* ifcvt.c (noce_process_if_block): Fail the conversion if X is

        referenced bewteen the condition and the jump.  Don't delete
        anything but the jump.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@33563 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 11 insertions, 6 deletions

diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c
index b831b3e14d2..ba310da9d84 100644
--- a/gcc/ifcvt.c
+++ b/gcc/ifcvt.c
@@ -1024,7 +1024,7 @@ noce_process_if_block (test_bb, then_bb, else_bb, join_bb)
   rtx insn_a, insn_b;
   rtx set_a, set_b;
   rtx orig_x, x, a, b;
-  rtx jump, cond;
+  rtx jump, cond, insn;
 
   /* If this is not a standard conditional jump, we can't parse it.  */
   jump = test_bb->end;
@@ -1046,6 +1046,11 @@ noce_process_if_block (test_bb, then_bb, else_bb, join_bb)
   x = SET_DEST (set_a);
   a = SET_SRC (set_a);
 
+  /* X may not be mentioned between cond_earliest and the jump.  */
+  for (insn = jump; insn != if_info.cond_earliest; insn = PREV_INSN (insn))
+    if (INSN_P (insn) && reg_mentioned_p (x, insn))
+      return FALSE;
+
   /* Look for the other potential set.  Make sure we've got equivalent
      destinations.  */
   /* ??? This is overconservative.  Storing to two different mems is
@@ -1165,10 +1170,10 @@ noce_process_if_block (test_bb, then_bb, else_bb, join_bb)
     }
 
   /* The new insns will have been inserted before cond_earliest.  We should
-     be able to remove cond_earliest through the jump with impunity.  */
-  insn_a = prev_nonnote_insn (if_info.cond_earliest);
-  flow_delete_insn_chain (if_info.cond_earliest, test_bb->end);
-  test_bb->end = insn_a;
+     be able to remove the jump with impunity, but the condition itself may
+     have been modified by gcse to be shared across basic blocks.  */
+  test_bb->end = PREV_INSN (jump);
+  flow_delete_insn (jump);
 
   /* If we used a temporary, fix it up now.  */
   if (orig_x != x)
@@ -1178,7 +1183,7 @@ noce_process_if_block (test_bb, then_bb, else_bb, join_bb)
       insn_b = gen_sequence ();
       end_sequence ();
 
-      test_bb->end = emit_insn_after (insn_b, insn_a);
+      test_bb->end = emit_insn_after (insn_b, test_bb->end);
     }
 
   /* Merge the blocks!  */