GLSL spec boneheadedly says (a ^^ a) must actually be evaluated.
Signed-off-by: Matt Turner <[email protected]>
---
Fortunately, shaders that do this are even more boneheaded.
src/glsl/opt_algebraic.cpp | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index cade961..5fc4fc8 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -320,7 +320,12 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
break;
case ir_binop_logic_xor:
- /* FINISHME: Also simplify (a ^^ a) to (false). */
+ /* From page 59 (page 65 of the PDF) of the GLSL 1.50 spec:
+ *
+ * "Exclusive or (^^) will always evaluate both operands."
+ *
+ * So we can't simplify (a ^^ a) to false.
+ */
if (is_vec_zero(op_const[0])) {
this->progress = true;
return ir->operands[1];
--
1.7.3.4
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