[flang][lowering] Add support for lowering of the `ieor` intrinsic

[awarzynski]

Summary

This patch adds support for lowering of the ieor intrinsic from Fortran
to the FIR dialect of MLIR.

This is part of the upstreaming effort from the fir-dev branch in [1].

[1] https://github.com/flang-compiler/f18-llvm-project

Co-authored-by: V Donaldson <[e-mail]>
Co-authored-by: Jean Perier <[e-mail]>
Co-authored-by: Valentin Clement <[e-mail]>

[clementval]

LGTM

flang/lib/Lower/IntrinsicCall.cpp

struct IntrinsicLibrary {
   fir::ExtendedValue genEoshift(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   template <Extremum, ExtremumBehavior>
   mlir::Value genExtremum(mlir::Type, llvm::ArrayRef<mlir::Value>);
   /// Lowering for the IAND intrinsic. The IAND intrinsic expects two arguments
   /// in the llvm::ArrayRef.
   mlir::Value genIand(mlir::Type, llvm::ArrayRef<mlir::Value>);
   mlir::Value genIbits(mlir::Type, llvm::ArrayRef<mlir::Value>);
   mlir::Value genIbset(mlir::Type, llvm::ArrayRef<mlir::Value>);
+  mlir::Value genIeor(mlir::Type, llvm::ArrayRef<mlir::Value>);
   mlir::Value genIshft(mlir::Type, llvm::ArrayRef<mlir::Value>);
   mlir::Value genIshftc(mlir::Type, llvm::ArrayRef<mlir::Value>);
   fir::ExtendedValue genLbound(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genNull(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genLen(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genLenTrim(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genMaxloc(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genMaxval(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
static constexpr IntrinsicHandler handlers[]{
      {{{"array", asBox},
        {"shift", asAddr},
        {"boundary", asBox, handleDynamicOptional},
        {"dim", asValue}}},
      /*isElemental=*/false},
     {"iand", &I::genIand},
     {"ibits", &I::genIbits},
     {"ibset", &I::genIbset},
+    {"ieor", &I::genIeor},
     {"ishft", &I::genIshft},
     {"ishftc", &I::genIshftc},
     {"len",
      &I::genLen,
      {{{"string", asInquired}, {"kind", asValue}}},
      /*isElemental=*/false},
     {"len_trim", &I::genLenTrim},
     {"lge", &I::genCharacterCompare<mlir::arith::CmpIPredicate::sge>},
mlir::Value IntrinsicLibrary::genIbset(mlir::Type resultType,
   // Return:  I | (1 << POS)
   assert(args.size() == 2);
   mlir::Value pos = builder.createConvert(loc, resultType, args[1]);
   mlir::Value one = builder.createIntegerConstant(loc, resultType, 1);
   auto mask = builder.create<mlir::arith::ShLIOp>(loc, one, pos);
   return builder.create<mlir::arith::OrIOp>(loc, args[0], mask);
 }
 
+// IEOR
+mlir::Value IntrinsicLibrary::genIeor(mlir::Type resultType,
+                                      llvm::ArrayRef<mlir::Value> args) {
+  assert(args.size() == 2);
+  return builder.create<mlir::arith::XOrIOp>(loc, args[0], args[1]);
+}
+
 // ISHFT
 mlir::Value IntrinsicLibrary::genIshft(mlir::Type resultType,
                                        llvm::ArrayRef<mlir::Value> args) {
   // A conformant ISHFT(I,SHIFT) call satisfies:
   //     abs(SHIFT) <= BIT_SIZE(I)
   // Return:  abs(SHIFT) >= BIT_SIZE(I)
   //              ? 0
   //              : SHIFT < 0

flang/test/Lower/Intrinsics/ieor.f90

+! RUN: bbc -emit-fir %s -o - | FileCheck %s
+
+! CHECK-LABEL: ieor_test
+subroutine ieor_test(a, b)
+  integer :: a, b
+  print *, ieor(a, b)
+  ! CHECK: %{{[0-9]+}} = arith.xori %{{[0-9]+}}, %{{[0-9]+}} : i{{(8|16|32|64|128)}}
+end subroutine ieor_test
+