Add modular exponentiation for UNSIGNED.

gcc/fortran/ChangeLog:

	* arith.cc (arith_power): Handle modular arithmetic for
	BT_UNSIGNED.
	(eval_intrinsic):  Error for unsigned exponentiation with
	-pedantic.
	* expr.cc (gfc_type_convert_binary): Use type of first
	argument for unsigned exponentiation.
	* gfortran.texi: Mention arithmetic exponentiation.
	* resolve.cc (resolve_operator): Allow unsigned exponentiation.
	* trans-decl.cc (gfc_build_intrinsic_function_decls): Build
	declarations for unsigned exponentiation.
	* trans-expr.cc (gfc_conv_cst_uint_power): New function.
	(gfc_conv_power_op): Call it.  Handle unsigned exponentiation.
	* trans.h (gfor_fndecl_unsigned_pow_list):  Add declaration.

libgfortran/ChangeLog:

	* Makefile.am: Add files for unsigned exponentiation.
	* Makefile.in: Regenerate.
	* gfortran.map: Add functions for unsigned exponentiation.
	* generated/pow_m16_m1.c: New file.
	* generated/pow_m16_m16.c: New file.
	* generated/pow_m16_m2.c: New file.
	* generated/pow_m16_m4.c: New file.
	* generated/pow_m16_m8.c: New file.
	* generated/pow_m1_m1.c: New file.
	* generated/pow_m1_m16.c: New file.
	* generated/pow_m1_m2.c: New file.
	* generated/pow_m1_m4.c: New file.
	* generated/pow_m1_m8.c: New file.
	* generated/pow_m2_m1.c: New file.
	* generated/pow_m2_m16.c: New file.
	* generated/pow_m2_m2.c: New file.
	* generated/pow_m2_m4.c: New file.
	* generated/pow_m2_m8.c: New file.
	* generated/pow_m4_m1.c: New file.
	* generated/pow_m4_m16.c: New file.
	* generated/pow_m4_m2.c: New file.
	* generated/pow_m4_m4.c: New file.
	* generated/pow_m4_m8.c: New file.
	* generated/pow_m8_m1.c: New file.
	* generated/pow_m8_m16.c: New file.
	* generated/pow_m8_m2.c: New file.
	* generated/pow_m8_m4.c: New file.
	* generated/pow_m8_m8.c: New file.
	* m4/powu.m4: New file.

gcc/testsuite/ChangeLog:

	* gfortran.dg/unsigned_15.f90: Adjust error messages.
	* gfortran.dg/unsigned_43.f90: New test.
	* gfortran.dg/unsigned_44.f90: New test.

1 files changed, 18 insertions, 4 deletions

diff --git a/gcc/fortran/arith.cc b/gcc/fortran/arith.cc
index 5fc9142..82a8b6f 100644
--- a/gcc/fortran/arith.cc
+++ b/gcc/fortran/arith.cc
@@ -1143,6 +1143,20 @@ arith_power (gfc_expr *op1, gfc_expr *op2, gfc_expr **resultp)
 		 op2->value.complex, GFC_MPC_RND_MODE);
       }
       break;
+    case BT_UNSIGNED:
+      {
+	int k;
+	mpz_t x;
+	gcc_assert (op1->ts.type == BT_UNSIGNED);
+	k = gfc_validate_kind (BT_UNSIGNED, op1->ts.kind, false);
+	/* Exponentiation is performed modulo x = 2**n.  */
+	mpz_init (x);
+	mpz_add_ui (x, gfc_unsigned_kinds[k].huge, 1);
+	mpz_powm (result->value.integer, op1->value.integer,
+		  op2->value.integer, x);
+	mpz_clear (x);
+      }
+      break;
     default:
       gfc_internal_error ("arith_power(): unknown type");
     }
@@ -1827,10 +1841,11 @@ eval_intrinsic (gfc_intrinsic_op op,
     gcc_fallthrough ();
     /* Numeric binary  */
     case INTRINSIC_POWER:
-      if (flag_unsigned && op == INTRINSIC_POWER)
+      if (pedantic && (op1->ts.type == BT_UNSIGNED || op2->ts.type == BT_UNSIGNED))
 	{
-	  if (op1->ts.type == BT_UNSIGNED || op2->ts.type == BT_UNSIGNED)
-	    goto runtime;
+	  gfc_error ("Unsigned exponentiation not permitted with -pedantic "
+		     "at %L", &op1->where);
+	  goto runtime;
 	}
 
       gcc_fallthrough ();
@@ -1940,7 +1955,6 @@ runtime:
   /* Create a run-time expression.  */
   result = gfc_get_operator_expr (&op1->where, op, op1, op2);
   result->ts = temp.ts;
-
   return result;
 }