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Revert: "Fix -ffast-math flags handling inconsistencies"

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This reverts commit c4fa3728ab,
which caused a regression in the default for flag_excess_precision.

2020-11-24  Ulrich Weigand  <uweigand@de.ibm.com>

gcc/
	PR tree-optimization/97970
	* doc/invoke.texi (-ffast-math): Revert last change.
	* opts.c: Revert last change.
This commit is contained in:
Ulrich Weigand 2020-11-24 19:30:01 +01:00
parent 1805dbc58b
commit ce2d9549f2
2 changed files with 29 additions and 35 deletions
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6
gcc/doc/invoke.texi
View File

@ -12342,10 +12342,10 @@ is unpredictable.
@opindex ffast-math
Sets the options @option{-fno-math-errno}, @option{-funsafe-math-optimizations},
@option{-ffinite-math-only}, @option{-fno-rounding-math},
@option{-fcx-limited-range} and @option{-fexcess-precision=fast}.
@option{-fno-signaling-nans}, @option{-fcx-limited-range} and
@option{-fexcess-precision=fast}.
Whenever all these options listed above are set to those values,
the preprocessor macro @code{__FAST_MATH__} will be defined.
This option causes the preprocessor macro @code{__FAST_MATH__} to be defined.
This option is not turned on by any @option{-O} option besides
@option{-Ofast} since it can result in incorrect output for programs

58
gcc/opts.c
View File

@ -193,12 +193,10 @@ static void set_debug_level (enum debug_info_type type, int extended,
const char *arg, struct gcc_options *opts,
struct gcc_options *opts_set,
location_t loc);
static void set_fast_math_flags (struct gcc_options *opts,
struct gcc_options *opts_set, int set);
static void set_fast_math_flags (struct gcc_options *opts, int set);
static void decode_d_option (const char *arg, struct gcc_options *opts,
location_t loc, diagnostic_context *dc);
static void set_unsafe_math_optimizations_flags (struct gcc_options *opts,
struct gcc_options *opts_set,
int set);
static void enable_warning_as_error (const char *arg, int value,
unsigned int lang_mask,
@ -2493,11 +2491,11 @@ common_handle_option (struct gcc_options *opts,
break;
case OPT_ffast_math:
set_fast_math_flags (opts, opts_set, value);
set_fast_math_flags (opts, value);
break;
case OPT_funsafe_math_optimizations:
set_unsafe_math_optimizations_flags (opts, opts_set, value);
set_unsafe_math_optimizations_flags (opts, value);
break;
case OPT_ffixed_:
@ -2878,44 +2876,44 @@ set_Wstrict_aliasing (struct gcc_options *opts, int onoff)
/* The following routines are useful in setting all the flags that
-ffast-math and -fno-fast-math imply. */
static void
set_fast_math_flags (struct gcc_options *opts,
struct gcc_options *opts_set, int set)
set_fast_math_flags (struct gcc_options *opts, int set)
{
if (!opts->frontend_set_flag_unsafe_math_optimizations
&& !opts_set->x_flag_unsafe_math_optimizations)
if (!opts->frontend_set_flag_unsafe_math_optimizations)
{
opts->x_flag_unsafe_math_optimizations = set;
set_unsafe_math_optimizations_flags (opts, opts_set, set);
set_unsafe_math_optimizations_flags (opts, set);
}
if (!opts->frontend_set_flag_finite_math_only)
SET_OPTION_IF_UNSET (opts, opts_set, flag_finite_math_only, set);
opts->x_flag_finite_math_only = set;
if (!opts->frontend_set_flag_errno_math)
SET_OPTION_IF_UNSET (opts, opts_set, flag_errno_math, !set);
if (!opts->frontend_set_flag_cx_limited_range)
SET_OPTION_IF_UNSET (opts, opts_set, flag_cx_limited_range, set);
if (!opts->frontend_set_flag_excess_precision)
SET_OPTION_IF_UNSET (opts, opts_set, flag_excess_precision,
set ? EXCESS_PRECISION_FAST
: EXCESS_PRECISION_DEFAULT);
// -ffast-math should also reset -frounding-math, but since this
// is off by default, there's nothing to do for now.
opts->x_flag_errno_math = !set;
if (set)
{
if (opts->frontend_set_flag_excess_precision == EXCESS_PRECISION_DEFAULT)
opts->x_flag_excess_precision
= set ? EXCESS_PRECISION_FAST : EXCESS_PRECISION_DEFAULT;
if (!opts->frontend_set_flag_signaling_nans)
opts->x_flag_signaling_nans = 0;
if (!opts->frontend_set_flag_rounding_math)
opts->x_flag_rounding_math = 0;
if (!opts->frontend_set_flag_cx_limited_range)
opts->x_flag_cx_limited_range = 1;
}
}
/* When -funsafe-math-optimizations is set the following
flags are set as well. */
static void
set_unsafe_math_optimizations_flags (struct gcc_options *opts,
struct gcc_options *opts_set, int set)
set_unsafe_math_optimizations_flags (struct gcc_options *opts, int set)
{
if (!opts->frontend_set_flag_trapping_math)
SET_OPTION_IF_UNSET (opts, opts_set, flag_trapping_math, !set);
opts->x_flag_trapping_math = !set;
if (!opts->frontend_set_flag_signed_zeros)
SET_OPTION_IF_UNSET (opts, opts_set, flag_signed_zeros, !set);
opts->x_flag_signed_zeros = !set;
if (!opts->frontend_set_flag_associative_math)
SET_OPTION_IF_UNSET (opts, opts_set, flag_associative_math, set);
opts->x_flag_associative_math = set;
if (!opts->frontend_set_flag_reciprocal_math)
SET_OPTION_IF_UNSET (opts, opts_set, flag_reciprocal_math, set);
opts->x_flag_reciprocal_math = set;
}
/* Return true iff flags in OPTS are set as if -ffast-math. */
@ -2923,14 +2921,10 @@ bool
fast_math_flags_set_p (const struct gcc_options *opts)
{
return (!opts->x_flag_trapping_math
&& !opts->x_flag_signed_zeros
&& opts->x_flag_associative_math
&& opts->x_flag_reciprocal_math
&& opts->x_flag_unsafe_math_optimizations
&& opts->x_flag_finite_math_only
&& !opts->x_flag_signed_zeros
&& !opts->x_flag_errno_math
&& !opts->x_flag_rounding_math
&& opts->x_flag_cx_limited_range
&& opts->x_flag_excess_precision == EXCESS_PRECISION_FAST);
}