glsl2: Add a pass for removing unused functions.
For a shader involving many small functions, this avoids running
optimization across all of them after they've been inlined
post-linking.
Reduces the runtime of linking and running a fragment shader from Yo
Frankie from 1.6 seconds to 0.9 seconds (-44.9%, +/- 3.3%).
diff --git a/src/glsl/ir_dead_functions.cpp b/src/glsl/ir_dead_functions.cpp
new file mode 100644
index 0000000..2655444
--- /dev/null
+++ b/src/glsl/ir_dead_functions.cpp
@@ -0,0 +1,151 @@
+ /*
+ * 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_dead_functions.cpp
+ *
+ * Eliminates unused functions from the linked program.
+ */
+
+ #include "ir.h"
+ #include "ir_visitor.h"
+ #include "ir_expression_flattening.h"
+ #include "glsl_types.h"
+
+ class signature_entry : public exec_node
+ {
+ public:
+ signature_entry(ir_function_signature *sig)
+ {
+ this->signature = sig;
+ this->used = false;
+ }
+
+ ir_function_signature *signature;
+ bool used;
+ };
+
+ class ir_dead_functions_visitor : public ir_hierarchical_visitor {
+ public:
+ ir_dead_functions_visitor()
+ {
+ this->mem_ctx = talloc_new(NULL);
+ }
+
+ ~ir_dead_functions_visitor()
+ {
+ talloc_free(this->mem_ctx);
+ }
+
+ virtual ir_visitor_status visit_enter(ir_function_signature *);
+ virtual ir_visitor_status visit_enter(ir_call *);
+
+ signature_entry *get_signature_entry(ir_function_signature *var);
+
+ bool (*predicate)(ir_instruction *ir);
+
+ /* List of signature_entry */
+ exec_list signature_list;
+ void *mem_ctx;
+ };
+
+
+ signature_entry *
+ ir_dead_functions_visitor::get_signature_entry(ir_function_signature *sig)
+ {
+ foreach_iter(exec_list_iterator, iter, this->signature_list) {
+ signature_entry *entry = (signature_entry *)iter.get();
+ if (entry->signature == sig)
+ return entry;
+ }
+
+ signature_entry *entry = new(mem_ctx) signature_entry(sig);
+ this->signature_list.push_tail(entry);
+ return entry;
+ }
+
+
+ ir_visitor_status
+ ir_dead_functions_visitor::visit_enter(ir_function_signature *ir)
+ {
+ signature_entry *entry = this->get_signature_entry(ir);
+
+ if (strcmp(ir->function_name(), "main") == 0) {
+ entry->used = true;
+ }
+
+ return visit_continue;
+ }
+
+
+ ir_visitor_status
+ ir_dead_functions_visitor::visit_enter(ir_call *ir)
+ {
+ signature_entry *entry = this->get_signature_entry(ir->get_callee());
+
+ entry->used = true;
+
+ return visit_continue;
+}
+
+bool
+do_dead_functions(exec_list *instructions)
+{
+ ir_dead_functions_visitor v;
+ bool progress = false;
+
+ visit_list_elements(&v, instructions);
+
+ /* Now that we've figured out which function signatures are used, remove
+ * the unused ones, and remove function definitions that have no more
+ * signatures.
+ */
+ foreach_iter(exec_list_iterator, iter, v.signature_list) {
+ signature_entry *entry = (signature_entry *)iter.get();
+
+ if (!entry->used) {
+ entry->signature->remove();
+ progress = true;
+ }
+ delete(entry);
+ }
+
+ /* We don't just do this above when we nuked a signature because of
+ * const pointers.
+ */
+ foreach_iter(exec_list_iterator, iter, *instructions) {
+ ir_instruction *ir = (ir_instruction *)iter.get();
+ ir_function *func = ir->as_function();
+
+ if (func && func->signatures.is_empty()) {
+ /* At this point (post-linking), the symbol table is no
+ * longer in use, so not removing the function from the
+ * symbol table should be OK.
+ */
+ func->remove();
+ progress = true;
+ }
+ }
+
+ return progress;
+}