[llvm] r207201 - [LCG] Now that the loop structure of the core SCC finding routine is

[Chandler Carruth]

Author: chandlerc
Date: Fri Apr 25 01:38:58 2014
New Revision: 207201

URL: http://llvm.org/viewvc/llvm-project?rev=207201&view=rev
Log:
[LCG] Now that the loop structure of the core SCC finding routine is
factored into a more reasonable form, replace the tail call with
a simple outer-loop continuation. It's sad that C++ makes this so
awkward to write, but it seems more direct and clear than the tail call
at this point.

Modified:
    llvm/trunk/lib/Analysis/LazyCallGraph.cpp

Modified: llvm/trunk/lib/Analysis/LazyCallGraph.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/LazyCallGraph.cpp?rev=207201&r1=207200&r2=207201&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/LazyCallGraph.cpp (original)
+++ llvm/trunk/lib/Analysis/LazyCallGraph.cpp Fri Apr 25 01:38:58 2014
@@ -449,6 +449,7 @@ LazyCallGraph::SCC *LazyCallGraph::getNe
     assert(N->DFSNumber != 0 && "We should always assign a DFS number "
                                 "before placing a node onto the stack.");
 
+    bool Recurse = false; // Used to simulate recursing onto a child.
     for (auto I = DFSStack.back().second, E = N->end(); I != E; ++I) {
       Node &ChildN = *I;
       if (ChildN.DFSNumber == 0) {
@@ -463,7 +464,8 @@ LazyCallGraph::SCC *LazyCallGraph::getNe
         ChildN.LowLink = ChildN.DFSNumber = NextDFSNumber++;
         SCCEntryNodes.remove(&ChildN.getFunction());
         DFSStack.push_back(std::make_pair(&ChildN, ChildN.begin()));
-        return LazyCallGraph::getNextSCCInPostOrder();
+        Recurse = true;
+        break;
       }
 
       // Track the lowest link of the childen, if any are still in the stack.
@@ -472,6 +474,11 @@ LazyCallGraph::SCC *LazyCallGraph::getNe
       if (ChildN.LowLink >= 0 && ChildN.LowLink < N->LowLink)
         N->LowLink = ChildN.LowLink;
     }
+    if (Recurse)
+      // Continue the outer loop when we exit the inner loop in order to
+      // recurse onto a child.
+      continue;
+
     // No more children to process here, pop the node off the stack.
     DFSStack.pop_back();