compiler: Lower constant string comparisons.

From-SVN: r184316

diff --git a/gcc/go/gofrontend/expressions.cc b/gcc/go/gofrontend/expressions.cc
index 0b53f72df213819f87344c6dcb982480e906ba94..20c49f13b0e2fb19c1126e93df0729bb06127c17 100644 (file)
--- a/gcc/go/gofrontend/expressions.cc
+++ b/gcc/go/gofrontend/expressions.cc
@@ -5824,15 +5824,46 @@ Binary_expression::do_lower(Gogo* gogo, Named_object*,
   }
 
   // String constant expressions.
-  if (op == OPERATOR_PLUS
-      && left->type()->is_string_type()
-      && right->type()->is_string_type())
+  if (left->type()->is_string_type() && right->type()->is_string_type())
     {
       std::string left_string;
       std::string right_string;
       if (left->string_constant_value(&left_string)
          && right->string_constant_value(&right_string))
-       return Expression::make_string(left_string + right_string, location);
+       {
+         if (op == OPERATOR_PLUS)
+           return Expression::make_string(left_string + right_string,
+                                          location);
+         else if (is_comparison)
+           {
+             int cmp = left_string.compare(right_string);
+             bool r;
+             switch (op)
+               {
+               case OPERATOR_EQEQ:
+                 r = cmp == 0;
+                 break;
+               case OPERATOR_NOTEQ:
+                 r = cmp != 0;
+                 break;
+               case OPERATOR_LT:
+                 r = cmp < 0;
+                 break;
+               case OPERATOR_LE:
+                 r = cmp <= 0;
+                 break;
+               case OPERATOR_GT:
+                 r = cmp > 0;
+                 break;
+               case OPERATOR_GE:
+                 r = cmp >= 0;
+                 break;
+               default:
+                 go_unreachable();
+               }
+             return Expression::make_boolean(r, location);
+           }
+       }
     }
 
   // Special case for shift of a floating point constant.