expmed.c (store_bit_field): Reset alias set for memory.

2002-03-13  Aldy Hernandez  <aldyh@redhat.com>

        * expmed.c (store_bit_field): Reset alias set for memory.
        (extract_bit_field): Same.

From-SVN: r50706

1 files changed, 18 insertions, 0 deletions

diff --git a/gcc/expmed.c b/gcc/expmed.c
index 6d58ea9957e..48a3ef60278 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -392,6 +392,15 @@ store_bit_field (str_rtx, bitsize, bitnum, fieldmode, value, total_size)
       }
   }
 
+  /* We may be accessing data outside the field, which means
+     we can alias adjacent data.  */
+  if (GET_CODE (op0) == MEM)
+    {
+      op0 = shallow_copy_rtx (op0);
+      set_mem_alias_set (op0, 0);
+      set_mem_expr (op0, 0);
+    }
+
   /* If OP0 is a register, BITPOS must count within a word.
      But as we have it, it counts within whatever size OP0 now has.
      On a bigendian machine, these are not the same, so convert.  */
@@ -1069,6 +1078,15 @@ extract_bit_field (str_rtx, bitsize, bitnum, unsignedp,
       }
   }
 
+  /* We may be accessing data outside the field, which means
+     we can alias adjacent data.  */
+  if (GET_CODE (op0) == MEM)
+    {
+      op0 = shallow_copy_rtx (op0);
+      set_mem_alias_set (op0, 0);
+      set_mem_expr (op0, 0);
+    }
+
   /* ??? We currently assume TARGET is at least as big as BITSIZE.
      If that's wrong, the solution is to test for it and set TARGET to 0
      if needed.  */