[CallGraph] Teach the CallGraph about non-leaf intrinsics.

Summary:
Currently intrinsics don't affect the creation of the call graph.
This is not accurate with respect to statepoint and patchpoint
intrinsics -- these do call (or invoke) LLVM level functions.

This change fixes this inconsistency by adding a call to the external
node for call sites that call these non-leaf intrinsics.  This coupled
with the fact that these intrinsics also escape the function pointer
they call gives us a conservatively correct call graph.

Reviewers: reames, chandlerc, atrick, pgavlin

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10526

llvm-svn: 240039

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/IPA/CallGraph.cpp b/llvm/lib/Analysis/IPA/CallGraph.cpp
index ee276393964..77c36033b47 100644
--- a/llvm/lib/Analysis/IPA/CallGraph.cpp
+++ b/llvm/lib/Analysis/IPA/CallGraph.cpp
@@ -79,8 +79,10 @@ void CallGraph::addToCallGraph(Function *F) {
       CallSite CS(cast<Value>(II));
       if (CS) {
         const Function *Callee = CS.getCalledFunction();
-        if (!Callee)
+        if (!Callee || !Intrinsic::isLeaf(Callee->getIntrinsicID()))
           // Indirect calls of intrinsics are not allowed so no need to check.
+          // We can be more precise here by using TargetArg returned by
+          // Intrinsic::isLeaf.
           Node->addCalledFunction(CS, CallsExternalNode);
         else if (!Callee->isIntrinsic())
           Node->addCalledFunction(CS, getOrInsertFunction(Callee));