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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
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2011-08-01 21:00 [Bug target/49939] New: [avr] Skip 2-word instructions if applicable gjl at gcc dot gnu.org
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2011-10-12 10:09 ` gjl at gcc dot gnu.org
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