[Bug target/19597] [4.0 Regression] avr-gcc 4.0, multiplication by constant, very long code

bernie at develer dot com gcc-bugzilla@gcc.gnu.org
Mon Jan 24 13:16:00 GMT 2005


------- Additional Comments From bernie at develer dot com  2005-01-24 13:15 -------
Subject: Re:  [4.0 Regression] avr-gcc 4.0, multiplication
 by constant, very long code

Bernardo Innocenti wrote:
> marekm at amelek dot gda dot pl wrote:
> 
>>------- Additional Comments From marekm at amelek dot gda dot pl  2005-01-24 09:24 -------
>>Subject: Re:  [4.0 Regression] avr-gcc 4.0, multiplication by constant, very long code
>>
>>On Mon, Jan 24, 2005 at 08:56:46AM -0000, giovannibajo at libero dot it wrote:
>>
>>
>>
>>>Marek, can you review this patch please?
>>
>>
>>>http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19597
>>
>>
>>Thanks.  Reviewing this will take some time - I agree the current rtx
>>costs are not perfect, but changing them can affect generated code in
>>unexpected ways.  It would be good to test it a lot on various test
>>cases, to make sure it doesn't introduce new code size regressions...
> 
> 
> I'm building avr-gcc right now with your two patches and
> this one applied.  I'll let you know shortly.

Not good.  With these two patches applied, the size of four
big AVR applications increased slightly.

These were built with -Os (the second one shows a minor improvement):

   text    data     bss     dec     hex filename
   8008     136     401    8545    2161 images-orig/dspslave.elf
   8032     136     401    8569    2179 images-patched/dspslave.elf

   text    data     bss     dec     hex filename
  18448     536     692   19676    4cdc images-orig/dspmaster.elf
  18428     536     692   19656    4cc8 images-patched/dspmaster.elf

These with -O2:

   text    data     bss     dec     hex filename
  60454    1832    1562   63848    f968 images-orig/kfront.elf
  60488    1832    1562   63882    f98a images-patched/kfront.elf

   text    data     bss     dec     hex filename
  36160     900    1713   38773    9775 images-orig/kcntrl.elf
  36344     900    1713   38957    982d images-patched/kcntrl.elf


Would you like to see some diffs?



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19597



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