1 files changed, 434 insertions, 436 deletions
diff --git a/mesalib/src/glsl/opt_constant_propagation.cpp b/mesalib/src/glsl/opt_constant_propagation.cpp
index 814f6e61f..55c271200 100644
--- a/mesalib/src/glsl/opt_constant_propagation.cpp
+++ b/mesalib/src/glsl/opt_constant_propagation.cpp
@@ -1,436 +1,434 @@
-/*
- * Copyright © 2010 Intel Corporation
- *
- * Permission is hereby granted, free of charge, to any person obtaining a
- * constant of this software and associated documentation files (the "Software"),
- * to deal in the Software without restriction, including without limitation
- * the rights to use, constant, modify, merge, publish, distribute, sublicense,
- * and/or sell copies of the Software, and to permit persons to whom the
- * Software is furnished to do so, subject to the following conditions:
- *
- * The above constantright notice and this permission notice (including the next
- * paragraph) shall be included in all copies or substantial portions of the
- * Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
- * THE AUTHORS OR CONSTANTRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
- * DEALINGS IN THE SOFTWARE.
- */
-
-/**
- * \file opt_constant_propagation.cpp
- *
- * Tracks assignments of constants to channels of variables, and
- * usage of those constant channels with direct usage of the constants.
- *
- * This can lead to constant folding and algebraic optimizations in
- * those later expressions, while causing no increase in instruction
- * count (due to constants being generally free to load from a
- * constant push buffer or as instruction immediate values) and
- * possibly reducing register pressure.
- */
-
-#include "ir.h"
-#include "ir_visitor.h"
-#include "ir_rvalue_visitor.h"
-#include "ir_basic_block.h"
-#include "ir_optimization.h"
-#include "glsl_types.h"
-
-using std::memset;
-
-class acp_entry : public exec_node
-{
-public:
-   acp_entry(ir_variable *var, unsigned write_mask, ir_constant *constant)
-   {
-      assert(var);
-      assert(constant);
-      this->var = var;
-      this->write_mask = write_mask;
-      this->constant = constant;
-   }
-
-   ir_variable *var;
-   ir_constant *constant;
-   unsigned write_mask;
-};
-
-
-class kill_entry : public exec_node
-{
-public:
-   kill_entry(ir_variable *var, unsigned write_mask)
-   {
-      assert(var);
-      this->var = var;
-      this->write_mask = write_mask;
-   }
-
-   ir_variable *var;
-   unsigned write_mask;
-};
-
-class ir_constant_propagation_visitor : public ir_rvalue_visitor {
-public:
-   ir_constant_propagation_visitor()
-   {
-      progress = false;
-      mem_ctx = ralloc_context(0);
-      this->acp = new(mem_ctx) exec_list;
-      this->kills = new(mem_ctx) exec_list;
-   }
-   ~ir_constant_propagation_visitor()
-   {
-      ralloc_free(mem_ctx);
-   }
-
-   virtual ir_visitor_status visit_enter(class ir_loop *);
-   virtual ir_visitor_status visit_enter(class ir_function_signature *);
-   virtual ir_visitor_status visit_enter(class ir_function *);
-   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 *);
-
-   void add_constant(ir_assignment *ir);
-   void kill(ir_variable *ir, unsigned write_mask);
-   void handle_if_block(exec_list *instructions);
-   void handle_rvalue(ir_rvalue **rvalue);
-
-   /** List of acp_entry: The available constants to propagate */
-   exec_list *acp;
-
-   /**
-    * List of kill_entry: The masks of variables whose values were
-    * killed in this block.
