Subject: [PATCH] math: Set 387 and SSE2 rounding mode for tgamma on i386 [BZ #23253]
To: libc-alpha@sourceware.org
Previously, only the SSE2 rounding mode was set, so the assembler
implementations using 387 were not following the expecting rounding
mode.
2018-06-20 Florian Weimer <fweimer@redhat.com>
[BZ #23253]
* sysdeps/generic/math_private.h (default_libc_feholdsetround_ctx):
Renamed from libc_feholdsetround_ctx.
(default_libc_feresetround_ctx): Renamed from
libc_feresetround_ctx.
(default_libc_feholdsetround_noex_ctx): Renamed from
libc_feholdsetround_noex_ctx.
(default_libc_feresetround_noex_ctx): Renamed from
libc_feresetround_noex_ctx.
[!HAVE_RM_CTX] (libc_feholdsetround_ctx, libc_feresetround_ctx)
(libc_feholdsetround_noex_ctx, libc_feresetround_noex_ctx): Macros
forwardning to the old implementations under the new names.
* sysdeps/i386/fpu/fenv_private.h [__SSE_MATH__]
(libc_feholdexcept_setround_ctx, libc_fesetenv_ctx)
(libc_feupdateenv_ctx, libc_feholdsetround_ctx)
(libc_feresetround_ctx): Forward to default implements for i386
and MATH_SET_BOTH_ROUNDING_MODES.
* sysdeps/i386/Makefile [$(subdir) == math] (CFLAGS-e_gamma_r.c):
Add -DMATH_SET_BOTH_ROUNDING_MODES.
@@ -428,33 +428,6 @@ default_libc_feupdateenv_test (fenv_t *e, int ex)
# define HAVE_RM_CTX 0
#endif
-#if HAVE_RM_CTX
-/* Set/Restore Rounding Modes only when necessary. If defined, these functions
- set/restore floating point state only if the state needed within the lexical
- block is different from the current state. This saves a lot of time when
- the floating point unit is much slower than the fixed point units. */
-
-# ifndef libc_feholdsetround_noex_ctx
-# define libc_feholdsetround_noex_ctx libc_feholdsetround_ctx
-# endif
-# ifndef libc_feholdsetround_noexf_ctx
-# define libc_feholdsetround_noexf_ctx libc_feholdsetroundf_ctx
-# endif
-# ifndef libc_feholdsetround_noexl_ctx
-# define libc_feholdsetround_noexl_ctx libc_feholdsetroundl_ctx
-# endif
-
-# ifndef libc_feresetround_noex_ctx
-# define libc_feresetround_noex_ctx libc_fesetenv_ctx
-# endif
-# ifndef libc_feresetround_noexf_ctx
-# define libc_feresetround_noexf_ctx libc_fesetenvf_ctx
-# endif
-# ifndef libc_feresetround_noexl_ctx
-# define libc_feresetround_noexl_ctx libc_fesetenvl_ctx
-# endif
-
-#else
/* Default implementation using standard fenv functions.
Avoid unnecessary rounding mode changes by first checking the
@@ -462,7 +435,7 @@ default_libc_feupdateenv_test (fenv_t *e, int ex)
important for performance. */
static __always_inline void
-libc_feholdsetround_ctx (struct rm_ctx *ctx, int round)
+default_libc_feholdsetround_ctx (struct rm_ctx *ctx, int round)
{
ctx->updated_status = false;
@@ -476,7 +449,7 @@ libc_feholdsetround_ctx (struct rm_ctx *ctx, int round)
}
static __always_inline void
-libc_feresetround_ctx (struct rm_ctx *ctx)
+default_libc_feresetround_ctx (struct rm_ctx *ctx)
{
/* Restore the rounding mode if updated. */
if (__glibc_unlikely (ctx->updated_status))
@@ -484,7 +457,7 @@ libc_feresetround_ctx (struct rm_ctx *ctx)
}
static __always_inline void
-libc_feholdsetround_noex_ctx (struct rm_ctx *ctx, int round)
+default_libc_feholdsetround_noex_ctx (struct rm_ctx *ctx, int round)
{
/* Save exception flags and rounding mode, and disable exception
traps. */
@@ -496,12 +469,45 @@ libc_feholdsetround_noex_ctx (struct rm_ctx *ctx, int round)
}
static __always_inline void
