Consider this testcase:

void %test(int* %P) {
        %X = volatile load int*%P
        volatile store int %X, int* %P
        ret void
}

The CBE currently emits:

void test(int *l1_P) {
  int l2_X;
  l2_X = *l1_P;
  *l1_P = l2_X;
  return;
}

... which GCC correctly optimizes to:

test:
        ret

The C Backend should emit volatile pointer qualifiers to get the right thing to
happen.

Fixed.  Testcase here:
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20050214/024098.html

Patch here:
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20050214/024099.html

-Chris

Actually that patch was not quite right.  This one fixes it:
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20050214/024121.html