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* [Bug middle-end/35288] New: Expression reassociation problem
@ 2008-02-22 6:36 xinliangli at gmail dot com
2008-02-22 10:56 ` [Bug middle-end/35288] " rguenth at gcc dot gnu dot org
0 siblings, 1 reply; 3+ messages in thread
From: xinliangli at gmail dot com @ 2008-02-22 6:36 UTC (permalink / raw)
To: gcc-bugs
The second instance of a1+a2 is not PREed due to missing expression
reassociation.
int foo(int a1, int a2, int a3)
{
int b1,b2;
b1 = a3 + a2 + a1;
b2 = a1 + a2;
return b1 + b2;
}
--
Summary: Expression reassociation problem
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: xinliangli at gmail dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35288
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug middle-end/35288] Expression reassociation problem
2008-02-22 6:36 [Bug middle-end/35288] New: Expression reassociation problem xinliangli at gmail dot com
@ 2008-02-22 10:56 ` rguenth at gcc dot gnu dot org
0 siblings, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-02-22 10:56 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from rguenth at gcc dot gnu dot org 2008-02-22 10:55 -------
Confirmed. Re-association generates
D.1548_3 = a1_4(D) + a1_4(D);
b1_5 = D.1548_3 + a2_2(D);
b2_6 = b1_5 + a2_2(D);
D.1549_7 = b2_6 + a3_1(D);
but that does not expose SSA_NAMEs with the same value.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2008-02-22 10:55:53
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35288
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug middle-end/35288] Expression reassociation problem
[not found] <bug-35288-4@http.gcc.gnu.org/bugzilla/>
@ 2010-11-02 23:40 ` xinliangli at gmail dot com
0 siblings, 0 replies; 3+ messages in thread
From: xinliangli at gmail dot com @ 2010-11-02 23:40 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35288
--- Comment #2 from davidxl <xinliangli at gmail dot com> 2010-11-02 23:40:15 UTC ---
LLVM got it right:
addl %esi, %edi
leal (%rdx,%rdi,2), %eax
vs gcc:
addl %esi, %edx
leal (%rsi,%rdi,2), %edi
leal (%rdi,%rdx), %eax
vs open64:
leal 0(%rdi,%rsi,1), %eax # [0]
addl %esi,%edx # [0]
addl %edx,%edi # [1]
addl %edi,%eax # [2]
David
^ permalink raw reply [flat|nested] 3+ messages in thread
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2008-02-22 6:36 [Bug middle-end/35288] New: Expression reassociation problem xinliangli at gmail dot com
2008-02-22 10:56 ` [Bug middle-end/35288] " rguenth at gcc dot gnu dot org
[not found] <bug-35288-4@http.gcc.gnu.org/bugzilla/>
2010-11-02 23:40 ` xinliangli at gmail dot com
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