[Mesa-dev] [PATCH] glsl: fix optimization of discard nested multiple levels

[Nicolai Hähnle]

From: Nicolai Hähnle <nicolai.haehnle at amd.com>

The order of optimizations can lead to the conditional discard optimization
being applied twice to the same discard statement. In this case, we must
ensure that both conditions are applied.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96762
Cc: mesa-stable at lists.freedesktop.org
---
 src/compiler/glsl/opt_conditional_discard.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/compiler/glsl/opt_conditional_discard.cpp b/src/compiler/glsl/opt_conditional_discard.cpp
index 1ca8803..a27bead 100644
--- a/src/compiler/glsl/opt_conditional_discard.cpp
+++ b/src/compiler/glsl/opt_conditional_discard.cpp
@@ -72,7 +72,14 @@ opt_conditional_discard_visitor::visit_leave(ir_if *ir)
 
    /* Move the condition and replace the ir_if with the ir_discard. */
    ir_discard *discard = (ir_discard *) ir->then_instructions.head;
-   discard->condition = ir->condition;
+   if (!discard->condition)
+      discard->condition = ir->condition;
+   else {
+      void *ctx = ralloc_parent(ir);
+      discard->condition = new(ctx) ir_expression(ir_binop_logic_and,
+                                                  ir->condition,
+                                                  discard->condition);
+   }
    ir->replace_with(discard);
 
    progress = true;
-- 
2.7.4