fold_indirect_ref bogous

[Richard Guenther]

fold_indirect_ref, called from the gimplifier happily converts

 const char *a;

...

 *(char *)&a[x] = 0;

to

 a[x] = 0;

confusing alias1 and ICEing in verify_ssa:

/net/alwazn/home/rguenth/src/gcc/cvs/gcc-4.1/gcc/testsuite/gcc.c-torture/execute/20031215-1.c:11:
error: Statement makes a memory store, but has no V_MAY_DEFS nor
V_MUST_DEFS
#   VUSE <ao_1>;
ao.ch[D.1242_5] = 0;
/net/alwazn/home/rguenth/src/gcc/cvs/gcc-4.1/gcc/testsuite/gcc.c-torture/execute/20031215-1.c:11:
internal compiler error: verify_ssa failed.

happens only for patched gcc where C frontend and fold happen to
produce .02.original:

;; Function test1 (test1)
;; enabled by -tree-original


{
  if (ao.ch[ao.l] != 0)
    {
      *(char *) &ao.ch[(unsigned int) ao.l] = 0;
    }
}

then, generic is already wrong:

test1 ()
{
  int D.1240;
  char D.1241;
  unsigned int D.1242;

  D.1240 = ao.l;
  D.1241 = ao.ch[D.1240];
  if (D.1241 != 0)
    {
      D.1240 = ao.l;
      D.1242 = (unsigned int) D.1240;
      ao.ch[D.1242] = 0;
    }

(not the missing cast).


something like the following patch fixes this.

Richard.


Index: fold-const.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/fold-const.c,v
retrieving revision 1.572
diff -c -3 -p -r1.572 fold-const.c
*** fold-const.c        26 Apr 2005 16:35:10 -0000      1.572
--- fold-const.c        27 Apr 2005 14:15:10 -0000
*************** fold_indirect_ref_1 (tree t)
*** 11322,11328 ****
    tree sub = t;
    tree subtype;

!   STRIP_NOPS (sub);
    subtype = TREE_TYPE (sub);
    if (!POINTER_TYPE_P (subtype))
      return NULL_TREE;
--- 11315,11321 ----
    tree sub = t;
    tree subtype;

!   STRIP_TYPE_NOPS (sub);
    subtype = TREE_TYPE (sub);
    if (!POINTER_TYPE_P (subtype))
      return NULL_TREE;