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//===-- BBLiveVar.cpp - Live Variable Analysis for a BasicBlock -----------===//
//
// This is a wrapper class for BasicBlock which is used by live var analysis.
//
//===----------------------------------------------------------------------===//
#include "BBLiveVar.h"
#include "llvm/Analysis/LiveVar/MethodLiveVarInfo.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/BasicBlock.h"
/// BROKEN: Should not include sparc stuff directly into here
#include "../../Target/Sparc/SparcInternals.h" // Only for PHI defn
using std::cerr;
BBLiveVar::BBLiveVar(const BasicBlock *bb, unsigned id)
: BB(bb), POID(id) {
InSetChanged = OutSetChanged = false;
}
//-----------------------------------------------------------------------------
// calculates def and use sets for each BB
// There are two passes over operands of a machine instruction. This is
// because, we can have instructions like V = V + 1, since we no longer
// assume single definition.
//-----------------------------------------------------------------------------
void BBLiveVar::calcDefUseSets() {
// get the iterator for machine instructions
const MachineCodeForBasicBlock &MIVec = BB->getMachineInstrVec();
// iterate over all the machine instructions in BB
for (MachineCodeForBasicBlock::const_reverse_iterator MII = MIVec.rbegin(),
MIE = MIVec.rend(); MII != MIE; ++MII) {
const MachineInstr *MI = *MII;
if (DEBUG_LV > 1) { // debug msg
cerr << " *Iterating over machine instr ";
MI->dump();
cerr << "\n";
}
// iterate over MI operands to find defs
for (MachineInstr::val_const_op_iterator OpI(MI); !OpI.done(); ++OpI)
if (OpI.isDef()) // add to Defs only if this operand is a def
addDef(*OpI);
// do for implicit operands as well
for (unsigned i = 0; i < MI->getNumImplicitRefs(); ++i)
if (MI->implicitRefIsDefined(i))
addDef(MI->getImplicitRef(i));
bool IsPhi = MI->getOpCode() == PHI;
// iterate over MI operands to find uses
for (MachineInstr::val_const_op_iterator OpI(MI); !OpI.done(); ++OpI) {
const Value *Op = *OpI;
if (Op->getType()->isLabelType())
continue; // don't process labels
if (!OpI.isDef()) { // add to Defs only if this operand is a use
addUse(Op);
if (IsPhi) { // for a phi node
// put args into the PhiArgMap (Val -> BB)
const Value *ArgVal = Op;
const Value *BBVal = *++OpI; // increment to point to BB of value
PhiArgMap[ArgVal] = cast<BasicBlock>(BBVal);
if (DEBUG_LV > 1)
cerr << " - phi operand " << RAV(ArgVal) << " came from BB "
<< RAV(PhiArgMap[ArgVal]) << "\n";
} // if( IsPhi )
} // if a use
} // for all operands
// do for implicit operands as well
for (unsigned i = 0; i < MI->getNumImplicitRefs(); ++i) {
assert(!IsPhi && "Phi cannot have implicit opeands");
const Value *Op = MI->getImplicitRef(i);
if (Op->getType()->isLabelType()) // don't process labels
continue;
if (!MI->implicitRefIsDefined(i))
addUse(Op);
}
} // for all machine instructions
}
//-----------------------------------------------------------------------------
// To add an operand which is a def
//-----------------------------------------------------------------------------
void BBLiveVar::addDef(const Value *Op) {
DefSet.insert(Op); // operand is a def - so add to def set
InSet.erase(Op); // this definition kills any uses
InSetChanged = true;
if (DEBUG_LV > 1) cerr << " +Def: " << RAV(Op) << "\n";
}
//-----------------------------------------------------------------------------
// To add an operand which is a use
//-----------------------------------------------------------------------------
void BBLiveVar::addUse(const Value *Op) {
InSet.insert(Op); // An operand is a use - so add to use set
OutSet.erase(Op); // remove if there is a def below this use
InSetChanged = true;
if (DEBUG_LV > 1) cerr << " Use: " << RAV(Op) << "\n";
}
//-----------------------------------------------------------------------------
// Applies the transfer function to a basic block to produce the InSet using
// the outset.
//-----------------------------------------------------------------------------
bool BBLiveVar::applyTransferFunc() {
// IMPORTANT: caller should check whether the OutSet changed
// (else no point in calling)
LiveVarSet OutMinusDef; // set to hold (Out[B] - Def[B])
OutMinusDef.setDifference(&OutSet, &DefSet);
InSetChanged = InSet.setUnion(&OutMinusDef);
OutSetChanged = false; // no change to OutSet since transf func applied
return InSetChanged;
}
//-----------------------------------------------------------------------------
// calculates Out set using In sets of the predecessors
//-----------------------------------------------------------------------------
bool BBLiveVar::setPropagate(LiveVarSet *OutSet, const LiveVarSet *InSet,
const BasicBlock *PredBB) {
bool Changed = false;
// for all all elements in InSet
for (LiveVarSet::const_iterator InIt = InSet->begin(), InE = InSet->end();
InIt != InE; ++InIt) {
const BasicBlock *PredBBOfPhiArg = PhiArgMap[*InIt];
// if this var is not a phi arg OR
// it's a phi arg and the var went down from this BB
if (!PredBBOfPhiArg || PredBBOfPhiArg == PredBB)
if (OutSet->insert(*InIt).second)
Changed = true;
}
return Changed;
}
//-----------------------------------------------------------------------------
// propogates in set to OutSets of PREDECESSORs
//-----------------------------------------------------------------------------
bool BBLiveVar::applyFlowFunc(std::map<const BasicBlock *, BBLiveVar *> &LVMap){
// IMPORTANT: caller should check whether inset changed
// (else no point in calling)
// If this BB changed any OutSets of preds whose POID is lower, than we need
// another iteration...
//
bool needAnotherIt = false;
for (BasicBlock::pred_const_iterator PI = BB->pred_begin(),
PE = BB->pred_begin(); PI != PE ; ++PI) {
BBLiveVar *PredLVBB = LVMap[*PI];
// do set union
if (setPropagate(&PredLVBB->OutSet, &InSet, *PI)) {
PredLVBB->OutSetChanged = true;
// if the predec POID is lower than mine
if (PredLVBB->getPOId() <= POID)
needAnotherIt = true;
}
} // for
return needAnotherIt;
}
// ----------------- Methods For Debugging (Printing) -----------------
void BBLiveVar::printAllSets() const {
cerr << " Defs: "; DefSet.printSet(); cerr << "\n";
cerr << " In: "; InSet.printSet(); cerr << "\n";
cerr << " Out: "; OutSet.printSet(); cerr << "\n";
}
void BBLiveVar::printInOutSets() const {
cerr << " In: "; InSet.printSet(); cerr << "\n";
cerr << " Out: "; OutSet.printSet(); cerr << "\n";
}
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