Mesa (7.10): glsl: Track initial mask in constant propagation live set

[Ian Romanick]

Module: Mesa
Branch: 7.10
Commit: cb6dd6c399da30b9555a284bc51b1940686e6058
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=cb6dd6c399da30b9555a284bc51b1940686e6058

Author: Ian Romanick <ian.d.romanick at intel.com>
Date:   Mon Jun 27 16:33:13 2011 -0700

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

---

 src/glsl/opt_constant_propagation.cpp |   17 ++++++++++++++---
 1 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/glsl/opt_constant_propagation.cpp b/src/glsl/opt_constant_propagation.cpp
index e1f6889..c139768 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);