Mesa (master): glsl: Refine the loop instruction counting.
Eric Anholt
anholt at kemper.freedesktop.org
Thu Mar 8 19:35:45 UTC 2012
Module: Mesa
Branch: master
Commit: be5f27a84d0d4efb57071d9d7ecda061223d03ef
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=be5f27a84d0d4efb57071d9d7ecda061223d03ef
Author: Eric Anholt <eric at anholt.net>
Date: Tue Feb 21 13:37:49 2012 -0800
glsl: Refine the loop instruction counting.
Before, we were only counting top-level instructions. But if we have
an assignment of a giant expression tree (such as the ones eventually
generated by glsl-fs-unroll), we were counting the same as an
assignment of a variable deref.
glsl-fs-unroll-explosion now fails in a reasonable amount of time on
i965 because the unrolling didn't go ridiculously far.
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
---
src/glsl/loop_unroll.cpp | 48 ++++++++++++++++++++++++++++++++++-----------
1 files changed, 36 insertions(+), 12 deletions(-)
diff --git a/src/glsl/loop_unroll.cpp b/src/glsl/loop_unroll.cpp
index d0bcaa6..3434fde 100644
--- a/src/glsl/loop_unroll.cpp
+++ b/src/glsl/loop_unroll.cpp
@@ -50,13 +50,44 @@ is_break(ir_instruction *ir)
&& ((ir_loop_jump *) ir)->is_break();
}
+class loop_unroll_count : public ir_hierarchical_visitor {
+public:
+ int nodes;
+ bool fail;
+
+ loop_unroll_count(exec_list *list)
+ {
+ nodes = 0;
+ fail = false;
+
+ run(list);
+ }
+
+ virtual ir_visitor_status visit_enter(ir_assignment *ir)
+ {
+ nodes++;
+ return visit_continue;
+ }
+
+ virtual ir_visitor_status visit_enter(ir_expression *ir)
+ {
+ nodes++;
+ return visit_continue;
+ }
+
+ virtual ir_visitor_status visit_enter(ir_loop *ir)
+ {
+ fail = true;
+ return visit_continue;
+ }
+};
+
ir_visitor_status
loop_unroll_visitor::visit_leave(ir_loop *ir)
{
loop_variable_state *const ls = this->state->get(ir);
int iterations;
- unsigned ir_count;
/* If we've entered a loop that hasn't been analyzed, something really,
* really bad has happened.
@@ -81,17 +112,10 @@ loop_unroll_visitor::visit_leave(ir_loop *ir)
/* Don't try to unroll nested loops and loops with a huge body.
*/
- ir_count = 0;
- foreach_list(node, &ir->body_instructions) {
- ++ir_count;
-
- /* If the loop body gets to huge, do not unroll. */
- if (5*max_iterations < ir_count*iterations)
- return visit_continue;
- /* Do not unroll loops with child loop nodes. */
- if (((ir_instruction *) node)->as_loop())
- return visit_continue;
- }
+ loop_unroll_count count(&ir->body_instructions);
+
+ if (count.fail || count.nodes * iterations > (int)max_iterations * 5)
+ return visit_continue;
if (ls->num_loop_jumps > 1)
return visit_continue;
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