Fix MIPS libc_feresetround*_ctx to preserve exceptions.

Testing on mips64 showed missing underflow exceptions (from exp, for
example) in non-default rounding modes, caused by
libc_feresetround*_ctx wrongly restoring a saved environment without
preserving exceptions, when that's only valid for the _noex variants.
(I don't know why Steve didn't see this in his testing.)  This patch
fixes this by using libc_feupdateenv_mips_ctx for the relevant macros
and removing the problem definitions.

The problem definitions aren't suitable for the _noex macros either
because they only discard exceptions in non-default rounding modes,
and while for some uses of *_noex/*_NOEX it doesn't matter whether
exceptions are discarded, dbl-64/e_remainder.c requires
SET_RESTORE_ROUND_NOEX to cause exceptions to be discarded.  I think
the accumulated set of macros / functions for optimized exception /
rounding mode handling could do with a careful review by now, and
possible refactoring, and at least one new feature (extracting the
saved rounding mode from an environment / context variable - see
dbl-64/e_sqrt.c for a case where this could be used).

Tested mips64.

	* sysdeps/mips/math_private.h [__mips_hard_float]
	(libc_feresetround_ctx): Define to libc_feupdateenv_mips_ctx not
	libc_feresetround_mips_ctx.
	[__mips_hard_float] (libc_feresetroundf_ctx): Likewise.
	[__mips_hard_float] (libc_feresetroundl_ctx): Likewise.
	[__mips_hard_float] (libc_feresetround_mips_ctx): Remove.

diff --git a/ChangeLog b/ChangeLog
index ca74dc312bb2bed385539496b8314479427a655b..cae7f85a688d35004346c83b1c97c17eddec1aa0 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2014-03-11  Joseph Myers  <joseph@codesourcery.com>
 
+       * sysdeps/mips/math_private.h [__mips_hard_float]
+       (libc_feresetround_ctx): Define to libc_feupdateenv_mips_ctx not
+       libc_feresetround_mips_ctx.
+       [__mips_hard_float] (libc_feresetroundf_ctx): Likewise.
+       [__mips_hard_float] (libc_feresetroundl_ctx): Likewise.
+       [__mips_hard_float] (libc_feresetround_mips_ctx): Remove.
+
        [BZ #16677]
        * math/s_nextafter.c (__nextafter): Do not return value from
        overflowing computation.

diff --git a/sysdeps/mips/math_private.h b/sysdeps/mips/math_private.h
index edf604728ce1fce00d1868b365513a2c6686e7c6..7f2cdf54598239007da5a13744471af8328fdb1a 100644 (file)
--- a/sysdeps/mips/math_private.h
+++ b/sysdeps/mips/math_private.h
@@ -217,6 +217,9 @@ libc_feupdateenv_mips_ctx (struct rm_ctx *ctx)
 # define libc_feupdateenv_ctx             libc_feupdateenv_mips_ctx
 # define libc_feupdateenvf_ctx            libc_feupdateenv_mips_ctx
 # define libc_feupdateenvl_ctx            libc_feupdateenv_mips_ctx
+# define libc_feresetround_ctx            libc_feupdateenv_mips_ctx
+# define libc_feresetroundf_ctx           libc_feupdateenv_mips_ctx
+# define libc_feresetroundl_ctx           libc_feupdateenv_mips_ctx
 
 static __always_inline void
 libc_feholdsetround_mips_ctx (struct rm_ctx *ctx, int round)
@@ -242,16 +245,6 @@ libc_feholdsetround_mips_ctx (struct rm_ctx *ctx, int round)
 # define libc_feholdsetroundf_ctx         libc_feholdsetround_mips_ctx
 # define libc_feholdsetroundl_ctx         libc_feholdsetround_mips_ctx
 
-static __always_inline void
-libc_feresetround_mips_ctx (struct rm_ctx *ctx)
-{
-  if (__glibc_unlikely (ctx->updated_status))
-    _FPU_SETCW (ctx->env);
-}
-# define libc_feresetround_ctx            libc_feresetround_mips_ctx
-# define libc_feresetroundf_ctx           libc_feresetround_mips_ctx
-# define libc_feresetroundl_ctx           libc_feresetround_mips_ctx
-
 #endif
 
 #include_next <math_private.h>