Mesa (glsl2): ir_structure_splitting: New pass to chop structures into their components.

Eric Anholt anholt at kemper.freedesktop.org
Thu Aug 5 12:59:55 PDT 2010


Module: Mesa
Branch: glsl2
Commit: 7f7eaf0285d011f7cc7e1a63133184a50b24ecaa
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=7f7eaf0285d011f7cc7e1a63133184a50b24ecaa

Author: Eric Anholt <eric at anholt.net>
Date:   Thu Aug  5 11:01:09 2010 -0700

ir_structure_splitting: New pass to chop structures into their components.

This doesn't do anything if your structure goes through an uninlined
function call or if whole-structure assignment occurs.  As such, the
impact is limited, at least until we do some global copy propagation
to reduce whole-structure assignment.

---

 src/glsl/Makefile                   |    1 +
 src/glsl/ir_optimization.h          |    1 +
 src/glsl/ir_structure_splitting.cpp |  378 +++++++++++++++++++++++++++++++++++
 src/glsl/linker.cpp                 |    1 +
 4 files changed, 381 insertions(+), 0 deletions(-)

diff --git a/src/glsl/Makefile b/src/glsl/Makefile
index 8443857..5356750 100644
--- a/src/glsl/Makefile
+++ b/src/glsl/Makefile
@@ -55,6 +55,7 @@ CXX_SOURCES = \
 	ir_mod_to_fract.cpp \
 	ir_print_visitor.cpp \
 	ir_reader.cpp \
+	ir_structure_splitting.cpp \
 	ir_swizzle_swizzle.cpp \
 	ir_tree_grafting.cpp \
 	ir_validate.cpp \
diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
index e0c0715..eac28dc 100644
--- a/src/glsl/ir_optimization.h
+++ b/src/glsl/ir_optimization.h
@@ -44,6 +44,7 @@ bool do_if_simplification(exec_list *instructions);
 bool do_if_to_cond_assign(exec_list *instructions);
 bool do_mat_op_to_vec(exec_list *instructions);
 bool do_mod_to_fract(exec_list *instructions);
+bool do_structure_splitting(exec_list *instructions);
 bool do_swizzle_swizzle(exec_list *instructions);
 bool do_tree_grafting(exec_list *instructions);
 bool do_vec_index_to_cond_assign(exec_list *instructions);
diff --git a/src/glsl/ir_structure_splitting.cpp b/src/glsl/ir_structure_splitting.cpp
new file mode 100644
index 0000000..f57ae44
--- /dev/null
+++ b/src/glsl/ir_structure_splitting.cpp
@@ -0,0 +1,378 @@
+/*
+ * Copyright © 2010 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, 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 copyright 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 COPYRIGHT 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_structure_splitting.cpp
+ *
+ * If a structure is only ever referenced by its components, then
+ * split those components out to individual variables so they can be
+ * handled normally by other optimization passes.
+ *
+ * This skips structures like uniforms, which need to be accessible as
+ * structures for their access by the GL.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "glsl_types.h"
+
+class variable_entry : public exec_node
+{
+public:
+   variable_entry(ir_variable *var)
+   {
+      this->var = var;
+      this->whole_structure_access = 0;
+      this->declaration = false;
+      this->components = NULL;
+      this->mem_ctx = NULL;
+   }
+
+   ir_variable *var; /* The key: the variable's pointer. */
+
+   /** Number of times the variable is referenced, including assignments. */
+   unsigned whole_structure_access;
+
+   bool declaration; /* If the variable had a decl in the instruction stream */
+
+   ir_variable **components;
+
+   /** talloc_parent(this->var) -- the shader's talloc context. */
+   void *mem_ctx;
+};
+
+class ir_structure_reference_visitor : public ir_hierarchical_visitor {
+public:
+   ir_structure_reference_visitor(void)
+   {
+      this->mem_ctx = talloc_new(NULL);
+      this->variable_list.make_empty();
+   }
+
+   ~ir_structure_reference_visitor(void)
+   {
+      talloc_free(mem_ctx);
+   }
+
+   virtual ir_visitor_status visit(ir_variable *);
+   virtual ir_visitor_status visit(ir_dereference_variable *);
+   virtual ir_visitor_status visit(ir_dereference_record *);
+
+   virtual ir_visitor_status visit_enter(ir_function_signature *);
