glsl: Track initial mask in constant propagation live set

The set of values initially available (before any kills) must be
tracked with each constant in the set.  Otherwise the wrong component
can be selected after earlier components have been killed.

NOTE: This is a candidate for the 7.10 and 7.11 branches.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=37383
Reviewed-by: Eric Anholt <[email protected]>
Cc: Kenneth Graunke <[email protected]>
Cc: Matthias Bentrup <[email protected]>

1 files changed, 14 insertions, 3 deletions

diff --git a/src/glsl/opt_constant_propagation.cpp b/src/glsl/opt_constant_propagation.cpp
index 4425f421193..af77e490689 100644
--- a/src/glsl/opt_constant_propagation.cpp
+++ b/src/glsl/opt_constant_propagation.cpp
@@ -51,11 +51,23 @@ public:
       this->var = var;
       this->write_mask = write_mask;
       this->constant = constant;
+      this->initial_values = write_mask;
+   }
+
+   acp_entry(const acp_entry *src)
+   {
+      this->var = src->var;
+      this->write_mask = src->write_mask;
+      this->constant = src->constant;
+      this->initial_values = src->initial_values;
    }
 
    ir_variable *var;
    ir_constant *constant;
    unsigned write_mask;
+
+   /** Mask of values initially available in the constant. */
+   unsigned initial_values;
 };
 
 
@@ -172,7 +184,7 @@ ir_constant_propagation_visitor::handle_rvalue(ir_rvalue **rvalue)
       for (int j = 0; j < 4; j++) {
 	 if (j == channel)
 	    break;
-	 if (found->write_mask & (1 << j))
+	 if (found->initial_values & (1 << j))
 	    rhs_channel++;
       }
 
@@ -285,8 +297,7 @@ ir_constant_propagation_visitor::handle_if_block(exec_list *instructions)
    /* Populate the initial acp with a constant of the original */
    foreach_iter(exec_list_iterator, iter, *orig_acp) {
       acp_entry *a = (acp_entry *)iter.get();
-      this->acp->push_tail(new(this->mem_ctx) acp_entry(a->var, a->write_mask,
-							a->constant));
+      this->acp->push_tail(new(this->mem_ctx) acp_entry(a));
    }
 
    visit_list_elements(this, instructions);