building on the new CallGraphSCC abstraction, teach CallGraphSCCPassManager

to keep the node entries in scc_iterator up to date instead of dangling as
the SCC mutates.

This is a really terrible problem which was causing -g to affect codegen 
because it would permute the memory image of the compiler process.

Thanks to Dale for expertly hunting it down.

llvm-svn: 101565

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp b/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp
index f5d24f005f5..7b73c5dffce 100644
--- a/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp
+++ b/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp
@@ -417,6 +417,11 @@ void CallGraphSCC::ReplaceNode(CallGraphNode *Old, CallGraphNode *New) {
     Nodes[i] = New;
     break;
   }
+  
+  // Update the active scc_iterator so that it doesn't contain dangling
+  // pointers to the old CallGraphNode.
+  scc_iterator<CallGraph*> *CGI = (scc_iterator<CallGraph*>*)Context;
+  CGI->ReplaceNode(Old, New);
 }