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/* Title: ValueSet.h
Author: Ruchira Sasanka
Date: Jun 30, 01
Purpose:
This is the interface for live variable info of a method that is required by
any other part of the compiler.
*/
#include "llvm/Analysis/LiveVar/MethodLiveVarInfo.h"
/************************** Constructor/Destructor ***************************/
MethodLiveVarInfo::MethodLiveVarInfo(Method *const MethPtr) : BB2BBLVMap()
{
Meth = MethPtr; // init BB2BBLVMap and records Method for future use
}
MethodLiveVarInfo:: ~MethodLiveVarInfo()
{
BBToBBLiveVarMapType::iterator HMI = BB2BBLVMap.begin(); // hash map iterator
for( ; HMI != BB2BBLVMap.end() ; HMI ++ ) {
if( (*HMI).first ) // delete all LiveVarSets in BB2BBLVMap
delete (*HMI).second;
}
}
// -------------------------- support functions -------------------------------
// constructs BBLiveVars and init Def and In sets
void MethodLiveVarInfo::constructBBs()
{
unsigned int POId = 0; // Reverse Depth-first Order ID
cfg::po_const_iterator BBI = cfg::po_begin(Meth);
for( ; BBI != cfg::po_end(Meth) ; ++BBI, ++POId)
{
if(DEBUG_LV) cout << "-- For BB " << (*BBI)->getName() << ":" << endl ;
const BasicBlock *BB = *BBI; // get the current BB
BBLiveVar * LVBB = new BBLiveVar( BB, POId ); // create a new BBLiveVar
BB2BBLVMap[ BB ] = LVBB; // insert the pair to Map
LVBB->calcDefUseSets(); // calculates the def and in set
if(DEBUG_LV) LVBB->printAllSets();
//cout << "InSetChanged: " << LVBB->isInSetChanged() << endl;
}
}
// do one backward pass over the CFG
bool MethodLiveVarInfo::doSingleBackwardPass()
{
bool ResultFlow, NeedAnotherIteration = false;
if(DEBUG_LV) cout << endl << "------- After Backward Pass --------" << endl;
cfg::po_const_iterator BBI = cfg::po_begin(Meth);
for( ; BBI != cfg::po_end(Meth) ; ++BBI)
{
BBLiveVar* LVBB = BB2BBLVMap[*BBI];
assert( LVBB );
if(DEBUG_LV) cout << "-- For BB " << (*BBI)->getName() << ":" << endl;
// cout << " (POId=" << LVBB->getPOId() << ")" << endl ;
ResultFlow = false;
if( LVBB->isOutSetChanged() )
LVBB->applyTransferFunc(); // apply the Transfer Func to calc the InSet
if( LVBB->isInSetChanged() )
ResultFlow = LVBB->applyFlowFunc( BB2BBLVMap ); // to calc Outsets of preds
if(DEBUG_LV) LVBB->printInOutSets();
//cout << "InChanged = " << LVBB->isInSetChanged()
//cout << " UpdatedBBwithLowerPOId = " << ResultFlow << endl;
if( ResultFlow ) NeedAnotherIteration = true;
}
return NeedAnotherIteration; // true if we need to reiterate over the CFG
}
void MethodLiveVarInfo::analyze() // performs live var anal for a method
{
//cout << "In analyze . . ." << cout;
constructBBs(); // create and initialize all the BBLiveVars of the CFG
bool NeedAnotherIteration = false;
do {
NeedAnotherIteration = doSingleBackwardPass( ); // do one pass over CFG
} while (NeedAnotherIteration ); // repeat until we need more iterations
}
/* This function will give the LiveVar info for any instruction in a method. It
should be called after a call to analyze().
This function calucluates live var info for all the instructions in a BB,
when LVInfo for one inst is requested. Hence, this function is useful when
live var info is required for many (or all) instructions in a basic block
Also, the arguments to this method does not require specific iterators
*/
const LiveVarSet *
MethodLiveVarInfo::getLiveVarSetBeforeInst(const Instruction *const Inst)
{
// get the BB corresponding to the instruction
const BasicBlock *const CurBB = Inst->getParent();
const LiveVarSet *LVSet = Inst2LVSetMap[Inst];
if( LVSet ) return LVSet; // if found, just return the set
const BasicBlock::InstListType& InstListInBB = CurBB->getInstList();
BasicBlock::InstListType::const_reverse_iterator
InstItEnd= InstListInBB.rend() - 1; // InstItEnd is set to the first instr
// LVSet of first instr = InSet
Inst2LVSetMap[*InstItEnd] = getInSetOfBB( CurBB );
// if the first instruction is requested, just return the InSet
if( Inst == *InstItEnd) return Inst2LVSetMap[Inst];
// else calculate for all other instruction in the BB
BasicBlock::InstListType::const_reverse_iterator
InstIt= InstListInBB.rbegin(); // get the iterator for instructions in BB
LiveVarSet *CurSet = new LiveVarSet();
CurSet->setUnion( getOutSetOfBB( CurBB )); // LVSet now contains the OutSet
// calculate LVSet for all instructions in the basic block (except the first)
for( ; InstIt != InstItEnd ; InstIt++) {
CurSet->applyTranferFuncForInst( *InstIt ); // apply the transfer Func
LiveVarSet *NewSet = new LiveVarSet(); // create a new set and
NewSet->setUnion( CurSet ); // copy the set after T/F to it
Inst2LVSetMap[*InstIt] = NewSet; // record that in the map
}
return Inst2LVSetMap[Inst];
}
/*
NOTES: delete all the LVBBs allocated by adding a destructor to the BB2BBLVMap???
use the dfo_iterator in the doSingleBackwardPass
*/
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