1 files changed, 24 insertions, 1 deletions
diff --git a/mesalib/src/glsl/opt_copy_propagation_elements.cpp b/mesalib/src/glsl/opt_copy_propagation_elements.cpp
index a91e624cb..ebfd4fd3f 100644
--- a/mesalib/src/glsl/opt_copy_propagation_elements.cpp
+++ b/mesalib/src/glsl/opt_copy_propagation_elements.cpp
@@ -108,6 +108,7 @@ public:
    virtual ir_visitor_status visit_leave(class ir_assignment *);
    virtual ir_visitor_status visit_enter(class ir_call *);
    virtual ir_visitor_status visit_enter(class ir_if *);
+   virtual ir_visitor_status visit_leave(class ir_swizzle *);
 
    void handle_rvalue(ir_rvalue **rvalue);
 
@@ -179,6 +180,15 @@ ir_copy_propagation_elements_visitor::visit_leave(ir_assignment *ir)
    return visit_continue;
 }
 
+ir_visitor_status
+ir_copy_propagation_elements_visitor::visit_leave(ir_swizzle *ir)
+{
+   /* Don't visit the values of swizzles since they are handled while
+    * visiting the swizzle itself.
+    */
+   return visit_continue;
+}
+
 /**
  * Replaces dereferences of ACP RHS variables with ACP LHS variables.
  *
@@ -451,7 +461,20 @@ ir_copy_propagation_elements_visitor::add_copy(ir_assignment *ir)
 	 swizzle[i] = orig_swizzle[j++];
    }
 
-   entry = new(this->mem_ctx) acp_entry(lhs->var, rhs->var, ir->write_mask,
+   int write_mask = ir->write_mask;
+   if (lhs->var == rhs->var) {
+      /* If this is a copy from the variable to itself, then we need
+       * to be sure not to include the updated channels from this
+       * instruction in the set of new source channels to be
+       * copy-propagated from.
+       */
+      for (int i = 0; i < 4; i++) {
+	 if (ir->write_mask & (1 << orig_swizzle[i]))
+	    write_mask &= ~(1 << i);
+      }
+   }
+
+   entry = new(this->mem_ctx) acp_entry(lhs->var, rhs->var, write_mask,
 					swizzle);
    this->acp->push_tail(entry);
 }