-    */
-   exec_list *kills;
-
-   bool progress;
-
-   bool killed_all;
-
-   void *mem_ctx;
-};
-
-
-void
-ir_constant_propagation_visitor::handle_rvalue(ir_rvalue **rvalue)
-{
-   if (this->in_assignee || !*rvalue)
-      return;
-
-   const glsl_type *type = (*rvalue)->type;
-   if (!type->is_scalar() && !type->is_vector())
-      return;
-
-   ir_swizzle *swiz = NULL;
-   ir_dereference_variable *deref = (*rvalue)->as_dereference_variable();
-   if (!deref) {
-      swiz = (*rvalue)->as_swizzle();
-      if (!swiz)
-	 return;
-
-      deref = swiz->val->as_dereference_variable();
-      if (!deref)
-	 return;
-   }
-
-   ir_constant_data data;
-   memset(&data, 0, sizeof(data));
-
-   for (unsigned int i = 0; i < type->components(); i++) {
-      int channel;
-      acp_entry *found = NULL;
-
-      if (swiz) {
-	 switch (i) {
-	 case 0: channel = swiz->mask.x; break;
-	 case 1: channel = swiz->mask.y; break;
-	 case 2: channel = swiz->mask.z; break;
-	 case 3: channel = swiz->mask.w; break;
-	 default: assert(!"shouldn't be reached"); channel = 0; break;
-	 }
-      } else {
-	 channel = i;
-      }
-
-      foreach_iter(exec_list_iterator, iter, *this->acp) {
-	 acp_entry *entry = (acp_entry *)iter.get();
-	 if (entry->var == deref->var && entry->write_mask & (1 << channel)) {
-	    found = entry;
-	    break;
-	 }
-      }
-
-      if (!found)
-	 return;
-
-      int rhs_channel = 0;
-      for (int j = 0; j < 4; j++) {
-	 if (j == channel)
-	    break;
-	 if (found->write_mask & (1 << j))
-	    rhs_channel++;
-      }
-
-      switch (type->base_type) {
-      case GLSL_TYPE_FLOAT:
-	 data.f[i] = found->constant->value.f[rhs_channel];
-	 break;
-      case GLSL_TYPE_INT:
-	 data.i[i] = found->constant->value.i[rhs_channel];
-	 break;
-      case GLSL_TYPE_UINT:
-	 data.u[i] = found->constant->value.u[rhs_channel];
-	 break;
-      case GLSL_TYPE_BOOL:
-	 data.b[i] = found->constant->value.b[rhs_channel];
-	 break;
-      default:
-	 assert(!"not reached");
-	 break;
-      }
-   }
-
-   *rvalue = new(ralloc_parent(deref)) ir_constant(type, &data);
-   this->progress = true;
-}
-
-ir_visitor_status
-ir_constant_propagation_visitor::visit_enter(ir_function_signature *ir)
-{
-   /* Treat entry into a function signature as a completely separate
-    * block.  Any instructions at global scope will be shuffled into
-    * main() at link time, so they're irrelevant to us.
-    */
-   exec_list *orig_acp = this->acp;
-   exec_list *orig_kills = this->kills;
-   bool orig_killed_all = this->killed_all;
-
-   this->acp = new(mem_ctx) exec_list;
-   this->kills = new(mem_ctx) exec_list;
-   this->killed_all = false;
-
-   visit_list_elements(this, &ir->body);
-
-   this->kills = orig_kills;
-   this->acp = orig_acp;
-   this->killed_all = orig_killed_all;
-
-   return visit_continue_with_parent;
-}
-
-ir_visitor_status
-ir_constant_propagation_visitor::visit_leave(ir_assignment *ir)
-{
-   if (this->in_assignee)
-      return visit_continue;
-
-   kill(ir->lhs->variable_referenced(), ir->write_mask);
-
-   add_constant(ir);
-
-   return visit_continue;
-}
-
-ir_visitor_status
-ir_constant_propagation_visitor::visit_enter(ir_function *ir)
-{
-   (void) ir;
-   return visit_continue;
-}
-
-ir_visitor_status
-ir_constant_propagation_visitor::visit_enter(ir_call *ir)
-{
-   /* Do constant propagation on call parameters, but skip any out params */
-   exec_list_iterator sig_param_iter = ir->get_callee()->parameters.iterator();
-   foreach_iter(exec_list_iterator, iter, ir->actual_parameters) {
-      ir_variable *sig_param = (ir_variable *)sig_param_iter.get();
-      ir_rvalue *param = (ir_rvalue *)iter.get();
-      if (sig_param->mode != ir_var_out && sig_param->mode != ir_var_inout) {
-	 ir_rvalue *new_param = param;
-	 handle_rvalue(&new_param);
-         if (new_param != param)
-	    param->replace_with(new_param);
-	 else
-	    param->accept(this);
-      }
-      sig_param_iter.next();
-   }
-
-   /* Since we're unlinked, we don't (necssarily) know the side effects of
-    * this call.  So kill all copies.
