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

[Sanjoy Das]

Hi bogner, chandlerc,

Since FunctionMap maps Function* (pointers) 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.

http://reviews.llvm.org/D10575

Files:
  lib/Analysis/IPA/CallGraph.cpp
  test/Analysis/CallGraph/non-leaf-intrinsics.ll

Index: lib/Analysis/IPA/CallGraph.cpp
===================================================================
--- lib/Analysis/IPA/CallGraph.cpp
+++ lib/Analysis/IPA/CallGraph.cpp
@@ -98,8 +98,29 @@
     OS << "<<null function: 0x" << Root << ">>\n";
   }
 
-  for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
-    I->second->print(OS);
+  // To be able to conveniently check -print-callgraph's output using FileCheck,
+  // we sort the CallGraphNodes by name before printing them.  Another way to
+  // achieve this is to make FunctionMap compare the keys by name and not
+  // pointer value.  However, that would slow down the normal, no-printing case
+  // in favor of speeding this exceptional case.
+
+  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 LHS->getFunction() == nullptr;
+  });
+
+  for (CallGraphNode *CN : Nodes)
+    CN->print(OS);
 }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
Index: test/Analysis/CallGraph/non-leaf-intrinsics.ll
===================================================================
--- test/Analysis/CallGraph/non-leaf-intrinsics.ll
+++ test/Analysis/CallGraph/non-leaf-intrinsics.ll
@@ -25,8 +25,8 @@
 ; CHECK: Call graph node <<null function>>
 ; CHECK:  CS<0x0> calls function 'f'
 
-; CHECK: Call graph node for function: 'calls_statepoint'
-; CHECK-NEXT:  CS<[[addr_0:[^>]+]]> calls external node
-
 ; CHECK: Call graph node for function: 'calls_patchpoint'
 ; CHECK-NEXT:  CS<[[addr_1:[^>]+]]> calls external node
+
+; CHECK: Call graph node for function: 'calls_statepoint'
+; CHECK-NEXT:  CS<[[addr_0:[^>]+]]> calls external node

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