Re: PATCH] PR 49580

[Razya Ladelsky <RAZYA at il dot ibm dot com>]

Zdenek Dvorak <rakdver@kam.mff.cuni.cz> wrote on 30/06/2011 15:21:43:

> From: Zdenek Dvorak <rakdver@kam.mff.cuni.cz>
> To: Razya Ladelsky/Haifa/IBM@IBMIL
> Cc: gcc-patches@gcc.gnu.org, Richard Guenther 
<richard.guenther@gmail.com>
> Date: 30/06/2011 15:21
> Subject: Re: PATCH] PR 49580
> 
> Hi,
> 
> > This patch fixes the build failure of gcc spec2006 benchmark.
> > The change is in  gimple_duplicate_sese_tail(), where we need to 
subtract 
> > 1 from the loop's number of iterations.
> > The stmt created to change the rhs of the loop's condition, used to be 

> > inserted right after the defining stmt of the rhs (an ssa name).
> > This requires special handling of different cases of the defining 
stmt:
> > 1.gimple_stmt
> > 2.gimple_phi
> > 3.default_def
> > 
> > Instead of handling each case separately, if we insert the new stmt at 
the 
> > begining of the loop's preheader, we're sure that 
> > it's already been defined.
> > 
> > Bootstrap and testsuite pass successfully (as autopar is not enabled 
by 
> > default).
> > No new regressions when the testsuite is run with autopar enabled.
> > No new regressions for the run of spec2006 with autopar enabled, and 
gcc 
> > benchmark now passes successfully.. 
> > 
> > OK for trunk? 
> 
> actually, I think a better approach would be not to have this kind 
> of pass-specific
> adjustments in gimple_duplicate_sese_tail at all.  The code 
> decreasing the number of
> iterations in gimple_duplicate_sese_tail only works because parloops
> does induction
> variable canonicalization first; should we need it to be used 
> anywhere else, it will break.
> I.e., parloops should first transform the condition so that it does 
> the comparison with
> the adjusted value, and then gimple_duplicate_sese_tail could do 
> just code copying
> and cfg changes,
> 
> Zdenek

Hi,

I moved the adjustment of the loop's iterations from 
gimple_duplicate_sese_tail
to tree-parloops.c, right before the call to gimple_duplicate_sese_tail.
I repeated the bootstrap, regression and spec runs - no new regressions.

OK to commit?
Thanks,
razya

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