From 58369fce30af484889356f225d89cb0b32009206 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Thomas=20K=C3=B6ppe?= <tkoeppe@google.com>
Date: Tue, 18 May 2021 23:44:25 +0000
Subject: [PATCH] Add a helper function to convert LogicalResult to int for
 return from main

At present, a lot of code contains main function bodies like "return failed(mlir::MlirOptMain(...);". This is unfortunate for two reasons: a) it uses ADL, which is maybe not what the free "failed" function was designed for; and b) it is a bit awkward to read, requring the reader to both understand the boolean nature of the value and the semantics of main's return value. (And it's also not portable, since 1 is not a portable success value.)

The replacement code, `return mlir::AsMainReturnCode(mlir::MlirOptMain(...))` is a bit more self-explanatory.

The change applies the new function to a few internal uses of MlirOptMain, too.

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D102641
---
 .../examples/standalone/standalone-opt/standalone-opt.cpp |  2 +-
 mlir/include/mlir/Support/MlirOptMain.h                   | 15 +++++++++++++++
 mlir/tools/mlir-opt/mlir-opt.cpp                          |  6 +++---
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/mlir/examples/standalone/standalone-opt/standalone-opt.cpp b/mlir/examples/standalone/standalone-opt/standalone-opt.cpp
index 0fb211a..97a996a 100644
--- a/mlir/examples/standalone/standalone-opt/standalone-opt.cpp
+++ b/mlir/examples/standalone/standalone-opt/standalone-opt.cpp
@@ -33,6 +33,6 @@ int main(int argc, char **argv) {
   // will be *parsed* by the tool, not the one generated
   // registerAllDialects(registry);
 
-  return failed(
+  return mlir::asMainReturnCode(
       mlir::MlirOptMain(argc, argv, "Standalone optimizer driver\n", registry));
 }
diff --git a/mlir/include/mlir/Support/MlirOptMain.h b/mlir/include/mlir/Support/MlirOptMain.h
index 8924e47..4ae3535 100644
--- a/mlir/include/mlir/Support/MlirOptMain.h
+++ b/mlir/include/mlir/Support/MlirOptMain.h
@@ -16,6 +16,7 @@
 #include "mlir/Support/LogicalResult.h"
 #include "llvm/ADT/StringRef.h"
 
+#include <cstdlib>
 #include <memory>
 
 namespace llvm {
@@ -61,6 +62,20 @@ LogicalResult MlirOptMain(int argc, char **argv, llvm::StringRef toolName,
                           DialectRegistry &registry,
                           bool preloadDialectsInContext = false);
 
+/// Helper wrapper to return the result of MlirOptMain directly from main.
+///
+/// Example:
+///
+///     int main(int argc, char **argv) {
+///       // ...
+///       return mlir::asMainReturnCode(mlir::MlirOptMain(
+///           argc, argv, /* ... */);
+///     }
+///
+inline int asMainReturnCode(LogicalResult r) {
+  return r.succeeded() ? EXIT_SUCCESS : EXIT_FAILURE;
+}
+
 } // end namespace mlir
 
 #endif // MLIR_SUPPORT_MLIROPTMAIN_H
diff --git a/mlir/tools/mlir-opt/mlir-opt.cpp b/mlir/tools/mlir-opt/mlir-opt.cpp
index 89b77ab..1ee3b6a 100644
--- a/mlir/tools/mlir-opt/mlir-opt.cpp
+++ b/mlir/tools/mlir-opt/mlir-opt.cpp
@@ -190,7 +190,7 @@ int main(int argc, char **argv) {
 #ifdef MLIR_INCLUDE_TESTS
   test::registerTestDialect(registry);
 #endif
-  return failed(MlirOptMain(argc, argv, "MLIR modular optimizer driver\n",
-                            registry,
-                            /*preloadDialectsInContext=*/false));
+  return mlir::asMainReturnCode(
+      mlir::MlirOptMain(argc, argv, "MLIR modular optimizer driver\n", registry,
+                        /*preloadDialectsInContext=*/false));
 }
-- 
2.7.4