On Tue, Apr 09, 2024 at 04:33:10PM +0100, Richard Sandiford wrote:
> Andrew Carlotti <andrew.carlo...@arm.com> writes:
> > There was an assumption in some places that the aarch64_fmv_feature_data
> > array contained FEAT_MAX elements. While this assumption held up till
> > now, it is safer and more flexible to use the array size directly.
> >
> > gcc/ChangeLog:
> >
> > * config/aarch64/aarch64.cc (compare_feature_masks):
> > Use ARRAY_SIZE to determine iteration bounds.
> > (aarch64_mangle_decl_assembler_name): Ditto.
> >
> >
> > diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
> > index
> > 1ea84c8bd7386e399f6ffa3a5e36408cf8831fc6..5de842fcc212c78beba1fa99639e79562d718579
> > 100644
> > --- a/gcc/config/aarch64/aarch64.cc
> > +++ b/gcc/config/aarch64/aarch64.cc
> > @@ -19899,7 +19899,8 @@ compare_feature_masks (aarch64_fmv_feature_mask
> > mask1,
> > auto diff_mask = mask1 ^ mask2;
> > if (diff_mask == 0ULL)
> > return 0;
> > - for (int i = FEAT_MAX - 1; i > 0; i--)
> > + static const int num_features = ARRAY_SIZE (aarch64_fmv_feature_data);
>
> There doesn't seem any need for this to be static (or const). Same for
> the second hunk.
Agreed - I'll fix that, and the other instance I added in a previous patch.
I originally copied this pattern from my driver-aarch64.c:252, which was added
by Kyrill back in 2015.
> > + for (int i = num_features - 1; i > 0; i--)
>
> Pre-existing, but is > 0 rather than >= 0 deliberate? Shouldn't we look
> at index 0 as well?
That was probably left over from when "default" was handled as part of the
list. I think a different instance of this mistake was mentioned in a previous
review. I'll fix this mistake and add a test.
> LGTM otherwise.
>
> Thanks,
> Richard
>
> > {
> > auto bit_mask = aarch64_fmv_feature_data[i].feature_mask;
> > if (diff_mask & bit_mask)
> > @@ -19982,7 +19983,8 @@ aarch64_mangle_decl_assembler_name (tree decl, tree
> > id)
> >
> > name += "._";
> >
> > - for (int i = 0; i < FEAT_MAX; i++)
> > + static const int num_features = ARRAY_SIZE
> > (aarch64_fmv_feature_data);
> > + for (int i = 0; i < num_features; i++)
> > {
> > if (feature_mask & aarch64_fmv_feature_data[i].feature_mask)
> > {
