glsl: Check for zero vectors in ir_binop_dot

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

diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index d397612..5a9881d 100644 (file)
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -309,6 +309,13 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
       }
       break;
 
+   case ir_binop_dot:
+      if (is_vec_zero(op_const[0]) || is_vec_zero(op_const[1])) {
+        this->progress = true;
+        return ir_constant::zero(mem_ctx, ir->type);
+      }
+      break;
+
    case ir_binop_logic_and:
       /* FINISHME: Also simplify (a && a) to (a). */
       if (is_vec_one(op_const[0])) {