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
