From c2a0ee58865c5abad40acc59549dd98f40a8f7aa Mon Sep 17 00:00:00 2001
From: Thomas Koenig <tkoenig@gcc.gnu.org>
Date: Mon, 27 Jan 2025 18:43:44 +0100
Subject: 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.
---
 gcc/fortran/expr.cc | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'gcc/fortran/expr.cc')

diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
index 7f3f6c5..e4ab3ba 100644
--- a/gcc/fortran/expr.cc
+++ b/gcc/fortran/expr.cc
@@ -981,6 +981,14 @@ gfc_type_convert_binary (gfc_expr *e, int wconversion)
 	  goto done;
 	}
 
+      /* Unsigned exponentiation is special, we need the type of the first
+	 argument here because of modulo arithmetic.  */
+      if (op1->ts.type == BT_UNSIGNED && e->value.op.op == INTRINSIC_POWER)
+	{
+	  e->ts = op1->ts;
+	  goto done;
+	}
+
       if (op1->ts.kind > op2->ts.kind)
 	gfc_convert_type_warn (op2, &op1->ts, 2, wconversion);
       else
-- 
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