-    */
-   acp->make_empty();
-   this->killed_all = true;
-
-   return visit_continue_with_parent;
-}
-
-void
-ir_constant_propagation_visitor::handle_if_block(exec_list *instructions)
-{
-   exec_list *orig_acp = this->acp;
-   exec_list *orig_kills = this->kills;
-   bool orig_killed_all = this->killed_all;
-
-   this->acp = new(mem_ctx) exec_list;
-   this->kills = new(mem_ctx) exec_list;
-   this->killed_all = false;
-
-   /* 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));
-   }
-
-   visit_list_elements(this, instructions);
-
-   if (this->killed_all) {
-      orig_acp->make_empty();
-   }
-
-   exec_list *new_kills = this->kills;
-   this->kills = orig_kills;
-   this->acp = orig_acp;
-   this->killed_all = this->killed_all || orig_killed_all;
-
-   foreach_iter(exec_list_iterator, iter, *new_kills) {
-      kill_entry *k = (kill_entry *)iter.get();
-      kill(k->var, k->write_mask);
-   }
-}
-
-ir_visitor_status
-ir_constant_propagation_visitor::visit_enter(ir_if *ir)
-{
-   ir->condition->accept(this);
-   handle_rvalue(&ir->condition);
-
-   handle_if_block(&ir->then_instructions);
-   handle_if_block(&ir->else_instructions);
-
-   /* handle_if_block() already descended into the children. */
-   return visit_continue_with_parent;
-}
-
-ir_visitor_status
-ir_constant_propagation_visitor::visit_enter(ir_loop *ir)
-{
-   exec_list *orig_acp = this->acp;
-   exec_list *orig_kills = this->kills;
-   bool orig_killed_all = this->killed_all;
-
-   /* FINISHME: For now, the initial acp for loops is totally empty.
-    * We could go through once, then go through again with the acp
-    * cloned minus the killed entries after the first run through.
-    */
-   this->acp = new(mem_ctx) exec_list;
-   this->kills = new(mem_ctx) exec_list;
-   this->killed_all = false;
-
-   visit_list_elements(this, &ir->body_instructions);
-
-   if (this->killed_all) {
-      orig_acp->make_empty();
-   }
-
-   exec_list *new_kills = this->kills;
-   this->kills = orig_kills;
-   this->acp = orig_acp;
-   this->killed_all = this->killed_all || orig_killed_all;
-
-   foreach_iter(exec_list_iterator, iter, *new_kills) {
-      kill_entry *k = (kill_entry *)iter.get();
-      kill(k->var, k->write_mask);
-   }
-
-   /* already descended into the children. */
-   return visit_continue_with_parent;
-}
-
-void
-ir_constant_propagation_visitor::kill(ir_variable *var, unsigned write_mask)
-{
-   assert(var != NULL);
-
-   /* We don't track non-vectors. */
-   if (!var->type->is_vector() && !var->type->is_scalar())
-      return;
-
-   /* Remove any entries currently in the ACP for this kill. */
-   foreach_iter(exec_list_iterator, iter, *this->acp) {
-      acp_entry *entry = (acp_entry *)iter.get();
-
-      if (entry->var == var) {
-	 entry->write_mask &= ~write_mask;
-	 if (entry->write_mask == 0)
-	    entry->remove();
-      }
-   }
-
-   /* Add this writemask of the variable to the list of killed
-    * variables in this block.
-    */
-   foreach_iter(exec_list_iterator, iter, *this->kills) {
-      kill_entry *entry = (kill_entry *)iter.get();
-
-      if (entry->var == var) {
-	 entry->write_mask |= write_mask;
-	 return;
-      }
-   }
-   /* Not already in the list.  Make new entry. */
-   this->kills->push_tail(new(this->mem_ctx) kill_entry(var, write_mask));
-}
-
-/**
- * Adds an entry to the available constant list if it's a plain assignment
- * of a variable to a variable.
- */
-void
-ir_constant_propagation_visitor::add_constant(ir_assignment *ir)
-{
-   acp_entry *entry;
-
-   if (ir->condition)
-      return;
-
-   if (!ir->write_mask)
-      return;
-
-   ir_dereference_variable *deref = ir->lhs->as_dereference_variable();
-   ir_constant *constant = ir->rhs->as_constant();
-
-   if (!deref || !constant)
-      return;
-
-   /* Only do constant propagation on vectors.  Constant matrices,
-    * arrays, or structures would require more work elsewhere.
