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* Re: optimization/7270: Redundant compares not eliminated on x86.
@ 2003-05-13 18:56 Dara Hazeghi
0 siblings, 0 replies; 3+ messages in thread
From: Dara Hazeghi @ 2003-05-13 18:56 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR optimization/7270; it has been noted by GNATS.
From: Dara Hazeghi <dhazeghi@yahoo.com>
To: gcc-gnats@gcc.gnu.org, anamax@earthlink.net
Cc:
Subject: Re: optimization/7270: Redundant compares not eliminated on x86.
Date: Tue, 13 May 2003 11:52:35 -0700
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-
trail&database=gcc&pr=7270
Hello,
this report is against gcc 3.1 which is now a bit outdated. Would it be
possible for you to test this on gcc 3.3 prerelease or cvs, and see if
this problem still occurs? Also, can you provide a sample of the
assembly which is unsatisfactory, and specifically note the
unsatisfactory parts? Thanks,
Dara
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: optimization/7270: Redundant compares not eliminated on x86.
@ 2003-05-14 10:28 giovannibajo
0 siblings, 0 replies; 3+ messages in thread
From: giovannibajo @ 2003-05-14 10:28 UTC (permalink / raw)
To: anamax, gcc-bugs, gcc-prs, nobody
Synopsis: Redundant compares not eliminated on x86.
State-Changed-From-To: open->feedback
State-Changed-By: bajo
State-Changed-When: Wed May 14 10:28:57 2003
State-Changed-Why:
See Dara's question.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7270
^ permalink raw reply [flat|nested] 3+ messages in thread
* optimization/7270: Redundant compares not eliminated on x86.
@ 2002-07-10 22:46 anamax
0 siblings, 0 replies; 3+ messages in thread
From: anamax @ 2002-07-10 22:46 UTC (permalink / raw)
To: gcc-gnats
>Number: 7270
>Category: optimization
>Synopsis: Redundant compares not eliminated on x86.
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: pessimizes-code
>Submitter-Id: net
>Arrival-Date: Wed Jul 10 22:46:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Andy Freeman
>Release: gcc 3.1
>Organization:
>Environment:
Redhat 7.3
>Description:
A <= compare&branch followed by a == test on the same arguments uses a redundant compare for the == on x86.
Using built-in specs.
Configured with: ../gcc-3.1/configure
Thread model: single
gcc version 3.1
>How-To-Repeat:
Look at the -O3 -S output for x86. Notice the two cmpls on either side of the "ja .L4". I believe that the second cmpl is unnecessary as the flags from the first should survive the "ja .L4".
>Fix:
Better value propagation.
>Release-Note:
>Audit-Trail:
>Unformatted:
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2003-05-13 18:56 optimization/7270: Redundant compares not eliminated on x86 Dara Hazeghi
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2003-05-14 10:28 giovannibajo
2002-07-10 22:46 anamax
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