// 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;
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.
};
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.
/// live out.
void addConstraints(ArrayRef<BlockConstraint> LiveBlocks);
+ /// 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.
+ /// @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);
- /// 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
virtual void releaseMemory();
void activate(unsigned);
- void iterate(const SmallVectorImpl<unsigned>&);
};
} // end namespace llvm