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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291 91177308-0d34-0410-b5e6-96231b3b80d8
130 lines
3.9 KiB
C++
130 lines
3.9 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 by
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any other part of the compiler
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It should 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 constructed in several ways:
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1. 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 efficient method if you need LV info for several (all)
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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 reverse it 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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2. Use the function getLiveVarSetBeforeInst(Instruction *) to get the LV Info
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just before an instruction.
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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.
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**BUGS: Cannot be called on a method prototype because the BB front()
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iterator causes a seg fault in CFG.h (Chris will fix this)
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So, currently, DO NOT call this for method prototypes.
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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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// for printing out debug messages
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#define DEBUG_LV (1)
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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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const Method *Meth; // Live var anal is done on this method
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// set by constructor
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BBToBBLiveVarMapType BB2BBLVMap; // A map betwn the BasicBlock and BBLiveVar
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InstToLiveVarSetMapType Inst2LVSetMap; // Instruction to LiveVarSet Map
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//- for providing LV info for each inst
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void constructBBs(); // constructs BBLiveVars and init Def and In sets
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bool doSingleBackwardPass(); // do one backward pass over the CFG
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public:
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MethodLiveVarInfo(Method *const Meth); // constructor
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~MethodLiveVarInfo(); // destructor
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void analyze(); // performs a liver var analysis of a single method
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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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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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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 *
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MethodLiveVarInfo::getLiveVarSetBeforeInst(const Instruction *const Inst);
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};
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#endif
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