Couple of small logical cleanups to use !empty rather than other

[oota-llvm.git] / lib / CodeGen / SpillPlacement.h

diff --git a/lib/CodeGen/SpillPlacement.h b/lib/CodeGen/SpillPlacement.h
index 9a4fc6dc970007e65af864f09b3209423643d2b2..105516bb62b1d3b94342f6d7967e6b56db3a4671 100644 (file)
--- a/lib/CodeGen/SpillPlacement.h
+++ b/lib/CodeGen/SpillPlacement.h
@@ -30,6 +30,7 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/Support/BlockFrequency.h"
 
 namespace llvm {
 
@@ -57,7 +58,7 @@ class SpillPlacement  : public MachineFunctionPass {
   SmallVector<unsigned, 8> RecentPositive;
 
   // Block frequencies are computed once. Indexed by block number.
-  SmallVector<float, 4> BlockFrequency;
+  SmallVector<BlockFrequency, 4> BlockFrequencies;
 
 public:
   static char ID; // Pass identification, replacement for typeid.
@@ -71,6 +72,7 @@ public:
     DontCare,  ///< Block doesn't care / variable not live.
     PrefReg,   ///< Block entry/exit prefers a register.
     PrefSpill, ///< Block entry/exit prefers a stack slot.
+    PrefBoth,  ///< Block entry prefers both register and stack.
     MustSpill  ///< A register is impossible, variable must be spilled.
   };
 
@@ -79,6 +81,11 @@ public:
     unsigned Number;            ///< Basic block number (from MBB::getNumber()).
     BorderConstraint Entry : 8; ///< Constraint on block entry.
     BorderConstraint Exit : 8;  ///< Constraint on block exit.
+
+    /// True when this block changes the value of the live range. This means
+    /// the block has a non-PHI def.  When this is false, a live-in value on
+    /// the stack can be live-out on the stack without inserting a spill.
+    bool ChangesValue;
   };
 
   /// prepare - Reset state and prepare for a new spill placement computation.
@@ -96,9 +103,13 @@ public:
   ///                   live out.
   void addConstraints(ArrayRef<BlockConstraint> LiveBlocks);
 
-  /// addPrefSpill - Add PrefSpill constraints to all blocks listed.
+  /// addPrefSpill - Add PrefSpill constraints to all blocks listed.  This is
+  /// equivalent to calling addConstraint with identical BlockConstraints with
+  /// Entry = Exit = PrefSpill, and ChangesValue = false.
+  ///
   /// @param Blocks Array of block numbers that prefer to spill in and out.
-  void addPrefSpill(ArrayRef<unsigned> Blocks);
+  /// @param Strong When true, double the negative bias for these blocks.
+  void addPrefSpill(ArrayRef<unsigned> Blocks, bool Strong);
 
   /// addLinks - Add transparent blocks with the given numbers.
   void addLinks(ArrayRef<unsigned> Links);
@@ -129,8 +140,8 @@ public:
 
   /// getBlockFrequency - Return the estimated block execution frequency per
   /// function invocation.
-  float getBlockFrequency(unsigned Number) const {
-    return BlockFrequency[Number];
+  BlockFrequency getBlockFrequency(unsigned Number) const {
+    return BlockFrequencies[Number];
   }
 
 private: