6 files changed, 486 insertions, 0 deletions

diff --git a/src/glsl/Makefile b/src/glsl/Makefile
index 0f8b290b65..841e2b9ce9 100644
--- a/src/glsl/Makefile
+++ b/src/glsl/Makefile
@@ -34,6 +34,7 @@ CXX_SOURCES = \
 	ir_clone.cpp \
 	ir_constant_expression.cpp \
 	ir_constant_folding.cpp \
+	ir_constant_propagation.cpp \
 	ir_constant_variable.cpp \
 	ir_copy_propagation.cpp \
 	ir.cpp \
diff --git a/src/glsl/ir_constant_propagation.cpp b/src/glsl/ir_constant_propagation.cpp
new file mode 100644
index 0000000000..adae0aa117
--- /dev/null
+++ b/src/glsl/ir_constant_propagation.cpp
@@ -0,0 +1,481 @@
+/*
+ * Constantright © 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 ir_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_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_hierarchical_visitor {
+public:
+   ir_constant_propagation_visitor()
+   {
+      progress = false;
+      mem_ctx = talloc_new(0);
+      this->acp = new(mem_ctx) exec_list;
+      this->kills = new(mem_ctx) exec_list;
+   }
+   ~ir_constant_propagation_visitor()
+   {
+      talloc_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_enter(class ir_assignment *);
+   virtual ir_visitor_status visit_leave(class ir_assignment *);
+   virtual ir_visitor_status visit_enter(class ir_expression *);
+   virtual ir_visitor_status visit_enter(class ir_call *);
+   virtual ir_visitor_status visit_enter(class ir_if *);
+   virtual ir_visitor_status visit_enter(class ir_dereference_array *);
+   virtual ir_visitor_status visit_enter(class ir_texture *);
+
+   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 (!*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;
+
+      switch (type->base_type) {
+      case GLSL_TYPE_FLOAT:
+	 data.f[i] = found->constant->value.f[channel];
+	 break;
+      case GLSL_TYPE_INT:
+	 data.i[i] = found->constant->value.i[channel];
+	 break;
+      case GLSL_TYPE_UINT:
+	 data.u[i] = found->constant->value.u[channel];
+	 break;
+      case GLSL_TYPE_BOOL:
+	 data.b[i] = found->constant->value.b[channel];
+	 break;
+      default:
+	 assert(!"not reached");
+	 break;
+      }
+   }
+
+   *rvalue = new(talloc_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_enter(ir_assignment *ir)
+{
+   handle_rvalue(&ir->condition);
+   handle_rvalue(&ir->rhs);
+
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_constant_propagation_visitor::visit_leave(ir_assignment *ir)
+{
+   kill(ir->lhs->variable_referenced(), ir->write_mask);
+
+   add_constant(ir);
+
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_constant_propagation_visitor::visit_enter(ir_expression *ir)
+{
+   for (unsigned int i = 0; i < ir->get_num_operands(); i++) {
+      handle_rvalue(&ir->operands[i]);
+   }
+
+   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_dereference_array *ir)
+{
+   handle_rvalue(&ir->array_index);
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_constant_propagation_visitor::visit_enter(ir_texture *ir)
+{
+   handle_rvalue(&ir->coordinate);
+   handle_rvalue(&ir->projector);
+   handle_rvalue(&ir->shadow_comparitor);
+
+   switch (ir->op) {
+   case ir_tex:
+      break;
+   case ir_txb:
+      handle_rvalue(&ir->lod_info.bias);
+      break;
+   case ir_txf:
+   case ir_txl:
+      handle_rvalue(&ir->lod_info.lod);
+      break;
+   case ir_txd:
+      handle_rvalue(&ir->lod_info.grad.dPdx);
+      handle_rvalue(&ir->lod_info.grad.dPdy);
+      break;
+   }
+
+   return visit_continue;
+}
+
+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) {
+      ir_constant *condition = ir->condition->as_constant();
+      if (!condition || !condition->value.b[0])
+	 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;
+}
diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
index c6e7beb447..97a0c25216 100644
--- a/src/glsl/ir_optimization.h
+++ b/src/glsl/ir_optimization.h
@@ -33,6 +33,7 @@ bool do_constant_folding(exec_list *instructions);
 bool do_constant_variable(exec_list *instructions);
 bool do_constant_variable_unlinked(exec_list *instructions);
 bool do_copy_propagation(exec_list *instructions);
+bool do_constant_propagation(exec_list *instructions);
 bool do_dead_code(exec_list *instructions);
 bool do_dead_code_local(exec_list *instructions);
 bool do_dead_code_unlinked(exec_list *instructions);
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index e93c2f5554..52c9322788 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1296,6 +1296,7 @@ link_shaders(struct gl_shader_program *prog)
 	 progress = do_dead_code_local(ir) || progress;
 	 progress = do_dead_code(ir) || progress;
 	 progress = do_tree_grafting(ir) || progress;
+	 progress = do_constant_propagation(ir) || progress;
 	 progress = do_constant_variable(ir) || progress;
 	 progress = do_constant_folding(ir) || progress;
 	 progress = do_algebraic(ir) || progress;
diff --git a/src/glsl/main.cpp b/src/glsl/main.cpp
index bc7292d155..24d6076d07 100644
--- a/src/glsl/main.cpp
+++ b/src/glsl/main.cpp
@@ -167,6 +167,7 @@ compile_shader(struct gl_shader *shader)
 	 progress = do_dead_code_local(shader->ir) || progress;
 	 progress = do_dead_code_unlinked(shader->ir) || progress;
 	 progress = do_tree_grafting(shader->ir) || progress;
+	 progress = do_constant_propagation(shader->ir) || progress;
 	 progress = do_constant_variable_unlinked(shader->ir) || progress;
 	 progress = do_constant_folding(shader->ir) || progress;
 	 progress = do_algebraic(shader->ir) || progress;
diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
index c6856eb5a4..5a272ab88a 100644
--- a/src/mesa/program/ir_to_mesa.cpp
+++ b/src/mesa/program/ir_to_mesa.cpp
@@ -2581,6 +2581,7 @@ _mesa_glsl_compile_shader(GLcontext *ctx, struct gl_shader *shader)
 	 progress = do_dead_code_local(shader->ir) || progress;
 	 progress = do_dead_code_unlinked(shader->ir) || progress;
 	 progress = do_tree_grafting(shader->ir) || progress;
+	 progress = do_constant_propagation(shader->ir) || progress;
 	 progress = do_constant_variable_unlinked(shader->ir) || progress;
 	 progress = do_constant_folding(shader->ir) || progress;
 	 progress = do_algebraic(shader->ir) || progress;