Build the Hopfield network incrementally when splitting global live ranges.
It is common for large live ranges to have few basic blocks with register uses
and many live-through blocks without any uses. This approach grows the Hopfield
network incrementally around the use blocks, completely avoiding checking
interference for some through blocks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129188 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SpillPlacement.h b/lib/CodeGen/SpillPlacement.h
index 46e64e6..6952ad8 100644
--- a/lib/CodeGen/SpillPlacement.h
+++ b/lib/CodeGen/SpillPlacement.h
@@ -49,8 +49,12 @@
// caller.
BitVector *ActiveNodes;
- // The number of active nodes with a positive bias.
- unsigned PositiveNodes;
+ // Nodes with active links. Populated by scanActiveBundles.
+ SmallVector<unsigned, 8> Linked;
+
+ // Nodes that went positive during the last call to scanActiveBundles or
+ // iterate.
+ SmallVector<unsigned, 8> RecentPositive;
// Block frequencies are computed once. Indexed by block number.
SmallVector<float, 4> BlockFrequency;
@@ -95,9 +99,20 @@
/// addLinks - Add transparent blocks with the given numbers.
void addLinks(ArrayRef<unsigned> Links);
- /// getPositiveNodes - Return the total number of graph nodes with a positive
- /// bias after adding constraints.
- unsigned getPositiveNodes() const { return PositiveNodes; }
+ /// scanActiveBundles - Perform an initial scan of all bundles activated by
+ /// addConstraints and addLinks, updating their state. Add all the bundles
+ /// that now prefer a register to RecentPositive.
+ /// Prepare internal data structures for iterate.
+ /// Return true is there are any positive nodes.
+ bool scanActiveBundles();
+
+ /// iterate - Update the network iteratively until convergence, or new bundles
+ /// are found.
+ void iterate();
+
+ /// getRecentPositive - Return an array of bundles that became positive during
+ /// the previous call to scanActiveBundles or iterate.
+ ArrayRef<unsigned> getRecentPositive() { return RecentPositive; }
/// finish - Compute the optimal spill code placement given the
/// constraints. No MustSpill constraints will be violated, and the smallest
@@ -120,7 +135,6 @@
virtual void releaseMemory();
void activate(unsigned);
- void iterate(const SmallVectorImpl<unsigned>&);
};
} // end namespace llvm