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157 lines
4.6 KiB
C++
157 lines
4.6 KiB
C++
/* Title: MethodLiveVarInfo.h
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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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It must be called like:
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MethodLiveVarInfo MLVI( Mehtod *); // initializes data structures
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MLVI.analyze(); // do the actural live variable anal
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After the analysis, getInSetOfBB or getOutSetofBB can be called to get
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live var info of a BB.
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The live var set before an instruction can be obtained in 2 ways:
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1. Use the method getLiveVarSetAfterInst(Instruction *) to get the LV Info
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just after an instruction. (also exists getLiveVarSetBeforeInst(..))
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This function caluclates the LV info for a BB only once and caches that
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info. If the cache does not contain the LV info of the instruction, it
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calculates the LV info for the whole BB and caches them.
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Getting liveVar info this way uses more memory since, LV info should be
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cached. However, if you need LV info of nearly all the instructions of a
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BB, this is the best and simplest interfrace.
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2. Use the OutSet and applyTranferFuncForInst(const Instruction *const Inst)
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declared in LiveVarSet and traverse the instructions of a basic block in
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reverse (using const_reverse_iterator in the BB class).
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This is the most memory efficient method if you need LV info for
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only several instructions in a BasicBlock. An example is given below:
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LiveVarSet LVSet; // this will be the set used to traverse through each BB
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// Initialize LVSet so that it is the same as OutSet of the BB
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LVSet.setUnion( LVI->getOutSetOfBB( *BBI ) );
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BasicBlock::InstListType::const_reverse_iterator
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InstIterator = InstListInBB.rbegin(); // get the rev iter for inst in BB
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// iterate over all the instructions in BB in reverse
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for( ; InstIterator != InstListInBB.rend(); InstIterator++) {
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//...... all code here which uses LVSet ........
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LVSet.applyTranferFuncForInst(*InstIterator);
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// Now LVSet contains live vars ABOVE the current instrution
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}
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See buildInterferenceGraph() for the above example.
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*/
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#ifndef METH_LIVE_VAR_INFO_H
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#define METH_LIVE_VAR_INFO_H
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// set DEBUG_LV for printing out debug messages
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// if DEBUG_LV is 1 normal output messages
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// if DEBUG_LV is 2 extensive debug info for each instr
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static const int DEBUG_LV = 0;
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#include "LiveVarSet.h"
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#include "llvm/BasicBlock.h"
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#include "llvm/Instruction.h"
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#include "llvm/Method.h"
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#include "llvm/CFG.h"
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#include "LiveVarMap.h"
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#include "BBLiveVar.h"
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class MethodLiveVarInfo
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{
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private:
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// Live var anal is done on this method - set by constructor
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const Method *const Meth;
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// A map betwn the BasicBlock and BBLiveVar
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BBToBBLiveVarMapType BB2BBLVMap;
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// Machine Instr to LiveVarSet Map for providing LVset BEFORE each inst
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MInstToLiveVarSetMapType MInst2LVSetBI;
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// Machine Instr to LiveVarSet Map for providing LVset AFTER each inst
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MInstToLiveVarSetMapType MInst2LVSetAI;
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// True if the analyze() method has been called. This is checked when
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// getInSet/OutSet is called to prevent calling those methods before analyze
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bool HasAnalyzed;
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// --------- private methods -----------------------------------------
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// constructs BBLiveVars and init Def and In sets
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void constructBBs();
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// do one backward pass over the CFG
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bool doSingleBackwardPass();
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// calculates live var sets for instructions in a BB
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void calcLiveVarSetsForBB(const BasicBlock *const BB);
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public:
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MethodLiveVarInfo(const Method *const Meth); // constructor
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~MethodLiveVarInfo(); // destructor
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// performs a liver var analysis of a single method
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void analyze();
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// gets OutSet of a BB
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inline const LiveVarSet *getOutSetOfBB( const BasicBlock *const BB) const {
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assert( HasAnalyzed && "call analyze() before calling this" );
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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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inline const LiveVarSet *getInSetOfBB( const BasicBlock *const BB) const {
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assert( HasAnalyzed && "call analyze() before calling this" );
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return ( (* (BB2BBLVMap.find(BB)) ).second )->getInSet();
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}
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// gets the Live var set BEFORE an instruction
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const LiveVarSet * getLiveVarSetBeforeMInst(const MachineInstr *const Inst,
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const BasicBlock *const CurBB);
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// gets the Live var set AFTER an instruction
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const LiveVarSet * getLiveVarSetAfterMInst(const MachineInstr *const MInst,
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const BasicBlock *const CurBB);
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};
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#endif
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