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authormarha <marha@users.sourceforge.net>2010-11-29 22:05:53 +0000
committermarha <marha@users.sourceforge.net>2010-11-29 22:05:53 +0000
commitfed109d6a33c0871291d1bb2f3f6b7a3d1a3e9d7 (patch)
treefa1ba494685a71e28a096990a8707680c7cb378b /mesalib/src/glsl/loop_unroll.cpp
parentae340911c1ba1f98b418bd8f1a487fa4d79491b0 (diff)
parent6fda93be42ace9eeab0e82ceebb6798961c9105c (diff)
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svn merge ^/branches/released .
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-rw-r--r--mesalib/src/glsl/loop_unroll.cpp187
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diff --git a/mesalib/src/glsl/loop_unroll.cpp b/mesalib/src/glsl/loop_unroll.cpp
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+++ b/mesalib/src/glsl/loop_unroll.cpp
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+/*
+ * 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.
+ */
+
+#include "glsl_types.h"
+#include "loop_analysis.h"
+#include "ir_hierarchical_visitor.h"
+
+class loop_unroll_visitor : public ir_hierarchical_visitor {
+public:
+ loop_unroll_visitor(loop_state *state, unsigned max_iterations)
+ {
+ this->state = state;
+ this->progress = false;
+ this->max_iterations = max_iterations;
+ }
+
+ virtual ir_visitor_status visit_leave(ir_loop *ir);
+
+ loop_state *state;
+
+ bool progress;
+ unsigned max_iterations;
+};
+
+
+ir_visitor_status
+loop_unroll_visitor::visit_leave(ir_loop *ir)
+{
+ loop_variable_state *const ls = this->state->get(ir);
+ int iterations;
+
+ /* If we've entered a loop that hasn't been analyzed, something really,
+ * really bad has happened.
+ */
+ if (ls == NULL) {
+ assert(ls != NULL);
+ return visit_continue;
+ }
+
+ iterations = ls->max_iterations;
+
+ /* Don't try to unroll loops where the number of iterations is not known
+ * at compile-time.
+ */
+ if (iterations < 0)
+ return visit_continue;
+
+ /* Don't try to unroll loops that have zillions of iterations either.
+ */
+ if (iterations > max_iterations)
+ return visit_continue;
+
+ if (ls->num_loop_jumps > 1)
+ return visit_continue;
+ else if (ls->num_loop_jumps) {
+ /* recognize loops in the form produced by ir_lower_jumps */
+ ir_instruction *last_ir =
+ ((ir_instruction*)ir->body_instructions.get_tail());
+
+ assert(last_ir != NULL);
+
+ ir_if *last_if = last_ir->as_if();
+ if (last_if) {
+ bool continue_from_then_branch;
+
+ /* Determine which if-statement branch, if any, ends with a break.
+ * The branch that did *not* have the break will get a temporary
+ * continue inserted in each iteration of the loop unroll.
+ *
+ * Note that since ls->num_loop_jumps is <= 1, it is impossible for
+ * both branches to end with a break.
+ */
+ ir_instruction *last =
+ (ir_instruction *) last_if->then_instructions.get_tail();
+
+ if (last && last->ir_type == ir_type_loop_jump
+ && ((ir_loop_jump*) last)->is_break()) {
+ continue_from_then_branch = false;
+ } else {
+ last = (ir_instruction *) last_if->then_instructions.get_tail();
+
+ if (last && last->ir_type == ir_type_loop_jump
+ && ((ir_loop_jump*) last)->is_break())
+ continue_from_then_branch = true;
+ else
+ /* Bail out if neither if-statement branch ends with a break.
+ */
+ return visit_continue;
+ }
+
+ /* Remove the break from the if-statement.
+ */
+ last->remove();
+
+ void *const mem_ctx = talloc_parent(ir);
+ ir_instruction *ir_to_replace = ir;
+
+ for (int i = 0; i < iterations; i++) {
+ exec_list copy_list;
+
+ copy_list.make_empty();
+ clone_ir_list(mem_ctx, &copy_list, &ir->body_instructions);
+
+ last_if = ((ir_instruction*)copy_list.get_tail())->as_if();
+ assert(last_if);
+
+ ir_to_replace->insert_before(&copy_list);
+ ir_to_replace->remove();
+
+ /* placeholder that will be removed in the next iteration */
+ ir_to_replace =
+ new(mem_ctx) ir_loop_jump(ir_loop_jump::jump_continue);
+
+ exec_list *const list = (continue_from_then_branch)
+ ? &last_if->then_instructions : &last_if->else_instructions;
+
+ list->push_tail(ir_to_replace);
+ }
+
+ ir_to_replace->remove();
+
+ this->progress = true;
+ return visit_continue;
+ } else if (last_ir->ir_type == ir_type_loop_jump
+ && ((ir_loop_jump *)last_ir)->is_break()) {
+ /* If the only loop-jump is a break at the end of the loop, the loop
+ * will execute exactly once. Remove the break, set the iteration
+ * count, and fall through to the normal unroller.
+ */
+ last_ir->remove();
+ iterations = 1;
+
+ this->progress = true;
+ } else
+ return visit_continue;
+ }
+
+ void *const mem_ctx = talloc_parent(ir);
+
+ for (int i = 0; i < iterations; i++) {
+ exec_list copy_list;
+
+ copy_list.make_empty();
+ clone_ir_list(mem_ctx, &copy_list, &ir->body_instructions);
+
+ ir->insert_before(&copy_list);
+ }
+
+ /* The loop has been replaced by the unrolled copies. Remove the original
+ * loop from the IR sequence.
+ */
+ ir->remove();
+
+ this->progress = true;
+ return visit_continue;
+}
+
+
+bool
+unroll_loops(exec_list *instructions, loop_state *ls, unsigned max_iterations)
+{
+ loop_unroll_visitor v(ls, max_iterations);
+
+ v.run(instructions);
+
+ return v.progress;
+}