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* Re: optimization/2391: Exponential compilation time explosion in combine
@ 2003-02-14 21:34 nemet
0 siblings, 0 replies; 4+ messages in thread
From: nemet @ 2003-02-14 21:34 UTC (permalink / raw)
To: bjh21, gcc-bugs, gcc-prs, nemet, nobody, rearnsha
Synopsis: Exponential compilation time explosion in combine
Responsible-Changed-From-To: unassigned->nemet
Responsible-Changed-By: nemet
Responsible-Changed-When: Fri Feb 14 21:34:33 2003
Responsible-Changed-Why:
.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=2391
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: optimization/2391: Exponential compilation time explosion in combine
@ 2003-02-16 1:44 nemet
0 siblings, 0 replies; 4+ messages in thread
From: nemet @ 2003-02-16 1:44 UTC (permalink / raw)
To: bjh21, gcc-bugs, gcc-prs, nemet, rearnsha
Synopsis: Exponential compilation time explosion in combine
State-Changed-From-To: open->closed
State-Changed-By: nemet
State-Changed-When: Sun Feb 16 01:44:17 2003
State-Changed-Why:
Fixed.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=2391
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: optimization/2391: Exponential compilation time explosion in combine
@ 2002-01-12 12:16 Craig Rodrigues
0 siblings, 0 replies; 4+ messages in thread
From: Craig Rodrigues @ 2002-01-12 12:16 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR optimization/2391; it has been noted by GNATS.
From: Craig Rodrigues <rodrigc@mediaone.net>
To: rearnsha@arm.com, gcc-gnats@gcc.gnu.org, gcc-prs@gcc.gnu.org,
bjh21@netbsd.org, gcc-bugs@gcc.gnu.org, nobody@gcc.gnu.org
Cc:
Subject: Re: optimization/2391: Exponential compilation time explosion in combine
Date: Sat, 12 Jan 2002 15:13:04 -0500
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=2391
PR 5333 was marked as a duplicate of this bug. Attachment from PR 5333
added
to this PR, with the following instructions:
===============================================================
When compiling the attached code with -O, GCC (configured as above)
seems to
run forever, eating CPU but not leaking memory. The command line (run
from
within the GCC source tree) was:
./xgcc -da -B. -O -v ~/mhz.i
The -da produces dumps up to mhz.i.30.mach. A workaround is to compile
without -O. This bug has been present since at least egcs 1.1.2.
^ permalink raw reply [flat|nested] 4+ messages in thread
* optimization/2391: Exponential compilation time explosion in combine
@ 2001-03-26 2:36 Richard Earnshaw
0 siblings, 0 replies; 4+ messages in thread
From: Richard Earnshaw @ 2001-03-26 2:36 UTC (permalink / raw)
To: gcc-gnats
>Number: 2391
>Category: optimization
>Synopsis: Exponential compilation time explosion in combine
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Mon Mar 26 02:36:00 PST 2001
>Closed-Date:
>Last-Modified:
>Originator: Richard Earnshaw
>Release: 3.1 20010323 (experimental)
>Organization:
ARM
>Environment:
System: SunOS sun18 5.7 Generic_106541-11 sun4u sparc SUNW,Ultra-5_10
Architecture: sun4
host: sparc-sun-solaris2.5.1
build: sparc-sun-solaris2.5.1
target: arm-unknown-elf
configured with: /home/rearnsha/gnusrc/egcs-cross/configure --target=arm-elf --with-headers=/home/rearnsha/gnusrc/utils/newlib/libc/include --prefix=/home/rearnsha/gnu/egcs/install/SunOS5
>Description:
The following code, when compiled with optimization on gcc/arm (any
configuration), demonstrates an exponential time behaviour in combine.
Each additional statement doubles the length of the compilation. This
is a long-standing problem that dates back to at least gcc-2.8
>How-To-Repeat:
Compile the following test case on arm-elf (or any other ARM target):
arm-elf-gcc -O test.c
unsigned mhz_2(register long n, unsigned a)
{
for (; n > 0; --n) {
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
a^=a+a; a^=a+a; a^=a+a; a^=a+a; a^=a+a;
}
return a;
}
>Fix:
Unknown.
>Release-Note:
>Audit-Trail:
>Unformatted:
^ permalink raw reply [flat|nested] 4+ messages in thread
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2003-02-14 21:34 optimization/2391: Exponential compilation time explosion in combine nemet
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2003-02-16 1:44 nemet
2002-01-12 12:16 Craig Rodrigues
2001-03-26 2:36 Richard Earnshaw
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