On 02/12/2015 06:19 AM, Iago Toral wrote: > Hi, > > is this assertion in ir_assignment::ir_assignment() src/glsl/ir.cpp > correct? > > assert(lhs_components == this->rhs->type->vector_elements); > > We will hit this any time we emit code such as this: > > assign(var1, expr, WRITEMASK_XY)
In this case expr must have two components. I think you want assign(var1, swizzle_for_size(expr, 2), WRITEMASK_XY) GLSL IR assignments match the components in order. If var1 is a vec3, all of the following are valid and different: assign(var1, swizzle_for_size(expr, 2), WRITEMASK_XY) assign(var1, swizzle_for_size(expr, 2), WRITEMASK_XZ) assign(var1, swizzle_for_size(expr, 2), WRITEMASK_YZ) So the writemask is definitely not useless. > where expr and var1 are vec3. At least if we emit that code from > lowering passes inside the driver. There is an example of this situation > in the i965 code (see brw_lower_texture_gradients.cpp). > > It feels like that assertion makes it so that the writemask parameter is > useless, since we always have to write all the elements available in the > rhs... I was tempted to rewrite that assertion as: > > assert(lhs_components <= this->rhs->type->vector_elements); > > or even remove it completely (just comparing the element count and not > the channels we are writing to does not seem to give us much...), but > the commit that introduced the assertion was willing to force that > behavior for some reason. > > If we want to keep the assertion then we have to rewrite the code in > brw_lower_texture_gradients.cpp (that is trivial because we don't really > need to restrict the offending assignment to XY only, I already have a > patch for that), but I wonder if that is really what we want to do here. > > Any thoughts? > > Iago > > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
