[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

3 files changed, 19 insertions, 3 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));
diff --git a/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp b/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp
index 65ba1c7c6c4..6b3e0634626 100644
--- a/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp
+++ b/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp
@@ -217,8 +217,10 @@ bool CGPassManager::RefreshCallGraph(CallGraphSCC &CurSCC,
           // another value. This can happen when constant folding happens
           // of well known functions etc.
           !CallSite(I->first) ||
-           (CallSite(I->first).getCalledFunction() &&
-            CallSite(I->first).getCalledFunction()->isIntrinsic())) {
+          (CallSite(I->first).getCalledFunction() &&
+           CallSite(I->first).getCalledFunction()->isIntrinsic() &&
+           Intrinsic::isLeaf(
+               CallSite(I->first).getCalledFunction()->getIntrinsicID()))) {
         assert(!CheckingMode &&
                "CallGraphSCCPass did not update the CallGraph correctly!");
         
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index bc57dee0af0..b50ad1262c6 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -846,6 +846,18 @@ bool Intrinsic::isOverloaded(ID id) {
 #undef GET_INTRINSIC_OVERLOAD_TABLE
 }
 
+bool Intrinsic::isLeaf(ID id) {
+  switch (id) {
+  default:
+    return true;
+
+  case Intrinsic::experimental_gc_statepoint:
+  case Intrinsic::experimental_patchpoint_void:
+  case Intrinsic::experimental_patchpoint_i64:
+    return false;
+  }
+}
+
 /// This defines the "Intrinsic::getAttributes(ID id)" method.
 #define GET_INTRINSIC_ATTRIBUTES
 #include "llvm/IR/Intrinsics.gen"