2007-10-31 03:37:57 +00:00
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//===- StrongPhiElimination.cpp - Eliminate PHI nodes by inserting copies -===//
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//
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// The LLVM Compiler Infrastructure
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//
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2007-12-29 20:36:04 +00:00
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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2007-10-31 03:37:57 +00:00
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass eliminates machine instruction PHI nodes by inserting copy
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// instructions, using an intelligent copy-folding technique based on
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// dominator information. This is technique is derived from:
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//
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// Budimlic, et al. Fast copy coalescing and live-range identification.
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// In Proceedings of the ACM SIGPLAN 2002 Conference on Programming Language
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// Design and Implementation (Berlin, Germany, June 17 - 19, 2002).
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// PLDI '02. ACM, New York, NY, 25-32.
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// DOI= http://doi.acm.org/10.1145/512529.512534
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "strongphielim"
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#include "llvm/CodeGen/Passes.h"
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2008-03-10 07:22:36 +00:00
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#include "llvm/CodeGen/LiveIntervalAnalysis.h"
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2007-10-31 03:37:57 +00:00
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#include "llvm/CodeGen/MachineDominators.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineInstr.h"
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2008-03-17 06:08:26 +00:00
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#include "llvm/CodeGen/MachineLoopInfo.h"
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2008-01-08 05:16:15 +00:00
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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2007-10-31 03:37:57 +00:00
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetMachine.h"
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2007-12-23 15:37:26 +00:00
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#include "llvm/ADT/DepthFirstIterator.h"
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2007-10-31 03:37:57 +00:00
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Support/Compiler.h"
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using namespace llvm;
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namespace {
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struct VISIBILITY_HIDDEN StrongPHIElimination : public MachineFunctionPass {
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static char ID; // Pass identification, replacement for typeid
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StrongPHIElimination() : MachineFunctionPass((intptr_t)&ID) {}
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2008-01-09 22:40:54 +00:00
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// Waiting stores, for each MBB, the set of copies that need to
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// be inserted into that MBB
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2007-12-10 08:07:09 +00:00
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DenseMap<MachineBasicBlock*,
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2007-12-23 15:37:26 +00:00
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std::map<unsigned, unsigned> > Waiting;
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2008-01-09 22:40:54 +00:00
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// Stacks holds the renaming stack for each register
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2007-12-23 15:37:26 +00:00
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std::map<unsigned, std::vector<unsigned> > Stacks;
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2008-01-09 22:40:54 +00:00
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// Registers in UsedByAnother are PHI nodes that are themselves
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// used as operands to another another PHI node
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2007-12-23 15:37:26 +00:00
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std::set<unsigned> UsedByAnother;
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2008-01-09 22:40:54 +00:00
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2008-03-12 03:13:29 +00:00
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// RenameSets are the sets of operands (and their VNInfo IDs) to a PHI
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2008-03-12 04:22:57 +00:00
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// (the defining instruction of the key) that can be renamed without copies.
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2008-03-12 03:13:29 +00:00
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std::map<unsigned, std::map<unsigned, unsigned> > RenameSets;
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2008-03-12 04:22:57 +00:00
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// PhiValueNumber holds the ID numbers of the VNs for each phi that we're
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// eliminating, indexed by the register defined by that phi.
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std::map<unsigned, unsigned> PhiValueNumber;
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2007-12-10 08:07:09 +00:00
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2008-01-09 22:40:54 +00:00
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// Store the DFS-in number of each block
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DenseMap<MachineBasicBlock*, unsigned> preorder;
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// Store the DFS-out number of each block
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DenseMap<MachineBasicBlock*, unsigned> maxpreorder;
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2007-11-06 04:49:43 +00:00
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bool runOnMachineFunction(MachineFunction &Fn);
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2007-10-31 03:37:57 +00:00
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<MachineDominatorTree>();
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2008-03-10 07:22:36 +00:00
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AU.addRequired<LiveIntervals>();
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// TODO: Actually make this true.
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AU.addPreserved<LiveIntervals>();
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2007-10-31 03:37:57 +00:00
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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virtual void releaseMemory() {
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preorder.clear();
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maxpreorder.clear();
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2007-11-06 04:49:43 +00:00
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2007-12-23 15:37:26 +00:00
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Waiting.clear();
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2008-01-09 22:40:54 +00:00
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Stacks.clear();
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UsedByAnother.clear();
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RenameSets.clear();
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2007-10-31 03:37:57 +00:00
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}
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private:
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2008-01-09 22:40:54 +00:00
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/// DomForestNode - Represents a node in the "dominator forest". This is
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/// a forest in which the nodes represent registers and the edges
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/// represent a dominance relation in the block defining those registers.
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2007-11-04 22:33:26 +00:00
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struct DomForestNode {
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private:
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2008-01-09 22:40:54 +00:00
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// Store references to our children
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2007-11-04 22:33:26 +00:00
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std::vector<DomForestNode*> children;
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2008-01-09 22:40:54 +00:00
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// The register we represent
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2007-11-06 05:22:43 +00:00
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unsigned reg;
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2007-11-04 22:33:26 +00:00
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2008-01-09 22:40:54 +00:00
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// Add another node as our child
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2007-11-04 22:33:26 +00:00
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void addChild(DomForestNode* DFN) { children.push_back(DFN); }
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public:
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typedef std::vector<DomForestNode*>::iterator iterator;
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2008-01-09 22:40:54 +00:00
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// Create a DomForestNode by providing the register it represents, and
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// the node to be its parent. The virtual root node has register 0
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// and a null parent.
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2007-11-06 05:22:43 +00:00
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DomForestNode(unsigned r, DomForestNode* parent) : reg(r) {
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2007-11-04 22:33:26 +00:00
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if (parent)
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parent->addChild(this);
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}
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2007-11-06 04:49:43 +00:00
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~DomForestNode() {
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for (iterator I = begin(), E = end(); I != E; ++I)
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delete *I;
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}
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2007-11-04 22:33:26 +00:00
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2008-01-09 22:40:54 +00:00
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/// getReg - Return the regiser that this node represents
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2007-11-06 05:22:43 +00:00
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inline unsigned getReg() { return reg; }
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2007-11-06 04:49:43 +00:00
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2008-01-09 22:40:54 +00:00
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// Provide iterator access to our children
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2007-11-06 04:49:43 +00:00
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inline DomForestNode::iterator begin() { return children.begin(); }
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inline DomForestNode::iterator end() { return children.end(); }
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2007-11-04 22:33:26 +00:00
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};
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2007-10-31 03:37:57 +00:00
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void computeDFS(MachineFunction& MF);
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2007-11-07 05:17:15 +00:00
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void processBlock(MachineBasicBlock* MBB);
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2007-11-04 22:33:26 +00:00
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2008-03-12 03:13:29 +00:00
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std::vector<DomForestNode*> computeDomForest(std::map<unsigned, unsigned>& instrs,
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2008-01-10 01:36:43 +00:00
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MachineRegisterInfo& MRI);
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2007-12-11 20:12:11 +00:00
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void processPHIUnion(MachineInstr* Inst,
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2008-03-12 03:13:29 +00:00
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std::map<unsigned, unsigned>& PHIUnion,
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2007-12-13 05:53:03 +00:00
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std::vector<StrongPHIElimination::DomForestNode*>& DF,
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std::vector<std::pair<unsigned, unsigned> >& locals);
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2007-12-24 22:12:23 +00:00
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void ScheduleCopies(MachineBasicBlock* MBB, std::set<unsigned>& pushed);
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2008-03-24 04:11:27 +00:00
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void InsertCopies(MachineBasicBlock* MBB,
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SmallPtrSet<MachineBasicBlock*, 16>& v);
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2008-03-12 03:13:29 +00:00
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void mergeLiveIntervals(unsigned primary, unsigned secondary, unsigned VN);
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2007-10-31 03:37:57 +00:00
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};
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char StrongPHIElimination::ID = 0;
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RegisterPass<StrongPHIElimination> X("strong-phi-node-elimination",
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"Eliminate PHI nodes for register allocation, intelligently");
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}
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const PassInfo *llvm::StrongPHIEliminationID = X.getPassInfo();
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/// computeDFS - Computes the DFS-in and DFS-out numbers of the dominator tree
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/// of the given MachineFunction. These numbers are then used in other parts
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/// of the PHI elimination process.
