From: Nathan Sidwell <nathan@acm.org>
Date: Thu, 17 Dec 2015 21:29:30 +0000 (+0000)
Subject: ipa-icf.c (sem_item_optimizer::merge): Don't pick 'main' as the source function.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=aa3987819a5ab392bcb125efe84008e75f99bbfc;p=gcc.git

ipa-icf.c (sem_item_optimizer::merge): Don't pick 'main' as the source function.

	gcc/
	* ipa-icf.c (sem_item_optimizer::merge): Don't pick 'main' as the
	source function.

	gcc/testsuite/
	* gcc.dg/ipa/ipa-icf-merge-1.c: New.

From-SVN: r231787
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 82a836d177c..a1f71bdfa86 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2015-12-17  Nathan Sidwell  <nathan@acm.org>
+
+	* ipa-icf.c (sem_item_optimizer::merge): Don't pick 'main' as the
+	source function.
+
 2015-12-17  Sebastian Pop  <s.pop@samsung.com>
 
 	* Makefile.in: Replace ISL with isl.
diff --git a/gcc/ipa-icf.c b/gcc/ipa-icf.c
index 889a07de697..4538677c860 100644
--- a/gcc/ipa-icf.c
+++ b/gcc/ipa-icf.c
@@ -3398,14 +3398,20 @@ sem_item_optimizer::merge_classes (unsigned int prev_class_count)
 	if (c->members.length () == 1)
 	  continue;
 
-	gcc_assert (c->members.length ());
-
 	sem_item *source = c->members[0];
 
-	for (unsigned int j = 1; j < c->members.length (); j++)
+	if (MAIN_NAME_P (DECL_NAME (source->decl)))
+	  /* If merge via wrappers, picking main as the target can be
+	     problematic.  */
+	  source = c->members[1];
+
+	for (unsigned int j = 0; j < c->members.length (); j++)
 	  {
 	    sem_item *alias = c->members[j];
 
+	    if (alias == source)
+	      continue;
+
 	    if (dump_file)
 	      {
 		fprintf (dump_file, "Semantic equality hit:%s->%s\n",
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 2cbde3b8552..d5ae2990097 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2015-12-17  Nathan Sidwell  <nathan@acm.org>
+
+	* gcc.dg/ipa/ipa-icf-merge-1.c: New.
+	
 2015-12-17  David Malcolm  <dmalcolm@redhat.com>
 
 	* gcc.dg/diagnostic-range-bad-return.c: New test case.
diff --git a/gcc/testsuite/gcc.dg/ipa/ipa-icf-merge-1.c b/gcc/testsuite/gcc.dg/ipa/ipa-icf-merge-1.c
new file mode 100644
index 00000000000..06958a4d69d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ipa/ipa-icf-merge-1.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-O2 -fdump-ipa-icf" } */
+
+/* Picking 'main' as a candiate target for equivalent functios is not a
+   good idea.  */
+
+int baz (int);
+
+int foo ()
+{
+  return baz (baz (0));
+}
+
+
+int main ()
+{
+  return baz (baz (0));
+}
+
+/* Notice the two functions are the same.  */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:foo->main" "icf" } } */
+
+/* Make sure we don't tail call main.  */
+/* { dg-final { scan-ipa-dump-not "= main \\(\\);" "icf" } } */
+
+/* Make sure we tail call foo.  */
+/* { dg-final { scan-ipa-dump "= foo \\(\\);" "icf" } } */