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Re: [PATCH] PR/34012, fwprop does not look at rtx_costs


Hello!

> > > Unlike CSE, fwprop has never looked at rtx_costs except for addressing
> > > mode selection.  This causes pessimizations, for example when the same
> > > expensive constant is used in many insns.  Then it is:

> 2007-11-07  Paolo Bonzini  <bonzini@gnu.org>
> 	    Jakub Jelinek  <jakub@redhat.com>

> 	PR rtl-optimization/34012
> 	* fwprop.c (try_fwprop_subst): Do not replace if the new
> 	SET_SRC has a higher cost than the old one.

> 	* gcc.target/i386/pr34012.c: New test.

> > Bootstrapped/regtested by Jakub on x86_64-linux, ppc64-linux (-m64
> > default) and ia64-linux.  No regressions.

> This is ok.  Please watch for any negative effects of this.

The referenced patch introduces:

Running /home/uros/gcc-test-svn/trunk/gcc/testsuite/gcc.target/i386/i386.exp ...
FAIL: gcc.target/i386/addr-sel-1.c scan-assembler a\\+1
FAIL: gcc.target/i386/addr-sel-1.c scan-assembler b\\+1

on 32bit x86 target.

Uros.


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