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void StrongPHIElimination::computeDFS(MachineFunction& MF) {
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SmallPtrSet<MachineDomTreeNode*, 8> frontier;
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SmallPtrSet<MachineDomTreeNode*, 8> visited;
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unsigned time = 0;
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MachineDominatorTree& DT = getAnalysis<MachineDominatorTree>();
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MachineDomTreeNode* node = DT.getRootNode();
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std::vector<MachineDomTreeNode*> worklist;
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worklist.push_back(node);
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while (!worklist.empty()) {
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MachineDomTreeNode* currNode = worklist.back();
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if (!frontier.count(currNode)) {
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frontier.insert(currNode);
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++time;
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preorder.insert(std::make_pair(currNode->getBlock(), time));
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}
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bool inserted = false;
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for (MachineDomTreeNode::iterator I = node->begin(), E = node->end();
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I != E; ++I)
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if (!frontier.count(*I) && !visited.count(*I)) {
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worklist.push_back(*I);
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inserted = true;
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break;
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}
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if (!inserted) {
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frontier.erase(currNode);
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visited.insert(currNode);
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maxpreorder.insert(std::make_pair(currNode->getBlock(), time));
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worklist.pop_back();
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}
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}
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2007-10-31 08:49:24 +00:00
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}
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2007-11-04 22:33:26 +00:00
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2007-11-06 05:26:02 +00:00
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/// PreorderSorter - a helper class that is used to sort registers
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/// according to the preorder number of their defining blocks
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2007-11-04 22:33:26 +00:00
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class PreorderSorter {
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private:
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DenseMap<MachineBasicBlock*, unsigned>& preorder;
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2008-01-10 01:36:43 +00:00
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MachineRegisterInfo& MRI;
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2007-11-04 22:33:26 +00:00
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public:
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2007-11-06 05:22:43 +00:00
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PreorderSorter(DenseMap<MachineBasicBlock*, unsigned>& p,
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2008-01-10 01:36:43 +00:00
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MachineRegisterInfo& M) : preorder(p), MRI(M) { }
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2007-11-04 22:33:26 +00:00
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2007-11-06 05:22:43 +00:00
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bool operator()(unsigned A, unsigned B) {
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2007-11-04 22:33:26 +00:00
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if (A == B)
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return false;
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2008-01-10 01:36:43 +00:00
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MachineBasicBlock* ABlock = MRI.getVRegDef(A)->getParent();
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MachineBasicBlock* BBlock = MRI.getVRegDef(B)->getParent();
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2007-11-06 05:22:43 +00:00
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if (preorder[ABlock] < preorder[BBlock])
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2007-11-04 22:33:26 +00:00
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return true;
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2007-11-06 05:22:43 +00:00
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else if (preorder[ABlock] > preorder[BBlock])
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2007-11-04 22:33:26 +00:00
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return false;
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2007-11-06 05:22:43 +00:00
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return false;
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2007-11-04 22:33:26 +00:00
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}
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};
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2007-11-06 05:26:02 +00:00
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/// computeDomForest - compute the subforest of the DomTree corresponding
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/// to the defining blocks of the registers in question
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2007-11-04 22:33:26 +00:00
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std::vector<StrongPHIElimination::DomForestNode*>
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2008-03-12 03:13:29 +00:00
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StrongPHIElimination::computeDomForest(std::map<unsigned, unsigned>& regs,
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2008-01-10 01:36:43 +00:00
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MachineRegisterInfo& MRI) {
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2008-01-09 22:40:54 +00:00
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// Begin by creating a virtual root node, since the actual results
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// may well be a forest. Assume this node has maximum DFS-out number.
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2007-11-04 22:33:26 +00:00
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DomForestNode* VirtualRoot = new DomForestNode(0, 0);
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maxpreorder.insert(std::make_pair((MachineBasicBlock*)0, ~0UL));
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2008-01-09 22:40:54 +00:00
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// Populate a worklist with the registers
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2007-11-06 05:22:43 +00:00
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std::vector<unsigned> worklist;
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worklist.reserve(regs.size());
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2008-03-12 03:13:29 +00:00
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for (std::map<unsigned, unsigned>::iterator I = regs.begin(), E = regs.end();
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2007-11-06 05:22:43 +00:00
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I != E; ++I)
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2008-03-12 03:13:29 +00:00
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worklist.push_back(I->first);
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2007-11-06 05:22:43 +00:00
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2008-01-09 22:40:54 +00:00
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// Sort the registers by the DFS-in number of their defining block
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2008-01-10 01:36:43 +00:00
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PreorderSorter PS(preorder, MRI);
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2007-11-04 22:33:26 +00:00
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std::sort(worklist.begin(), worklist.end(), PS);
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2008-01-09 22:40:54 +00:00
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// Create a "current parent" stack, and put the virtual root on top of it
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2007-11-04 22:33:26 +00:00
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DomForestNode* CurrentParent = VirtualRoot;
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std::vector<DomForestNode*> stack;
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stack.push_back(VirtualRoot);
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2008-01-09 22:40:54 +00:00
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// Iterate over all the registers in the previously computed order
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2007-11-06 05:22:43 +00:00
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for (std::vector<unsigned>::iterator I = worklist.begin(), E = worklist.end();
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I != E; ++I) {
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2008-01-10 01:36:43 +00:00
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unsigned pre = preorder[MRI.getVRegDef(*I)->getParent()];
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2008-01-09 06:19:05 +00:00
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MachineBasicBlock* parentBlock = CurrentParent->getReg() ?
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2008-01-10 01:36:43 +00:00
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MRI.getVRegDef(CurrentParent->getReg())->getParent() :
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2008-01-09 06:19:05 +00:00
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0;
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2007-11-06 05:22:43 +00:00
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2008-01-09 22:40:54 +00:00
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// If the DFS-in number of the register is greater than the DFS-out number
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// of the current parent, repeatedly pop the parent stack until it isn't.
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2007-11-06 05:22:43 +00:00
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while (pre > maxpreorder[parentBlock]) {
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2007-11-04 22:33:26 +00:00
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stack.pop_back();
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CurrentParent = stack.back();
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2007-11-06 05:22:43 +00:00
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2008-01-09 10:41:39 +00:00
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parentBlock = CurrentParent->getReg() ?