-    */
-   if (!deref->var->type->is_vector() && !deref->var->type->is_scalar())
-      return;
-
-   entry = new(this->mem_ctx) acp_entry(deref->var, ir->write_mask, constant);
-   this->acp->push_tail(entry);
-}
-
-/**
- * Does a constant propagation pass on the code present in the instruction stream.
- */
-bool
-do_constant_propagation(exec_list *instructions)
-{
-   ir_constant_propagation_visitor v;
-
-   visit_list_elements(&v, instructions);
-
-   return v.progress;
-}
+/*
+ * Copyright © 2010 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * constant of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, constant, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above constantright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR CONSTANTRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file opt_constant_propagation.cpp
+ *
+ * Tracks assignments of constants to channels of variables, and
+ * usage of those constant channels with direct usage of the constants.
+ *
+ * This can lead to constant folding and algebraic optimizations in
+ * those later expressions, while causing no increase in instruction
+ * count (due to constants being generally free to load from a
+ * constant push buffer or as instruction immediate values) and
+ * possibly reducing register pressure.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "ir_rvalue_visitor.h"
+#include "ir_basic_block.h"
+#include "ir_optimization.h"
+#include "glsl_types.h"
+
+class acp_entry : public exec_node
+{
+public:
+   acp_entry(ir_variable *var, unsigned write_mask, ir_constant *constant)
+   {
+      assert(var);
+      assert(constant);
+      this->var = var;
+      this->write_mask = write_mask;
+      this->constant = constant;
+   }
+
+   ir_variable *var;
+   ir_constant *constant;
+   unsigned write_mask;
+};
+
+
+class kill_entry : public exec_node
+{
+public:
+   kill_entry(ir_variable *var, unsigned write_mask)
+   {
+      assert(var);
+      this->var = var;
+      this->write_mask = write_mask;
+   }
+
+   ir_variable *var;
+   unsigned write_mask;
+};
+
+class ir_constant_propagation_visitor : public ir_rvalue_visitor {
+public:
+   ir_constant_propagation_visitor()
+   {
+      progress = false;
+      mem_ctx = ralloc_context(0);
+      this->acp = new(mem_ctx) exec_list;
+      this->kills = new(mem_ctx) exec_list;
+   }
+   ~ir_constant_propagation_visitor()
+   {
+      ralloc_free(mem_ctx);
+   }
+
+   virtual ir_visitor_status visit_enter(class ir_loop *);
+   virtual ir_visitor_status visit_enter(class ir_function_signature *);
+   virtual ir_visitor_status visit_enter(class ir_function *);
+   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 *);
+
+   void add_constant(ir_assignment *ir);
+   void kill(ir_variable *ir, unsigned write_mask);
+   void handle_if_block(exec_list *instructions);
+   void handle_rvalue(ir_rvalue **rvalue);
+
+   /** List of acp_entry: The available constants to propagate */
+   exec_list *acp;
+
+   /**
+    * List of kill_entry: The masks of variables whose values were
+    * killed in this block.
