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Add inlining of the C99 math functions isinf/isnan/signbit/isfinite/isnormal/fpclassify using GCC

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built-ins when available. Since going through the PLT is expensive for these small functions,
inlining results in major speedups (about 7x on Cortex-A57 for isinf). The GCC built-ins are not
correct if signalling NaN support is required, and thus are turned off in that case (see GCC bug
66462). The test-snan.c tests sNaNs and so must be explicitly built with -fsignaling-nans.

2015-09-18  Wilco Dijkstra  <wdijkstr@arm.com>

        [BZ #15367]
        [BZ #17441]

        * math/Makefile: Build test-snan.c with -fsignaling-nans.
        * math/math.h (fpclassify): Use __builtin_fpclassify when
        available.  (signbit): Use __builtin_signbit(f/l).
        (isfinite): Use__builtin_isfinite.  (isnormal): Use
        __builtin_isnormal.  (isnan): Use __builtin_isnan.
        (isinf): Use __builtin_isinf_sign.
This commit is contained in:
Wilco Dijkstra
2015-09-18 16:30:43 +01:00
parent cb2f668d46
commit 8df4e219e4
4 changed files with 56 additions and 16 deletions
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42
math/math.h
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@ -225,8 +225,16 @@ enum
FP_NORMAL
};
/* GCC bug 66462 means we cannot use the math builtins with -fsignaling-nan,
so disable builtins if this is enabled. When fixed in a newer GCC,
the __SUPPORT_SNAN__ check may be skipped for those versions. */
/* Return number of classification appropriate for X. */
# ifdef __NO_LONG_DOUBLE_MATH
# if __GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__ \
&& !defined __OPTIMIZE_SIZE__
# define fpclassify(x) __builtin_fpclassify (FP_NAN, FP_INFINITE, \
FP_NORMAL, FP_SUBNORMAL, FP_ZERO, x)
# elif defined __NO_LONG_DOUBLE_MATH
# define fpclassify(x) \
(sizeof (x) == sizeof (float) ? __fpclassifyf (x) : __fpclassify (x))
# else
@ -238,19 +246,29 @@ enum
# endif
/* Return nonzero value if sign of X is negative. */
# ifdef __NO_LONG_DOUBLE_MATH
# if __GNUC_PREREQ (4,0)
# define signbit(x) \
(sizeof (x) == sizeof (float) ? __signbitf (x) : __signbit (x))
(sizeof (x) == sizeof (float) \
? __builtin_signbitf (x) \
: sizeof (x) == sizeof (double) \
? __builtin_signbit (x) : __builtin_signbitl (x))
# else
# define signbit(x) \
# ifdef __NO_LONG_DOUBLE_MATH
# define signbit(x) \
(sizeof (x) == sizeof (float) ? __signbitf (x) : __signbit (x))
# else
# define signbit(x) \
(sizeof (x) == sizeof (float) \
? __signbitf (x) \
: sizeof (x) == sizeof (double) \
? __signbit (x) : __signbitl (x))
# endif
# endif
/* Return nonzero value if X is not +-Inf or NaN. */
# ifdef __NO_LONG_DOUBLE_MATH
# if __GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__
# define isfinite(x) __builtin_isfinite (x)
# elif defined __NO_LONG_DOUBLE_MATH
# define isfinite(x) \
(sizeof (x) == sizeof (float) ? __finitef (x) : __finite (x))
# else
@ -262,11 +280,17 @@ enum
# endif
/* Return nonzero value if X is neither zero, subnormal, Inf, nor NaN. */
# define isnormal(x) (fpclassify (x) == FP_NORMAL)
# if __GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__
# define isnormal(x) __builtin_isnormal (x)
# else
# define isnormal(x) (fpclassify (x) == FP_NORMAL)
# endif
/* Return nonzero value if X is a NaN. We could use `fpclassify' but
we already have this functions `__isnan' and it is faster. */
# ifdef __NO_LONG_DOUBLE_MATH
# if __GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__
# define isnan(x) __builtin_isnan (x)
# elif defined __NO_LONG_DOUBLE_MATH
# define isnan(x) \
(sizeof (x) == sizeof (float) ? __isnanf (x) : __isnan (x))
# else
@ -278,7 +302,9 @@ enum
# endif
/* Return nonzero value if X is positive or negative infinity. */
# ifdef __NO_LONG_DOUBLE_MATH
# if __GNUC_PREREQ (4,4) && !defined __SUPPORT_SNAN__
# define isinf(x) __builtin_isinf_sign (x)
# elif defined __NO_LONG_DOUBLE_MATH
# define isinf(x) \
(sizeof (x) == sizeof (float) ? __isinff (x) : __isinf (x))
# else