glsl: Transform dot product by a basis vector into a swizzle

Reviewed-by: Kenneth Graunke <[email protected]>

1 files changed, 24 insertions, 0 deletions

diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index 5a9881dbebe..75948db16fa 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -84,6 +84,12 @@ is_vec_one(ir_constant *ir)
    return (ir == NULL) ? false : ir->is_one();
 }
 
+static inline bool
+is_vec_basis(ir_constant *ir)
+{
+   return (ir == NULL) ? false : ir->is_basis();
+}
+
 static void
 update_type(ir_expression *ir)
 {
@@ -314,6 +320,24 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
 	 this->progress = true;
 	 return ir_constant::zero(mem_ctx, ir->type);
       }
+      if (is_vec_basis(op_const[0])) {
+	 this->progress = true;
+	 unsigned component = 0;
+	 for (unsigned c = 0; c < op_const[0]->type->vector_elements; c++) {
+	    if (op_const[0]->value.f[c] == 1.0)
+	       component = c;
+	 }
+	 return new(mem_ctx) ir_swizzle(ir->operands[1], component, 0, 0, 0, 1);
+      }
+      if (is_vec_basis(op_const[1])) {
+	 this->progress = true;
+	 unsigned component = 0;
+	 for (unsigned c = 0; c < op_const[1]->type->vector_elements; c++) {
+	    if (op_const[1]->value.f[c] == 1.0)
+	       component = c;
+	 }
+	 return new(mem_ctx) ir_swizzle(ir->operands[0], component, 0, 0, 0, 1);
+      }
       break;
 
    case ir_binop_logic_and: