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[PATCH] Fix first match heuristics
- From: Martin LiÅka <mliska at suse dot cz>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Cc: Jan Hubicka <hubicka at ucw dot cz>
- Date: Thu, 2 Jun 2016 13:18:50 +0200
- Subject: [PATCH] Fix first match heuristics
- Authentication-results: sourceware.org; auth=none
Hi.
Following patch fixes a typo in first match heuristics that blocks
selection of best first match heuristics.
It's questionable whether to add a spacial test-case for that? I'm bit
concerned that it can be a bit fragile.
Bootstrapped and regtested on x86_64-linux.
Ready for trunk?
Thanks,
Martin
>From 4106928c3eea80c732d32d73d653525c698515d6 Mon Sep 17 00:00:00 2001
From: marxin <mliska@suse.cz>
Date: Thu, 2 Jun 2016 11:51:57 +0200
Subject: [PATCH] Fix first match heuristics
gcc/ChangeLog:
2016-06-02 Martin Liska <mliska@suse.cz>
* predict.c (combine_predictions_for_bb): Fix first match in
cases where a first predictor contains more than one occurence
in list of predictors. Take the best value in such case.
gcc/testsuite/ChangeLog:
2016-06-02 Martin Liska <mliska@suse.cz>
* gcc.dg/predict-9.c: New test.
---
gcc/predict.c | 2 +-
gcc/testsuite/gcc.dg/predict-9.c | 23 +++++++++++++++++++++++
2 files changed, 24 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/predict-9.c
diff --git a/gcc/predict.c b/gcc/predict.c
index e9dda20..429f44e 100644
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -939,7 +939,7 @@ combine_predictions_for_bb (basic_block bb, bool dry_run)
pred2; pred2 = pred2->ep_next)
if (pred2 != pred && pred2->ep_predictor == pred->ep_predictor)
{
- int probability2 = pred->ep_probability;
+ int probability2 = pred2->ep_probability;
if (pred2->ep_edge != first)
probability2 = REG_BR_PROB_BASE - probability2;
diff --git a/gcc/testsuite/gcc.dg/predict-9.c b/gcc/testsuite/gcc.dg/predict-9.c
new file mode 100644
index 0000000..59be16e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/predict-9.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-profile_estimate" } */
+
+extern int global;
+extern int global2;
+extern int global3;
+
+void foo (int base)
+{
+ int i;
+ while (global < 10)
+ {
+ if(global || global2 || global3)
+ return;
+
+ for (i = base; i < 10; i++)
+ if (i > 123)
+ return;
+ }
+}
+
+/* { dg-final { scan-tree-dump-times "first match heuristics: 2.0%" 4 "profile_estimate"} } */
+/* { dg-final { scan-tree-dump-times "first match heuristics: 4.5%" 0 "profile_estimate"} } */
--
2.8.3