-/* 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"
+//===-- FunctionLiveVarInfo.cpp - Live Variable Analysis for a Function ---===//
+//
+// This is the interface to function level live variable information that is
+// provided by live variable analysis.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/FunctionLiveVarInfo.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Support/CFG.h"
+#include "Support/PostOrderIterator.h"
+#include "Support/SetOperations.h"
+#include "Support/CommandLine.h"
+#include "BBLiveVar.h"
+
+static RegisterAnalysis<FunctionLiveVarInfo>
+X("livevar", "Live Variable Analysis");
+
+LiveVarDebugLevel_t DEBUG_LV;
+
+static cl::opt<LiveVarDebugLevel_t, true>
+DEBUG_LV_opt("dlivevar", cl::Hidden, cl::location(DEBUG_LV),
+ cl::desc("enable live-variable debugging information"),
+ cl::values(
+clEnumValN(LV_DEBUG_None , "n", "disable debug output"),
+clEnumValN(LV_DEBUG_Normal , "y", "enable debug output"),
+clEnumValN(LV_DEBUG_Instr, "i", "print live-var sets before/after "
+ "every machine instrn"),
+clEnumValN(LV_DEBUG_Verbose, "v", "print def, use sets for every instrn also"),
+ 0));
+
+
+
+//-----------------------------------------------------------------------------
+// Accessor Functions
+//-----------------------------------------------------------------------------
+
+// gets OutSet of a BB
+const ValueSet &FunctionLiveVarInfo::getOutSetOfBB(const BasicBlock *BB) const {
+ return BBLiveVar::GetFromBB(*BB)->getOutSet();
+}
+ ValueSet &FunctionLiveVarInfo::getOutSetOfBB(const BasicBlock *BB) {
+ return BBLiveVar::GetFromBB(*BB)->getOutSet();
+}
+// gets InSet of a BB
+const ValueSet &FunctionLiveVarInfo::getInSetOfBB(const BasicBlock *BB) const {
+ return BBLiveVar::GetFromBB(*BB)->getInSet();
+}
+ ValueSet &FunctionLiveVarInfo::getInSetOfBB(const BasicBlock *BB) {
+ return BBLiveVar::GetFromBB(*BB)->getInSet();
+}
+//-----------------------------------------------------------------------------
+// Performs live var analysis for a function
+//-----------------------------------------------------------------------------
-/************************** Constructor/Destructor ***************************/
+bool FunctionLiveVarInfo::runOnFunction(Function &F) {
+ M = &F;
+ if (DEBUG_LV) std::cerr << "Analysing live variables ...\n";
+ // create and initialize all the BBLiveVars of the CFG
+ constructBBs(M);
-MethodLiveVarInfo::MethodLiveVarInfo(Method *const MethPtr) : BB2BBLVMap()
-{
- Meth = MethPtr; // init BB2BBLVMap and records Method for future use
+ unsigned int iter=0;
+ while (doSingleBackwardPass(M, iter++))
+ ; // Iterate until we are done.
+
+ if (DEBUG_LV) std::cerr << "Live Variable Analysis complete!\n";
+ return false;
}
-
-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;
- }
+//-----------------------------------------------------------------------------
+// constructs BBLiveVars and init Def and In sets
+//-----------------------------------------------------------------------------
+
+void FunctionLiveVarInfo::constructBBs(const Function *F) {
+ unsigned POId = 0; // Reverse Depth-first Order ID
+ std::map<const BasicBlock*, unsigned> PONumbering;
+
+ for (po_iterator<const Function*> BBI = po_begin(M), BBE = po_end(M);
+ BBI != BBE; ++BBI)
+ PONumbering[*BBI] = POId++;
+
+ MachineFunction &MF = MachineFunction::get(F);
+ for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
+ const BasicBlock &BB = *I->getBasicBlock(); // get the current BB
+ if (DEBUG_LV) std::cerr << " For BB " << RAV(BB) << ":\n";
+
+ BBLiveVar *LVBB;
+ std::map<const BasicBlock*, unsigned>::iterator POI = PONumbering.find(&BB);
+ if (POI != PONumbering.end()) {
+ // create a new BBLiveVar
+ LVBB = BBLiveVar::CreateOnBB(BB, *I, POId);
+ } else {
+ // The PO iterator does not discover unreachable blocks, but the random
+ // iterator later may access these blocks. We must make sure to
+ // initialize unreachable blocks as well. However, LV info is not correct
+ // for those blocks (they are not analyzed)
+ //
+ LVBB = BBLiveVar::CreateOnBB(BB, *I, ++POId);
+ }
+
+ if (DEBUG_LV)
+ LVBB->printAllSets();
+ }
}
-// -------------------------- support functions -------------------------------
-
-
-
- // constructs BBLiveVars and init Def and In sets
-void MethodLiveVarInfo::constructBBs()
-{
- unsigned int POId = 0; // Reverse Depth-first Order ID
+//-----------------------------------------------------------------------------
+// do one backward pass over the CFG (for iterative analysis)
+//-----------------------------------------------------------------------------
- cfg::po_const_iterator BBI = cfg::po_begin(Meth);
