Fix PR69866

2017-06-20  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	Backport from mainline
	2017-06-15  Jan Hubicka  <hubicka@ucw.cz>
		    Thomas Preud'homme  <thomas.preudhomme@arm.com>

	gcc/
	PR lto/69866
	* lto-symtab.c (lto_symtab_merge_symbols): Drop useless definitions
	that resolved externally.
	2017-06-15  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	gcc/testsuite/
	PR lto/69866
	* gcc.dg/lto/pr69866_0.c: New test.
	* gcc.dg/lto/pr69866_1.c: Likewise.

	Backport from mainline
	2017-06-18  Jan Hubicka  <hubicka@ucw.cz>

	gcc/testsuite/
	* gcc.dg/lto/pr69866_0.c: This test needs alias.


git-svn-id: https://gcc.gnu.org/svn/gcc/branches/ARM/embedded-6-branch@249406 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 79 insertions, 0 deletions

diff --git a/gcc/lto/ChangeLog.arm b/gcc/lto/ChangeLog.arm
new file mode 100644
index 00000000000..5766abaf39d
--- /dev/null
+++ b/gcc/lto/ChangeLog.arm
@@ -0,0 +1,9 @@
+2017-06-20  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	Backport from mainline
+	2017-06-15  Jan Hubicka  <hubicka@ucw.cz>
+		    Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	PR lto/69866
+	* lto-symtab.c (lto_symtab_merge_symbols): Drop useless definitions
+	that resolved externally.
diff --git a/gcc/lto/lto-symtab.c b/gcc/lto/lto-symtab.c
index 94b919b53e6..c298fb6dd9f 100644
--- a/gcc/lto/lto-symtab.c
+++ b/gcc/lto/lto-symtab.c
@@ -942,6 +942,42 @@ lto_symtab_merge_symbols (void)
 	      if (tgt)
 		node->resolve_alias (tgt, true);
 	    }
+	  /* If the symbol was preempted outside IR, see if we want to get rid
+	     of the definition.  */
+	  if (node->analyzed
+	      && !DECL_EXTERNAL (node->decl)
+	      && (node->resolution == LDPR_PREEMPTED_REG
+		  || node->resolution == LDPR_RESOLVED_IR
+		  || node->resolution == LDPR_RESOLVED_EXEC
+		  || node->resolution == LDPR_RESOLVED_DYN))
+	    {
+	      DECL_EXTERNAL (node->decl) = 1;
+	      /* If alias to local symbol was preempted by external definition,
+		 we know it is not pointing to the local symbol.  Remove it.  */
+	      if (node->alias
+		  && !node->weakref
+		  && !node->transparent_alias
+		  && node->get_alias_target ()->binds_to_current_def_p ())
+		{
+		  node->alias = false;
+		  node->remove_all_references ();
+		  node->definition = false;
+		  node->analyzed = false;
+		  node->cpp_implicit_alias = false;
+		}
+	      else if (!node->alias
+		       && node->definition
+		       && node->get_availability () <= AVAIL_INTERPOSABLE)
+		{
+		  if ((cnode = dyn_cast <cgraph_node *> (node)) != NULL)
+		    cnode->reset ();
+		  else
+		    {
+		      node->analyzed = node->definition = false;
+		      node->remove_all_references ();
+		    }
+		}
+	    }
 
 	  if (!(cnode = dyn_cast <cgraph_node *> (node))
 	      || !cnode->clone_of
diff --git a/gcc/testsuite/ChangeLog.arm b/gcc/testsuite/ChangeLog.arm
index 4dd6a22a5f8..acffbde59b7 100644
--- a/gcc/testsuite/ChangeLog.arm
+++ b/gcc/testsuite/ChangeLog.arm
@@ -1,6 +1,20 @@
 2017-06-20  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
 	Backport from mainline
+	2017-06-15  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	PR lto/69866
+	* gcc.dg/lto/pr69866_0.c: New test.
+	* gcc.dg/lto/pr69866_1.c: Likewise.
+
+	Backport from mainline
+	2017-06-18  Jan Hubicka  <hubicka@ucw.cz>
+
+	* gcc.dg/lto/pr69866_0.c: This test needs alias.
+
+2017-06-20  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	Backport from mainline
 	2017-06-20  Prakhar Bahuguna  <prakhar.bahuguna@arm.com>
 
 	* gcc.target/arm/acle/cdp.c: Add feature macro bitmap test.
diff --git a/gcc/testsuite/gcc.dg/lto/pr69866_0.c b/gcc/testsuite/gcc.dg/lto/pr69866_0.c
new file mode 100644
index 00000000000..8c90030a57d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/pr69866_0.c
@@ -0,0 +1,14 @@
+/* { dg-lto-do link } */
+/* { dg-require-alias "" } */
+
+int _umh(int i)
+{
+  return i+1;
+}
+
+int weaks(int i) __attribute__((weak, alias("_umh")));
+
+int main()
+{
+  return weaks(10);
+}
diff --git a/gcc/testsuite/gcc.dg/lto/pr69866_1.c b/gcc/testsuite/gcc.dg/lto/pr69866_1.c
new file mode 100644
index 00000000000..3a14f850eef
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/pr69866_1.c
@@ -0,0 +1,6 @@
+/* { dg-options { -fno-lto } } */
+
+int weaks(int i)
+{
+  return i+1;
+}