[llvm-commits] [llvm] r115666 - /llvm/trunk/lib/CodeGen/SplitKit.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Tue Oct  5 15:36:28 2010
New Revision: 115666

URL: http://llvm.org/viewvc/llvm-project?rev=115666&view=rev
Log:
When we find a reaching definition, make sure it is visited from all paths by
erasing it from the visited set. That ensures we create the right phi defs.

Modified:
    llvm/trunk/lib/CodeGen/SplitKit.cpp

Modified: llvm/trunk/lib/CodeGen/SplitKit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SplitKit.cpp?rev=115666&r1=115665&r2=115666&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SplitKit.cpp (original)
+++ llvm/trunk/lib/CodeGen/SplitKit.cpp Tue Oct  5 15:36:28 2010
@@ -424,10 +424,14 @@
   // This may change during the DFS as we create new phi-defs.
   typedef DenseMap<MachineBasicBlock*, VNInfo*> MBBValueMap;
   MBBValueMap DomValue;
+  typedef SplitAnalysis::BlockPtrSet BlockPtrSet;
+  BlockPtrSet Visited;
 
-  for (idf_iterator<MachineBasicBlock*>
-         IDFI = idf_begin(IdxMBB),
-         IDFE = idf_end(IdxMBB); IDFI != IDFE;) {
+  // Iterate over IdxMBB predecessors in a depth-first order.
+  // Skip begin() since that is always IdxMBB.
+  for (idf_ext_iterator<MachineBasicBlock*, BlockPtrSet>
+         IDFI = llvm::next(idf_ext_begin(IdxMBB, Visited)),
+         IDFE = idf_ext_end(IdxMBB, Visited); IDFI != IDFE;) {
     MachineBasicBlock *MBB = *IDFI;
     SlotIndex End = lis_.getMBBEndIdx(MBB).getPrevSlot();
 
@@ -444,7 +448,10 @@
       continue;
     }
 
-    // Yes, VNI dominates MBB. Track the path back to IdxMBB, creating phi-defs
+    // Yes, VNI dominates MBB. Make sure we visit MBB again from other paths.
+    Visited.erase(MBB);
+
+    // Track the path back to IdxMBB, creating phi-defs
     // as needed along the way.
     for (unsigned PI = IDFI.getPathLength()-1; PI != 0; --PI) {
       // Start from MBB's immediate successor. End at IdxMBB.