Define the following macros in terms of [gi]cc builtins when the

builtins are available: HUGE_VAL, HUGE_VALF, HUGE_VALL, INFINITY,
and NAN.  These macros now expand to floating-point constant
expressions rather than external references, as required by C99.
Other compilers will retain the historical behavior.  Note that
it is not possible say, e.g.
#define	HUGE_VAL	1.0e9999
because the above may result in diagnostics at translation time
and spurious exceptions at runtime.  Hence the need for compiler
support for these features.

Also use builtins to implement the macros isgreater(),
isgreaterequal(), isless(), islessequal(), islessgreater(),
and isunordered() when such builtins are available.
Although the old macros are correct, the builtin versions
are much faster, and they avoid double-expansion problems.

1 files changed, 29 insertions, 0 deletions

diff --git a/lib/msun/src/math.h b/lib/msun/src/math.h
index 2da3de7..754599e 100644
--- a/lib/msun/src/math.h
+++ b/lib/msun/src/math.h
@@ -34,15 +34,35 @@ extern const union __nan_un {
 	float		__uf;
 } __nan;
 
+#if (defined(__GNUC__) && __GNUC__ >= 3) || defined(__INTEL_COMPILER)
+#define	__MATH_BUILTIN_CONSTANTS
+#endif
+
+#if (defined(__GNUC__) && __GNUC__ >= 3)
+#define	__MATH_BUILTIN_RELOPS
+#endif
+
+#ifdef __MATH_BUILTIN_CONSTANTS
+#define	HUGE_VAL	__builtin_huge_val()
+#else
 #define	HUGE_VAL	(__infinity.__ud)
+#endif
 
 #if __ISO_C_VISIBLE >= 1999
 #define	FP_ILOGB0	(-__INT_MAX)
 #define	FP_ILOGBNAN	__INT_MAX
+
+#ifdef __MATH_BUILTIN_CONSTANTS
+#define	HUGE_VALF	__builtin_huge_valf()
+#define	HUGE_VALL	__builtin_huge_vall()
+#define	INFINITY	__builtin_inf()
+#define	NAN		__builtin_nan("")
+#else
 #define	HUGE_VALF	(float)HUGE_VAL
 #define	HUGE_VALL	(long double)HUGE_VAL
 #define	INFINITY	HUGE_VALF
 #define	NAN		(__nan.__uf)
+#endif /* __MATH_BUILTIN_CONSTANTS */
 
 #define	MATH_ERRNO	1
 #define	MATH_ERREXCEPT	2
@@ -64,6 +84,14 @@ extern const union __nan_un {
 #define	isnan(x)	(fpclassify(x) == FP_NAN)
 #define	isnormal(x)	(fpclassify(x) == FP_NORMAL)
 
+#ifdef __MATH_BUILTIN_RELOPS
+#define	isgreater(x, y)		__builtin_isgreater((x), (y))
+#define	isgreaterequal(x, y)	__builtin_isgreaterequal((x), (y))
+#define	isless(x, y)		__builtin_isless((x), (y))
+#define	islessequal(x, y)	__builtin_islessequal((x), (y))
+#define	islessgreater(x, y)	__builtin_islessgreater((x), (y))
+#define	isunordered(x, y)	__builtin_isunordered((x), (y))
+#else
 #define	isgreater(x, y)		(!isunordered((x), (y)) && (x) > (y))
 #define	isgreaterequal(x, y)	(!isunordered((x), (y)) && (x) >= (y))
 #define	isless(x, y)		(!isunordered((x), (y)) && (x) < (y))
@@ -71,6 +99,7 @@ extern const union __nan_un {
 #define	islessgreater(x, y)	(!isunordered((x), (y)) && \
 					((x) > (y) || (y) > (x)))
 #define	isunordered(x, y)	(isnan(x) || isnan(y))
+#endif /* __MATH_BUILTIN_RELOPS */
 
 #define	signbit(x)	__signbit(x)