[MCJIT] Fix an iterator invalidation bug in MCJIT::finalizeObject.

The finalizeObject method calls generateCodeForModule on each of the currently
'added' objects, but generateCodeForModule moves objects out of the 'added'
set as it's called. To avoid iterator invalidation issues, the added set is
copied out before any calls to generateCodeForModule.

This should fix http://llvm.org/PR20851 .

llvm-svn: 217291

2 files changed, 10 insertions, 5 deletions

diff --git a/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp b/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp
index 3dd205751d1..8ff41ffd7d6 100644
--- a/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp
+++ b/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp
@@ -225,12 +225,14 @@ void MCJIT::finalizeLoadedModules() {
 void MCJIT::finalizeObject() {
   MutexGuard locked(lock);
 
-  for (ModulePtrSet::iterator I = OwnedModules.begin_added(),
-                              E = OwnedModules.end_added();
-       I != E; ++I) {
-    Module *M = *I;
+  // Generate code for module is going to move objects out of the 'added' list,
+  // so we need to copy that out before using it:
+  SmallVector<Module*, 16> ModsToAdd;
+  for (auto M : OwnedModules.added())
+    ModsToAdd.push_back(M);
+
+  for (auto M : ModsToAdd)
     generateCodeForModule(M);
-  }
 
   finalizeLoadedModules();
 }
diff --git a/llvm/lib/ExecutionEngine/MCJIT/MCJIT.h b/llvm/lib/ExecutionEngine/MCJIT/MCJIT.h
index 9a4e53f27f2..624a4317a3b 100644
--- a/llvm/lib/ExecutionEngine/MCJIT/MCJIT.h
+++ b/llvm/lib/ExecutionEngine/MCJIT/MCJIT.h
@@ -118,6 +118,9 @@ class MCJIT : public ExecutionEngine {
 
     ModulePtrSet::iterator begin_added() { return AddedModules.begin(); }
     ModulePtrSet::iterator end_added() { return AddedModules.end(); }
+    iterator_range<ModulePtrSet::iterator> added() {
+      return iterator_range<ModulePtrSet::iterator>(begin_added(), end_added());
+    }
 
     ModulePtrSet::iterator begin_loaded() { return LoadedModules.begin(); }
     ModulePtrSet::iterator end_loaded() { return LoadedModules.end(); }