+    */
+   exec_list *kills;
+
+   bool progress;
+
+   bool killed_all;
+
+   void *mem_ctx;
+};
+
+
+void
+ir_constant_propagation_visitor::handle_rvalue(ir_rvalue **rvalue)
+{
+   if (this->in_assignee || !*rvalue)
+      return;
+
+   const glsl_type *type = (*rvalue)->type;
+   if (!type->is_scalar() && !type->is_vector())
+      return;
+
+   ir_swizzle *swiz = NULL;
+   ir_dereference_variable *deref = (*rvalue)->as_dereference_variable();
+   if (!deref) {
+      swiz = (*rvalue)->as_swizzle();
+      if (!swiz)
+	 return;
+
+      deref = swiz->val->as_dereference_variable();
+      if (!deref)
+	 return;
+   }
+
+   ir_constant_data data;
+   memset(&data, 0, sizeof(data));
+
+   for (unsigned int i = 0; i < type->components(); i++) {
+      int channel;
+      acp_entry *found = NULL;
+
+      if (swiz) {
+	 switch (i) {
+	 case 0: channel = swiz->mask.x; break;
+	 case 1: channel = swiz->mask.y; break;
+	 case 2: channel = swiz->mask.z; break;
+	 case 3: channel = swiz->mask.w; break;
+	 default: assert(!"shouldn't be reached"); channel = 0; break;
+	 }
+      } else {
+	 channel = i;
+      }
+
+      foreach_iter(exec_list_iterator, iter, *this->acp) {
+	 acp_entry *entry = (acp_entry *)iter.get();
+	 if (entry->var == deref->var && entry->write_mask & (1 << channel)) {
+	    found = entry;
+	    break;
+	 }
+      }
+
+      if (!found)
+	 return;
+
+      int rhs_channel = 0;
+      for (int j = 0; j < 4; j++) {
+	 if (j == channel)
+	    break;
+	 if (found->write_mask & (1 << j))
+	    rhs_channel++;
+      }
+
+      switch (type->base_type) {
+      case GLSL_TYPE_FLOAT:
+	 data.f[i] = found->constant->value.f[rhs_channel];
+	 break;
+      case GLSL_TYPE_INT:
+	 data.i[i] = found->constant->value.i[rhs_channel];
+	 break;
+      case GLSL_TYPE_UINT:
+	 data.u[i] = found->constant->value.u[rhs_channel];
+	 break;
+      case GLSL_TYPE_BOOL:
+	 data.b[i] = found->constant->value.b[rhs_channel];
+	 break;
+      default:
+	 assert(!"not reached");
+	 break;
+      }
+   }
+
+   *rvalue = new(ralloc_parent(deref)) ir_constant(type, &data);
+   this->progress = true;
+}
+
+ir_visitor_status
+ir_constant_propagation_visitor::visit_enter(ir_function_signature *ir)
+{
+   /* Treat entry into a function signature as a completely separate
+    * block.  Any instructions at global scope will be shuffled into
+    * main() at link time, so they're irrelevant to us.
+    */
+   exec_list *orig_acp = this->acp;
+   exec_list *orig_kills = this->kills;
+   bool orig_killed_all = this->killed_all;
+
+   this->acp = new(mem_ctx) exec_list;
+   this->kills = new(mem_ctx) exec_list;
+   this->killed_all = false;
+
+   visit_list_elements(this, &ir->body);
+
+   this->kills = orig_kills;
+   this->acp = orig_acp;
+   this->killed_all = orig_killed_all;
+
+   return visit_continue_with_parent;
+}
+
+ir_visitor_status
+ir_constant_propagation_visitor::visit_leave(ir_assignment *ir)
+{
+   if (this->in_assignee)
+      return visit_continue;
+
+   kill(ir->lhs->variable_referenced(), ir->write_mask);
+
+   add_constant(ir);
+
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_constant_propagation_visitor::visit_enter(ir_function *ir)
+{
+   (void) ir;
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_constant_propagation_visitor::visit_enter(ir_call *ir)
+{
+   /* Do constant propagation on call parameters, but skip any out params */
+   exec_list_iterator sig_param_iter = ir->get_callee()->parameters.iterator();
+   foreach_iter(exec_list_iterator, iter, ir->actual_parameters) {
+      ir_variable *sig_param = (ir_variable *)sig_param_iter.get();
+      ir_rvalue *param = (ir_rvalue *)iter.get();
+      if (sig_param->mode != ir_var_out && sig_param->mode != ir_var_inout) {
+	 ir_rvalue *new_param = param;
+	 handle_rvalue(&new_param);
+         if (new_param != param)
+	    param->replace_with(new_param);
+	 else
+	    param->accept(this);
+      }
+      sig_param_iter.next();
+   }
+
+   /* Since we're unlinked, we don't (necssarily) know the side effects of
+    * this call.  So kill all copies.
