1 files changed, 115 insertions, 0 deletions
diff --git a/toolchain/gcc/4.7.0/200-gcc-pr52734.patch b/toolchain/gcc/4.7.0/200-gcc-pr52734.patch
new file mode 100644
index 000000000..a1ac6017d
--- /dev/null
+++ b/toolchain/gcc/4.7.0/200-gcc-pr52734.patch
@@ -0,0 +1,115 @@
+Index: gcc/tree-ssa-tail-merge.c
+===================================================================
+--- a/gcc/tree-ssa-tail-merge.c (revision 185028)
++++ b/gcc/tree-ssa-tail-merge.c (working copy)
+@@ -1123,18 +1123,31 @@ gimple_equal_p (same_succ same_succ, gim
+     }
+ }
+ 
+-/* Let GSI skip backwards over local defs.  */
++/* Let GSI skip backwards over local defs.  Return the earliest vuse in VUSE.
++   Return true in VUSE_ESCAPED if the vuse influenced a SSA_OP_DEF of one of the
++   processed statements.  */
+ 
+ static void
+-gsi_advance_bw_nondebug_nonlocal (gimple_stmt_iterator *gsi)
++gsi_advance_bw_nondebug_nonlocal (gimple_stmt_iterator *gsi, tree *vuse,
++				  bool *vuse_escaped)
+ {
+   gimple stmt;
++  tree lvuse;
+ 
+   while (true)
+     {
+       if (gsi_end_p (*gsi))
+ 	return;
+       stmt = gsi_stmt (*gsi);
++
++      lvuse = gimple_vuse (stmt);
++      if (lvuse != NULL_TREE)
++	{
++	  *vuse = lvuse;
++	  if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_DEF))
++	    *vuse_escaped = true;
++	}
++
+       if (!(is_gimple_assign (stmt) && local_def (gimple_get_lhs (stmt))
+ 	    && !gimple_has_side_effects (stmt)))
+ 	return;
+@@ -1150,9 +1163,11 @@ find_duplicate (same_succ same_succ, bas
+ {
+   gimple_stmt_iterator gsi1 = gsi_last_nondebug_bb (bb1);
+   gimple_stmt_iterator gsi2 = gsi_last_nondebug_bb (bb2);
++  tree vuse1 = NULL_TREE, vuse2 = NULL_TREE;
++  bool vuse_escaped = false;
+ 
+-  gsi_advance_bw_nondebug_nonlocal (&gsi1);
+-  gsi_advance_bw_nondebug_nonlocal (&gsi2);
++  gsi_advance_bw_nondebug_nonlocal (&gsi1, &vuse1, &vuse_escaped);
++  gsi_advance_bw_nondebug_nonlocal (&gsi2, &vuse2, &vuse_escaped);
+ 
+   while (!gsi_end_p (gsi1) && !gsi_end_p (gsi2))
+     {
+@@ -1161,13 +1176,20 @@ find_duplicate (same_succ same_succ, bas
+ 
+       gsi_prev_nondebug (&gsi1);
+       gsi_prev_nondebug (&gsi2);
+-      gsi_advance_bw_nondebug_nonlocal (&gsi1);
+-      gsi_advance_bw_nondebug_nonlocal (&gsi2);
++      gsi_advance_bw_nondebug_nonlocal (&gsi1, &vuse1, &vuse_escaped);
++      gsi_advance_bw_nondebug_nonlocal (&gsi2, &vuse2, &vuse_escaped);
+     }
+ 
+   if (!(gsi_end_p (gsi1) && gsi_end_p (gsi2)))
+     return;
+ 
++  /* If the incoming vuses are not the same, and the vuse escaped into an
++     SSA_OP_DEF, then merging the 2 blocks will change the value of the def,
++     which potentially means the semantics of one of the blocks will be changed.
++     TODO: make this check more precise.  */
++  if (vuse_escaped && vuse1 != vuse2)
++    return;
++
+   if (dump_file)
+     fprintf (dump_file, "find_duplicates: <bb %d> duplicate of <bb %d>\n",
+ 	     bb1->index, bb2->index);
+Index: gcc/testsuite/gcc.dg/pr52734.c
+===================================================================
+--- a/dev/null (new file)
++++ b/gcc/testsuite/gcc.dg/pr52734.c (revision 0)
+@@ -0,0 +1,35 @@
++/* { dg-do run } */
++/* { dg-options "-O2" } */
++
++int bbb = 0;
++
++int __attribute__((noinline,noclone)) aaa(void)
++{
++    ++bbb;
++    return 0;
++}
++
++int __attribute__((noinline,noclone)) ccc(void)
++{
++  int ddd;
++  /* bbb == 0 */
++  if (aaa())
++    return bbb;
++
++  /* bbb == 1 */
++  ddd = bbb;
++  /* bbb == ddd == 1 */
++  if (aaa ())
++    return 0;
++  /* bbb == 2, ddd == 1 */
++
++  return ddd;
++}
++
++int main(void)
++{
++    if (ccc() != 1)
++	__builtin_abort();
++    return 0;
++}
++