From: "Paul A. Clarke" <pc@us.ibm.com>
To: libc-alpha@sourceware.org
Cc: tuliom@ascii.art.br, murphyp@linux.ibm.com
Subject: [PATCH] [powerpc] libc_feupdateenv_test: optimize FPSCR access
Date: Sun, 8 Sep 2019 13:29:33 -0500 [thread overview]
Message-ID: <1567967373-27052-1-git-send-email-pc@us.ibm.com> (raw)
From: "Paul A. Clarke" <pc@us.ibm.com>
ROUND_TO_ODD and a couple of other places use libc_feupdateenv_test to
restore the rounding mode and exception enables, preserve exception flags,
and test whether given exception(s) were generated.
If the exception flags haven't changed, then it is sufficient and a bit
more efficient to just restore the rounding mode and enables, rather than
writing the full Floating-Point Status and Control Register (FPSCR).
2019-09-08 Paul A. Clarke <pc@us.ibm.com>
* sysdeps/powerpc/fpu/fenv_libc.h (FPSCR_EXCEPTIONS_MASK): New.
* sysdeps/powerpc/fpu/fenv_private.h (__libc_femergeenv_ppc): Optimize
to write FPSCR control only, if exceptions have not changed.
---
sysdeps/powerpc/fpu/fenv_libc.h | 4 ++++
sysdeps/powerpc/fpu/fenv_private.h | 16 ++++++++++++++--
2 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/sysdeps/powerpc/fpu/fenv_libc.h b/sysdeps/powerpc/fpu/fenv_libc.h
index b703c8d..0aad897 100644
--- a/sysdeps/powerpc/fpu/fenv_libc.h
+++ b/sysdeps/powerpc/fpu/fenv_libc.h
@@ -204,6 +204,10 @@ enum {
(FPSCR_VE_MASK|FPSCR_OE_MASK|FPSCR_UE_MASK|FPSCR_ZE_MASK|FPSCR_XE_MASK)
#define FPSCR_BASIC_EXCEPTIONS_MASK \
(FPSCR_VX_MASK|FPSCR_OX_MASK|FPSCR_UX_MASK|FPSCR_ZX_MASK|FPSCR_XX_MASK)
+#define FPSCR_EXCEPTIONS_MASK (FPSCR_BASIC_EXCEPTIONS_MASK| \
+ FPSCR_VXSNAN_MASK|FPSCR_VXISI_MASK|FPSCR_VXIDI_MASK|FPSCR_VXZDZ_MASK| \
+ FPSCR_VXIMZ_MASK|FPSCR_VXVC_MASK|FPSCR_VXSOFT_MASK|FPSCR_VXSQRT_MASK| \
+ FPSCR_VXCVI_MASK)
#define FPSCR_FPRF_MASK \
(FPSCR_FPRF_C_MASK|FPSCR_FPRF_FL_MASK|FPSCR_FPRF_FG_MASK| \
FPSCR_FPRF_FE_MASK|FPSCR_FPRF_FU_MASK)
diff --git a/sysdeps/powerpc/fpu/fenv_private.h b/sysdeps/powerpc/fpu/fenv_private.h
index 5ebe6cd..af72560 100644
--- a/sysdeps/powerpc/fpu/fenv_private.h
+++ b/sysdeps/powerpc/fpu/fenv_private.h
@@ -116,8 +116,20 @@ __libc_femergeenv_ppc (const fenv_t *envp, unsigned long long old_mask,
if ((old.l & _FPU_ALL_TRAPS) != 0 && (new.l & _FPU_ALL_TRAPS) == 0)
(void) __fe_mask_env ();
- /* Atomically enable and raise (if appropriate) exceptions set in `new'. */
- fesetenv_register (new.fenv);
+ /* If requesting to keep status, replace control, and merge exceptions,
+ and exceptions haven't changed, we can just set new control instead
+ of the whole FPSCR. */
+ if ((old_mask & (FPSCR_CONTROL_MASK|FPSCR_STATUS_MASK|FPSCR_EXCEPTIONS_MASK))
+ == (FPSCR_STATUS_MASK|FPSCR_EXCEPTIONS_MASK) &&
+ (new_mask & (FPSCR_CONTROL_MASK|FPSCR_STATUS_MASK|FPSCR_EXCEPTIONS_MASK))
+ == (FPSCR_CONTROL_MASK|FPSCR_EXCEPTIONS_MASK) &&
+ (old.l & FPSCR_EXCEPTIONS_MASK) == (new.l & FPSCR_EXCEPTIONS_MASK))
+ {
+ fesetenv_mode (new.fenv);
+ }
+ else
+ /* Atomically enable and raise (if appropriate) exceptions set in `new'. */
+ fesetenv_register (new.fenv);
return old.l;
}
--
1.8.3.1
next reply other threads:[~2019-09-08 18:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-08 18:29 Paul A. Clarke [this message]
2019-09-11 23:00 ` [PATCH] [powerpc] libc_feupdateenv_test: optimize FPSCR access Paul E Murphy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/libc/involved.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1567967373-27052-1-git-send-email-pc@us.ibm.com \
--to=pc@us.ibm.com \
--cc=libc-alpha@sourceware.org \
--cc=murphyp@linux.ibm.com \
--cc=tuliom@ascii.art.br \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).