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* [Bug target/49939] New: [avr] Skip 2-word instructions if applicable
@ 2011-08-01 21:00 gjl at gcc dot gnu.org
2011-10-12 10:00 ` [Bug target/49939] " gjl at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: gjl at gcc dot gnu.org @ 2011-08-01 21:00 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49939
Summary: [avr] Skip 2-word instructions if applicable
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: target
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: gjl@gcc.gnu.org
CC: eric.weddington@atmel.com
Target: avr
Curent avr-gcc from trunk compiles this C code
char c;
void foo (char a, char b)
{
if (a)
c = b;
}
with -Os to
foo:
tst r24 ; 7 *cmpqi/1 [length = 1]
breq .L1 ; 8 branch [length = 1]
sts c,r22 ; 10 *movqi/3 [length = 2]
.L1:
ret ; 19 return [length = 1]
which could be smarter using a CPSE skip instruction instead like so:
foo:
cpse r24, __zero_reg__
sts c,r22
.L1:
ret
At current, avr-gcc just emits skips over 1-word instructions.
As of http://gcc.gnu.org/viewcvs?view=revision&revision=177049
avr-gcc now knows if it is also legal to skip 2-word instructions.
^ permalink raw reply [flat|nested] 4+ messages in thread* [Bug target/49939] [avr] Skip 2-word instructions if applicable 2011-08-01 21:00 [Bug target/49939] New: [avr] Skip 2-word instructions if applicable gjl at gcc dot gnu.org @ 2011-10-12 10:00 ` gjl at gcc dot gnu.org 2011-10-12 10:09 ` gjl at gcc dot gnu.org 2012-02-29 10:02 ` gjl at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: gjl at gcc dot gnu.org @ 2011-10-12 10:00 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49939 --- Comment #1 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2011-10-12 09:59:34 UTC --- Author: gjl Date: Wed Oct 12 09:59:30 2011 New Revision: 179843 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=179843 Log: PR target/49939 * config/avr/avr.md (*movqi): Rename to movqi_insn. (*call_insn): Rename to call_insn. (*call_value_insn): Rename to call_value_insn. * config/avr/avr.c (avr_2word_insn_p): New static function. (jump_over_one_insn_p): Use it. Modified: trunk/gcc/ChangeLog trunk/gcc/config/avr/avr.c trunk/gcc/config/avr/avr.md ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/49939] [avr] Skip 2-word instructions if applicable 2011-08-01 21:00 [Bug target/49939] New: [avr] Skip 2-word instructions if applicable gjl at gcc dot gnu.org 2011-10-12 10:00 ` [Bug target/49939] " gjl at gcc dot gnu.org @ 2011-10-12 10:09 ` gjl at gcc dot gnu.org 2012-02-29 10:02 ` gjl at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: gjl at gcc dot gnu.org @ 2011-10-12 10:09 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49939 Georg-Johann Lay <gjl at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution| |FIXED Target Milestone|--- |4.7.0 Known to fail| |4.6.2 --- Comment #2 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2011-10-12 10:09:16 UTC --- Fixed in 4.7. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/49939] [avr] Skip 2-word instructions if applicable 2011-08-01 21:00 [Bug target/49939] New: [avr] Skip 2-word instructions if applicable gjl at gcc dot gnu.org 2011-10-12 10:00 ` [Bug target/49939] " gjl at gcc dot gnu.org 2011-10-12 10:09 ` gjl at gcc dot gnu.org @ 2012-02-29 10:02 ` gjl at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: gjl at gcc dot gnu.org @ 2012-02-29 10:02 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49939 --- Comment #3 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2012-02-29 09:50:24 UTC --- Author: gjl Date: Wed Feb 29 09:50:19 2012 New Revision: 184656 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=184656 Log: PR target/49939 * config/avr/avr.h (ASM_SPEC): Add -mno-skip-bug if we know that the device does not have the skip-bug. Modified: trunk/gcc/ChangeLog trunk/gcc/config/avr/avr.h ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-02-29 9:51 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2011-08-01 21:00 [Bug target/49939] New: [avr] Skip 2-word instructions if applicable gjl at gcc dot gnu.org 2011-10-12 10:00 ` [Bug target/49939] " gjl at gcc dot gnu.org 2011-10-12 10:09 ` gjl at gcc dot gnu.org 2012-02-29 10:02 ` gjl at gcc dot gnu.org
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