Re: [PATCH]ira: recompute regstat as max_regno changes [PR97705]

[Vladimir Makarov <vmakarov@redhat.com>]

On 2020-11-06 1:15 a.m., Kewen.Lin wrote:
> Hi,
>
> As PR97705 shows, my commit r11-4637 caused some dumping
> comparison difference error on pass ira.  It exposed one
> issue about the newly introduced function remove_scratches,
> which can increase the largest pseudo reg number if it
> succeeds, later some function will use the max_reg_num()
> to get the latest max_regno, when iterating the numbers
> we can access some data structures which are allocated as
> the previous max_regno, some out of array bound accesses
> can occur, the failure can be random since the values
> beyond the array could be random.
>
> This patch is to free/reinit/recompute the relevant data
> structures that is regstat_n_sets_and_refs and reg_info_p
> to ensure we won't access beyond some array bounds.
>
> Bootstrapped/regtested on powerpc64le-linux-gnu P9 and
> powerpc64-linux-gnu P8.
>
> Any thoughts?  Is it a reasonable fix?
>
Sure, Kewen.  A bit unexpected to see lambda to use for this but I 
checked and found couple places in GCC where lambdas are already used.

The patch is ok.  Please, commit it to the mainline.

Thank you for the patch.