[CallGraph] Given -print-callgraph a stable printing order.

Summary:
Since FunctionMap has llvm::Function pointers as keys, the order in
which the traversal happens can differ from run to run, causing spurious
FileCheck failures.  Have CallGraph::print sort the CallGraphNodes by
name before printing them.

Reviewers: bogner, chandlerc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10575

llvm-svn: 240191

1 files changed, 20 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/IPA/CallGraph.cpp b/llvm/lib/Analysis/IPA/CallGraph.cpp
index 77c36033b47..e2799d965a7 100644
--- a/llvm/lib/Analysis/IPA/CallGraph.cpp
+++ b/llvm/lib/Analysis/IPA/CallGraph.cpp
@@ -98,8 +98,26 @@ void CallGraph::print(raw_ostream &OS) const {
     OS << "<<null function: 0x" << Root << ">>\n";
   }
 
-  for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
-    I->second->print(OS);
+  // Print in a deterministic order by sorting CallGraphNodes by name.  We do
+  // this here to avoid slowing down the non-printing fast path.
+
+  SmallVector<CallGraphNode *, 16> Nodes;
+  Nodes.reserve(FunctionMap.size());
+
+  for (auto I = begin(), E = end(); I != E; ++I)
+    Nodes.push_back(I->second);
+
+  std::sort(Nodes.begin(), Nodes.end(),
+            [](CallGraphNode *LHS, CallGraphNode *RHS) {
+    if (Function *LF = LHS->getFunction())
+      if (Function *RF = RHS->getFunction())
+        return LF->getName() < RF->getName();
+
+    return RHS->getFunction() != nullptr;
+  });
+
+  for (CallGraphNode *CN : Nodes)
+    CN->print(OS);
 }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)