[flang] Upstream partial lowering of EXIT intrinsic

This patch adds partial lowering of the "EXIT" intrinsic to
the backend runtime hook implemented in patch D110741. It also adds a
helper function to the `RuntimeCallTestBase.h` for testing for an
intrinsic function call in a `mlir::Block`.

Differential Revision: https://reviews.llvm.org/D118141

flang/include/flang/Optimizer/Builder/Runtime/Stop.h

@@ -0,0 +1,27 @@
+//===-- Stop.h - generate stop runtime API calls ----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef FORTRAN_OPTIMIZER_BUILDER_RUNTIME_STOP_H
+#define FORTRAN_OPTIMIZER_BUILDER_RUNTIME_STOP_H
+
+namespace mlir {
+class Value;
+class Location;
+} // namespace mlir
+
+namespace fir {
+class FirOpBuilder;
+}
+
+namespace fir::runtime {
+
+/// Generate call to EXIT intrinsic runtime routine.
+void genExit(fir::FirOpBuilder &, mlir::Location, mlir::Value status);
+
+} // namespace fir::runtime
+#endif // FORTRAN_OPTIMIZER_BUILDER_RUNTIME_STOP_H

flang/lib/Optimizer/Builder/CMakeLists.txt

@@ -14,6 +14,7 @@ add_flang_library(FIRBuilder
   Runtime/Numeric.cpp
   Runtime/Ragged.cpp
   Runtime/Reduction.cpp
+  Runtime/Stop.cpp
   Runtime/Transformational.cpp
 
   DEPENDS

flang/lib/Optimizer/Builder/Runtime/Stop.cpp

@@ -0,0 +1,22 @@
+//===-- Stop.h - generate stop runtime API calls ----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "flang/Optimizer/Builder/Runtime/Stop.h"
+#include "flang/Optimizer/Builder/FIRBuilder.h"
+#include "flang/Optimizer/Builder/Runtime/RTBuilder.h"
+#include "flang/Runtime/stop.h"
+
+using namespace Fortran::runtime;
+
+void fir::runtime::genExit(fir::FirOpBuilder &builder, mlir::Location loc,
+                           mlir::Value status) {
+  auto exitFunc = fir::runtime::getRuntimeFunc<mkRTKey(Exit)>(loc, builder);
+  llvm::SmallVector<mlir::Value> args =
+      fir::runtime::createArguments(builder, loc, exitFunc.getType(), status);
+  builder.create<fir::CallOp>(loc, exitFunc, args);
+}

flang/unittests/Optimizer/Builder/Runtime/RuntimeCallTestBase.h

@@ -120,4 +120,24 @@ static inline void checkCallOpFromResultBox(mlir::Value result,
   checkCallOpFromResultBox(convOp.getResult(), fctName, nbArgs, addLocArgs);
 }
 
+/// Check the operations in \p block for a `fir::CallOp` operation where the
+/// function being called shares its function name with \p fctName and the
+/// number of arguments is equal to \p nbArgs. Note that this check only cares
+/// if the operation exists, and not the order in when the operation is called.
+/// This results in exiting the test as soon as the first correct instance of
+/// `fir::CallOp` is found).
+static inline void checkBlockForCallOp(
+    mlir::Block *block, llvm::StringRef fctName, unsigned nbArgs) {
+  assert(block && "mlir::Block given is a nullptr");
+  for (auto &op : block->getOperations()) {
+    if (auto callOp = mlir::dyn_cast<fir::CallOp>(op)) {
+      if (fctName == callOp.callee()->getRootReference().getValue()) {
+        EXPECT_EQ(nbArgs, callOp.args().size());
+        return;
+      }
+    }
+  }
+  FAIL() << "No calls to " << fctName << " were found!";
+}
+
 #endif // FORTRAN_OPTIMIZER_BUILDER_RUNTIME_RUNTIMECALLTESTBASE_H

flang/unittests/Optimizer/Builder/Runtime/StopTest.cpp

@@ -0,0 +1,20 @@
+//===- StopTest.cpp -- Stop runtime builder unit tests ---------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "flang/Optimizer/Builder/Runtime/Stop.h"
+#include "RuntimeCallTestBase.h"
+#include "gtest/gtest.h"
+
+TEST_F(RuntimeCallTest, genExitTest) {
+  mlir::Location loc = firBuilder->getUnknownLoc();
+  mlir::Value status = firBuilder->createIntegerConstant(loc, i32Ty, 0);
+  fir::runtime::genExit(*firBuilder, loc, status);
+  mlir::Block *block = firBuilder->getBlock();
+  EXPECT_TRUE(block) << "Failed to retrieve the block!";
+  checkBlockForCallOp(block, "_FortranAExit", 1);
+}

flang/unittests/Optimizer/CMakeLists.txt

@@ -20,6 +20,7 @@ add_flang_unittest(FlangOptimizerTests
   Builder/Runtime/NumericTest.cpp
   Builder/Runtime/RaggedTest.cpp
   Builder/Runtime/ReductionTest.cpp
+  Builder/Runtime/StopTest.cpp
   Builder/Runtime/TransformationalTest.cpp
   FIRContextTest.cpp
   InternalNamesTest.cpp