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RE: [PATCH 1/2, combine] Try REG_EQUAL for nonzero_bits


> From: Alan Modra [mailto:amodra@gmail.com]
> Sent: Thursday, February 12, 2015 4:35 PM
> > >
> > >Actually this bit seems unnecessary as there is already some logic in
> > >nonzero_bits1 for the CONST_INT case. So I guess the code can be
> > >removed and the comment be moved there at the very least but
> > >I'd prefer people from one of the affected target to test it.
> 
> I can tell you that the following doesn't trigger on an
> --enable-targets=all,go powerpc64-linux bootstrap.  (Ada not built due
> to lack of gnat on the machine I used.)  So for powerpc it looks like
> the combine SHORT_IMMEDIATES_SIGN_EXTEND code can disappear.
> The
> rtlanal.c occurrence *is* executed.

So I build a lm32-elf cross-compiler with and without the code guarded by
this macro (both in combine.c and rtlanal.c) and then compiled as much as
I could of gcc (make -I -k) and compared the object files.

diff tells me that there is no difference whatsoever. If you want me to do
tests on other programs or for other target please let me know.

Best regards,

Thomas





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