+    */
+   acp->make_empty();
+   this->killed_all = true;
+
+   return visit_continue_with_parent;
+}
+
+void
+ir_constant_propagation_visitor::handle_if_block(exec_list *instructions)
+{
+   exec_list *orig_acp = this->acp;
+   exec_list *orig_kills = this->kills;
+   bool orig_killed_all = this->killed_all;
+
+   this->acp = new(mem_ctx) exec_list;
+   this->kills = new(mem_ctx) exec_list;
+   this->killed_all = false;
+
+   /* 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));
+   }
+
+   visit_list_elements(this, instructions);
+
+   if (this->killed_all) {
+      orig_acp->make_empty();
+   }
+
+   exec_list *new_kills = this->kills;
+   this->kills = orig_kills;
+   this->acp = orig_acp;
+   this->killed_all = this->killed_all || orig_killed_all;
+
+   foreach_iter(exec_list_iterator, iter, *new_kills) {
+      kill_entry *k = (kill_entry *)iter.get();
+      kill(k->var, k->write_mask);
+   }
+}
+
+ir_visitor_status
+ir_constant_propagation_visitor::visit_enter(ir_if *ir)
+{
+   ir->condition->accept(this);
+   handle_rvalue(&ir->condition);
+
+   handle_if_block(&ir->then_instructions);
+   handle_if_block(&ir->else_instructions);
+
+   /* handle_if_block() already descended into the children. */
+   return visit_continue_with_parent;
+}
+
+ir_visitor_status
+ir_constant_propagation_visitor::visit_enter(ir_loop *ir)
+{
+   exec_list *orig_acp = this->acp;
+   exec_list *orig_kills = this->kills;
+   bool orig_killed_all = this->killed_all;
+
+   /* FINISHME: For now, the initial acp for loops is totally empty.
+    * We could go through once, then go through again with the acp
+    * cloned minus the killed entries after the first run through.
+    */
+   this->acp = new(mem_ctx) exec_list;
+   this->kills = new(mem_ctx) exec_list;
+   this->killed_all = false;
+
+   visit_list_elements(this, &ir->body_instructions);
+
+   if (this->killed_all) {
+      orig_acp->make_empty();
+   }
+
+   exec_list *new_kills = this->kills;
+   this->kills = orig_kills;
+   this->acp = orig_acp;
+   this->killed_all = this->killed_all || orig_killed_all;
+
+   foreach_iter(exec_list_iterator, iter, *new_kills) {
+      kill_entry *k = (kill_entry *)iter.get();
+      kill(k->var, k->write_mask);
+   }
+
+   /* already descended into the children. */
+   return visit_continue_with_parent;
+}
+
+void
+ir_constant_propagation_visitor::kill(ir_variable *var, unsigned write_mask)
+{
+   assert(var != NULL);
+
+   /* We don't track non-vectors. */
+   if (!var->type->is_vector() && !var->type->is_scalar())
+      return;
+
+   /* Remove any entries currently in the ACP for this kill. */
+   foreach_iter(exec_list_iterator, iter, *this->acp) {
+      acp_entry *entry = (acp_entry *)iter.get();
+
+      if (entry->var == var) {
+	 entry->write_mask &= ~write_mask;
+	 if (entry->write_mask == 0)
+	    entry->remove();
+      }
+   }
+
+   /* Add this writemask of the variable to the list of killed
+    * variables in this block.
+    */
+   foreach_iter(exec_list_iterator, iter, *this->kills) {
+      kill_entry *entry = (kill_entry *)iter.get();
+
+      if (entry->var == var) {
+	 entry->write_mask |= write_mask;
+	 return;
+      }
+   }
+   /* Not already in the list.  Make new entry. */
+   this->kills->push_tail(new(this->mem_ctx) kill_entry(var, write_mask));
+}
+
+/**
+ * Adds an entry to the available constant list if it's a plain assignment
+ * of a variable to a variable.
+ */
+void
+ir_constant_propagation_visitor::add_constant(ir_assignment *ir)
+{
+   acp_entry *entry;
+
+   if (ir->condition)
+      return;
+
+   if (!ir->write_mask)
+      return;
+
+   ir_dereference_variable *deref = ir->lhs->as_dereference_variable();
+   ir_constant *constant = ir->rhs->as_constant();
+
+   if (!deref || !constant)
+      return;
+
+   /* Only do constant propagation on vectors.  Constant matrices,
+    * arrays, or structures would require more work elsewhere.
+    */
+   if (!deref->var->type->is_vector() && !deref->var->type->is_scalar())
+      return;
+
+   entry = new(this->mem_ctx) acp_entry(deref->var, ir->write_mask, constant);
+   this->acp->push_tail(entry);
+}
+
+/**
+ * Does a constant propagation pass on the code present in the instruction stream.
+ */
+bool
+do_constant_propagation(exec_list *instructions)
+{
+   ir_constant_propagation_visitor v;
+
+   visit_list_elements(&v, instructions);
+
+   return v.progress;
+}