[llvm] r310967 - [ThinLTO] Fix ThinLTO crash while destroying context

[Charles Saternos via llvm-commits]

Author: ncharlie
Date: Tue Aug 15 15:23:44 2017
New Revision: 310967

URL: http://llvm.org/viewvc/llvm-project?rev=310967&view=rev
Log:
[ThinLTO] Fix ThinLTO crash while destroying context

Fix for PR32763

An assert that checks if a Ref was untracked fails during ThinLTO context cleanup. The issue is because lazy loading temporary nodes didn't properly track ValueAsMetadata nodes. This patch ensures that the temporary nodes are properly tracked when they're replaced with the value.


Modified:
    llvm/trunk/include/llvm/IR/Metadata.h
    llvm/trunk/tools/llvm-dis/llvm-dis.cpp

Modified: llvm/trunk/include/llvm/IR/Metadata.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/Metadata.h?rev=310967&r1=310966&r2=310967&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/Metadata.h (original)
+++ llvm/trunk/include/llvm/IR/Metadata.h Tue Aug 15 15:23:44 2017
@@ -1303,7 +1303,13 @@ public:
     if (!Use)
       return;
     *Use = MD;
-    Use = nullptr;
+
+    if (*Use)
+      MetadataTracking::track(*Use);
+
+    Metadata *T = cast<Metadata>(this);
+    MetadataTracking::untrack(T);
+    assert(!Use && "Use is still being tracked despite being untracked!");
   }
 };
 

Modified: llvm/trunk/tools/llvm-dis/llvm-dis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-dis/llvm-dis.cpp?rev=310967&r1=310966&r2=310967&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-dis/llvm-dis.cpp (original)
+++ llvm/trunk/tools/llvm-dis/llvm-dis.cpp Tue Aug 15 15:23:44 2017
@@ -51,8 +51,13 @@ static cl::opt<bool>
 DontPrint("disable-output", cl::desc("Don't output the .ll file"), cl::Hidden);
 
 static cl::opt<bool>
-ShowAnnotations("show-annotations",
-                cl::desc("Add informational comments to the .ll file"));
+    SetImporting("set-importing",
+                 cl::desc("Set lazy loading to pretend to import a module"),
+                 cl::Hidden);
+
+static cl::opt<bool>
+    ShowAnnotations("show-annotations",
+                    cl::desc("Add informational comments to the .ll file"));
 
 static cl::opt<bool> PreserveAssemblyUseListOrder(
     "preserve-ll-uselistorder",
@@ -142,9 +147,9 @@ static ExitOnError ExitOnErr;
 static std::unique_ptr<Module> openInputFile(LLVMContext &Context) {
   std::unique_ptr<MemoryBuffer> MB =
       ExitOnErr(errorOrToExpected(MemoryBuffer::getFileOrSTDIN(InputFilename)));
-  std::unique_ptr<Module> M =
-      ExitOnErr(getOwningLazyBitcodeModule(std::move(MB), Context,
-                                           /*ShouldLazyLoadMetadata=*/true));
+  std::unique_ptr<Module> M = ExitOnErr(getOwningLazyBitcodeModule(
+      std::move(MB), Context,
+      /*ShouldLazyLoadMetadata=*/true, SetImporting));
   if (MaterializeMetadata)
     ExitOnErr(M->materializeMetadata());
   else