2 * mingwex/Makefile.in (MATH_DISTFILES): Remove pow.c,

	(MATH_OBJS): Remove pow,o.
	* include/math.h (pow): Declare with _CRTIMP.
	Add comment on how to avoid excess precision problems.

3 files changed, 48 insertions, 7 deletions

diff --git a/winsup/mingw/ChangeLog b/winsup/mingw/ChangeLog
index 64cad4ee4..28a97d214 100644
--- a/winsup/mingw/ChangeLog
+++ b/winsup/mingw/ChangeLog
@@ -1,3 +1,10 @@
+2004-07-02 Danny Smith  <dannysmith@users.sourceforge.net>
+
+	* mingwex/Makefile.in (MATH_DISTFILES): Remove pow.c,
+	(MATH_OBJS): Remove pow,o.
+	* include/math.h (pow): Declare with _CRTIMP.
+	Add comment on how to avoid excess precision problems.
+
 2004-06-30  Danny Smith  <dannysmith@users.sourceforge.net>
 
 	* include/stdio.h (__mingw_fseeko64): Add prototype.
diff --git a/winsup/mingw/include/math.h b/winsup/mingw/include/math.h
index fd6ce95d3..68ba5c752 100644
--- a/winsup/mingw/include/math.h
+++ b/winsup/mingw/include/math.h
@@ -129,7 +129,6 @@ struct _exception
 	double	retval;
 };
 
-
 _CRTIMP double __cdecl sin (double);
 _CRTIMP double __cdecl cos (double);
 _CRTIMP double __cdecl tan (double);
@@ -143,10 +142,7 @@ _CRTIMP double __cdecl atan2 (double, double);
 _CRTIMP double __cdecl exp (double);
 _CRTIMP double __cdecl log (double);
 _CRTIMP double __cdecl log10 (double);
-#ifdef __NO_ISOCEXT
-_CRTIMP
-#endif
-	double __cdecl pow (double, double);
+_CRTIMP	double __cdecl pow (double, double);
 _CRTIMP double __cdecl sqrt (double);
 _CRTIMP double __cdecl ceil (double);
 _CRTIMP double __cdecl floor (double);
@@ -156,6 +152,44 @@ _CRTIMP double __cdecl frexp (double, int*);
 _CRTIMP double __cdecl modf (double, double*);
 _CRTIMP double __cdecl fmod (double, double);
 
+/* Excess precision when using a 64-bit mantissa for FPU math ops can
+   cause unexpected results with some of the MSVCRT math functions.  For
+   example, unless the function return value is stored (truncating to
+   53-bit mantissa), calls to pow with both x and y as integral values
+   sometimes produce a non-integral result.
+   One workaround is to reset the FPU env to 53-bit mantissa
+   by a call to fesetenv (FE_PC53_ENV).  Amother is to force storage
+   of the return value of individual math functions using wrappers.
+   NB, using these wrappers will disable builtin math functions and
+   hence disable the folding of function results at compile time when
+   arguments are constant.  */
+
+#if 0
+#define __DEFINE_FLOAT_STORE_MATHFN_D1(fn1)	\
+static __inline__ double			\
+__float_store_ ## fn1 (double x)		\
+{						\
+   __volatile__ double res = (fn1) (x);		\
+  return res;					\
+}
+
+#define __DEFINE_FLOAT_STORE_MATHFN_D2(fn2)	\
+static __inline__ double			\
+__float_store_ ## fn2 (double x, double y)	\
+{						\
+  __volatile__ double res = (fn2) (x, y);	\
+  return res;					\
+}
+#endif
+
+/* For example, here is how to force the result of the pow function
+   to be stored:   */
+#if 0
+#undef pow
+/* Define the ___float_store_pow function and use it instead of pow().  */
+__DEFINE_FLOAT_STORE_MATHFN_D2 (pow)
+#define pow __float_store_pow
+#endif
 
 #ifndef __STRICT_ANSI__
 
diff --git a/winsup/mingw/mingwex/Makefile.in b/winsup/mingw/mingwex/Makefile.in
index db26626c2..6853ca32d 100644
--- a/winsup/mingw/mingwex/Makefile.in
+++ b/winsup/mingw/mingwex/Makefile.in
@@ -53,7 +53,7 @@ MATH_DISTFILES = \
 	log2l.S logb.c logbf.c logbl.c logf.S logl.S lrint.c lrintf.c \
 	lrintl.c lround.c lroundf.c lroundl.c modff.c modfl.c \
 	nearbyint.S nearbyintf.S nearbyintl.S nextafterf.c \
-	pow.c powf.c powi.c powif.c powil.c powl.c \
+	powf.c powi.c powif.c powil.c powl.c \
 	remainder.S remainderf.S remainderl.S remquo.S \
 	remquof.S remquol.S rint.c rintf.c rintl.c round.c roundf.c \
 	roundl.c scalbn.S scalbnf.S scalbnl.S s_erf.c sf_erf.c \
@@ -135,7 +135,7 @@ MATH_OBJS = \
 	log2l.o logb.o logbf.o logbl.o logf.o logl.o lrint.o lrintf.o \
 	lrintl.o lround.o lroundf.o lroundl.o modff.o modfl.o \
 	nearbyint.o nearbyintf.o nearbyintl.o nextafterf.o \
-	pow.o powf.o powi.o powif.o powil.o powl.o \
+	powf.o powi.o powif.o powil.o powl.o \
 	remainder.o remainderf.o remainderl.o remquo.o \
 	remquof.o remquol.o rint.o rintf.o rintl.o round.o roundf.o \
 	roundl.o scalbn.o scalbnf.o scalbnl.o s_erf.o sf_erf.o \