1 //===-- BBLiveVar.cpp - Live Variable Analysis for a BasicBlock -----------===//
3 // This is a wrapper class for BasicBlock which is used by live var analysis.
5 //===----------------------------------------------------------------------===//
8 #include "llvm/Analysis/LiveVar/MethodLiveVarInfo.h"
9 #include "llvm/CodeGen/MachineInstr.h"
10 #include "llvm/BasicBlock.h"
11 #include "Support/SetOperations.h"
13 /// BROKEN: Should not include sparc stuff directly into here
14 #include "../../Target/Sparc/SparcInternals.h" // Only for PHI defn
18 BBLiveVar::BBLiveVar(const BasicBlock *bb, unsigned id)
20 InSetChanged = OutSetChanged = false;
23 //-----------------------------------------------------------------------------
24 // calculates def and use sets for each BB
25 // There are two passes over operands of a machine instruction. This is
26 // because, we can have instructions like V = V + 1, since we no longer
27 // assume single definition.
28 //-----------------------------------------------------------------------------
30 void BBLiveVar::calcDefUseSets() {
31 // get the iterator for machine instructions
32 const MachineCodeForBasicBlock &MIVec = BB->getMachineInstrVec();
34 // iterate over all the machine instructions in BB
35 for (MachineCodeForBasicBlock::const_reverse_iterator MII = MIVec.rbegin(),
36 MIE = MIVec.rend(); MII != MIE; ++MII) {
37 const MachineInstr *MI = *MII;
39 if (DEBUG_LV > 1) { // debug msg
40 cerr << " *Iterating over machine instr ";
45 // iterate over MI operands to find defs
46 for (MachineInstr::val_const_op_iterator OpI(MI); !OpI.done(); ++OpI)
47 if (OpI.isDef()) // add to Defs only if this operand is a def
50 // do for implicit operands as well
51 for (unsigned i = 0; i < MI->getNumImplicitRefs(); ++i)
52 if (MI->implicitRefIsDefined(i))
53 addDef(MI->getImplicitRef(i));
55 bool IsPhi = MI->getOpCode() == PHI;
57 // iterate over MI operands to find uses
58 for (MachineInstr::val_const_op_iterator OpI(MI); !OpI.done(); ++OpI) {
59 const Value *Op = *OpI;
61 if (Op->getType()->isLabelType())
62 continue; // don't process labels
64 if (!OpI.isDef()) { // add to Defs only if this operand is a use
67 if (IsPhi) { // for a phi node
68 // put args into the PhiArgMap (Val -> BB)
69 const Value *ArgVal = Op;
70 const Value *BBVal = *++OpI; // increment to point to BB of value
72 PhiArgMap[ArgVal] = cast<BasicBlock>(BBVal);
75 cerr << " - phi operand " << RAV(ArgVal) << " came from BB "
76 << RAV(PhiArgMap[ArgVal]) << "\n";
81 // do for implicit operands as well
82 for (unsigned i = 0; i < MI->getNumImplicitRefs(); ++i) {
83 assert(!IsPhi && "Phi cannot have implicit opeands");
84 const Value *Op = MI->getImplicitRef(i);
86 if (Op->getType()->isLabelType()) // don't process labels
89 if (!MI->implicitRefIsDefined(i))
92 } // for all machine instructions
97 //-----------------------------------------------------------------------------
98 // To add an operand which is a def
99 //-----------------------------------------------------------------------------
100 void BBLiveVar::addDef(const Value *Op) {
101 DefSet.insert(Op); // operand is a def - so add to def set
102 InSet.erase(Op); // this definition kills any uses
105 if (DEBUG_LV > 1) cerr << " +Def: " << RAV(Op) << "\n";
109 //-----------------------------------------------------------------------------
110 // To add an operand which is a use
111 //-----------------------------------------------------------------------------
112 void BBLiveVar::addUse(const Value *Op) {
113 InSet.insert(Op); // An operand is a use - so add to use set
114 OutSet.erase(Op); // remove if there is a def below this use
117 if (DEBUG_LV > 1) cerr << " Use: " << RAV(Op) << "\n";
121 //-----------------------------------------------------------------------------
122 // Applies the transfer function to a basic block to produce the InSet using
124 //-----------------------------------------------------------------------------
126 bool BBLiveVar::applyTransferFunc() {
127 // IMPORTANT: caller should check whether the OutSet changed
128 // (else no point in calling)
130 ValueSet OutMinusDef = set_difference(OutSet, DefSet);
131 InSetChanged = set_union(InSet, OutMinusDef);
133 OutSetChanged = false; // no change to OutSet since transf func applied
138 //-----------------------------------------------------------------------------
139 // calculates Out set using In sets of the predecessors
140 //-----------------------------------------------------------------------------
142 bool BBLiveVar::setPropagate(ValueSet *OutSet, const ValueSet *InSet,
143 const BasicBlock *PredBB) {
144 bool Changed = false;
146 // for all all elements in InSet
147 for (ValueSet::const_iterator InIt = InSet->begin(), InE = InSet->end();
148 InIt != InE; ++InIt) {
149 const BasicBlock *PredBBOfPhiArg = PhiArgMap[*InIt];
151 // if this var is not a phi arg OR
152 // it's a phi arg and the var went down from this BB
153 if (!PredBBOfPhiArg || PredBBOfPhiArg == PredBB)
154 if (OutSet->insert(*InIt).second)
162 //-----------------------------------------------------------------------------
163 // propogates in set to OutSets of PREDECESSORs
164 //-----------------------------------------------------------------------------
166 bool BBLiveVar::applyFlowFunc(std::map<const BasicBlock *, BBLiveVar *> &LVMap){
167 // IMPORTANT: caller should check whether inset changed
168 // (else no point in calling)
170 // If this BB changed any OutSets of preds whose POID is lower, than we need
171 // another iteration...
173 bool needAnotherIt = false;
175 for (BasicBlock::pred_const_iterator PI = BB->pred_begin(),
176 PE = BB->pred_begin(); PI != PE ; ++PI) {
177 BBLiveVar *PredLVBB = LVMap[*PI];
180 if (setPropagate(&PredLVBB->OutSet, &InSet, *PI)) {
181 PredLVBB->OutSetChanged = true;
183 // if the predec POID is lower than mine
184 if (PredLVBB->getPOId() <= POID)
185 needAnotherIt = true;
189 return needAnotherIt;
194 // ----------------- Methods For Debugging (Printing) -----------------
196 void BBLiveVar::printAllSets() const {
197 cerr << " Defs: "; printSet(DefSet); cerr << "\n";
198 cerr << " In: "; printSet(InSet); cerr << "\n";
199 cerr << " Out: "; printSet(OutSet); cerr << "\n";
202 void BBLiveVar::printInOutSets() const {
203 cerr << " In: "; printSet(InSet); cerr << "\n";
204 cerr << " Out: "; printSet(OutSet); cerr << "\n";