Add spliceFunction to the CallGraph interface. This allows users to efficiently

update a callGraph when performing the common operation of splicing the body to
a new function and updating all callers (such as via RAUW).

No users yet, though this is intended for DeadArgumentElimination as part of
PR8887.

llvm-svn: 122728

1 files changed, 15 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/IPA/CallGraph.cpp b/llvm/lib/Analysis/IPA/CallGraph.cpp
index f2d747089d5..690c4b4b6f1 100644
--- a/llvm/lib/Analysis/IPA/CallGraph.cpp
+++ b/llvm/lib/Analysis/IPA/CallGraph.cpp
@@ -230,6 +230,21 @@ Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
   return F;
 }
 
+/// spliceFunction - Replace the function represented by this node by another.
+/// This does not rescan the body of the function, so it is suitable when
+/// splicing the body of the old function to the new while also updating all
+/// callers from old to new.
+///
+void CallGraph::spliceFunction(const Function *From, const Function *To) {
+  assert(FunctionMap.count(From) && "No CallGraphNode for function!");
+  assert(!FunctionMap.count(To) &&
+         "Pointing CallGraphNode at a function that already exists");
+  FunctionMapTy::iterator I = FunctionMap.find(From);
+  I->second->F = const_cast<Function*>(To);
+  FunctionMap[To] = I->second;
+  FunctionMap.erase(I);
+}
+
 // getOrInsertFunction - This method is identical to calling operator[], but
 // it will insert a new CallGraphNode for the specified function if one does
 // not already exist.
@@ -276,7 +291,6 @@ void CallGraphNode::removeCallEdgeFor(CallSite CS) {
   }
 }
 
-
 // removeAnyCallEdgeTo - This method removes any call edges from this node to
 // the specified callee function.  This takes more time to execute than
 // removeCallEdgeTo, so it should not be used unless necessary.