r12-4526 cancelled jump thread path rotates loop. It exposes a issue in
profile-estimate when predict_extra_loop_exits, outer loop's exit edge
is marked as inner loop's extra loop exit and set with incorrect
prediction, then a hot inner loop will become cold loop finally through
optimizations, this patch add loop check when searching extra exit edges
to avoid unexpected predict_edge from predict_paths_for_bb.
Regression tested on P8LE, OK for master?
gcc/ChangeLog:
PR middle-end/103270
* predict.c (predict_extra_loop_exits): Add loop parameter.
(predict_loops): Call with loop argument.
gcc/testsuite/ChangeLog:
PR middle-end/103270
* gcc.dg/pr103270.c: New test.
---
gcc/predict.c | 10 ++++++----
gcc/testsuite/gcc.dg/pr103270.c | 19 +++++++++++++++++++
2 files changed, 25 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr103270.c
diff --git a/gcc/predict.c b/gcc/predict.c
index 3cb4e3c0eb5..5b6e0cf722b 100644
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -1859,7 +1859,7 @@ predict_iv_comparison (class loop *loop, basic_block bb,
exits to predict them using PRED_LOOP_EXTRA_EXIT. */
static void
-predict_extra_loop_exits (edge exit_edge)
+predict_extra_loop_exits (class loop *loop, edge exit_edge)
{
unsigned i;
bool check_value_one;
@@ -1912,12 +1912,14 @@ predict_extra_loop_exits (edge exit_edge)
continue;
if (EDGE_COUNT (e->src->succs) != 1)
{
- predict_paths_leading_to_edge (e, PRED_LOOP_EXTRA_EXIT, NOT_TAKEN);
+ predict_paths_leading_to_edge (e, PRED_LOOP_EXTRA_EXIT, NOT_TAKEN,
+ loop);
continue;
}
FOR_EACH_EDGE (e1, ei, e->src->preds)
- predict_paths_leading_to_edge (e1, PRED_LOOP_EXTRA_EXIT, NOT_TAKEN);
+ predict_paths_leading_to_edge (e1, PRED_LOOP_EXTRA_EXIT, NOT_TAKEN,
+ loop);
}
}
@@ -2008,7 +2010,7 @@ predict_loops (void)
ex->src->index, ex->dest->index);
continue;
}
- predict_extra_loop_exits (ex);
+ predict_extra_loop_exits (loop, ex);
if (number_of_iterations_exit (loop, ex, &niter_desc, false, false))
niter = niter_desc.niter;
diff --git a/gcc/testsuite/gcc.dg/pr103270.c b/gcc/testsuite/gcc.dg/pr103270.c
new file mode 100644
index 00000000000..819310e360e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr103270.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-profile_estimate" } */
+
+void test(int a, int* i)
+{
+ for (; a < 5; ++a)
+ {
+ int b = 0;
+ int c = 0;
+ for (; b != -11; b--)
+ for (int d = 0; d ==0; d++)
+ {
+ *i += c & a;
+ c = b;
+ }
+ }
+}
+
+/* { dg-final { scan-tree-dump-not "extra loop exit heuristics of
edge\[^:\]*:" "profile_estimate"} } */
--
2.25.1
