Switch DIDescriptor to use a TrackingVH. - This makes it much safer to work with debug info, since it was extraordinarily easy to have dangling pointers thanks to MDNode uniquing.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82507 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/DebugInfo.cpp b/lib/Analysis/DebugInfo.cpp
index a072161..531f609 100644
--- a/lib/Analysis/DebugInfo.cpp
+++ b/lib/Analysis/DebugInfo.cpp
@@ -267,8 +267,17 @@
return;
assert (!D.isNull() && "Can not replace with null");
- DbgNode->replaceAllUsesWith(D.getNode());
- delete DbgNode;
+
+ // Since we use a TrackingVH for the node, its easy for clients to manufacture
+ // legitimate situations where they want to replaceAllUsesWith() on something
+ // which, due to uniquing, has merged with the source. We shield clients from
+ // this detail by allowing a value to be replaced with replaceAllUsesWith()
+ // itself.
+ if (getNode() != D.getNode()) {
+ MDNode *Node = DbgNode;
+ Node->replaceAllUsesWith(D.getNode());
+ delete Node;
+ }
}
/// Verify - Verify that a compile unit is well formed.
@@ -395,7 +404,7 @@
/// dump - Print descriptor.
void DIDescriptor::dump() const {
errs() << "[" << dwarf::TagString(getTag()) << "] ";
- errs().write_hex((intptr_t)DbgNode) << ']';
+ errs().write_hex((intptr_t) &*DbgNode) << ']';
}
/// dump - Print compile unit.