public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug target/51797] New: Arm backend missed the mls related optimization
@ 2012-01-09 8:45 carrot at google dot com
2012-01-11 12:03 ` [Bug target/51797] " ramana at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: carrot at google dot com @ 2012-01-09 8:45 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51797
Bug #: 51797
Summary: Arm backend missed the mls related optimization
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: carrot@google.com
Target: arm-linux-androideabi
compile the following code with options -march=armv7-a -mthumb -Os
int t0i(int a, int b)
{
return a - 368 * b;
}
GCC 4.7 generates:
t0i:
ldr r3, .L2
mla r0, r3, r1, r0
bx lr
.L3:
.align 2
.L2:
.word -368
When compiled with -O3, gcc generates:
t0i:
movw r3, #65168
movt r3, 65535
mla r0, r3, r1, r0
bx lr
But an optimized result should be:
t0i:
movw r3, 368
mls r0, r3, r1, r0
bx lr
It is faster and smaller than either of Os/O3 result.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug target/51797] Arm backend missed the mls related optimization
2012-01-09 8:45 [Bug target/51797] New: Arm backend missed the mls related optimization carrot at google dot com
@ 2012-01-11 12:03 ` ramana at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: ramana at gcc dot gnu.org @ 2012-01-11 12:03 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51797
Ramana Radhakrishnan <ramana at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Keywords| |missed-optimization
Last reconfirmed| |2012-01-11
CC| |ramana at gcc dot gnu.org
Ever Confirmed|0 |1
Severity|normal |enhancement
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2012-01-11 12:03 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-01-09 8:45 [Bug target/51797] New: Arm backend missed the mls related optimization carrot at google dot com
2012-01-11 12:03 ` [Bug target/51797] " ramana at gcc dot gnu.org
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).