From 7265688e0922a197a4be9095f6a727aa4b5cb2c1 Mon Sep 17 00:00:00 2001
From: Mehdi Amini <joker.eph@gmail.com>
Date: Tue, 18 Jan 2022 06:23:31 +0000
Subject: [PATCH] Use more references in MLIR Diagnostic handling (NFC)

This saves some copies of non-trivial objects, flagged by Coverity.

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D117525
---
 mlir/include/mlir/IR/Diagnostics.h |  5 +++--
 mlir/lib/IR/Diagnostics.cpp        | 12 ++++++------
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/mlir/include/mlir/IR/Diagnostics.h b/mlir/include/mlir/IR/Diagnostics.h
index 8ccfe49..b259e51 100644
--- a/mlir/include/mlir/IR/Diagnostics.h
+++ b/mlir/include/mlir/IR/Diagnostics.h
@@ -431,8 +431,9 @@ public:
   }
 
   /// Emit a diagnostic using the registered issue handler if present, or with
-  /// the default behavior if not.
-  void emit(Diagnostic diag);
+  /// the default behavior if not. The diagnostic instance is consumed in the
+  /// process.
+  void emit(Diagnostic &&diag);
 
 private:
   friend class MLIRContextImpl;
diff --git a/mlir/lib/IR/Diagnostics.cpp b/mlir/lib/IR/Diagnostics.cpp
index d29feac..e4d58c6 100644
--- a/mlir/lib/IR/Diagnostics.cpp
+++ b/mlir/lib/IR/Diagnostics.cpp
@@ -209,7 +209,7 @@ namespace detail {
 struct DiagnosticEngineImpl {
   /// Emit a diagnostic using the registered issue handle if present, or with
   /// the default behavior if not.
-  void emit(Diagnostic diag);
+  void emit(Diagnostic &&diag);
 
   /// A mutex to ensure that diagnostics emission is thread-safe.
   llvm::sys::SmartMutex<true> mutex;
@@ -228,7 +228,7 @@ struct DiagnosticEngineImpl {
 
 /// Emit a diagnostic using the registered issue handle if present, or with
 /// the default behavior if not.
-void DiagnosticEngineImpl::emit(Diagnostic diag) {
+void DiagnosticEngineImpl::emit(Diagnostic &&diag) {
   llvm::sys::SmartScopedLock<true> lock(mutex);
 
   // Try to process the given diagnostic on one of the registered handlers.
@@ -277,7 +277,7 @@ void DiagnosticEngine::eraseHandler(HandlerID handlerID) {
 
 /// Emit a diagnostic using the registered issue handler if present, or with
 /// the default behavior if not.
-void DiagnosticEngine::emit(Diagnostic diag) {
+void DiagnosticEngine::emit(Diagnostic &&diag) {
   assert(diag.getSeverity() != DiagnosticSeverity::Note &&
          "notes should not be emitted directly");
   impl->emit(std::move(diag));
@@ -869,13 +869,13 @@ struct ParallelDiagnosticHandlerImpl : public llvm::PrettyStackTraceEntry {
       return;
 
     // Emit the diagnostics back to the context.
-    emitDiagnostics([&](Diagnostic diag) {
+    emitDiagnostics([&](Diagnostic &diag) {
       return context->getDiagEngine().emit(std::move(diag));
     });
   }
 
   /// Utility method to emit any held diagnostics.
-  void emitDiagnostics(llvm::function_ref<void(Diagnostic)> emitFn) const {
+  void emitDiagnostics(llvm::function_ref<void(Diagnostic &)> emitFn) const {
     // Stable sort all of the diagnostics that were emitted. This creates a
     // deterministic ordering for the diagnostics based upon which order id they
     // were emitted for.
@@ -883,7 +883,7 @@ struct ParallelDiagnosticHandlerImpl : public llvm::PrettyStackTraceEntry {
 
     // Emit each diagnostic to the context again.
     for (ThreadDiagnostic &diag : diagnostics)
-      emitFn(std::move(diag.diag));
+      emitFn(diag.diag);
   }
 
   /// Set the order id for the current thread.
-- 
2.7.4