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From: "carrot at google dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/41442] New: missed optimization for boolean expression Date: Wed, 23 Sep 2009 06:49:00 -0000 [thread overview] Message-ID: <bug-41442-17659@http.gcc.gnu.org/bugzilla/> (raw) 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
next reply other threads:[~2009-09-23 6:49 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-09-23 6:49 carrot at google dot com [this message] 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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