[Piglit] [PATCH] shaders: Add test for conditional mod propagation with different types.

Kenneth Graunke kenneth at whitecape.org
Tue Mar 3 13:44:16 PST 2015


On Monday, March 02, 2015 11:03:01 AM Matt Turner wrote:
> The i965 driver has a pass that merges comparisons with zero into the
> instruction that generated the result. For example:
> 
> 	add        tmp    x     y
> 	cmp.ge.f0  null   tmp   0.0
> 
> is optimized into
> 
> 	add.ge.f0  tmp    x     y
> 
> If the types of tmp are different in the add and cmp, comparisons
> against zero might not work the same. For instance if the addition is on
> unsigned integers, they may generate a result of 0x80000000 which is
> -0.0 reinterpreted as a float.
> 
> I think this test triggers the same bug as this bug report.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89317

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
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