[llvm-commits] CVS: llvm/lib/Transforms/Scalar/LoopPreheaders.cpp

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

LoopPreheaders.cpp updated: 1.11 -> 1.12

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Log message:

Fix bug: LoopPreheaders/2003-05-12-PreheaderExitOfChild.ll


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Diffs of the changes:

Index: llvm/lib/Transforms/Scalar/LoopPreheaders.cpp
diff -u llvm/lib/Transforms/Scalar/LoopPreheaders.cpp:1.11 llvm/lib/Transforms/Scalar/LoopPreheaders.cpp:1.12
--- llvm/lib/Transforms/Scalar/LoopPreheaders.cpp:1.11	Wed Apr 23 11:37:42 2003
+++ llvm/lib/Transforms/Scalar/LoopPreheaders.cpp	Mon May 12 17:04:34 2003
@@ -167,6 +167,19 @@
   return NewBB;
 }
 
+// ChangeExitBlock - This recursive function is used to change any exit blocks
+// that use OldExit to use NewExit instead.  This is recursive because children
+// may need to be processed as well.
+//
+static void ChangeExitBlock(Loop *L, BasicBlock *OldExit, BasicBlock *NewExit) {
+  if (L->hasExitBlock(OldExit)) {
+    L->changeExitBlock(OldExit, NewExit);
+    const std::vector<Loop*> &SubLoops = L->getSubLoops();
+    for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
+      ChangeExitBlock(SubLoops[i], OldExit, NewExit);
+  }
+}
+
 
 /// InsertPreheaderForLoop - Once we discover that a loop doesn't have a
 /// preheader, this method is called to insert one.  This method has two phases:
@@ -197,18 +210,19 @@
   // If the header for the loop used to be an exit node for another loop, then
   // we need to update this to know that the loop-preheader is now the exit
   // node.  Note that the only loop that could have our header as an exit node
-  // is a sibling loop, ie, one with the same parent loop.
+  // is a sibling loop, ie, one with the same parent loop, or one if it's
+  // children.
+  //
   const std::vector<Loop*> *ParentSubLoops;
   if (Loop *Parent = L->getParentLoop())
     ParentSubLoops = &Parent->getSubLoops();
   else       // Must check top-level loops...
     ParentSubLoops = &getAnalysis<LoopInfo>().getTopLevelLoops();
 
-  // Loop over all sibling loops, performing the substitution...
+  // Loop over all sibling loops, performing the substitution (recursively to
+  // include child loops)...
   for (unsigned i = 0, e = ParentSubLoops->size(); i != e; ++i)
-    if ((*ParentSubLoops)[i]->hasExitBlock(Header))
-      (*ParentSubLoops)[i]->changeExitBlock(Header, NewBB);
-
+    ChangeExitBlock((*ParentSubLoops)[i], Header, NewBB);
   
   DominatorSet &DS = getAnalysis<DominatorSet>();  // Update dominator info
   {