Fix some nasty callgraph dangling pointer problems in

argpromotion and structretpromote.  Basically, when replacing
a function, they used the 'changeFunction' api which changes
the entry in the function map (and steals/reuses the callgraph
node).

This has some interesting effects: first, the problem is that it doesn't
update the "callee" edges in any callees of the function in the call graph.
Second, this covers for a major problem in all the CGSCC pass stuff, which 
is that it is completely broken when functions are deleted if they *don't*
reuse a CGN.  (there is a cute little fixme about this though :).

This patch changes the protocol that CGSCC passes must obey: now the CGSCC 
pass manager copies the SCC and preincrements its iterator to avoid passes
invalidating it.  This allows CGSCC passes to mutate the current SCC.  However
multiple passes may be run on that SCC, so if passes do this, they are now
required to *update* the SCC to be current when they return.

Other less interesting parts of this patch are that it makes passes update
the CG more directly, eliminates changeFunction, and requires clients of
replaceCallSite to specify the new callee CGN if they are changing it.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80527 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 7 deletions

diff --git a/include/llvm/Analysis/CallGraph.h b/include/llvm/Analysis/CallGraph.h
index f405f63f96..59dc3449b7 100644
--- a/include/llvm/Analysis/CallGraph.h
+++ b/include/llvm/Analysis/CallGraph.h
@@ -130,12 +130,6 @@ public:
     return removeFunctionFromModule((*this)[F]);
   }
 
-  /// changeFunction - This method changes the function associated with this
-  /// CallGraphNode, for use by transformations that need to change the
-  /// prototype of a Function (thus they must create a new Function and move the
-  /// old code over).
-  void changeFunction(Function *OldF, Function *NewF);
-
   /// 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.
@@ -212,6 +206,15 @@ public:
   void removeAllCalledFunctions() {
     CalledFunctions.clear();
   }
+  
+  /// stealCalledFunctionsFrom - Move all the callee information from N to this
+  /// node.
+  void stealCalledFunctionsFrom(CallGraphNode *N) {
+    assert(CalledFunctions.empty() &&
+           "Cannot steal callsite information if I already have some");
+    std::swap(CalledFunctions, N->CalledFunctions);
+  }
+  
 
   /// addCalledFunction - Add a function to the list of functions called by this
   /// one.
@@ -236,7 +239,7 @@ public:
   /// replaceCallSite - Make the edge in the node for Old CallSite be for
   /// New CallSite instead.  Note that this method takes linear time, so it
   /// should be used sparingly.
-  void replaceCallSite(CallSite Old, CallSite New);
+  void replaceCallSite(CallSite Old, CallSite New, CallGraphNode *NewCallee);
 
   friend class CallGraph;