Fix type of bitstart in vectorizable_live_operation

[Richard Sandiford]

This patch changes the type of the multiplier applied by
vectorizable_live_operation from unsigned_type_node to bitsizetype,
which matches the type of TYPE_SIZE and is the type expected of a
BIT_FIELD_REF bit position.  This is shown by existing tests when
SVE is added.

Tested on aarch64-linux-gnu, x86_64-linux-gnu and powerpc64le-linux-gnu.
OK to install?

Richard


2017-09-15  Richard Sandiford  <richard.sandif...@linaro.org>
            Alan Hayward  <alan.hayw...@arm.com>
            David Sherwood  <david.sherw...@arm.com>

gcc/
        * tree-vect-loop.c (vectorizable_live_operation): Fix type of
        bitstart.

Index: gcc/tree-vect-loop.c
===================================================================
--- gcc/tree-vect-loop.c        2017-09-15 11:37:45.639244036 +0100
+++ gcc/tree-vect-loop.c        2017-09-15 11:38:33.276424843 +0100
@@ -7090,7 +7090,7 @@ vectorizable_live_operation (gimple *stm
       vec_lhs = gimple_get_lhs (SLP_TREE_VEC_STMTS (slp_node)[vec_entry]);
 
       /* Get entry to use.  */
-      bitstart = build_int_cst (unsigned_type_node, vec_index);
+      bitstart = bitsize_int (vec_index);
       bitstart = int_const_binop (MULT_EXPR, bitsize, bitstart);
     }
   else