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* [Bug tree-optimization/41442] New: missed optimization for boolean expression
@ 2009-09-23 6:49 carrot at google dot com
2009-09-23 6:50 ` [Bug tree-optimization/41442] " carrot at google dot com
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: carrot at google dot com @ 2009-09-23 6:49 UTC (permalink / raw)
To: gcc-bugs
The boolean expression ((p1->next && !p2->next) || p2->next) can be simplified
as (p1->next || p2->next), but gcc failed to detect this.
The attached source code is an example, compile it with options -Os
-march=armv5te -mthumb, I got
push {lr}
ldr r3, [r0]
cmp r3, #0
beq .L2
ldr r3, [r1] // redundant load and comparison
mov r0, #0
cmp r3, #0 //
beq .L3 // can branch to L3 directly
.L2:
ldr r0, [r1]
neg r3, r0
adc r0, r0, r3
.L3:
@ sp needed for prologue
pop {pc}
--
Summary: missed optimization for boolean expression
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: carrot at google dot com
GCC build triplet: i686-linux
GCC host triplet: i686-linux
GCC target triplet: arm-eabi
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41442
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug tree-optimization/41442] missed optimization for boolean expression 2009-09-23 6:49 [Bug tree-optimization/41442] New: missed optimization for boolean expression carrot at google dot com @ 2009-09-23 6:50 ` carrot at google dot com 2009-09-23 8:50 ` rguenth at gcc dot gnu dot org ` (3 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: carrot at google dot com @ 2009-09-23 6:50 UTC (permalink / raw) To: gcc-bugs ------- Comment #1 from carrot at google dot com 2009-09-23 06:49 ------- Created an attachment (id=18634) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18634&action=view) test case -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41442 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/41442] missed optimization for boolean expression 2009-09-23 6:49 [Bug tree-optimization/41442] New: missed optimization for boolean expression carrot at google dot com 2009-09-23 6:50 ` [Bug tree-optimization/41442] " carrot at google dot com @ 2009-09-23 8:50 ` rguenth at gcc dot gnu dot org 2009-09-23 9:24 ` jakub at gcc dot gnu dot org ` (2 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: rguenth at gcc dot gnu dot org @ 2009-09-23 8:50 UTC (permalink / raw) To: gcc-bugs ------- Comment #2 from rguenth at gcc dot gnu dot org 2009-09-23 08:50 ------- You wound need to enable PRE implement code hoisting to remove the redundant load (or write the condition as p2->next || (p1->next && !p2->next)). PRE is run too late to help generate optimal code though as ifcombine runs before it and ifcombine wouldn't deal with the if-converted form that is present then. -- rguenth at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |enhancement Status|UNCONFIRMED |NEW Ever Confirmed|0 |1 Last reconfirmed|0000-00-00 00:00:00 |2009-09-23 08:50:35 date| | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41442 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/41442] missed optimization for boolean expression 2009-09-23 6:49 [Bug tree-optimization/41442] New: missed optimization for boolean expression carrot at google dot com 2009-09-23 6:50 ` [Bug tree-optimization/41442] " carrot at google dot com 2009-09-23 8:50 ` rguenth at gcc dot gnu dot org @ 2009-09-23 9:24 ` jakub at gcc dot gnu dot org 2010-04-24 18:54 ` bernds at gcc dot gnu dot org 2010-05-05 18:49 ` bernds at gcc dot gnu dot org 4 siblings, 0 replies; 6+ messages in thread From: jakub at gcc dot gnu dot org @ 2009-09-23 9:24 UTC (permalink / raw) To: gcc-bugs ------- Comment #3 from jakub at gcc dot gnu dot org 2009-09-23 09:24 ------- Or fold could handle this... -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41442 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/41442] missed optimization for boolean expression 2009-09-23 6:49 [Bug tree-optimization/41442] New: missed optimization for boolean expression carrot at google dot com ` (2 preceding siblings ...) 2009-09-23 9:24 ` jakub at gcc dot gnu dot org @ 2010-04-24 18:54 ` bernds at gcc dot gnu dot org 2010-05-05 18:49 ` bernds at gcc dot gnu dot org 4 siblings, 0 replies; 6+ messages in thread From: bernds at gcc dot gnu dot org @ 2010-04-24 18:54 UTC (permalink / raw) To: gcc-bugs ------- Comment #4 from bernds at gcc dot gnu dot org 2010-04-24 18:54 ------- Subject: Bug 41442 Author: bernds Date: Sat Apr 24 18:53:47 2010 New Revision: 158689 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=158689 Log: gcc/ PR tree-optimization/41442 * fold-const.c (merge_truthop_with_opposite_arm): New function. (fold_binary_loc): Call it. gcc/testsuite/ PR tree-optimization/41442 * gcc.target/i386/pr41442.c: New test. Added: trunk/gcc/testsuite/gcc.target/i386/pr41442.c Modified: trunk/gcc/ChangeLog trunk/gcc/fold-const.c trunk/gcc/testsuite/ChangeLog -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41442 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/41442] missed optimization for boolean expression 2009-09-23 6:49 [Bug tree-optimization/41442] New: missed optimization for boolean expression carrot at google dot com ` (3 preceding siblings ...) 2010-04-24 18:54 ` bernds at gcc dot gnu dot org @ 2010-05-05 18:49 ` bernds at gcc dot gnu dot org 4 siblings, 0 replies; 6+ messages in thread From: bernds at gcc dot gnu dot org @ 2010-05-05 18:49 UTC (permalink / raw) To: gcc-bugs ------- Comment #5 from bernds at gcc dot gnu dot org 2010-05-05 18:48 ------- Fixed. -- bernds at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |FIXED http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41442 ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2010-05-05 18:49 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2009-09-23 6:49 [Bug tree-optimization/41442] New: missed optimization for boolean expression carrot at google dot com 2009-09-23 6:50 ` [Bug tree-optimization/41442] " carrot at google dot com 2009-09-23 8:50 ` rguenth at gcc dot gnu dot org 2009-09-23 9:24 ` jakub at gcc dot gnu dot org 2010-04-24 18:54 ` bernds at gcc dot gnu dot org 2010-05-05 18:49 ` bernds at gcc dot gnu dot org
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