https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114052
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |needs-bisection
--- Comment #13 from Richard Biener <rguenth at gcc dot gnu.org> ---
On trunk the testcase now works - because of the cunroll side-effect change we
go from
size: 6-1, last_iteration: 6-1
Loop size: 6
Estimated size after unrolling: 6
t2.c:1:5: optimized: loop with 1 iterations completely unrolled (header
execution count 10233758)
to
size: 6-1, last_iteration: 6-1
Loop size: 6
Estimated size after unrolling: 10-2
Not unrolling loop 1: size would grow.
and we only allow unrolling if the size doesn't grow because there's a call
in the body. We'd need a new testcase there.
For the issue at hand (not trying to handle other cases we don't have a
testcase for), copying parts of the
tree-ssa-loop-im.cc:fill_always_executed_in_1
handling works (irreducible inner loop and exit not copied).
diff --git a/gcc/tree-ssa-loop-niter.cc b/gcc/tree-ssa-loop-niter.cc
index b71eb67fbc7..0615fb307d9 100644
--- a/gcc/tree-ssa-loop-niter.cc
+++ b/gcc/tree-ssa-loop-niter.cc
@@ -4378,11 +4378,28 @@ infer_loop_bounds_from_undefined (class loop *loop,
basic_block *bbs)
gimple_stmt_iterator bsi;
basic_block bb;
bool reliable;
+ class loop *inn_loop = loop;
for (i = 0; i < loop->num_nodes; i++)
{
bb = bbs[i];
+ if (!flow_bb_inside_loop_p (inn_loop, bb))
+ {
+ /* When we are leaving a possibly infinite inner loop
+ we have to stop processing. */
+ if (!finite_loop_p (inn_loop))
+ break;
+ /* If the loop was finite we can continue with processing
+ the loop we exited to. */
+ inn_loop = bb->loop_father;
+ }
+
+ if (bb->loop_father->header == bb)
+ /* Record that we enter into a subloop since it might not
+ be finite. */
+ inn_loop = bb->loop_father;
+
/* If BB is not executed in each iteration of the loop, we cannot
use the operations in it to infer reliable upper bound on the
# of iterations of the loop. However, we can use it as a guess.
@@ -4812,7 +4829,7 @@ estimate_numbers_of_iterations (class loop *loop)
diagnose those loops with -Waggressive-loop-optimizations. */
number_of_latch_executions (loop);
- basic_block *body = get_loop_body (loop);
+ basic_block *body = get_loop_body_in_dom_order (loop);
auto_vec<edge> exits = get_loop_exit_edges (loop, body);
likely_exit = single_likely_exit (loop, exits);
FOR_EACH_VEC_ELT (exits, i, ex)
