Re: RFA: version 2 patch to fix PR37514

[Jeff Law <law at redhat dot com>]

Vladimir Makarov wrote:
> The following patch solves a latent reload bug (in reload inheritance) 
> triggered by IRA.  It is a second version (less pessimistic in reload 
> inheritance optimization) of the patch
>
> The problem is described on
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514
>
>
> The patch invalidates reg_last_reload_reg set in previous insns for 
> INC/DEC if reg_last_reload_reg set is not set for the current insn for 
> some reasons (e.g. the hard register is used in other insn reloads 
> besides reload for INC/DEC).
>
> The patch was tested on SH (with -m4 -ml -O3 -fomit-frame-pointer) and 
> successfully bootstrapped on itanium (another port using INC/DEC 
> heavily).
>
>
> Ok to commit?
>
> 2008-11-25  Vladimir Makarov  <vmakarov@redhat.com>
>
>    PR rtl-optimization/37514
>    * reload1.c (reload_as_needed): Invalidate reg_last_reload
>    from previous insns.
This is fine.  However, at this stage we should be more focused on the 
simpler, safer fix rather than picking up these uncommon 
micro-optimizations. 

Jeff