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-rw-r--r--src/glsl/loop_unroll.cpp93
1 files changed, 89 insertions, 4 deletions
diff --git a/src/glsl/loop_unroll.cpp b/src/glsl/loop_unroll.cpp
index 80f9217159..90797bde37 100644
--- a/src/glsl/loop_unroll.cpp
+++ b/src/glsl/loop_unroll.cpp
@@ -47,6 +47,7 @@ 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.
@@ -56,23 +57,107 @@ loop_unroll_visitor::visit_leave(ir_loop *ir)
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 (ls->max_iterations < 0)
+ if (iterations < 0)
return visit_continue;
/* Don't try to unroll loops that have zillions of iterations either.
*/
- if (ls->max_iterations > max_iterations)
+ if (iterations > max_iterations)
return visit_continue;
- if (ls->num_loop_jumps > 0)
+ 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 < ls->max_iterations; i++) {
+ for (int i = 0; i < iterations; i++) {
exec_list copy_list;
copy_list.make_empty();