RFA: Fix type incompatibility in get_addr_base_and_unit_offset_1

[Richard Sandiford]

get_addr_base_and_unit_offset_1 and get_ref_base_and_extent have similar
code to handle array indices.  The code in tree-dfa.c extends from the
precision of the index, as before wide-int, but the tree-dfa.h version
was updated in a way that could introduce a type inconsistency (flagged
by a patch I'm working on).  This version makes them the same again,
as per the patch for PR59356.

Tested on x86_64-limux-gnu.  OK to install?

Thanks,
Richard


gcc/
        * tree-dfa.h (get_addr_base_and_unit_offset_1): Update array index
        calculation to match get_ref_base_and_extent.

Index: gcc/tree-dfa.h
===================================================================
--- gcc/tree-dfa.h      2014-05-10 14:02:40.112187344 +0100
+++ gcc/tree-dfa.h      2014-05-10 14:02:50.414275258 +0100
@@ -103,7 +103,8 @@ get_addr_base_and_unit_offset_1 (tree ex
                    TREE_CODE (unit_size) == INTEGER_CST))
              {
                offset_int woffset
-                 = offset_int::from (wi::sub (index, low_bound), SIGNED);
+                 = wi::sext (wi::to_offset (index) - wi::to_offset (low_bound),
+                             TYPE_PRECISION (TREE_TYPE (index)));
                woffset *= wi::to_offset (unit_size);
                byte_offset += woffset.to_shwi ();
              }