[llvm-commits] [llvm] r129021 - in /llvm/trunk/lib/CodeGen: RegAllocGreedy.cpp SpillPlacement.cpp SpillPlacement.h

[Jakob Stoklund Olesen]

Author: stoklund
Date: Wed Apr  6 14:14:00 2011
New Revision: 129021

URL: http://llvm.org/viewvc/llvm-project?rev=129021&view=rev
Log:
Keep track of the number of positively biased nodes when adding constraints.

If there are no positive nodes, the algorithm can be aborted early.

Modified:
    llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp
    llvm/trunk/lib/CodeGen/SpillPlacement.cpp
    llvm/trunk/lib/CodeGen/SpillPlacement.h

Modified: llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp?rev=129021&r1=129020&r2=129021&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp Wed Apr  6 14:14:00 2011
@@ -772,6 +772,7 @@
 
     SpillPlacer->prepare(LiveBundles);
     SpillPlacer->addConstraints(SplitConstraints);
+    DEBUG(dbgs() << ", " << SpillPlacer->getPositiveNodes() << " biased nodes");
     SpillPlacer->finish();
 
     // No live bundles, defer to splitSingleBlocks().

Modified: llvm/trunk/lib/CodeGen/SpillPlacement.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SpillPlacement.cpp?rev=129021&r1=129020&r2=129021&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SpillPlacement.cpp (original)
+++ llvm/trunk/lib/CodeGen/SpillPlacement.cpp Wed Apr  6 14:14:00 2011
@@ -134,10 +134,14 @@
   }
 
   /// addBias - Bias this node from an ingoing[0] or outgoing[1] link.
-  void addBias(float w, bool out) {
+  /// Return the change to the total number of positive biases.
+  int addBias(float w, bool out) {
     // Normalize w relative to all connected blocks from that direction.
     w /= Frequency[out];
+    int Before = Bias > 0;
     Bias += w;
+    int After = Bias > 0;
+    return After - Before;
   }
 
   /// update - Recompute Value from Bias and Links. Return true when node
@@ -237,14 +241,14 @@
     if (I->Entry != DontCare) {
       unsigned ib = bundles->getBundle(I->Number, 0);
       activate(ib);
-      nodes[ib].addBias(Freq * Bias[I->Entry], 1);
+      PositiveNodes += nodes[ib].addBias(Freq * Bias[I->Entry], 1);
     }
 
     // Live-out from block?
     if (I->Exit != DontCare) {
       unsigned ob = bundles->getBundle(I->Number, 1);
       activate(ob);
-      nodes[ob].addBias(Freq * Bias[I->Exit], 0);
+      PositiveNodes += nodes[ob].addBias(Freq * Bias[I->Exit], 0);
     }
   }
 }
@@ -292,6 +296,7 @@
   ActiveNodes = &RegBundles;
   ActiveNodes->clear();
   ActiveNodes->resize(bundles->getNumBundles());
+  PositiveNodes = 0;
 }
 
 bool

Modified: llvm/trunk/lib/CodeGen/SpillPlacement.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SpillPlacement.h?rev=129021&r1=129020&r2=129021&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SpillPlacement.h (original)
+++ llvm/trunk/lib/CodeGen/SpillPlacement.h Wed Apr  6 14:14:00 2011
@@ -49,6 +49,9 @@
   // caller.
   BitVector *ActiveNodes;
 
+  // The number of active nodes with a positive bias.
+  unsigned PositiveNodes;
+
   // Block frequencies are computed once. Indexed by block number.
   SmallVector<float, 4> BlockFrequency;
 
@@ -91,6 +94,10 @@
   ///                   out, but not live in.
   void addConstraints(ArrayRef<BlockConstraint> LiveBlocks);
 
+  /// getPositiveNodes - Return the total number of graph nodes with a positive
+  /// bias after adding constraints.
+  unsigned getPositiveNodes() const { return PositiveNodes; }
+
   /// finish - Compute the optimal spill code placement given the
   /// constraints. No MustSpill constraints will be violated, and the smallest
   /// possible number of PrefX constraints will be violated, weighted by