Consider the following innocuous-looking code:
pan_merge(packed, vtx->attributes[i], ATTRIBUTE);
Under the current implementation, this code is completely broken. Why?
The current implemention is a macro which hardcodes the loop index i,
which shadows the i used to index attributes. Pull out a helper method
so we do the right thing without resulting to further preprocessor abuse
(__COUNTER__).
While making things more robust, assert the crucial pan_merge
invariant that the total size is a multiple of 4; if this fails, the
routine risks memory corruption.
Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14119>
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