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2008-01-10 01:36:43 +00:00
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MRI.getVRegDef(CurrentParent->getReg())->getParent() :
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2008-01-09 10:41:39 +00:00
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0;
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2007-11-04 22:33:26 +00:00
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}
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2008-01-09 22:40:54 +00:00
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// Now that we've found the appropriate parent, create a DomForestNode for
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// this register and attach it to the forest
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2007-11-04 22:33:26 +00:00
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DomForestNode* child = new DomForestNode(*I, CurrentParent);
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2008-01-09 22:40:54 +00:00
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// Push this new node on the "current parent" stack
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2007-11-04 22:33:26 +00:00
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stack.push_back(child);
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CurrentParent = child;
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}
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2008-01-09 22:40:54 +00:00
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// Return a vector containing the children of the virtual root node
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2007-11-04 22:33:26 +00:00
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std::vector<DomForestNode*> ret;
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ret.insert(ret.end(), VirtualRoot->begin(), VirtualRoot->end());
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return ret;
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}
|
2007-11-06 04:49:43 +00:00
|
|
|
|
2008-03-10 07:22:36 +00:00
|
|
|
/// isLiveIn - helper method that determines, from a regno, if a register
|
2007-11-07 05:17:15 +00:00
|
|
|
/// is live into a block
|
2008-01-10 01:36:43 +00:00
|
|
|
static bool isLiveIn(unsigned r, MachineBasicBlock* MBB,
|
2008-03-10 07:22:36 +00:00
|
|
|
LiveIntervals& LI) {
|
|
|
|
LiveInterval& I = LI.getOrCreateInterval(r);
|
|
|
|
unsigned idx = LI.getMBBStartIdx(MBB);
|
|
|
|
return I.liveBeforeAndAt(idx);
|
2007-11-06 05:22:43 +00:00
|
|
|
}
|
|
|
|
|
2008-03-10 07:22:36 +00:00
|
|
|
/// isLiveOut - help method that determines, from a regno, if a register is
|
2007-11-07 05:17:15 +00:00
|
|
|
/// live out of a block.
|
2008-01-10 01:36:43 +00:00
|
|
|
static bool isLiveOut(unsigned r, MachineBasicBlock* MBB,
|
2008-03-10 07:22:36 +00:00
|
|
|
LiveIntervals& LI) {
|
|
|
|
for (MachineBasicBlock::succ_iterator PI = MBB->succ_begin(),
|
|
|
|
E = MBB->succ_end(); PI != E; ++PI) {
|
|
|
|
if (isLiveIn(r, *PI, LI))
|
|
|
|
return true;
|
2007-11-08 01:32:45 +00:00
|
|
|
}
|
2007-11-07 05:17:15 +00:00
|
|
|
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
|
2007-12-16 05:44:27 +00:00
|
|
|
/// interferes - checks for local interferences by scanning a block. The only
|
|
|
|
/// trick parameter is 'mode' which tells it the relationship of the two
|
|
|
|
/// registers. 0 - defined in the same block, 1 - first properly dominates
|
|
|
|
/// second, 2 - second properly dominates first
|
2008-01-10 00:33:11 +00:00
|
|
|
static bool interferes(unsigned a, unsigned b, MachineBasicBlock* scan,
|
2008-03-10 07:22:36 +00:00
|
|
|
LiveIntervals& LV, unsigned mode) {
|
2007-12-16 05:44:27 +00:00
|
|
|
MachineInstr* def = 0;
|
|
|
|
MachineInstr* kill = 0;
|
|
|
|
|
2008-01-10 01:36:43 +00:00
|
|
|
// The code is still in SSA form at this point, so there is only one
|
|
|
|
// definition per VReg. Thus we can safely use MRI->getVRegDef().
|
|
|
|
const MachineRegisterInfo* MRI = &scan->getParent()->getRegInfo();
|
2008-01-10 00:33:11 +00:00
|
|
|
|
2007-12-16 05:44:27 +00:00
|
|
|
bool interference = false;
|
|
|
|
|
|
|
|
// Wallk the block, checking for interferences
|
|
|
|
for (MachineBasicBlock::iterator MBI = scan->begin(), MBE = scan->end();
|
|
|
|
MBI != MBE; ++MBI) {
|
|
|
|
MachineInstr* curr = MBI;
|
|
|
|
|
|
|
|
// Same defining block...
|
|
|
|
if (mode == 0) {
|
2008-01-10 01:36:43 +00:00
|
|
|
if (curr == MRI->getVRegDef(a)) {
|
|
|
|
// If we find our first definition, save it
|
2007-12-16 05:44:27 +00:00
|
|
|
if (!def) {
|
|
|
|
def = curr;
|
2008-01-10 01:36:43 +00:00
|
|
|
// If there's already an unkilled definition, then
|
2007-12-16 05:44:27 +00:00
|
|
|
// this is an interference
|
|
|
|
} else if (!kill) {
|
|
|
|
interference = true;
|
|
|
|
break;
|
2008-01-10 01:36:43 +00:00
|
|
|
// If there's a definition followed by a KillInst, then
|
2007-12-16 05:44:27 +00:00
|
|
|
// they can't interfere
|
|
|
|
} else {
|
|
|
|
interference = false;
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
// Symmetric with the above
|
2008-01-10 01:36:43 +00:00
|
|
|
} else if (curr == MRI->getVRegDef(b)) {
|
2007-12-16 05:44:27 +00:00
|
|
|
if (!def) {
|
|
|
|
def = curr;
|
|
|
|
} else if (!kill) {
|
|
|
|
interference = true;
|
|
|
|
break;
|
|
|
|
} else {
|
|
|
|
interference = false;
|
|
|
|
break;
|
|
|
|
}
|
2008-01-10 01:36:43 +00:00
|
|
|
// Store KillInsts if they match up with the definition
|
2008-03-05 00:59:57 +00:00
|
|
|
} else if (curr->killsRegister(a)) {
|
2008-01-10 01:36:43 +00:00
|
|
|
if (def == MRI->getVRegDef(a)) {
|
2007-12-16 05:44:27 +00:00
|
|
|
kill = curr;
|
2008-03-05 00:59:57 +00:00
|
|
|
} else if (curr->killsRegister(b)) {
|
2008-01-10 01:36:43 +00:00
|
|
|
if (def == MRI->getVRegDef(b)) {
|
2007-12-16 05:44:27 +00:00
|
|
|
kill = curr;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
// First properly dominates second...
|
|
|
|
} else if (mode == 1) {
|
2008-01-10 01:36:43 +00:00
|
|
|
if (curr == MRI->getVRegDef(b)) {
|
|
|
|
// Definition of second without kill of first is an interference
|
2007-12-16 05:44:27 +00:00
|
|
|
if (!kill) {
|
|
|
|
interference = true;
|
|
|
|
break;
|
2008-01-10 01:36:43 +00:00
|
|
|
// Definition after a kill is a non-interference
|
2007-12-16 05:44:27 +00:00
|
|
|
} else {
|
|
|
|
interference = false;
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
// Save KillInsts of First
|
2008-03-05 00:59:57 +00:00
|
|
|
} else if (curr->killsRegister(a)) {
|
2007-12-16 05:44:27 +00:00
|
|
|
kill = curr;
|
|
|
|
}
|
|
|
|
// Symmetric with the above
|
|
|
|
} else if (mode == 2) {
|
2008-01-10 01:36:43 +00:00
|
|
|
if (curr == MRI->getVRegDef(a)) {
|
2007-12-16 05:44:27 +00:00
|
|
|
if (!kill) {
|
|
|
|
interference = true;
|
|
|
|
break;
|
|
|
|
} else {
|
|
|
|
interference = false;
|
|
|
|
break;
|
|
|
|
}
|
2008-03-05 00:59:57 +00:00
|
|
|
} else if (curr->killsRegister(b)) {
|
2007-12-16 05:44:27 +00:00
|
|
|
kill = curr;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
return interference;
|
|
|
|
}
|
|
|
|
|
2008-01-10 00:47:01 +00:00
|
|
|
/// processBlock - Determine how to break up PHIs in the current block. Each
|
|
|
|
/// PHI is broken up by some combination of renaming its operands and inserting
|
|
|
|
/// copies. This method is responsible for determining which operands receive
|
|
|
|
/// which treatment.
|
2007-11-07 05:17:15 +00:00
|
|
|
void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) {
|
2008-03-10 07:22:36 +00:00
|
|
|
LiveIntervals& LI = getAnalysis<LiveIntervals>();
|
2008-01-10 01:36:43 +00:00
|
|
|
MachineRegisterInfo& MRI = MBB->getParent()->getRegInfo();
|
2007-11-07 05:17:15 +00:00
|
|
|
|
|
|
|
// Holds names that have been added to a set in any PHI within this block
|
|
|
|
// before the current one.
