[wide-int] Make more use of const references

[Richard Sandiford]

Some cases where we could use const references instead of passing by value.

Tested on powerpc64-linux-gnu and by rerunning the assembly comparison.
OK to install?

Thanks,
Richard


Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c    2013-11-09 09:39:27.373805197 +0000
+++ gcc/fold-const.c    2013-11-09 09:39:28.207810833 +0000
@@ -9886,7 +9886,7 @@ exact_inverse (tree type, tree cst)
 /*  Mask out the tz least significant bits of X of type TYPE where
     tz is the number of trailing zeroes in Y.  */
 static wide_int
-mask_with_tz (tree type, wide_int x, wide_int y)
+mask_with_tz (tree type, const wide_int &x, const wide_int &y)
 {
   int tz = wi::ctz (y);
   if (tz > 0)
Index: gcc/tree-ssanames.c
===================================================================
--- gcc/tree-ssanames.c 2013-11-09 09:39:17.714739914 +0000
+++ gcc/tree-ssanames.c 2013-11-09 09:39:28.208810840 +0000
@@ -179,7 +179,7 @@ make_ssa_name_fn (struct function *fn, t
 /* Store range information MIN, and MAX to tree ssa_name NAME.  */
 
 void
-set_range_info (tree name, widest_int min, widest_int max)
+set_range_info (tree name, const widest_int &min, const widest_int &max)
 {
   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
@@ -201,16 +201,15 @@ set_range_info (tree name, widest_int mi
   if (wi::cmp (min, max, TYPE_SIGN (TREE_TYPE (name))) != 1)
     {
       int prec = TYPE_PRECISION (TREE_TYPE (name));
-      widest_int xorv;
 
-      min = wi::zext (min, prec);
-      max = wi::zext (max, prec);
-      xorv = min ^ max;
+      widest_int ext_min = wi::zext (min, prec);
+      widest_int ext_max = wi::zext (max, prec);
+      widest_int xorv = ext_min ^ ext_max;
       if (xorv != 0)
        xorv = wi::mask <widest_int> (MAX_BITSIZE_MODE_ANY_INT
                                      - wi::clz (xorv),
                                      false);
-      ri->nonzero_bits = ri->nonzero_bits & (min | xorv);
+      ri->nonzero_bits = ri->nonzero_bits & (ext_min | xorv);
     }
 }
 
@@ -254,7 +253,7 @@ get_range_info (const_tree name, widest_
 /* Change non-zero bits bitmask of NAME.  */
 
 void
-set_nonzero_bits (tree name, widest_int mask)
+set_nonzero_bits (tree name, const widest_int &mask)
 {
   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
   if (SSA_NAME_RANGE_INFO (name) == NULL)
Index: gcc/tree-ssanames.h
===================================================================
--- gcc/tree-ssanames.h 2013-11-09 09:39:17.714739914 +0000
+++ gcc/tree-ssanames.h 2013-11-09 09:39:28.208810840 +0000
@@ -70,11 +70,11 @@ #define ssa_name(i) ((*cfun->gimple_df->
 enum value_range_type { VR_UNDEFINED, VR_RANGE, VR_ANTI_RANGE, VR_VARYING };
 
 /* Sets the value range to SSA.  */
-extern void set_range_info (tree, widest_int, widest_int);
+extern void set_range_info (tree, const widest_int &, const widest_int &);
 /* Gets the value range from SSA.  */
 extern enum value_range_type get_range_info (const_tree, widest_int *,
                                             widest_int *);
-extern void set_nonzero_bits (tree, widest_int);
+extern void set_nonzero_bits (tree, const widest_int &);
 extern widest_int get_nonzero_bits (const_tree);
 extern void init_ssanames (struct function *, int);
 extern void fini_ssanames (void);