-libc_feresetround_noex_ctx (struct rm_ctx *ctx)
+default_libc_feresetround_noex_ctx (struct rm_ctx *ctx)
{
/* Restore exception flags and rounding mode. */
__fesetenv (&ctx->env);
}
+#if HAVE_RM_CTX
+/* Set/Restore Rounding Modes only when necessary. If defined, these functions
+ set/restore floating point state only if the state needed within the lexical
+ block is different from the current state. This saves a lot of time when
+ the floating point unit is much slower than the fixed point units. */
+
+# ifndef libc_feholdsetround_noex_ctx
+# define libc_feholdsetround_noex_ctx libc_feholdsetround_ctx
+# endif
+# ifndef libc_feholdsetround_noexf_ctx
+# define libc_feholdsetround_noexf_ctx libc_feholdsetroundf_ctx
+# endif
+# ifndef libc_feholdsetround_noexl_ctx
+# define libc_feholdsetround_noexl_ctx libc_feholdsetroundl_ctx
+# endif
+
+# ifndef libc_feresetround_noex_ctx
+# define libc_feresetround_noex_ctx libc_fesetenv_ctx
+# endif
+# ifndef libc_feresetround_noexf_ctx
+# define libc_feresetround_noexf_ctx libc_fesetenvf_ctx
+# endif
+# ifndef libc_feresetround_noexl_ctx
+# define libc_feresetround_noexl_ctx libc_fesetenvl_ctx
+# endif
+
+#else
+
+# define libc_feholdsetround_ctx default_libc_feholdsetround_ctx
+# define libc_feresetround_ctx default_libc_feresetround_ctx
+# define libc_feholdsetround_noex_ctx default_libc_feholdsetround_noex_ctx
+# define libc_feresetround_noex_ctx default_libc_feresetround_noex_ctx
+
# define libc_feholdsetroundf_ctx libc_feholdsetround_ctx
# define libc_feholdsetroundl_ctx libc_feholdsetround_ctx
# define libc_feresetroundf_ctx libc_feresetround_ctx
@@ -5,6 +5,14 @@ asm-CPPFLAGS += -DGAS_SYNTAX
# The i386 `long double' is a distinct type we support.
long-double-fcts = yes
+ifeq ($(subdir),math)
+# These functions change the rounding mode internally and need to
+# update both the SSE2 rounding mod and the 387 rounding mode. See
+# the handling of MATH_SET_BOTH_ROUNDING_MODES in
+# sysdeps/i386/fpu/fenv_private.h.
+CFLAGS-e_gamma_r.c += -DMATH_SET_BOTH_ROUNDING_MODES
+endif
+
ifeq ($(subdir),string)
sysdep_routines += cacheinfo
endif
@@ -460,11 +460,19 @@ libc_feupdateenv_387_ctx (struct rm_ctx *ctx)
#endif /* __SSE_MATH__ */
#ifdef __SSE2_MATH__
-# define libc_feholdexcept_setround_ctx libc_feholdexcept_setround_sse_ctx
-# define libc_fesetenv_ctx libc_fesetenv_sse_ctx
-# define libc_feupdateenv_ctx libc_feupdateenv_sse_ctx
-# define libc_feholdsetround_ctx libc_feholdsetround_sse_ctx
-# define libc_feresetround_ctx libc_feresetround_sse_ctx
+# if defined (__x86_64__) || !defined (MATH_SET_BOTH_ROUNDING_MODES)
+# define libc_feholdexcept_setround_ctx libc_feholdexcept_setround_sse_ctx
+# define libc_fesetenv_ctx libc_fesetenv_sse_ctx
+# define libc_feupdateenv_ctx libc_feupdateenv_sse_ctx
+# define libc_feholdsetround_ctx libc_feholdsetround_sse_ctx
+# define libc_feresetround_ctx libc_feresetround_sse_ctx
+# else
+# define libc_feholdexcept_setround_ctx default_libc_feholdexcept_setround_ctx
+# define libc_fesetenv_ctx default_libc_fesetenv_ctx
+# define libc_feupdateenv_ctx default_libc_feupdateenv_ctx
+# define libc_feholdsetround_ctx default_libc_feholdsetround_ctx
+# define libc_feresetround_ctx default_libc_feresetround_ctx
+# endif
#else
# define libc_feholdexcept_setround_ctx libc_feholdexcept_setround_387_ctx
# define libc_feupdateenv_ctx libc_feupdateenv_387_ctx