|
|
|
|
std::set<unsigned> ProcessedNames;
|
|
|
|
|
2008-03-17 06:08:26 +00:00
|
|
|
MachineBasicBlock::iterator FirstNonPHI = MBB->begin();
|
|
|
|
while (FirstNonPHI->getOpcode() == TargetInstrInfo::PHI) FirstNonPHI++;
|
|
|
|
|
2008-01-10 00:47:01 +00:00
|
|
|
// Iterate over all the PHI nodes in this block
|
2007-11-07 05:17:15 +00:00
|
|
|
MachineBasicBlock::iterator P = MBB->begin();
|
2008-03-17 06:08:26 +00:00
|
|
|
while (P != FirstNonPHI && P->getOpcode() == TargetInstrInfo::PHI) {
|
2007-12-10 08:07:09 +00:00
|
|
|
unsigned DestReg = P->getOperand(0).getReg();
|
|
|
|
|
2008-03-26 03:03:23 +00:00
|
|
|
// Don't both doing PHI elimination for dead PHI's.
|
|
|
|
if (P->registerDefIsDead(DestReg)) {
|
|
|
|
++P;
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
|
2008-03-12 04:22:57 +00:00
|
|
|
LiveInterval& PI = LI.getOrCreateInterval(DestReg);
|
2008-03-17 06:08:26 +00:00
|
|
|
unsigned pIdx = LI.getInstructionIndex(FirstNonPHI);
|
2008-03-12 04:22:57 +00:00
|
|
|
VNInfo* PVN = PI.getLiveRangeContaining(pIdx)->valno;
|
|
|
|
PhiValueNumber.insert(std::make_pair(DestReg, PVN->id));
|
|
|
|
|
2008-01-10 00:47:01 +00:00
|
|
|
// PHIUnion is the set of incoming registers to the PHI node that
|
|
|
|
// are going to be renames rather than having copies inserted. This set
|
|
|
|
// is refinded over the course of this function. UnionedBlocks is the set
|
|
|
|
// of corresponding MBBs.
|
2008-03-12 03:13:29 +00:00
|
|
|
std::map<unsigned, unsigned> PHIUnion;
|
2008-03-24 04:11:27 +00:00
|
|
|
SmallPtrSet<MachineBasicBlock*, 8> UnionedBlocks;
|
2007-11-07 05:17:15 +00:00
|
|
|
|
2008-01-10 00:47:01 +00:00
|
|
|
// Iterate over the operands of the PHI node
|
2007-11-07 05:17:15 +00:00
|
|
|
for (int i = P->getNumOperands() - 1; i >= 2; i-=2) {
|
|
|
|
unsigned SrcReg = P->getOperand(i-1).getReg();
|
|
|
|
|
2008-01-10 00:47:01 +00:00
|
|
|
// Check for trivial interferences via liveness information, allowing us
|
|
|
|
// to avoid extra work later. Any registers that interfere cannot both
|
|
|
|
// be in the renaming set, so choose one and add copies for it instead.
|
|
|
|
// The conditions are:
|
|
|
|
// 1) if the operand is live into the PHI node's block OR
|
|
|
|
// 2) if the PHI node is live out of the operand's defining block OR
|
|
|
|
// 3) if the operand is itself a PHI node and the original PHI is
|
|
|
|
// live into the operand's defining block OR
|
|
|
|
// 4) if the operand is already being renamed for another PHI node
|
|
|
|
// in this block OR
|
|
|
|
// 5) if any two operands are defined in the same block, insert copies
|
|
|
|
// for one of them
|
2008-03-10 07:22:36 +00:00
|
|
|
if (isLiveIn(SrcReg, P->getParent(), LI) ||
|
2008-01-10 01:36:43 +00:00
|
|
|
isLiveOut(P->getOperand(0).getReg(),
|
2008-03-10 07:22:36 +00:00
|
|
|
MRI.getVRegDef(SrcReg)->getParent(), LI) ||
|
2008-01-10 01:36:43 +00:00
|
|
|
( MRI.getVRegDef(SrcReg)->getOpcode() == TargetInstrInfo::PHI &&
|
|
|
|
isLiveIn(P->getOperand(0).getReg(),
|
2008-03-10 07:22:36 +00:00
|
|
|
MRI.getVRegDef(SrcReg)->getParent(), LI) ) ||
|
2007-12-10 08:07:09 +00:00
|
|
|
ProcessedNames.count(SrcReg) ||
|
2008-01-10 01:36:43 +00:00
|
|
|
UnionedBlocks.count(MRI.getVRegDef(SrcReg)->getParent())) {
|
2007-12-10 08:07:09 +00:00
|
|
|
|
2008-01-10 00:47:01 +00:00
|
|
|
// Add a copy for the selected register
|
2007-12-30 23:10:15 +00:00
|
|
|
MachineBasicBlock* From = P->getOperand(i).getMBB();
|
2007-12-23 15:37:26 +00:00
|
|
|
Waiting[From].insert(std::make_pair(SrcReg, DestReg));
|
|
|
|
UsedByAnother.insert(SrcReg);
|
2007-11-07 05:17:15 +00:00
|
|
|
} else {
|
2008-01-10 00:47:01 +00:00
|
|
|
// Otherwise, add it to the renaming set
|
2008-03-12 03:13:29 +00:00
|
|
|
LiveInterval& I = LI.getOrCreateInterval(SrcReg);
|
|
|
|
unsigned idx = LI.getMBBEndIdx(P->getOperand(i).getMBB());
|
|
|
|
VNInfo* VN = I.getLiveRangeContaining(idx)->valno;
|
|
|
|
|
|
|
|
assert(VN && "No VNInfo for register?");
|
|
|
|
|
|
|
|
PHIUnion.insert(std::make_pair(SrcReg, VN->id));
|
2008-01-10 01:36:43 +00:00
|
|
|
UnionedBlocks.insert(MRI.getVRegDef(SrcReg)->getParent());
|
2007-11-07 05:17:15 +00:00
|
|
|
}
|
2007-11-06 05:22:43 +00:00
|
|
|
}
|
2007-11-07 05:17:15 +00:00
|
|
|
|
2008-01-10 00:47:01 +00:00
|
|
|
// Compute the dominator forest for the renaming set. This is a forest
|
|
|
|
// where the nodes are the registers and the edges represent dominance
|
|
|
|
// relations between the defining blocks of the registers
|
2007-11-13 20:13:24 +00:00
|
|
|
std::vector<StrongPHIElimination::DomForestNode*> DF =
|
2008-01-10 01:36:43 +00:00
|
|
|
computeDomForest(PHIUnion, MRI);
|
2007-11-13 20:13:24 +00:00
|
|
|
|
2008-01-10 00:47:01 +00:00
|
|
|
// Walk DomForest to resolve interferences at an inter-block level. This
|
|
|
|
// will remove registers from the renaming set (and insert copies for them)
|
|
|
|
// if interferences are found.
|
2007-12-13 05:53:03 +00:00
|
|
|
std::vector<std::pair<unsigned, unsigned> > localInterferences;
|
|
|
|
processPHIUnion(P, PHIUnion, DF, localInterferences);
|
|
|
|
|
2008-01-10 00:47:01 +00:00
|
|
|
// The dominator forest walk may have returned some register pairs whose
|
|
|
|
// interference cannot be determines from dominator analysis. We now
|
|
|
|
// examine these pairs for local interferences.
