From: Jakub Jelinek <jakub@redhat.com>
Date: Sun, 16 Jan 2011 20:21:42 +0000 (+0100)
Subject: backport: re PR tree-optimization/43655 (-ftree-ter causes FAIL: g++.old-deja/g+... 
X-Git-Tag: releases/gcc-4.5.3~303
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=07d76b8988b7fc149a63e2ed07f1f03790da6c85;p=thirdparty%2Fgcc.git

backport: re PR tree-optimization/43655 (-ftree-ter causes FAIL: g++.old-deja/g++.law/temps5.C execution test)

	Backport from mainline
	2010-12-16  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/43655
	* tree-ssa-ter.c (is_replaceable_p): Don't use
	gimple_references_memory_p for -O0, instead check for load
	by looking at rhs.

	* g++.dg/opt/pr43655.C: New test.

From-SVN: r168866
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d65bebc20198..db6b41f75757 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -3,6 +3,11 @@
 	Backport from mainline
 	2010-12-16  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/43655
+	* tree-ssa-ter.c (is_replaceable_p): Don't use
+	gimple_references_memory_p for -O0, instead check for load
+	by looking at rhs.
+
 	PR debug/46893
 	* cfgexpand.c (expand_debug_expr): If GET_MODE (op0) is VOIDmode,
 	use TYPE_MODE (TREE_TYPE (tem)) instead of mode1.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fd8d27dc2a47..b83af10d258a 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -3,6 +3,9 @@
 	Backport from mainline
 	2010-12-16  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/43655
+	* g++.dg/opt/pr43655.C: New test.
+
 	PR debug/46893
 	* gcc.dg/pr46893.c: New test.
 
diff --git a/gcc/testsuite/g++.dg/opt/pr43655.C b/gcc/testsuite/g++.dg/opt/pr43655.C
new file mode 100644
index 000000000000..f7e370b9e426
--- /dev/null
+++ b/gcc/testsuite/g++.dg/opt/pr43655.C
@@ -0,0 +1,34 @@
+// PR tree-optimization/43655
+// { dg-do run }
+// { dg-options "-O0 -ftree-ter" }
+
+extern "C" void abort ();
+
+struct C
+{
+  C (int i) : val(i) { }
+  C (const C& c) : val(c.val) { }
+  ~C (void) { val = 999; }
+  C& operator = (const C& c) { val = c.val; return *this; }
+  C& inc (int i) { val += i; return *this; }
+  int val;
+};
+
+C
+f ()
+{
+  return C (3);
+}
+
+C
+f (int i)
+{
+  return f ().inc (i);
+}
+
+int
+main ()
+{
+  if (f (2).val != 5)
+    abort ();
+}
diff --git a/gcc/tree-ssa-ter.c b/gcc/tree-ssa-ter.c
index 902b1f07f362..8c25748a94bb 100644
--- a/gcc/tree-ssa-ter.c
+++ b/gcc/tree-ssa-ter.c
@@ -416,7 +416,9 @@ is_replaceable_p (gimple stmt)
     return false;
 
   /* Without alias info we can't move around loads.  */
-  if (gimple_references_memory_p (stmt) && !optimize)
+  if (!optimize
+      && gimple_assign_single_p (stmt)
+      && !is_gimple_val (gimple_assign_rhs1 (stmt)))
     return false;
 
   /* Float expressions must go through memory if float-store is on.  */