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authorWilco Dijkstra <wdijkstr@arm.com>2015-09-18 16:30:43 +0100
committerWilco Dijkstra <wdijkstr@arm.com>2015-09-18 16:34:45 +0100
commit8df4e219e43a4a257d0759b54fef8c488e2f282e (patch)
treefd17e1976bc8fb5443476300f9bcf9645de920a9 /math
parentcb2f668d4692df8d31b2ccf9b18b86bebe2d9174 (diff)
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Add inlining of the C99 math functions isinf/isnan/signbit/isfinite/isnormal/fpclassify using GCC
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.
Diffstat (limited to 'math')
-rw-r--r--math/Makefile3
-rw-r--r--math/math.h42
2 files changed, 36 insertions, 9 deletions
diff --git a/math/Makefile b/math/Makefile
index 48e7e4c..2e5291a 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -176,6 +176,8 @@ CFLAGS-test-tgmath.c = -fno-builtin
CFLAGS-test-tgmath2.c = -fno-builtin
CFLAGS-test-tgmath-ret.c = -fno-builtin
CFLAGS-test-powl.c = -fno-builtin
+
+CFLAGS-test-snan.c = -fsignaling-nans
CPPFLAGS-test-ifloat.c = -U__LIBC_INTERNAL_MATH_INLINES \
$(libm-test-fast-math-cflags)
CPPFLAGS-test-idouble.c = -U__LIBC_INTERNAL_MATH_INLINES \
@@ -183,7 +185,6 @@ CPPFLAGS-test-idouble.c = -U__LIBC_INTERNAL_MATH_INLINES \
CPPFLAGS-test-ildoubl.c = -U__LIBC_INTERNAL_MATH_INLINES \
$(libm-test-fast-math-cflags)
-
# The -lieee module sets the _LIB_VERSION_ switch to IEEE mode
# for error handling in the -lm functions.
install-lib += libieee.a
diff --git a/math/math.h b/math/math.h
index 63511a6..fa476e0 100644
--- a/math/math.h
+++ b/math/math.h
@@ -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