glsl: Don't copy propagate or tree graft precise values.
This is kind of a hack. We currently track precise requirements by decorating ir_variables. Propagating or grafting the RHS of an assignment to a precise value into some other expression tree can lose those decorations. In the long run, it might be better to replace these ir_variable decorations with an "exact" decoration on ir_expression nodes, similar to what NIR does. In the short run, this is probably good enough. It preserves enough information for glsl_to_nir to generate "exact" decorations, and NIR will then handle optimizing these expressions reasonably. Fixes ES31-CTS.gpu_shader5.precise_qualifier. v2: Drop invariant handling, as it shouldn't be necessary (caught by Jason Ekstrand). Signed-off-by: Kenneth Graunke <email@example.com> Reviewed-by: Jason Ekstrand <firstname.lastname@example.org>