|
2007-12-16 05:44:27 +00:00
|
|
|
for (std::vector<std::pair<unsigned, unsigned> >::iterator I =
|
|
|
|
localInterferences.begin(), E = localInterferences.end(); I != E; ++I) {
|
|
|
|
std::pair<unsigned, unsigned> p = *I;
|
|
|
|
|
|
|
|
MachineDominatorTree& MDT = getAnalysis<MachineDominatorTree>();
|
|
|
|
|
|
|
|
// Determine the block we need to scan and the relationship between
|
|
|
|
// the two registers
|
|
|
|
MachineBasicBlock* scan = 0;
|
|
|
|
unsigned mode = 0;
|
2008-01-10 01:36:43 +00:00
|
|
|
if (MRI.getVRegDef(p.first)->getParent() ==
|
|
|
|
MRI.getVRegDef(p.second)->getParent()) {
|
|
|
|
scan = MRI.getVRegDef(p.first)->getParent();
|
2007-12-16 05:44:27 +00:00
|
|
|
mode = 0; // Same block
|
2008-01-10 01:36:43 +00:00
|
|
|
} else if (MDT.dominates(MRI.getVRegDef(p.first)->getParent(),
|
|
|
|
MRI.getVRegDef(p.second)->getParent())) {
|
|
|
|
scan = MRI.getVRegDef(p.second)->getParent();
|
2007-12-16 05:44:27 +00:00
|
|
|
mode = 1; // First dominates second
|
|
|
|
} else {
|
2008-01-10 01:36:43 +00:00
|
|
|
scan = MRI.getVRegDef(p.first)->getParent();
|
2007-12-16 05:44:27 +00:00
|
|
|
mode = 2; // Second dominates first
|
|
|
|
}
|
|
|
|
|
|
|
|
// If there's an interference, we need to insert copies
|
2008-03-10 07:22:36 +00:00
|
|
|
if (interferes(p.first, p.second, scan, LI, mode)) {
|
2007-12-16 05:44:27 +00:00
|
|
|
// Insert copies for First
|
|
|
|
for (int i = P->getNumOperands() - 1; i >= 2; i-=2) {
|
|
|
|
if (P->getOperand(i-1).getReg() == p.first) {
|
|
|
|
unsigned SrcReg = p.first;
|
|
|
|
MachineBasicBlock* From = P->getOperand(i).getMBB();
|
|
|
|
|
2007-12-23 15:37:26 +00:00
|
|
|
Waiting[From].insert(std::make_pair(SrcReg,
|
|
|
|
P->getOperand(0).getReg()));
|
|
|
|
UsedByAnother.insert(SrcReg);
|
|
|
|
|
2007-12-16 05:44:27 +00:00
|
|
|
PHIUnion.erase(SrcReg);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
2007-11-13 20:13:24 +00:00
|
|
|
|
2008-01-10 00:47:01 +00:00
|
|
|
// Add the renaming set for this PHI node to our overal renaming information
|
2008-01-08 21:54:52 +00:00
|
|
|
RenameSets.insert(std::make_pair(P->getOperand(0).getReg(), PHIUnion));
|
2007-12-22 04:59:10 +00:00
|
|
|
|
2008-01-10 00:47:01 +00:00
|
|
|
// Remember which registers are already renamed, so that we don't try to
|
|
|
|
// rename them for another PHI node in this block
|
2008-03-12 03:13:29 +00:00
|
|
|
for (std::map<unsigned, unsigned>::iterator I = PHIUnion.begin(),
|
|
|
|
E = PHIUnion.end(); I != E; ++I)
|
|
|
|
ProcessedNames.insert(I->first);
|
2008-01-10 00:47:01 +00:00
|
|
|
|
2007-11-07 05:17:15 +00:00
|
|
|
++P;
|
2007-11-06 05:22:43 +00:00
|
|
|
}
|
2007-11-07 05:17:15 +00:00
|
|
|
}
|
|
|
|
|
2008-03-06 10:51:21 +00:00
|
|
|
/// processPHIUnion - Take a set of candidate registers to be coalesced when
|
2007-12-16 04:07:23 +00:00
|
|
|
/// decomposing the PHI instruction. Use the DominanceForest to remove the ones
|
|
|
|
/// that are known to interfere, and flag others that need to be checked for
|
|
|
|
/// local interferences.
|
2007-12-11 20:12:11 +00:00
|
|
|
void StrongPHIElimination::processPHIUnion(MachineInstr* Inst,
|
2008-03-12 03:13:29 +00:00
|
|
|
std::map<unsigned, unsigned>& PHIUnion,
|
2007-12-13 05:53:03 +00:00
|
|
|
std::vector<StrongPHIElimination::DomForestNode*>& DF,
|
|
|
|
std::vector<std::pair<unsigned, unsigned> >& locals) {
|
2007-12-11 20:12:11 +00:00
|
|
|
|
|
|
|
std::vector<DomForestNode*> worklist(DF.begin(), DF.end());
|
|
|
|
SmallPtrSet<DomForestNode*, 4> visited;
|
|
|
|
|
2008-01-10 01:36:43 +00:00
|
|
|
// Code is still in SSA form, so we can use MRI::getVRegDef()
|
|
|
|
MachineRegisterInfo& MRI = Inst->getParent()->getParent()->getRegInfo();
|
|
|
|
|
2008-03-10 07:22:36 +00:00
|
|
|
LiveIntervals& LI = getAnalysis<LiveIntervals>();
|
2007-12-11 20:12:11 +00:00
|
|
|
unsigned DestReg = Inst->getOperand(0).getReg();
|
|
|
|
|
2007-12-16 04:07:23 +00:00
|
|
|
// DF walk on the DomForest
|
2007-12-11 20:12:11 +00:00
|
|
|
while (!worklist.empty()) {
|
|
|
|
DomForestNode* DFNode = worklist.back();
|
|
|
|
|
|
|
|
visited.insert(DFNode);
|
|
|
|
|
|
|
|
bool inserted = false;
|
|
|
|
for (DomForestNode::iterator CI = DFNode->begin(), CE = DFNode->end();
|
|
|
|
CI != CE; ++CI) {
|
|
|
|
DomForestNode* child = *CI;
|
2008-01-21 22:01:01 +00:00
|
|
|
|
|
|
|
// If the current node is live-out of the defining block of one of its
|
2008-01-21 22:03:00 +00:00
|
|
|
// children, insert a copy for it. NOTE: The paper actually calls for
|
|
|
|
// a more elaborate heuristic for determining whether to insert copies
|
|
|
|
// for the child or the parent. In the interest of simplicity, we're
|
|
|
|
// just always choosing the parent.
|
2008-01-10 01:36:43 +00:00
|
|
|
if (isLiveOut(DFNode->getReg(),
|
2008-03-10 07:22:36 +00:00
|
|
|
MRI.getVRegDef(child->getReg())->getParent(), LI)) {
|
2007-12-11 20:12:11 +00:00
|
|
|
// Insert copies for parent
|
|
|
|
for (int i = Inst->getNumOperands() - 1; i >= 2; i-=2) {
|
|
|
|
if (Inst->getOperand(i-1).getReg() == DFNode->getReg()) {
|
2007-12-12 01:25:08 +00:00
|
|
|
unsigned SrcReg = DFNode->getReg();
|
2007-12-11 20:12:11 +00:00
|
|
|
MachineBasicBlock* From = Inst->getOperand(i).getMBB();
|
|
|
|
|
2007-12-23 15:37:26 +00:00
|
|
|
Waiting[From].insert(std::make_pair(SrcReg, DestReg));
|
|
|
|
UsedByAnother.insert(SrcReg);
|
|
|
|
|
2007-12-12 01:25:08 +00:00
|
|
|
PHIUnion.erase(SrcReg);
|
2007-12-11 20:12:11 +00:00
|
|
|
}
|
|
|
|
}
|
2008-01-21 22:01:01 +00:00
|
|
|
|
|
|
|
// If a node is live-in to the defining block of one of its children, but
|
|
|
|
// not live-out, then we need to scan that block for local interferences.
