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-rw-r--r--src/glsl/loop_unroll.cpp292
1 files changed, 184 insertions, 108 deletions
diff --git a/src/glsl/loop_unroll.cpp b/src/glsl/loop_unroll.cpp
index ff97766f17b..e1009169370 100644
--- a/src/glsl/loop_unroll.cpp
+++ b/src/glsl/loop_unroll.cpp
@@ -37,6 +37,10 @@ public:
}
virtual ir_visitor_status visit_leave(ir_loop *ir);
+ void simple_unroll(ir_loop *ir, int iterations);
+ void complex_unroll(ir_loop *ir, int iterations,
+ bool continue_from_then_branch);
+ void splice_post_if_instructions(ir_if *ir_if, exec_list *splice_dest);
loop_state *state;
@@ -86,6 +90,138 @@ public:
};
+/**
+ * Unroll a loop which does not contain any jumps. For example, if the input
+ * is:
+ *
+ * (loop (...) ...instrs...)
+ *
+ * And the iteration count is 3, the output will be:
+ *
+ * ...instrs... ...instrs... ...instrs...
+ */
+void
+loop_unroll_visitor::simple_unroll(ir_loop *ir, int iterations)
+{
+ void *const mem_ctx = ralloc_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+ /* The loop has been replaced by the unrolled copies.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;
+}
+
+
+/**
+ * Unroll a loop whose last statement is an ir_if. If \c
+ * continue_from_then_branch is true, the loop is repeated only when the
+ * "then" branch of the if is taken; otherwise it is repeated only when the
+ * "else" branch of the if is taken.
+ *
+ * For example, if the input is:
+ *
+ * (loop (...)
+ * ...body...
+ * (if (cond)
+ * (...then_instrs...)
+ * (...else_instrs...)))
+ *
+ * And the iteration count is 3, and \c continue_from_then_branch is true,
+ * then the output will be:
+ *
+ * ...body...
+ * (if (cond)
+ * (...then_instrs...
+ * ...body...
+ * (if (cond)
+ * (...then_instrs...
+ * ...body...
+ * (if (cond)
+ * (...then_instrs...)
+ * (...else_instrs...)))
+ * (...else_instrs...)))
+ * (...else_instrs))
+ */
+void
+loop_unroll_visitor::complex_unroll(ir_loop *ir, int iterations,
+ bool continue_from_then_branch)
+{
+ void *const mem_ctx = ralloc_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);
+
+ ir_if *ir_if = ((ir_instruction *) copy_list.get_tail())->as_if();
+ assert(ir_if != NULL);
+
+ 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)
+ ? &ir_if->then_instructions : &ir_if->else_instructions;
+
+ list->push_tail(ir_to_replace);
+ }
+
+ ir_to_replace->remove();
+
+ this->progress = true;
+}
+
+
+/**
+ * Move all of the instructions which follow \c ir_if to the end of
+ * \c splice_dest.
+ *
+ * For example, in the code snippet:
+ *
+ * (if (cond)
+ * (...then_instructions...
+ * break)
+ * (...else_instructions...))
+ * ...post_if_instructions...
+ *
+ * If \c ir_if points to the "if" instruction, and \c splice_dest points to
+ * (...else_instructions...), the code snippet is transformed into:
+ *
+ * (if (cond)
+ * (...then_instructions...
+ * break)
+ * (...else_instructions...
+ * ...post_if_instructions...))
