Re: [patch] Fix PR tree-optimization/70884

[Richard Biener <richard.guenther@gmail.com>]

On Sat, May 7, 2016 at 11:22 PM, Eric Botcazou <ebotcazou@adacore.com> wrote:
> Hi,
>
> this is a tentative fix for the regression introduced in SRA by the machinery
> which deals with the constant pool.  initialize_constant_pool_replacements is
> supposed to issues new loads from the pool for scalarized variables, but it
> fails to do so for variables that are only partially scalarized.
>
> Tested on PowerPC/Linux and x86-64/Linux, OK for mainline and 6 branch?

Hmm, the patch looks obvious if it was the intent to allow constant
pool replacements
_not_ only when the whole constant pool entry may go away.  But I
think the intent was
to not do this otherwise it will generate worse code by forcing all
loads from the constant pool to appear at
function start.

So - the "real" issue may be a missing
should_scalarize_away_bitmap/cannot_scalarize_away_bitmap
check somewhere.

Alan?

Thanks,
Richrd.

>
> 2016-05-07  Eric Botcazou  <ebotcazou@adacore.com>
>
>         PR tree-optimization/70884
>         * tree-sra.c (initialize_constant_pool_replacements): Process all the
>         candidate variables.
>
>
> 2016-05-07  Eric Botcazou  <ebotcazou@adacore.com>
>
>         * gcc.dg/pr70884.c: New test.
>
> --
> Eric Botcazou