|
2008-01-10 01:36:43 +00:00
|
|
|
} else if (isLiveIn(DFNode->getReg(),
|
2008-03-10 07:22:36 +00:00
|
|
|
MRI.getVRegDef(child->getReg())->getParent(), LI) ||
|
2008-01-10 01:36:43 +00:00
|
|
|
MRI.getVRegDef(DFNode->getReg())->getParent() ==
|
|
|
|
MRI.getVRegDef(child->getReg())->getParent()) {
|
2007-12-13 05:53:03 +00:00
|
|
|
// Add (p, c) to possible local interferences
|
|
|
|
locals.push_back(std::make_pair(DFNode->getReg(), child->getReg()));
|
2007-12-11 20:12:11 +00:00
|
|
|
}
|
2007-12-16 04:07:23 +00:00
|
|
|
|
2007-12-13 05:43:37 +00:00
|
|
|
if (!visited.count(child)) {
|
|
|
|
worklist.push_back(child);
|
|
|
|
inserted = true;
|
2007-12-11 20:12:11 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
if (!inserted) worklist.pop_back();
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2007-12-23 15:37:26 +00:00
|
|
|
/// ScheduleCopies - Insert copies into predecessor blocks, scheduling
|
|
|
|
/// them properly so as to avoid the 'lost copy' and the 'virtual swap'
|
|
|
|
/// problems.
|
|
|
|
///
|
|
|
|
/// Based on "Practical Improvements to the Construction and Destruction
|
|
|
|
/// of Static Single Assignment Form" by Briggs, et al.
|
2007-12-24 22:12:23 +00:00
|
|
|
void StrongPHIElimination::ScheduleCopies(MachineBasicBlock* MBB,
|
|
|
|
std::set<unsigned>& pushed) {
|
2008-01-08 05:16:15 +00:00
|
|
|
// FIXME: This function needs to update LiveVariables
|
2007-12-23 15:37:26 +00:00
|
|
|
std::map<unsigned, unsigned>& copy_set= Waiting[MBB];
|
|
|
|
|
|
|
|
std::map<unsigned, unsigned> worklist;
|
|
|
|
std::map<unsigned, unsigned> map;
|
|
|
|
|
|
|
|
// Setup worklist of initial copies
|
|
|
|
for (std::map<unsigned, unsigned>::iterator I = copy_set.begin(),
|
|
|
|
E = copy_set.end(); I != E; ) {
|
|
|
|
map.insert(std::make_pair(I->first, I->first));
|
|
|
|
map.insert(std::make_pair(I->second, I->second));
|
|
|
|
|
|
|
|
if (!UsedByAnother.count(I->first)) {
|
|
|
|
worklist.insert(*I);
|
|
|
|
|
|
|
|
// Avoid iterator invalidation
|
|
|
|
unsigned first = I->first;
|
|
|
|
++I;
|
|
|
|
copy_set.erase(first);
|
|
|
|
} else {
|
|
|
|
++I;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2008-03-10 07:22:36 +00:00
|
|
|
LiveIntervals& LI = getAnalysis<LiveIntervals>();
|
2008-01-08 05:16:15 +00:00
|
|
|
MachineFunction* MF = MBB->getParent();
|
2008-01-10 01:36:43 +00:00
|
|
|
MachineRegisterInfo& MRI = MF->getRegInfo();
|
2008-01-08 05:16:15 +00:00
|
|
|
const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
|
2007-12-23 15:37:26 +00:00
|
|
|
|
|
|
|
// Iterate over the worklist, inserting copies
|
|
|
|
while (!worklist.empty() || !copy_set.empty()) {
|
|
|
|
while (!worklist.empty()) {
|
|
|
|
std::pair<unsigned, unsigned> curr = *worklist.begin();
|
|
|
|
worklist.erase(curr.first);
|
|
|
|
|
2008-01-08 05:16:15 +00:00
|
|
|
const TargetRegisterClass *RC = MF->getRegInfo().getRegClass(curr.first);
|
|
|
|
|
2008-03-10 07:22:36 +00:00
|
|
|
if (isLiveOut(curr.second, MBB, LI)) {
|
2008-01-08 05:16:15 +00:00
|
|
|
// Create a temporary
|
|
|
|
unsigned t = MF->getRegInfo().createVirtualRegister(RC);
|
|
|
|
|
|
|
|
// Insert copy from curr.second to a temporary at
|
|
|
|
// the Phi defining curr.second
|
2008-01-10 01:36:43 +00:00
|
|
|
MachineBasicBlock::iterator PI = MRI.getVRegDef(curr.second);
|
|
|
|
TII->copyRegToReg(*PI->getParent(), PI, t,
|
2008-01-08 05:16:15 +00:00
|
|
|
curr.second, RC, RC);
|
|
|
|
|
2007-12-23 15:37:26 +00:00
|
|
|
// Push temporary on Stacks
|
2008-01-08 05:16:15 +00:00
|
|
|
Stacks[curr.second].push_back(t);
|
|
|
|
|
|
|
|
// Insert curr.second in pushed
|
|
|
|
pushed.insert(curr.second);
|
2007-12-23 15:37:26 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
// Insert copy from map[curr.first] to curr.second
|
2008-01-10 00:01:41 +00:00
|
|
|
TII->copyRegToReg(*MBB, MBB->getFirstTerminator(), curr.second,
|
2008-01-08 05:16:15 +00:00
|
|
|
map[curr.first], RC, RC);
|
2007-12-23 15:37:26 +00:00
|
|
|
map[curr.first] = curr.second;
|
|
|
|
|
|
|
|
// If curr.first is a destination in copy_set...
|
|
|
|
for (std::map<unsigned, unsigned>::iterator I = copy_set.begin(),
|
|
|
|
E = copy_set.end(); I != E; )
|
|
|
|
if (curr.first == I->second) {
|
|
|
|
std::pair<unsigned, unsigned> temp = *I;
|
|
|
|
|
|
|
|
// Avoid iterator invalidation
|
|
|
|
++I;
|
|
|
|
copy_set.erase(temp.first);
|
|
|
|
worklist.insert(temp);
|
|
|
|
|
|
|
|
break;
|
|
|
|
} else {
|
|
|
|
++I;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
if (!copy_set.empty()) {
|
|
|
|
std::pair<unsigned, unsigned> curr = *copy_set.begin();
|
|
|
|
copy_set.erase(curr.first);
|
|
|
|
|
2008-01-08 05:16:15 +00:00
|
|
|
const TargetRegisterClass *RC = MF->getRegInfo().getRegClass(curr.first);
|
|
|
|
|
2007-12-23 15:37:26 +00:00
|
|
|
// Insert a copy from dest to a new temporary t at the end of b
|
2008-01-08 05:16:15 +00:00
|
|
|
unsigned t = MF->getRegInfo().createVirtualRegister(RC);
|
2008-01-10 00:01:41 +00:00
|
|
|
TII->copyRegToReg(*MBB, MBB->getFirstTerminator(), t,
|
2008-01-08 05:16:15 +00:00
|
|
|
curr.second, RC, RC);
|
|
|
|
map[curr.second] = t;
|
2007-12-23 15:37:26 +00:00
|
|
|
|
|
|
|
worklist.insert(curr);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2007-12-24 22:12:23 +00:00
|
|
|
/// InsertCopies - insert copies into MBB and all of its successors
|
2008-01-09 10:32:30 +00:00
|
|
|
void StrongPHIElimination::InsertCopies(MachineBasicBlock* MBB,
|
2008-03-24 04:11:27 +00:00
|
|
|
SmallPtrSet<MachineBasicBlock*, 16>& visited) {
|
2008-01-09 10:32:30 +00:00
|
|
|
visited.insert(MBB);
|
|
|
|
|
2007-12-24 22:12:23 +00:00
|
|
|
std::set<unsigned> pushed;
|
|
|
|
|
|
|
|
// Rewrite register uses from Stacks
|
|
|
|
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
|
|
|
|
I != E; ++I)
|
|
|
|
for (unsigned i = 0; i < I->getNumOperands(); ++i)
|
|
|
|
if (I->getOperand(i).isRegister() &&
|
|
|
|
Stacks[I->getOperand(i).getReg()].size()) {
|
|
|
|
I->getOperand(i).setReg(Stacks[I->getOperand(i).getReg()].back());
|
|
|
|
}
|
|
|
|
|
|
|
|
// Schedule the copies for this block
|
|
|
|
ScheduleCopies(MBB, pushed);
|
|
|
|
|
|
|
|
// Recur to our successors
|
|
|
|
for (GraphTraits<MachineBasicBlock*>::ChildIteratorType I =
|
|
|
|
GraphTraits<MachineBasicBlock*>::child_begin(MBB), E =
|
|
|
|
GraphTraits<MachineBasicBlock*>::child_end(MBB); I != E; ++I)
|
2008-01-09 10:32:30 +00:00
|
|
|
if (!visited.count(*I))
|
|
|
|
InsertCopies(*I, visited);
|
2007-12-24 22:12:23 +00:00
|
|
|
|
|
|
|
// As we exit this block, pop the names we pushed while processing it
|
|
|
|
for (std::set<unsigned>::iterator I = pushed.begin(),
|
|
|
|
E = pushed.end(); I != E; ++I)
|
|
|
|
Stacks[*I].pop_back();
|
|
|
|
}
|
|
|
|
|
2008-03-17 06:08:26 +00:00
|
|
|
/// ComputeUltimateVN - Assuming we are going to join two live intervals,
|
|
|
|
/// compute what the resultant value numbers for each value in the input two
|
|
|
|
/// ranges will be. This is complicated by copies between the two which can
|
|
|
|
/// and will commonly cause multiple value numbers to be merged into one.
