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Fix MIPS libc_feresetround*_ctx to preserve exceptions

Message ID Pine.LNX.4.64.1403112231340.23789@digraph.polyomino.org.uk
State Committed
Headers show

Commit Message

Joseph Myers March 11, 2014, 10:33 p.m. UTC
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 and committed.  (No Bugzilla bug because the problem
postdates the last release.)

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.
diff mbox

Patch

diff --git a/sysdeps/mips/math_private.h b/sysdeps/mips/math_private.h
index edf6047..7f2cdf5 100644
--- 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>