[PATCH] Fix PR50698

[Richard Guenther]

This fixes PR50698, a failure to disambiguate &MEM[&mem + 10] from
&MEM[&mem] in data-reference analysis.  Fixed by also looking
at offsets for non-subsetted references.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.

Richard.

2011-10-13  Richard Guenther  <rguent...@suse.de>

        PR tree-optimization/50698
        * tree-data-ref.c (split_constant_offset_1): Also process
        offsets of &MEM.

        * g++.dg/vect/pr50698.cc: New testcase.

Index: gcc/tree-data-ref.c
===================================================================
*** gcc/tree-data-ref.c (revision 179856)
--- gcc/tree-data-ref.c (working copy)
*************** split_constant_offset_1 (tree type, tree
*** 589,597 ****
        int punsignedp, pvolatilep;
  
        op0 = TREE_OPERAND (op0, 0);
-       if (!handled_component_p (op0))
-         return false;
- 
        base = get_inner_reference (op0, &pbitsize, &pbitpos, &poffset,
                                    &pmode, &punsignedp, &pvolatilep, false);
  
--- 589,594 ----
Index: gcc/testsuite/g++.dg/vect/pr50698.cc
===================================================================
*** gcc/testsuite/g++.dg/vect/pr50698.cc        (revision 0)
--- gcc/testsuite/g++.dg/vect/pr50698.cc        (revision 0)
***************
*** 0 ****
--- 1,27 ----
+ // { dg-do compile }
+ // { dg-require-effective-target vect_float }
+ 
+ float mem[4096];
+ const int N=1024;
+ 
+ struct XYZ {
+     float * mem;
+     int n;
+     float * x() { return mem;}
+     float * y() { return x()+n;}
+     float * z() { return y()+n;}
+ };
+ 
+ inline
+ void sum(float * x, float * y, float * z, int n) {
+     for (int i=0;i!=n; ++i)
+       x[i]=y[i]+z[i];
+ }
+ 
+ void sumS() {
+     XYZ xyz; xyz.mem=mem; xyz.n=N;
+     sum(xyz.x(),xyz.y(),xyz.z(),xyz.n);
+ }
+ 
+ // { dg-final { scan-tree-dump-not "run-time aliasing" "vect" } }
+ // { dg-final { cleanup-tree-dump "vect" } }