+bool FunctionLiveVarInfo::doSingleBackwardPass(const Function *M,
+ unsigned iter) {
+ if (DEBUG_LV) std::cerr << "\n After Backward Pass " << iter << "...\n";
- for( ; BBI != cfg::po_end(Meth) ; ++BBI, ++POId)
- {
+ bool NeedAnotherIteration = false;
+ for (po_iterator<const Function*> BBI = po_begin(M), BBE = po_end(M);
+ BBI != BBE; ++BBI) {
+ BBLiveVar *LVBB = BBLiveVar::GetFromBB(**BBI);
+ assert(LVBB && "BasicBlock information not set for block!");
- if(DEBUG_LV) cout << "-- For BB " << (*BBI)->getName() << ":" << endl ;
+ if (DEBUG_LV) std::cerr << " For BB " << (*BBI)->getName() << ":\n";
- const BasicBlock *BB = *BBI; // get the current BB
- BBLiveVar * LVBB = new BBLiveVar( BB, POId ); // create a new BBLiveVar
+ // InSets are initialized to "GenSet". Recompute only if OutSet changed.
+ if(LVBB->isOutSetChanged())
+ LVBB->applyTransferFunc(); // apply the Tran Func to calc InSet
- BB2BBLVMap[ BB ] = LVBB; // insert the pair to Map
+ // OutSets are initialized to EMPTY. Recompute on first iter or if InSet
+ // changed.
+ if (iter == 0 || LVBB->isInSetChanged()) // to calc Outsets of preds
+ NeedAnotherIteration |= LVBB->applyFlowFunc();
- LVBB->calcDefUseSets(); // calculates the def and in set
-
- if(DEBUG_LV) LVBB->printAllSets();
- //cout << "InSetChanged: " << LVBB->isInSetChanged() << endl;
+ if (DEBUG_LV) LVBB->printInOutSets();
}
-
+ // true if we need to reiterate over the CFG
+ return NeedAnotherIteration;
}
- // 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 );
+void FunctionLiveVarInfo::releaseMemory() {
+ // First remove all BBLiveVar annotations created in constructBBs().
+ if (M)
+ for (Function::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
+ BBLiveVar::RemoveFromBB(*I);
+ M = 0;
+
+ // Then delete all objects of type ValueSet created in calcLiveVarSetsForBB
+ // and entered into MInst2LVSetBI and MInst2LVSetAI (these are caches
+ // to return ValueSet's before/after a machine instruction quickly).
+ // We do not need to free up ValueSets in MInst2LVSetAI because it holds
+ // pointers to the same sets as in MInst2LVSetBI (for all instructions
+ // except the last one in a BB) or in BBLiveVar (for the last instruction).
+ //
+ for (hash_map<const MachineInstr*, ValueSet*>::iterator
+ MI = MInst2LVSetBI.begin(),
+ ME = MInst2LVSetBI.end(); MI != ME; ++MI)
+ delete MI->second; // delete all ValueSets in MInst2LVSetBI
+
+ MInst2LVSetBI.clear();
+ MInst2LVSetAI.clear();
+}
- 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;
+//-----------------------------------------------------------------------------
+// Following functions will give the LiveVar info for any machine instr in
+// a function. It should be called after a call to analyze().
+//
+// Thsese functions calucluates live var info for all the machine instrs 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 function does not require specific
+// iterators.
+//-----------------------------------------------------------------------------
- if( ResultFlow ) NeedAnotherIteration = true;
+//-----------------------------------------------------------------------------
+// Gives live variable information before a machine instruction
+//-----------------------------------------------------------------------------
+const ValueSet &
+FunctionLiveVarInfo::getLiveVarSetBeforeMInst(const MachineInstr *MI,
+ const BasicBlock *BB) {
+ ValueSet* &LVSet = MInst2LVSetBI[MI]; // ref. to map entry
+ if (LVSet == NULL && BB != NULL) { // if not found and BB provided
+ calcLiveVarSetsForBB(BB); // calc LVSet for all instrs in BB
+ assert(LVSet != NULL);
}
-
- return NeedAnotherIteration; // true if we need to reiterate over the CFG
+ return *LVSet;
}
+//-----------------------------------------------------------------------------
+// Gives live variable information after a machine instruction
+//-----------------------------------------------------------------------------
+const ValueSet &
+FunctionLiveVarInfo::getLiveVarSetAfterMInst(const MachineInstr *MI,
+ const BasicBlock *BB) {
-
-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
+ ValueSet* &LVSet = MInst2LVSetAI[MI]; // ref. to map entry
+ if (LVSet == NULL && BB != NULL) { // if not found and BB provided
+ calcLiveVarSetsForBB(BB); // calc LVSet for all instrs in BB
+ assert(LVSet != NULL);
+ }
+ return *LVSet;
}
+// This function applies a machine instr to a live var set (accepts OutSet) and
+// makes necessary changes to it (produces InSet). Note that two for loops are
+// used to first kill all defs and then to add all uses. This is because there
+// can be instructions like Val = Val + 1 since we allow multipe defs to a
+// machine instruction operand.
