[RFA:] Fix PR rtl-optimization/20527, combine mishandling postincrement

[Roger Sayle]

On Tue, 22 Mar 2005, Hans-Peter Nilsson wrote:
>
> 	PR rtl-optimization/20527
> 	* combine.c (can_combine_p) [AUTO_INC_DEC]: When INSN has an
> 	REG_INC note, test that the register also isn't mentioned in PRED
> 	or SUCC.
>
> gcc/testsuite:
> 	* gcc.c-torture/execute/pr20527-1.c: New test.

This is OK for mainline.  If there are no reported problems with this
change after two or three days, OK for the 4.0 and 3.4 branches (after
bootstraps and regression tests against the relevant branch).

Thanks for fixing this.  There's a possibility that this may also
be related to PR 19454, which was recently shown by Joseph Myers
to be related to handling post_inc expressions in combine.c:
http://gcc.gnu.org/ml/gcc-patches/2005-03/msg01980.html

Roger
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