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221 lines
8.0 KiB
C++
221 lines
8.0 KiB
C++
/* Title: MethodLiveVarInfo.cpp
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Author: Ruchira Sasanka
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Date: Jun 30, 01
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Purpose:
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This is the interface for live variable info of a method that is required
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by any other part of the compiler.
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*/
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#include "llvm/Analysis/LiveVar/MethodLiveVarInfo.h"
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#include "BBLiveVar.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/BasicBlock.h"
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#include "Support/PostOrderIterator.h"
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#include <iostream>
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AnalysisID MethodLiveVarInfo::ID(AnalysisID::create<MethodLiveVarInfo>());
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//-----------------------------------------------------------------------------
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// Accessor Functions
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//-----------------------------------------------------------------------------
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// gets OutSet of a BB
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const LiveVarSet *MethodLiveVarInfo::getOutSetOfBB(const BasicBlock *BB) const {
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return BB2BBLVMap.find(BB)->second->getOutSet();
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}
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// gets InSet of a BB
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const LiveVarSet *MethodLiveVarInfo::getInSetOfBB(const BasicBlock *BB) const {
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return BB2BBLVMap.find(BB)->second->getInSet();
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}
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//-----------------------------------------------------------------------------
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// Performs live var analysis for a method
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//-----------------------------------------------------------------------------
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bool MethodLiveVarInfo::runOnMethod(Method *M) {
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if (DEBUG_LV) std::cerr << "Analysing live variables ...\n";
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// create and initialize all the BBLiveVars of the CFG
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constructBBs(M);
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while (doSingleBackwardPass(M))
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; // Iterate until we are done.
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if (DEBUG_LV) std::cerr << "Live Variable Analysis complete!\n";
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return false;
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}
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//-----------------------------------------------------------------------------
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// constructs BBLiveVars and init Def and In sets
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//-----------------------------------------------------------------------------
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void MethodLiveVarInfo::constructBBs(const Method *M) {
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unsigned int POId = 0; // Reverse Depth-first Order ID
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for(po_iterator<const Method*> BBI = po_begin(M), BBE = po_end(M);
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BBI != BBE; ++BBI, ++POId) {
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const BasicBlock *BB = *BBI; // get the current BB
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if (DEBUG_LV) { std::cerr << " For BB "; printValue(BB); cerr << ":\n"; }
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// create a new BBLiveVar
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BBLiveVar *LVBB = new BBLiveVar(BB, POId);
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BB2BBLVMap[BB] = LVBB; // insert the pair to Map
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LVBB->calcDefUseSets(); // calculates the def and in set
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if (DEBUG_LV)
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LVBB->printAllSets();
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}
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// Since the PO iterator does not discover unreachable blocks,
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// go over the random iterator and init those blocks as well.
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// However, LV info is not correct for those blocks (they are not
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// analyzed)
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//
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for (Method::const_iterator BBRI = M->begin(), BBRE = M->end();
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BBRI != BBRE; ++BBRI, ++POId)
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if (!BB2BBLVMap[*BBRI]) // Not yet processed?