|
|
|
|
///
|
|
|
|
/// VN is the value number that we're trying to resolve. InstDefiningValue
|
|
|
|
/// keeps track of the new InstDefiningValue assignment for the result
|
|
|
|
/// LiveInterval. ThisFromOther/OtherFromThis are sets that keep track of
|
|
|
|
/// whether a value in this or other is a copy from the opposite set.
|
|
|
|
/// ThisValNoAssignments/OtherValNoAssignments keep track of value #'s that have
|
|
|
|
/// already been assigned.
|
|
|
|
///
|
|
|
|
/// ThisFromOther[x] - If x is defined as a copy from the other interval, this
|
|
|
|
/// contains the value number the copy is from.
|
|
|
|
///
|
|
|
|
static unsigned ComputeUltimateVN(VNInfo *VNI,
|
|
|
|
SmallVector<VNInfo*, 16> &NewVNInfo,
|
|
|
|
DenseMap<VNInfo*, VNInfo*> &ThisFromOther,
|
|
|
|
DenseMap<VNInfo*, VNInfo*> &OtherFromThis,
|
|
|
|
SmallVector<int, 16> &ThisValNoAssignments,
|
|
|
|
SmallVector<int, 16> &OtherValNoAssignments) {
|
|
|
|
unsigned VN = VNI->id;
|
|
|
|
|
|
|
|
// If the VN has already been computed, just return it.
|
|
|
|
if (ThisValNoAssignments[VN] >= 0)
|
|
|
|
return ThisValNoAssignments[VN];
|
|
|
|
// assert(ThisValNoAssignments[VN] != -2 && "Cyclic case?");
|
|
|
|
|
|
|
|
// If this val is not a copy from the other val, then it must be a new value
|
|
|
|
// number in the destination.
|
|
|
|
DenseMap<VNInfo*, VNInfo*>::iterator I = ThisFromOther.find(VNI);
|
|
|
|
if (I == ThisFromOther.end()) {
|
|
|
|
NewVNInfo.push_back(VNI);
|
|
|
|
return ThisValNoAssignments[VN] = NewVNInfo.size()-1;
|
|
|
|
}
|
|
|
|
VNInfo *OtherValNo = I->second;
|
|
|
|
|
|
|
|
// Otherwise, this *is* a copy from the RHS. If the other side has already
|
|
|
|
// been computed, return it.
|
|
|
|
if (OtherValNoAssignments[OtherValNo->id] >= 0)
|
|
|
|
return ThisValNoAssignments[VN] = OtherValNoAssignments[OtherValNo->id];
|
|
|
|
|
|
|
|
// Mark this value number as currently being computed, then ask what the
|
|
|
|
// ultimate value # of the other value is.
|
|
|
|
ThisValNoAssignments[VN] = -2;
|
|
|
|
unsigned UltimateVN =
|
|
|
|
ComputeUltimateVN(OtherValNo, NewVNInfo, OtherFromThis, ThisFromOther,
|
|
|
|
OtherValNoAssignments, ThisValNoAssignments);
|
|
|
|
return ThisValNoAssignments[VN] = UltimateVN;
|
|
|
|
}
|
|
|
|
|
2008-03-12 03:13:29 +00:00
|
|
|
void StrongPHIElimination::mergeLiveIntervals(unsigned primary,
|
2008-03-24 04:11:27 +00:00
|
|
|
unsigned secondary,
|
|
|
|
unsigned secondaryVN) {
|
2008-03-17 06:08:26 +00:00
|
|
|
|
|
|
|
LiveIntervals& LI = getAnalysis<LiveIntervals>();
|
|
|
|
LiveInterval& LHS = LI.getOrCreateInterval(primary);
|
|
|
|
LiveInterval& RHS = LI.getOrCreateInterval(secondary);
|
|
|
|
|
|
|
|
// Compute the final value assignment, assuming that the live ranges can be
|
|
|
|
// coalesced.
|
|
|
|
SmallVector<int, 16> LHSValNoAssignments;
|
|
|
|
SmallVector<int, 16> RHSValNoAssignments;
|
|
|
|
DenseMap<VNInfo*, VNInfo*> LHSValsDefinedFromRHS;
|
|
|
|
DenseMap<VNInfo*, VNInfo*> RHSValsDefinedFromLHS;
|
|
|
|
SmallVector<VNInfo*, 16> NewVNInfo;
|
|
|
|
|
|
|
|
LHSValNoAssignments.resize(LHS.getNumValNums(), -1);
|
|
|
|
RHSValNoAssignments.resize(RHS.getNumValNums(), -1);
|
|
|
|
NewVNInfo.reserve(LHS.getNumValNums() + RHS.getNumValNums());
|
|
|
|
|
|
|
|
for (LiveInterval::vni_iterator I = LHS.vni_begin(), E = LHS.vni_end();
|
|
|
|
I != E; ++I) {
|
|
|
|
VNInfo *VNI = *I;
|
|
|
|
unsigned VN = VNI->id;
|
|
|
|
if (LHSValNoAssignments[VN] >= 0 || VNI->def == ~1U)
|
|
|
|
continue;
|
|
|
|
ComputeUltimateVN(VNI, NewVNInfo,
|
|
|
|
LHSValsDefinedFromRHS, RHSValsDefinedFromLHS,
|
|
|
|
LHSValNoAssignments, RHSValNoAssignments);
|
|
|
|
}
|
|
|
|
|
|
|
|
for (LiveInterval::vni_iterator I = RHS.vni_begin(), E = RHS.vni_end();
|
|
|
|
I != E; ++I) {
|
|
|
|
VNInfo *VNI = *I;
|
|
|
|
unsigned VN = VNI->id;
|
|
|
|
if (RHSValNoAssignments[VN] >= 0 || VNI->def == ~1U)
|
|
|
|
continue;
|
|
|
|
// If this value number isn't a copy from the LHS, it's a new number.
