From cbb70ce070d220642b038ea101d9c0f9fbf860d6 Mon Sep 17 00:00:00 2001
From: dim <dim@FreeBSD.org>
Date: Sun, 20 Feb 2011 12:57:14 +0000
Subject: Vendor import of llvm trunk r126079:
http://llvm.org/svn/llvm-project/llvm/trunk@126079
---
lib/CodeGen/SpillPlacement.h | 108 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 108 insertions(+)
create mode 100644 lib/CodeGen/SpillPlacement.h
(limited to 'lib/CodeGen/SpillPlacement.h')
diff --git a/lib/CodeGen/SpillPlacement.h b/lib/CodeGen/SpillPlacement.h
new file mode 100644
index 0000000..ef2d516
--- /dev/null
+++ b/lib/CodeGen/SpillPlacement.h
@@ -0,0 +1,108 @@
+//===-- SpillPlacement.h - Optimal Spill Code Placement --------*- C++ -*--===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This analysis computes the optimal spill code placement between basic blocks.
+//
+// The runOnMachineFunction() method only precomputes some profiling information
+// about the CFG. The real work is done by placeSpills() which is called by the
+// register allocator.
+//
+// Given a variable that is live across multiple basic blocks, and given
+// constraints on the basic blocks where the variable is live, determine which
+// edge bundles should have the variable in a register and which edge bundles
+// should have the variable in a stack slot.
+//
+// The returned bit vector can be used to place optimal spill code at basic
+// block entries and exits. Spill code placement inside a basic block is not
+// considered.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_SPILLPLACEMENT_H
+#define LLVM_CODEGEN_SPILLPLACEMENT_H
+
+#include "llvm/CodeGen/MachineFunctionPass.h"
+
+namespace llvm {
+
+class BitVector;
+class EdgeBundles;
+class MachineBasicBlock;
+class MachineLoopInfo;
+template <typename> class SmallVectorImpl;
+
+class SpillPlacement : public MachineFunctionPass {
+ struct Node;
+ const MachineFunction *MF;
+ const EdgeBundles *bundles;
+ const MachineLoopInfo *loops;
+ Node *nodes;
+
+ // Nodes that are active in the current computation. Owned by the placeSpills
+ // caller.
+ BitVector *ActiveNodes;
+
+public:
+ static char ID; // Pass identification, replacement for typeid.
+
+ SpillPlacement() : MachineFunctionPass(ID), nodes(0) {}
+ ~SpillPlacement() { releaseMemory(); }
+
+ /// BorderConstraint - A basic block has separate constraints for entry and
+ /// exit.
+ enum BorderConstraint {
+ DontCare, ///< Block doesn't care / variable not live.
+ PrefReg, ///< Block entry/exit prefers a register.
+ PrefSpill, ///< Block entry/exit prefers a stack slot.
+ MustSpill ///< A register is impossible, variable must be spilled.
+ };
+
+ /// BlockConstraint - Entry and exit constraints for a basic block.
+ struct BlockConstraint {
+ unsigned Number; ///< Basic block number (from MBB::getNumber()).
+ BorderConstraint Entry : 8; ///< Constraint on block entry.
+ BorderConstraint Exit : 8; ///< Constraint on block exit.
+ };
+
+ /// placeSpills - 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
+ /// expected execution frequencies.
+ /// @param LiveBlocks Constraints for blocks that have the variable live in or
+ /// live out. DontCare/DontCare means the variable is live
+ /// through the block. DontCare/X means the variable is live
+ /// out, but not live in.
+ /// @param RegBundles Bit vector to receive the edge bundles where the
+ /// variable should be kept in a register. Each bit
+ /// corresponds to an edge bundle, a set bit means the
+ /// variable should be kept in a register through the
+ /// bundle. A clear bit means the variable should be
+ /// spilled.
+ /// @return True if a perfect solution was found, allowing the variable to be
+ /// in a register through all relevant bundles.
+ bool placeSpills(const SmallVectorImpl<BlockConstraint> &LiveBlocks,
+ BitVector &RegBundles);
+
+ /// getBlockFrequency - Return the estimated block execution frequency per
+ /// function invocation.
+ float getBlockFrequency(const MachineBasicBlock*);
+
+private:
+ virtual bool runOnMachineFunction(MachineFunction&);
+ virtual void getAnalysisUsage(AnalysisUsage&) const;
+ virtual void releaseMemory();
+
+ void activate(unsigned);
+ void prepareNodes(const SmallVectorImpl<BlockConstraint>&);
+ void iterate(const SmallVectorImpl<unsigned>&);
+};
+
+} // end namespace llvm
+
+#endif
--
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