[Mesa-dev] [PATCH] glsl: skip comparison opt when adding vars of different size

[Timothy Arceri]

The spec allows adding scalars a vector or matrix. In this case
the opt was losing any swizzle or size information.

This fixes a bug with Doom (2016) shaders.
---
 src/compiler/glsl/opt_algebraic.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/compiler/glsl/opt_algebraic.cpp b/src/compiler/glsl/opt_algebraic.cpp
index 1a8ee361652..ff4be269578 100644
--- a/src/compiler/glsl/opt_algebraic.cpp
+++ b/src/compiler/glsl/opt_algebraic.cpp
@@ -709,6 +709,12 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
          if (!is_vec_zero(zero))
             continue;
 
+         /* We are allowed to add scalars with a vector or matrix. In that
+          * case lets just exit early.
+          */
+         if (add->operands[0]->type != add->operands[1]->type)
+            continue;
+
          /* Depending of the zero position we want to optimize
           * (0 cmp x+y) into (-x cmp y) or (x+y cmp 0) into (x cmp -y)
           */
-- 
2.17.1