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 <eric@anholt.net>
Cc: Kenneth Graunke <kenneth@whitecape.org>
Cc: Matthias Bentrup <matthias.bentrup@googlemail.com>
(cherry picked from commit 0eb97979584b73907327eebc547302e6b8d8976a)

1 files changed, 14 insertions, 3 deletions

diff --git a/src/glsl/opt_constant_propagation.cpp b/src/glsl/opt_constant_propagation.cpp
index e1f68892fbe..c1397683fbb 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);