[PATCH vkd3d v2 2/9] vkd3d-shader/hlsl: Check types when folding constants.

[Francisco Casas]

Signed-off-by: Francisco Casas <fcasas at codeweavers.com>


March 29, 2022 6:48 AM, "Giovanni Mascellani" <gmascellani at codeweavers.com> wrote:

> Hi,
> 
> Il 28/03/22 20:35, Zebediah Figura ha scritto:
> 
>> We currently can't construct HLSL_IR_CONSTANT nodes that aren't vectors > anyway, though (as
>> evidenced by patch 6/9). Is there a real situation, > now or in the future, where we might need
>> this?
> 
> WRT the check on the arguments, as you say no HLSL_IR_CONSTANT object should ever be of type >
> VECTOR, which is why the check is an assert(). Any assert() is strictly speaking not necessary, but
> they are useful for making the code easier to read.
> 
> As for the check on the result type, let us consider the expression "(float1x4)float4(1.0, 2.0,
> 3.0, 4.0)". Unless I am missing something (and supposing that the compiler was able to see
> "float4(1.0, 2.0, 3.0, 4.0)" as a constant), hlsl_fold_constants() would see that it is an
> expression with constant operands, and would try to create an HLSL_IR_CONSTANT to accommodate the
> result, without realizing that it is a matrix type. This would introduce an inconsistency. So I
> think it is appropriate to have one additional check.
> 
> I guess in the long run this problem would go away because eventually all matrix types will have
> been lowered before we go through constant folding, but we're not still there.
> 
> Giovanni.