[Mesa-dev] [PATCH] glsl: Fix array indexing when constant folding built-in functions.

[Kenneth Graunke]

On 04/01/2013 11:30 AM, Ian Romanick wrote:
> On 03/29/2013 02:13 PM, Paul Berry wrote:
>> Mesa constant-folds built-in functions by using a miniature GLSL
>> interpreter (see
>> ir_function_signature::constant_expression_evaluate_expression_list()).
>> This interpreter had a bug in its handling of array indexing, which
>> caused expressions like "m[i][j]" (where m is a matrix) to be handled
>> incorrectly.  Specifically, it incorrectly treated j as indexing into
>> the whole matrix (rather than indexing just into the vector m[i]); as
>> a result the offset computed for m[i] was lost and m[i][j] was treated
>> as m[j][0].
>>
>> Fixes piglit tests inverse-mat[234].{vert,frag}.
>>
>> NOTE: This is a candidate for the 9.1 branch.
>
> Good catch.  The test case fails only in 9.1 and later because it
> requires OpenGL 3.1, but I think the bug exists in earlier versions.
>
> Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=57436
>
> I already pushed my work-around to master (but not to 9.1).  You can
> revert it when you push this change if you like.

I would like to keep the change to use dot(), as that seems like an 
actual improvement.  For the other changes, I guess I don't have a 
strong preference.

--Ken