PR rtl-optimization/51495

	* function.c (thread_prologue_and_epilogue_insns): Don't add
	to bb_tail basic blocks that have EDGE_COMPLEX predecessor edges
	from basic blocks not needing prologue.

	* gcc.c-torture/compile/pr51495.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@182265 138bc75d-0d04-0410-961f-82ee72b054a4

gcc/ChangeLog

@@ -1,5 +1,10 @@
 2011-12-12  Jakub Jelinek  <jakub@redhat.com>
 
+	PR rtl-optimization/51495
+	* function.c (thread_prologue_and_epilogue_insns): Don't add
+	to bb_tail basic blocks that have EDGE_COMPLEX predecessor edges
+	from basic blocks not needing prologue.
+
 	PR tree-optimization/51481
 	* gimple-fold.c (gimple_fold_call): Call
 	maybe_clean_or_replace_eh_stmt.  Avoid optimization if stmt has EH

gcc/function.c

@@ -5956,9 +5956,22 @@ thread_prologue_and_epilogue_insns (void)
 	  FOR_EACH_EDGE (e, ei, tmp_bb->preds)
 	    if (single_succ_p (e->src)
 		&& !bitmap_bit_p (&bb_on_list, e->src->index)
-		&& can_duplicate_block_p (e->src)
-		&& bitmap_set_bit (&bb_tail, e->src->index))
-	      VEC_quick_push (basic_block, vec, e->src);
+		&& can_duplicate_block_p (e->src))
+	      {
+		edge pe;
+		edge_iterator pei;
+
+		/* If there is predecessor of e->src which doesn't
+		   need prologue and the edge is complex,
+		   we might not be able to redirect the branch
+		   to a copy of e->src.  */
+		FOR_EACH_EDGE (pe, pei, e->src->preds)
+		  if ((pe->flags & EDGE_COMPLEX) != 0
+		      && !bitmap_bit_p (&bb_flags, pe->src->index))
+		    break;
+		if (pe == NULL && bitmap_set_bit (&bb_tail, e->src->index))
+		  VEC_quick_push (basic_block, vec, e->src);
+	      }
 	}
 
       /* Now walk backwards from every block that is marked as needing

gcc/testsuite/ChangeLog

@@ -1,5 +1,8 @@
 2011-12-12  Jakub Jelinek  <jakub@redhat.com>
 
+	PR rtl-optimization/51495
+	* gcc.c-torture/compile/pr51495.c: New test.
+
 	PR tree-optimization/51481
 	* gcc.dg/pr51481.c: New test.
 

gcc/testsuite/gcc.c-torture/compile/pr51495.c

@@ -0,0 +1,14 @@
+/* PR rtl-optimization/51495 */
+
+void bar (void);
+
+int
+foo (int i)
+{
+  static const void *const table[] = { &&begin, &&end };
+  goto *(table[i]);
+begin:
+  bar ();
+end:
+  return 0;
+}