayle <sayle@gcc.gnu.org> | 2007-01-19 19:35:22 +0000 |
| commit | db02da79174dea480aa4217dbe7afd3d3b8364d1 (patch) | |
| tree | e158e5c13ab326a2c00f9dd76f5137fb2f592973 /gcc/doc | |
| parent | d88c64564e9c9c57bea4c6ce15fd400f589f9de3 (diff) | |
| download | gcc-db02da79174dea480aa4217dbe7afd3d3b8364d1.zip gcc-db02da79174dea480aa4217dbe7afd3d3b8364d1.tar.gz gcc-db02da79174dea480aa4217dbe7afd3d3b8364d1.tar.bz2 | |
common.opt (fsigned-zeros): New command line option.
* common.opt (fsigned-zeros): New command line option.
* flags.h (HONOR_SIGNED_ZEROS): Control via flag_signed_zeros instead
of flag_unsafe_math_optimizations.
* opts.c (set_fast_math_flags): The -ffast-math command line option
implies -fno-signed-zeros.
(fast_math_flags_set_p): Likewise.
* doc/invoke.texi: Document new -fno-signed-zeros option, and update
the documentation of -ffast-math appropriately. Wrap long lines.
* gcc.dg/pr30172-1.c: Specify the -fno-signed-zeros command line
option instead of -funsafe-math-optimizations.
From-SVN: r120978
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/invoke.texi | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 3447ff8..5337288 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -323,7 +323,8 @@ Objective-C and Objective-C++ Dialects}. -fno-default-inline -fno-defer-pop -fmove-loop-invariants @gol -fno-function-cse -fno-guess-branch-probability @gol -fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol --funsafe-math-optimizations -funsafe-loop-optimizations -ffinite-math-only @gol +-funsafe-math-optimizations -funsafe-loop-optimizations @gol +-ffinite-math-only -fno-signed-zeros @gol -fno-toplevel-reorder -fno-trapping-math -fno-zero-initialized-in-bss @gol -fomit-frame-pointer -foptimize-register-move @gol -foptimize-sibling-calls -fprefetch-loop-arrays @gol @@ -5631,8 +5632,8 @@ them to store all pertinent intermediate computations into variables. @opindex ffast-math Sets @option{-fno-math-errno}, @option{-funsafe-math-optimizations}, @* @option{-fno-trapping-math}, @option{-ffinite-math-only}, -@option{-fno-rounding-math}, @option{-fno-signaling-nans} -and @option{fcx-limited-range}. +@option{-fno-rounding-math}, @option{-fno-signaling-nans}, +@option{-fno-signed-zeros} and @option{fcx-limited-range}. This option causes the preprocessor macro @code{__FAST_MATH__} to be defined. @@ -5655,9 +5656,9 @@ math functions. The default is @option{-fmath-errno}. -On Darwin systems, the math library never sets @code{errno}. There is therefore -no reason for the compiler to consider the possibility that it might, -and @option{-fno-math-errno} is the default. +On Darwin systems, the math library never sets @code{errno}. There is +therefore no reason for the compiler to consider the possibility that +it might, and @option{-fno-math-errno} is the default. @item -funsafe-math-optimizations @opindex funsafe-math-optimizations @@ -5685,6 +5686,16 @@ an exact implementation of IEEE or ISO rules/specifications. The default is @option{-fno-finite-math-only}. +@item -fno-signed-zeros +@opindex fno-signed-zeros +Allow optimizations for floating point arithmetic that ignore the +signedness of zero. IEEE arithmetic specifies the behavior of +distinct +0.0 and -0.0 values, which then prohibits simplification +of expressions such as x+0.0 or 0.0*x (even with @option{-ffinte-math-only}). +This option implies that the sign of a zero result isn't significant. + +The default is @option{-fsigned-zeros}. + @item -fno-trapping-math @opindex fno-trapping-math Compile code assuming that floating-point operations cannot generate |