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Re: [Bug middle-end/34400] [4.3 regression] bad interaction between DF and SJLJ exceptions


For the record:
the patch is approved (approval was given over the phone before this message).
Kenny's answers to my question is on PR34400.

Seongbae

2008/1/17 Seongbae Park (박성배, 朴成培) <seongbae.park@gmail.com>:
> I just talked to Kenny on the phone, and my suggestion is wrong
> since it changes the return value - doing my naive suggestion
> would lead to infinite loop, as the transfer function will almost always
> return true, even when the out set didn't change.
> Can you add a comment to that effect there ?
> Also please add a comment above df_live_scratch definition
> that this is an optimization to reduce memory allocation overhead
> for the scratch.
>
> Can you explain why the hunk in df_live_bb_local_compute() is correct ?
> As this seems to change what DF_REF_AT_TOP means for artificial defs...
>
> Seongbae
>
> On Jan 17, 2008 1:31 PM, Seongbae Park (박성배, 朴成培)
>
> <seongbae.park@gmail.com> wrote:
> > In df_live_transfer_function:
> >
> > Doesn't look like we need df_live_scratch - can't we do:
> >
> > bitmap_and (out, gen, bb_lr_info->out);
> > bitmap_and_into (in, bb_lr_info->in);
> > return bitmap_ior_and_compl_into (out, in, kill);
> >
> > ?
> >
> > Seongbae
> >
> >
> > On Jan 17, 2008 1:05 PM, Kenneth Zadeck <zadeck@naturalbridge.com> wrote:
> > > This is the second of three patches to fix 34400.  This patch also makes
> > > some progress on 26854 but more work is required that is not going to be
> > > done in 4.3 to fix the problems here.
> > >
> > > This patch uses the output of the df_lr problem to make the df_live
> > > problem converge faster.
> > > This not only saves time but also space since the size of the df_live
> > > bitmaps never grows and the space of our bitmaps is proportional to the
> > > number of 1 bits.
> > >
> > > This has been tested on several platforms and along with the patch just
> > > committed cuts the time on the 34400 problems significantly.  I believe
> > > that this patch also has some modest improvement on bootstrap time, i.e
> > > regular programs.
> > >
> > > The change to df_live_reset is a slightly related latent bug fix.
> > >
> > > Ok to commit?
> > >
> > > Kenny
> > >
> > >
> > > 2008-01-17  Kenneth Zadeck  <zadeck@naturalbridge.com>
> > >         Steven Bosscher  <stevenb.gcc@gmail.com>
> > >
> > >     PR rtl-optimization/26854
> > >     PR rtl-optimization/34400
> > >     * df-problems.c (df_live_scratch): New scratch bitmap.
> > >     (df_live_alloc): Allocate df_live_scratch when doing df_live.
> > >     (df_live_reset): Clear the proper bitmaps.
> > >     (df_live_bb_local_compute): Only process the artificial defs once
> > >     since the order is not important.
> > >     (df_live_init): Init the df_live sets only with the variables
> > >     found live by df_lr.
> > >     (df_live_transfer_function): Use the df_lr sets to prune the
> > >     df_live sets as they are being computed.
> > >     (df_live_free): Free df_live_scratch.
> > >
> > >
> >
> >
> >
> > --
> > #pragma ident "Seongbae Park, compiler, http://seongbae.blogspot.com";
> >
>
>
>
> --
> #pragma ident "Seongbae Park, compiler, http://seongbae.blogspot.com";
>



-- 
#pragma ident "Seongbae Park, compiler, http://seongbae.blogspot.com";

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