[PATCH] Fix VN value-numbering with VIEW_CONVERT_EXPRs

[Richard Guenther]

VN ops comparison code value-numbers

  VIEW_CONVERT_EXPR<struct iterator>(__thing_31).._M_node

and

  __thing_31->_M_node

the same because it fails to check for *__thing_31 vs. __thing_31.

Bootstrap & regtest pending on x86_64.

Richard.

2012-01-25  Richard Guenther  <rguent...@suse.de>

        * tree-ssa-sccvn.c (vn_reference_eq): Also compare if both
        bases are dereferenced.

Index: gcc/tree-ssa-sccvn.c
===================================================================
--- gcc/tree-ssa-sccvn.c        (revision 183514)
+++ gcc/tree-ssa-sccvn.c        (working copy)
@@ -556,6 +556,7 @@ vn_reference_eq (const void *p1, const v
          tem1.type = TREE_TYPE (tem1.op0);
          tem1.opcode = TREE_CODE (tem1.op0);
          vro1 = &tem1;
+         deref1 = false;
        }
       if (deref2 && vro2->opcode == ADDR_EXPR)
        {
@@ -564,7 +565,10 @@ vn_reference_eq (const void *p1, const v
          tem2.type = TREE_TYPE (tem2.op0);
          tem2.opcode = TREE_CODE (tem2.op0);
          vro2 = &tem2;
+         deref2 = false;
        }
+      if (deref1 != deref2)
+       return false;
       if (!vn_reference_op_eq (vro1, vro2))
        return false;
       ++j;