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* [Bug target/42496] New: wrong if conversion optimization
@ 2009-12-25 8:13 carrot at google dot com
2009-12-25 8:14 ` [Bug target/42496] " carrot at google dot com
2009-12-27 0:46 ` steven at gcc dot gnu dot org
0 siblings, 2 replies; 3+ messages in thread
From: carrot at google dot com @ 2009-12-25 8:13 UTC (permalink / raw)
To: gcc-bugs
Compile the attached test case with options -Os, I can get the ideal result:
foo:
cmp r0, #0
ldr r3, .L5
movne r2, #10
moveq r2, #20
str r2, [r3, #0]
bx lr
But when I changed the options to -O2, I got:
foo:
cmp r0, #0
ldrne r3, .L4 // A
ldreq r3, .L4 // B
movne r2, #10
moveq r2, #20
strne r2, [r3, #0] // C
streq r2, [r3, #0] // D
bx lr
Instructions A/B/C/D should not executed conditionally since they do the same
thing in either case.
Similarly when I changed to options to -Os -fpic, I got:
foo:
ldr r3, .L5
ldr r2, .L5+4
.LPIC0:
add r3, pc, r3
cmp r0, #0
ldrne r3, [r3, r2] // E
ldreq r3, [r3, r2] // F
movne r2, #10
moveq r2, #20
str r2, [r3, #0]
bx lr
Instructions E/F should not execute conditionally.
--
Summary: wrong if conversion optimization
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
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=42496
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/42496] wrong if conversion optimization
2009-12-25 8:13 [Bug target/42496] New: wrong if conversion optimization carrot at google dot com
@ 2009-12-25 8:14 ` carrot at google dot com
2009-12-27 0:46 ` steven at gcc dot gnu dot org
1 sibling, 0 replies; 3+ messages in thread
From: carrot at google dot com @ 2009-12-25 8:14 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from carrot at google dot com 2009-12-25 08:14 -------
Created an attachment (id=19389)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19389&action=view)
test case
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42496
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/42496] wrong if conversion optimization
2009-12-25 8:13 [Bug target/42496] New: wrong if conversion optimization carrot at google dot com
2009-12-25 8:14 ` [Bug target/42496] " carrot at google dot com
@ 2009-12-27 0:46 ` steven at gcc dot gnu dot org
1 sibling, 0 replies; 3+ messages in thread
From: steven at gcc dot gnu dot org @ 2009-12-27 0:46 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from steven at gcc dot gnu dot org 2009-12-27 00:45 -------
*** This bug has been marked as a duplicate of 21803 ***
--
steven at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |DUPLICATE
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42496
^ permalink raw reply [flat|nested] 3+ messages in thread
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2009-12-25 8:13 [Bug target/42496] New: wrong if conversion optimization carrot at google dot com
2009-12-25 8:14 ` [Bug target/42496] " carrot at google dot com
2009-12-27 0:46 ` steven at gcc dot gnu dot org
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