[Mesa-dev] shader_test for glsl-to-tgsi ceil bug

[Ian Romanick]

On 05/07/2012 04:16 PM, Christoph Bumiller wrote:
> On 05/07/2012 08:34 PM, Eric Anholt wrote:
>> On Sat, 05 May 2012 14:43:44 +0200, Christoph Bumiller
>> <e0425955 at student.tuwien.ac.at>  wrote:
>>> Test case for the "glsl_to_tgsi: use TGSI_OPCODE_CEIL for
>>> ir_unop_ceil" patch attached.
>>
>> This wasn't caught by the generated test for ceil()?  That seems
>> strange.
> It's not, because it's not really meant to test the functionality of
> ceil() itself, but rather a bug in glsl-to-tgsi, which implemented it
> as -floor(-x), that causes the second negation to be lost if the
> result was used in a certain way, like the reciprocal here.
>
> I just sent the test along to illustrate the bug my patch was supposed
> to fix, although including those kinds of failures in piglit would
> probably be a good idea, too.
>
> Of course testing multiple values, including fractional ones, won't
> harm either, even if it doesn't make a difference for that specific bug.

We *have* a bunch of ceil tests in piglit.  What Eric wanted to know was 
whether or not the existing tests already reproduce the failure.  If 
they do not, then they should be extended.