|
|
|
|
if (RHSValsDefinedFromLHS.find(VNI) == RHSValsDefinedFromLHS.end()) {
|
|
|
|
NewVNInfo.push_back(VNI);
|
|
|
|
RHSValNoAssignments[VN] = NewVNInfo.size()-1;
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
|
|
|
|
ComputeUltimateVN(VNI, NewVNInfo,
|
|
|
|
RHSValsDefinedFromLHS, LHSValsDefinedFromRHS,
|
|
|
|
RHSValNoAssignments, LHSValNoAssignments);
|
|
|
|
}
|
|
|
|
|
|
|
|
// Update kill info. Some live ranges are extended due to copy coalescing.
|
|
|
|
for (DenseMap<VNInfo*, VNInfo*>::iterator I = LHSValsDefinedFromRHS.begin(),
|
|
|
|
E = LHSValsDefinedFromRHS.end(); I != E; ++I) {
|
|
|
|
VNInfo *VNI = I->first;
|
|
|
|
unsigned LHSValID = LHSValNoAssignments[VNI->id];
|
|
|
|
LiveInterval::removeKill(NewVNInfo[LHSValID], VNI->def);
|
|
|
|
NewVNInfo[LHSValID]->hasPHIKill |= VNI->hasPHIKill;
|
|
|
|
RHS.addKills(NewVNInfo[LHSValID], VNI->kills);
|
|
|
|
}
|
|
|
|
|
|
|
|
// Update kill info. Some live ranges are extended due to copy coalescing.
|
|
|
|
for (DenseMap<VNInfo*, VNInfo*>::iterator I = RHSValsDefinedFromLHS.begin(),
|
|
|
|
E = RHSValsDefinedFromLHS.end(); I != E; ++I) {
|
|
|
|
VNInfo *VNI = I->first;
|
|
|
|
unsigned RHSValID = RHSValNoAssignments[VNI->id];
|
|
|
|
LiveInterval::removeKill(NewVNInfo[RHSValID], VNI->def);
|
|
|
|
NewVNInfo[RHSValID]->hasPHIKill |= VNI->hasPHIKill;
|
|
|
|
LHS.addKills(NewVNInfo[RHSValID], VNI->kills);
|
|
|
|
}
|
|
|
|
|
|
|
|
// Use the VNInfo we collected earlier to ensure that the phi copy is
|
|
|
|
// merged correctly.
|
2008-03-24 04:11:27 +00:00
|
|
|
// FIXME: This is not working correctly yet.
|
|
|
|
// RHSValNoAssignments[secondaryVN] = primaryVN;
|
2008-03-17 06:08:26 +00:00
|
|
|
|
|
|
|
// If we get here, we know that we can coalesce the live ranges. Ask the
|
|
|
|
// intervals to coalesce themselves now.
|
2008-03-25 22:25:27 +00:00
|
|
|
|
|
|
|
LHS.join(RHS, &LHSValNoAssignments[0], &RHSValNoAssignments[0], NewVNInfo);
|
|
|
|
LI.removeInterval(secondary);
|
2008-03-12 03:13:29 +00:00
|
|
|
}
|
|
|
|
|
2007-11-07 05:17:15 +00:00
|
|
|
bool StrongPHIElimination::runOnMachineFunction(MachineFunction &Fn) {
|
2007-12-23 15:37:26 +00:00
|
|
|
// Compute DFS numbers of each block
|
2007-11-07 05:17:15 +00:00
|
|
|
computeDFS(Fn);
|
|
|
|
|
2007-12-23 15:37:26 +00:00
|
|
|
// Determine which phi node operands need copies
|
2007-11-07 05:17:15 +00:00
|
|
|
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
|
|
|
|
if (!I->empty() &&
|
|
|
|
I->begin()->getOpcode() == TargetInstrInfo::PHI)
|
|
|
|
processBlock(I);
|
2007-11-06 04:49:43 +00:00
|
|
|
|
2007-12-23 15:37:26 +00:00
|
|
|
// Insert copies
|
2007-12-24 22:12:23 +00:00
|
|
|
// FIXME: This process should probably preserve LiveVariables
|
2008-03-24 04:11:27 +00:00
|
|
|
SmallPtrSet<MachineBasicBlock*, 16> visited;
|
2008-01-09 10:32:30 +00:00
|
|
|
InsertCopies(Fn.begin(), visited);
|
2007-12-23 15:37:26 +00:00
|
|
|
|
2008-01-08 21:54:52 +00:00
|
|
|
// Perform renaming
|
2008-03-12 03:13:29 +00:00
|
|
|
typedef std::map<unsigned, std::map<unsigned, unsigned> > RenameSetType;
|
2008-01-08 21:54:52 +00:00
|
|
|
for (RenameSetType::iterator I = RenameSets.begin(), E = RenameSets.end();
|
|
|
|
I != E; ++I)
|
2008-03-12 03:13:29 +00:00
|
|
|
for (std::map<unsigned, unsigned>::iterator SI = I->second.begin(),
|
|
|
|
SE = I->second.end(); SI != SE; ++SI) {
|
|
|
|
mergeLiveIntervals(I->first, SI->first, SI->second);
|
|
|
|
Fn.getRegInfo().replaceRegWith(SI->first, I->first);
|
|
|
|
}
|
2008-01-08 21:54:52 +00:00
|
|
|
|
|
|
|
// FIXME: Insert last-minute copies
|
|
|
|
|
|
|
|
// Remove PHIs
|
2008-01-22 23:58:54 +00:00
|
|
|
std::vector<MachineInstr*> phis;
|
|
|
|
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
|
2008-01-08 21:54:52 +00:00
|
|
|
for (MachineBasicBlock::iterator BI = I->begin(), BE = I->end();
|
|
|
|
BI != BE; ++BI)
|
|
|
|
if (BI->getOpcode() == TargetInstrInfo::PHI)
|
2008-01-22 23:58:54 +00:00
|
|
|
phis.push_back(BI);
|
|
|
|
}
|
|
|
|
|
2008-03-24 04:11:27 +00:00
|
|
|
LiveIntervals& LI = getAnalysis<LiveIntervals>();
|
|
|
|
|
2008-01-22 23:58:54 +00:00
|
|
|
for (std::vector<MachineInstr*>::iterator I = phis.begin(), E = phis.end();
|
2008-03-24 04:11:27 +00:00
|
|
|
I != E; ++I) {
|
2008-03-26 03:03:23 +00:00
|
|
|
// If this is a dead PHI node, then remove it from LiveIntervals.
|
|
|
|
unsigned DestReg = (*I)->getOperand(0).getReg();
|
|
|
|
if ((*I)->registerDefIsDead(DestReg)) {
|
|
|
|
LiveInterval& PI = LI.getInterval(DestReg);
|
|
|
|
|
|
|
|
if (PI.containsOneValue()) {
|
|
|
|
LI.removeInterval(DestReg);
|
|
|
|
} else {
|
|
|
|
MachineBasicBlock::iterator PIter = *I;
|
|
|
|
while (PIter->getOpcode() == TargetInstrInfo::PHI) ++PIter;
|
|
|
|
unsigned idx = LI.getInstructionIndex(PIter);
|
|
|
|
|
|
|
|
PI.removeRange(*PI.getLiveRangeContaining(idx), true);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2008-03-24 04:11:27 +00:00
|
|
|
LI.RemoveMachineInstrFromMaps(*I);
|
2008-01-22 23:58:54 +00:00
|
|
|
(*I)->eraseFromParent();
|
2008-03-24 04:11:27 +00:00
|
|
|
}
|
2007-12-22 04:59:10 +00:00
|
|
|
|
2007-11-06 04:49:43 +00:00
|
|
|
return false;
|
|
|
|
}
|