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BB2BBLVMap[*BBRI] = new BBLiveVar(*BBRI, POId);
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}
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//-----------------------------------------------------------------------------
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// do one backward pass over the CFG (for iterative analysis)
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//-----------------------------------------------------------------------------
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bool MethodLiveVarInfo::doSingleBackwardPass(const Method *M) {
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if (DEBUG_LV) std::cerr << "\n After Backward Pass ...\n";
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bool NeedAnotherIteration = false;
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for (po_iterator<const Method*> BBI = po_begin(M); BBI != po_end(M) ; ++BBI) {
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BBLiveVar *LVBB = BB2BBLVMap[*BBI];
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assert(LVBB && "BasicBlock information not set for block!");
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if (DEBUG_LV) std::cerr << " For BB " << (*BBI)->getName() << ":\n";
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if(LVBB->isOutSetChanged())
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LVBB->applyTransferFunc(); // apply the Tran Func to calc InSet
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if (LVBB->isInSetChanged()) // to calc Outsets of preds
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NeedAnotherIteration |= LVBB->applyFlowFunc(BB2BBLVMap);
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if (DEBUG_LV) LVBB->printInOutSets();
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}
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// true if we need to reiterate over the CFG
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return NeedAnotherIteration;
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}
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void MethodLiveVarInfo::releaseMemory() {
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// First delete all BBLiveVar objects created in constructBBs(). A new object
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// of type BBLiveVar is created for every BasicBlock in the method
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//
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for (std::map<const BasicBlock *, BBLiveVar *>::iterator
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HMI = BB2BBLVMap.begin(),
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HME = BB2BBLVMap.end(); HMI != HME; ++HMI)
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delete HMI->second; // delete all BBLiveVar in BB2BBLVMap
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BB2BBLVMap.clear();
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// Then delete all objects of type LiveVarSet created in calcLiveVarSetsForBB
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// and entered into MInst2LVSetBI and MInst2LVSetAI (these are caches
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// to return LiveVarSet's before/after a machine instruction quickly). It
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// is sufficient to free up all LiveVarSet using only one cache since
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// both caches refer to the same sets
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//
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for (std::map<const MachineInstr*, const LiveVarSet*>::iterator
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MI = MInst2LVSetBI.begin(),
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ME = MInst2LVSetBI.end(); MI != ME; ++MI)
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delete MI->second; // delete all LiveVarSets in MInst2LVSetBI
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MInst2LVSetBI.clear();
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MInst2LVSetAI.clear();
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}
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//-----------------------------------------------------------------------------
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// Following functions will give the LiveVar info for any machine instr in
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// a method. It should be called after a call to analyze().
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//
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// Thsese functions calucluates live var info for all the machine instrs in a
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// BB when LVInfo for one inst is requested. Hence, this function is useful
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// when live var info is required for many (or all) instructions in a basic
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// block. Also, the arguments to this method does not require specific
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// iterators.
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//-----------------------------------------------------------------------------
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//-----------------------------------------------------------------------------
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// Gives live variable information before a machine instruction
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//-----------------------------------------------------------------------------
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const LiveVarSet *
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MethodLiveVarInfo::getLiveVarSetBeforeMInst(const MachineInstr *MInst,
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const BasicBlock *BB) {
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if (const LiveVarSet *LVSet = MInst2LVSetBI[MInst]) {
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return LVSet; // if found, just return the set
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} else {
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calcLiveVarSetsForBB(BB); // else, calc for all instrs in BB
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return MInst2LVSetBI[MInst];
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}
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}
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//-----------------------------------------------------------------------------
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// Gives live variable information after a machine instruction
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//-----------------------------------------------------------------------------
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const LiveVarSet *
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MethodLiveVarInfo::getLiveVarSetAfterMInst(const MachineInstr *MI,
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const BasicBlock *BB) {
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if (const LiveVarSet *LVSet = MInst2LVSetAI[MI]) {
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return LVSet; // if found, just return the set
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} else {
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calcLiveVarSetsForBB(BB); // else, calc for all instrs in BB
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return MInst2LVSetAI[MI];
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}
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}
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//-----------------------------------------------------------------------------
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// This method calculates the live variable information for all the
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// instructions in a basic block and enter the newly constructed live
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// variable sets into a the caches (MInst2LVSetAI, MInst2LVSetBI)
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//-----------------------------------------------------------------------------
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void MethodLiveVarInfo::calcLiveVarSetsForBB(const BasicBlock *BB) {
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const MachineCodeForBasicBlock &MIVec = BB->getMachineInstrVec();
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LiveVarSet *CurSet = new LiveVarSet();
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const LiveVarSet *SetAI = getOutSetOfBB(BB); // init SetAI with OutSet
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CurSet->setUnion(SetAI); // CurSet now contains OutSet
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// iterate over all the machine instructions in BB
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for (MachineCodeForBasicBlock::const_reverse_iterator MII = MIVec.rbegin(),
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MIE = MIVec.rend(); MII != MIE; ++MII) {
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// MI is cur machine inst
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const MachineInstr *MI = *MII;
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MInst2LVSetAI[MI] = SetAI; // record in After Inst map
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CurSet->applyTranferFuncForMInst(MI); // apply the transfer Func
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LiveVarSet *NewSet = new LiveVarSet(); // create a new set and
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NewSet->setUnion(CurSet); // copy the set after T/F to it
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MInst2LVSetBI[MI] = NewSet; // record in Before Inst map
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// SetAI will be used in the next iteration
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SetAI = NewSet;
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}
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}
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