[llvm] ff52121 - [Orc] Fix race condition in DebugObjectManagerPlugin

[Stefan Gränitz via llvm-commits]

Author: Stefan Gränitz
Date: 2021-03-12T14:04:09+01:00
New Revision: ff52121bba0c30c0cfe745791b27d2604dee4fda

URL: https://github.com/llvm/llvm-project/commit/ff52121bba0c30c0cfe745791b27d2604dee4fda
DIFF: https://github.com/llvm/llvm-project/commit/ff52121bba0c30c0cfe745791b27d2604dee4fda.diff

LOG: [Orc] Fix race condition in DebugObjectManagerPlugin

During finalization the debug object is registered with the target. Materialization must wait for this process to finish. Otherwise we might start running code before the debugger finished processing the corresponding debug info.

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D98417

Added: 
    

Modified: 
    llvm/lib/ExecutionEngine/Orc/DebugObjectManagerPlugin.cpp

Removed: 
    


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diff  --git a/llvm/lib/ExecutionEngine/Orc/DebugObjectManagerPlugin.cpp b/llvm/lib/ExecutionEngine/Orc/DebugObjectManagerPlugin.cpp
index 6909928f3cfa..1da87dd34681 100644
--- a/llvm/lib/ExecutionEngine/Orc/DebugObjectManagerPlugin.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/DebugObjectManagerPlugin.cpp
@@ -18,6 +18,7 @@
 #include "llvm/Object/ELFObjectFile.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/Errc.h"
+#include "llvm/Support/MSVCErrorWorkarounds.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/raw_ostream.h"
@@ -463,26 +464,38 @@ Error DebugObjectManagerPlugin::notifyEmitted(
   DebugObject *UnownedDebugObj = It->second.release();
   PendingObjs.erase(It);
 
+  // During finalization the debug object is registered with the target.
+  // Materialization must wait for this process to finish. Otherwise we might
+  // start running code before the debugger processed the corresponding debug
+  // info.
+  std::promise<MSVCPError> FinalizePromise;
+  std::future<MSVCPError> FinalizeErr = FinalizePromise.get_future();
+
   // FIXME: We released ownership of the DebugObject, so we can easily capture
   // the raw pointer in the continuation function, which re-owns it immediately.
   if (UnownedDebugObj)
     UnownedDebugObj->finalizeAsync(
-        [this, Key, UnownedDebugObj](Expected<sys::MemoryBlock> TargetMem) {
+        [this, Key, UnownedDebugObj,
+         &FinalizePromise](Expected<sys::MemoryBlock> TargetMem) {
           std::unique_ptr<DebugObject> ReownedDebugObj(UnownedDebugObj);
           if (!TargetMem) {
-            ES.reportError(TargetMem.takeError());
+            FinalizePromise.set_value(TargetMem.takeError());
             return;
           }
           if (Error Err = Target->registerDebugObject(*TargetMem)) {
-            ES.reportError(std::move(Err));
+            FinalizePromise.set_value(std::move(Err));
             return;
           }
 
+          // Registration successful, notifyEmitted() can return now and
+          // materialization can finish.
+          FinalizePromise.set_value(Error::success());
+
           std::lock_guard<std::mutex> Lock(RegisteredObjsLock);
           RegisteredObjs[Key].push_back(std::move(ReownedDebugObj));
         });
 
-  return Error::success();
+  return FinalizeErr.get();
 }
 
 Error DebugObjectManagerPlugin::notifyFailed(