+
+   variable_entry *get_variable_entry(ir_variable *var);
+
+   /* List of variable_entry */
+   exec_list variable_list;
+
+   void *mem_ctx;
+};
+
+variable_entry *
+ir_structure_reference_visitor::get_variable_entry(ir_variable *var)
+{
+   assert(var);
+
+   if (!var->type->is_record())
+      return NULL;
+
+   foreach_iter(exec_list_iterator, iter, this->variable_list) {
+      variable_entry *entry = (variable_entry *)iter.get();
+      if (entry->var == var)
+	 return entry;
+   }
+
+   variable_entry *entry = new(mem_ctx) variable_entry(var);
+   this->variable_list.push_tail(entry);
+   return entry;
+}
+
+
+ir_visitor_status
+ir_structure_reference_visitor::visit(ir_variable *ir)
+{
+   variable_entry *entry = this->get_variable_entry(ir);
+
+   if (entry)
+      entry->declaration = true;
+
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_structure_reference_visitor::visit(ir_dereference_variable *ir)
+{
+   ir_variable *const var = ir->variable_referenced();
+   variable_entry *entry = this->get_variable_entry(var);
+
+   if (entry)
+      entry->whole_structure_access++;
+
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_structure_reference_visitor::visit(ir_dereference_record *ir)
+{
+   /* Don't descend into the ir_dereference_variable below. */
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_structure_reference_visitor::visit_enter(ir_function_signature *ir)
+{
+   /* We don't want to descend into the function parameters and
+    * dead-code eliminate them, so just accept the body here.
+    */
+   visit_list_elements(this, &ir->body);
+   return visit_continue_with_parent;
+}
+
+class ir_structure_splitting_visitor : public ir_hierarchical_visitor {
+public:
+   ir_structure_splitting_visitor(exec_list *vars)
+   {
+      this->variable_list = vars;
+   }
+
+   virtual ~ir_structure_splitting_visitor()
+   {
+   }
+
+   virtual ir_visitor_status visit_leave(ir_assignment *);
+   virtual ir_visitor_status visit_leave(ir_call *);
+   virtual ir_visitor_status visit_leave(ir_dereference_array *);
+   virtual ir_visitor_status visit_leave(ir_expression *);
+   virtual ir_visitor_status visit_leave(ir_if *);
+   virtual ir_visitor_status visit_leave(ir_return *);
+   virtual ir_visitor_status visit_leave(ir_swizzle *);
+   virtual ir_visitor_status visit_leave(ir_texture *);
+
+   void split_deref(ir_dereference **deref);
+   void split_rvalue(ir_rvalue **rvalue);
+   struct variable_entry *get_splitting_entry(ir_variable *var);
+
+   exec_list *variable_list;
+   void *mem_ctx;
+};
+
+struct variable_entry *
+ir_structure_splitting_visitor::get_splitting_entry(ir_variable *var)
+{
+   assert(var);
+
+   if (!var->type->is_record())
+      return NULL;
+
+   foreach_iter(exec_list_iterator, iter, *this->variable_list) {
+      variable_entry *entry = (variable_entry *)iter.get();
+      if (entry->var == var) {
+	 return entry;
+      }
+   }
+
+   return NULL;
+}
+
+void
+ir_structure_splitting_visitor::split_deref(ir_dereference **deref)
+{
+   if ((*deref)->ir_type != ir_type_dereference_record)
+      return;
+
+   ir_dereference_record *deref_record = (ir_dereference_record *)deref;
+   ir_dereference_variable *deref_var = deref_record->as_dereference_variable();
+   if (!deref_var)
+      return;
+
+   variable_entry *entry = get_splitting_entry(deref_var->var);
+   if (entry)
+      return;
+
+   unsigned int i;
+   for (i = 0; i < entry->var->type->length; i++) {
+      if (strcmp(deref_record->field,
+		 entry->var->type->fields.structure[i].name) == 0)
+	 break;
+   }
+   assert(i != entry->var->type->length);
+
+   *deref = new(entry->mem_ctx) ir_dereference_variable(entry->components[i]);
+}
+
+void
+ir_structure_splitting_visitor::split_rvalue(ir_rvalue **rvalue)
+{
+   ir_dereference *deref = (*rvalue)->as_dereference();
+
+   if (!deref)
+      return;
+
+   split_deref(&deref);
+   *rvalue = deref;
+}
+
+ir_visitor_status
+ir_structure_splitting_visitor::visit_leave(ir_expression *ir)