+ */
+void
+loop_unroll_visitor::splice_post_if_instructions(ir_if *ir_if,
+ exec_list *splice_dest)
+{
+ while (!ir_if->get_next()->is_tail_sentinel()) {
+ ir_instruction *move_ir = (ir_instruction *) ir_if->get_next();
+
+ move_ir->remove();
+ splice_dest->push_tail(move_ir);
+ }
+}
+
+
ir_visitor_status
loop_unroll_visitor::visit_leave(ir_loop *ir)
{
@@ -122,125 +258,65 @@ loop_unroll_visitor::visit_leave(ir_loop *ir)
if (ls->num_loop_jumps > 1)
return visit_continue;
- else if (ls->num_loop_jumps) {
- ir_instruction *last_ir = (ir_instruction *) ir->body_instructions.get_tail();
- assert(last_ir != NULL);
-
- if (is_break(last_ir)) {
- /* 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 {
- ir_if *ir_if = NULL;
- ir_instruction *break_ir = NULL;
- bool continue_from_then_branch = false;
-
- foreach_list(node, &ir->body_instructions) {
- /* recognize loops in the form produced by ir_lower_jumps */
- ir_instruction *cur_ir = (ir_instruction *) node;
-
- ir_if = cur_ir->as_if();
- if (ir_if != NULL) {
- /* 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 *ir_if_last =
- (ir_instruction *) ir_if->then_instructions.get_tail();
-
- if (is_break(ir_if_last)) {
- continue_from_then_branch = false;
- break_ir = ir_if_last;
- break;
- } else {
- ir_if_last =
- (ir_instruction *) ir_if->else_instructions.get_tail();
-
- if (is_break(ir_if_last)) {
- break_ir = ir_if_last;
- continue_from_then_branch = true;
- break;
- }
- }
- }
- }
-
- if (break_ir == NULL)
- return visit_continue;
-
- /* move instructions after then if in the continue branch */
- while (!ir_if->get_next()->is_tail_sentinel()) {
- ir_instruction *move_ir = (ir_instruction *) ir_if->get_next();
-
- move_ir->remove();
- if (continue_from_then_branch)
- ir_if->then_instructions.push_tail(move_ir);
- else
- ir_if->else_instructions.push_tail(move_ir);
- }
-
- /* Remove the break from the if-statement.
- */
- break_ir->remove();
- void *const mem_ctx = ralloc_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);
+ if (ls->num_loop_jumps == 0) {
+ simple_unroll(ir, iterations);
+ return visit_continue;
+ }
- ir_if = ((ir_instruction *) copy_list.get_tail())->as_if();
- assert(ir_if != NULL);
+ ir_instruction *last_ir = (ir_instruction *) ir->body_instructions.get_tail();
+ assert(last_ir != NULL);
- ir_to_replace->insert_before(&copy_list);
- ir_to_replace->remove();
+ if (is_break(last_ir)) {
+ /* If the only loop-jump is a break at the end of the loop, the loop
+ * will execute exactly once. Remove the break and use the simple
+ * unroller with an iteration count of 1.
+ */
+ last_ir->remove();
- /* placeholder that will be removed in the next iteration */
- ir_to_replace =
- new(mem_ctx) ir_loop_jump(ir_loop_jump::jump_continue);
+ simple_unroll(ir, 1);
+ return visit_continue;
+ }
- exec_list *const list = (continue_from_then_branch)
- ? &ir_if->then_instructions : &ir_if->else_instructions;
+ foreach_list(node, &ir->body_instructions) {
+ /* recognize loops in the form produced by ir_lower_jumps */
+ ir_instruction *cur_ir = (ir_instruction *) node;
+
+ ir_if *ir_if = cur_ir->as_if();
+ if (ir_if != NULL) {
+ /* 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 *ir_if_last =
+ (ir_instruction *) ir_if->then_instructions.get_tail();
- list->push_tail(ir_to_replace);
+ if (is_break(ir_if_last)) {
+ splice_post_if_instructions(ir_if, &ir_if->else_instructions);
+ ir_if_last->remove();
+ complex_unroll(ir, iterations, false);
+ return visit_continue;
+ } else {
+ ir_if_last =
+ (ir_instruction *) ir_if->else_instructions.get_tail();
+
+ if (is_break(ir_if_last)) {
+ splice_post_if_instructions(ir_if, &ir_if->then_instructions);
+ ir_if_last->remove();
+ complex_unroll(ir, iterations, true);
+ return visit_continue;
+ }
}
-
- ir_to_replace->remove();
-
- this->progress = true;
- return visit_continue;
}
}
- void *const mem_ctx = ralloc_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.
+ /* Did not find the break statement. It must be in a complex if-nesting,
+ * so don't try to unroll.
*/
- ir->remove();
-
- this->progress = true;
return visit_continue;
}
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