[Mesa-dev] [PATCH 3/8] glsl: Handle conditional discards in lower_discard_flow().

[Kenneth Graunke]

This pass wasn't prepared to handle conditional discards.

Instead of initializing the "discarded" temporary to "true", set it to
the condition.  Then, refer to the variable for the condition, to avoid
duplicating the expression tree.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/glsl/lower_discard_flow.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/glsl/lower_discard_flow.cpp b/src/glsl/lower_discard_flow.cpp
index 1bc56d7..ee45bf2 100644
--- a/src/glsl/lower_discard_flow.cpp
+++ b/src/glsl/lower_discard_flow.cpp
@@ -90,7 +90,14 @@ ir_visitor_status
 lower_discard_flow_visitor::visit_enter(ir_discard *ir)
 {
    ir_dereference *lhs = new(mem_ctx) ir_dereference_variable(discarded);
-   ir_rvalue *rhs = new(mem_ctx) ir_constant(true);
+   ir_rvalue *rhs;
+   if (ir->condition) {
+      /* discarded <- condition, use (var_ref discarded) as the condition */
+      rhs = ir->condition;
+      ir->condition = new(mem_ctx) ir_dereference_variable(discarded);
+   } else {
+      rhs = new(mem_ctx) ir_constant(true);
+   }
    ir_assignment *assign = new(mem_ctx) ir_assignment(lhs, rhs);
    ir->insert_before(assign);
 
-- 
2.2.2