+{
+   unsigned int operand;
+
+   for (operand = 0; operand < ir->get_num_operands(); operand++) {
+      split_rvalue(&ir->operands[operand]);
+   }
+
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_structure_splitting_visitor::visit_leave(ir_texture *ir)
+{
+   split_rvalue(&ir->coordinate);
+   split_rvalue(&ir->projector);
+   split_rvalue(&ir->shadow_comparitor);
+
+   switch (ir->op) {
+   case ir_tex:
+      break;
+   case ir_txb:
+      split_rvalue(&ir->lod_info.bias);
+      break;
+   case ir_txf:
+   case ir_txl:
+      split_rvalue(&ir->lod_info.lod);
+      break;
+   case ir_txd:
+      split_rvalue(&ir->lod_info.grad.dPdx);
+      split_rvalue(&ir->lod_info.grad.dPdy);
+      break;
+   }
+
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_structure_splitting_visitor::visit_leave(ir_swizzle *ir)
+{
+   split_rvalue(&ir->val);
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_structure_splitting_visitor::visit_leave(ir_dereference_array *ir)
+{
+   split_rvalue(&ir->array_index);
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_structure_splitting_visitor::visit_leave(ir_assignment *ir)
+{
+   split_rvalue(&ir->rhs);
+   split_rvalue(&ir->condition);
+   split_deref(&ir->lhs);
+
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_structure_splitting_visitor::visit_leave(ir_call *ir)
+{
+   foreach_iter(exec_list_iterator, iter, *ir) {
+      ir_rvalue *param = (ir_rvalue *)iter.get();
+      ir_rvalue *new_param = param;
+      split_rvalue(&new_param);
+
+      if (new_param != param) {
+	 param->replace_with(new_param);
+      }
+   }
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_structure_splitting_visitor::visit_leave(ir_return *ir)
+{
+   split_rvalue(&ir->value);;
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_structure_splitting_visitor::visit_leave(ir_if *ir)
+{
+   split_rvalue(&ir->condition);
+   return visit_continue;
+}
+
+
+bool
+do_structure_splitting(exec_list *instructions)
+{
+   ir_structure_reference_visitor refs;
+   void *mem_ctx = talloc_new(NULL);
+
+   /* Trim out variables we can't split. */
+   foreach_iter(exec_list_iterator, iter, refs.variable_list) {
+      variable_entry *entry = (variable_entry *)iter.get();
+      if (!entry->declaration || entry->whole_structure_access) {
+	 entry->remove();
+      }
+   }
+
+   if (refs.variable_list.is_empty())
+      return false;
+
+   /* Replace the decls of the structures to be split with their split
+    * components.
+    */
+   foreach_iter(exec_list_iterator, iter, refs.variable_list) {
+      variable_entry *entry = (variable_entry *)iter.get();
+      const struct glsl_type *type = entry->var->type;
+
+      entry->mem_ctx = talloc_parent(entry->var);
+
+      entry->components = talloc_array(mem_ctx,
+				       ir_variable *,
+				       type->length);
+
+      for (unsigned int i = 0; i < entry->var->type->length; i++) {
+	 const char *name = talloc_asprintf(mem_ctx, "%s_%s",
+					    type->name,
+					    type->fields.structure[i].name);
+
+	 entry->components[i] =
+	    new(entry->mem_ctx) ir_variable(type->fields.structure[i].type,
+					    name,
+					    ir_var_temporary);
+	 entry->var->insert_before(entry->components[i]);
+      }
+
+      entry->var->remove();
+   }
+
+   ir_structure_splitting_visitor split(&refs.variable_list);
+   visit_list_elements(&split, instructions);
+
+   talloc_free(mem_ctx);
+
+   return true;
+}
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index f9e24ca..0501169 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1287,6 +1287,7 @@ link_shaders(struct gl_shader_program *prog)
 
 	 progress = do_function_inlining(ir) || progress;
 	 progress = do_dead_functions(ir) || progress;
+	 progress = do_structure_splitting(ir) || progress;
 	 progress = do_if_simplification(ir) || progress;
 	 progress = do_copy_propagation(ir) || progress;
 	 progress = do_dead_code_local(ir) || progress;



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