+//
+static void applyTranferFuncForMInst(ValueSet &LVS, const MachineInstr *MInst) {
+ for (MachineInstr::const_val_op_iterator OpI = MInst->begin(),
+ OpE = MInst->end(); OpI != OpE; ++OpI) {
+ if (OpI.isDefOnly() || OpI.isDefAndUse()) // kill if this operand is a def
+ LVS.erase(*OpI); // this definition kills any uses
+ }
+ // do for implicit operands as well
+ for (unsigned i=0; i < MInst->getNumImplicitRefs(); ++i) {
+ if (MInst->getImplicitOp(i).opIsDefOnly() ||
+ MInst->getImplicitOp(i).opIsDefAndUse())
+ LVS.erase(MInst->getImplicitRef(i));
+ }
-
-/* 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
+ for (MachineInstr::const_val_op_iterator OpI = MInst->begin(),
+ OpE = MInst->end(); OpI != OpE; ++OpI) {
+ if (!isa<BasicBlock>(*OpI)) // don't process labels
+ // add only if this operand is a use
+ if (!OpI.isDefOnly() || OpI.isDefAndUse() )
+ LVS.insert(*OpI); // An operand is a use - so add to use set
}
- return Inst2LVSetMap[Inst];
+ // do for implicit operands as well
+ for (unsigned i = 0, e = MInst->getNumImplicitRefs(); i != e; ++i)
+ if (MInst->getImplicitOp(i).opIsUse() ||
+ MInst->getImplicitOp(i).opIsDefAndUse())
+ LVS.insert(MInst->getImplicitRef(i));
}
-
-
-/*
-NOTES: delete all the LVBBs allocated by adding a destructor to the BB2BBLVMap???
- use the dfo_iterator in the doSingleBackwardPass
-*/
-
-
-
-
-
-
-
-
-
-
-
+//-----------------------------------------------------------------------------
+// This method calculates the live variable information for all the
+// instructions in a basic block and enter the newly constructed live
+// variable sets into a the caches (MInst2LVSetAI, MInst2LVSetBI)
+//-----------------------------------------------------------------------------
+
+void FunctionLiveVarInfo::calcLiveVarSetsForBB(const BasicBlock *BB) {
+ BBLiveVar *BBLV = BBLiveVar::GetFromBB(*BB);
+ assert(BBLV && "BBLiveVar annotation doesn't exist?");
+ const MachineBasicBlock &MIVec = BBLV->getMachineBasicBlock();
+ const MachineFunction &MF = MachineFunction::get(M);
+ const TargetMachine &TM = MF.getTarget();
+
+ if (DEBUG_LV >= LV_DEBUG_Instr)
+ std::cerr << "\n======For BB " << BB->getName()
+ << ": Live var sets for instructions======\n";
+
+ ValueSet *SetAI = &getOutSetOfBB(BB); // init SetAI with OutSet
+ ValueSet CurSet(*SetAI); // CurSet now contains OutSet
+
+ // iterate over all the machine instructions in BB
+ for (MachineBasicBlock::const_reverse_iterator MII = MIVec.rbegin(),
+ MIE = MIVec.rend(); MII != MIE; ++MII) {
+ // MI is cur machine inst
+ const MachineInstr *MI = *MII;
+
+ MInst2LVSetAI[MI] = SetAI; // record in After Inst map
+
+ applyTranferFuncForMInst(CurSet, MI); // apply the transfer Func
+ ValueSet *NewSet = new ValueSet(CurSet); // create a new set with a copy
+ // of the set after T/F
+ MInst2LVSetBI[MI] = NewSet; // record in Before Inst map
+
+ // If the current machine instruction has delay slots, mark values
+ // used by this instruction as live before and after each delay slot
+ // instruction (After(MI) is the same as Before(MI+1) except for last MI).
+ if (unsigned DS = TM.getInstrInfo().getNumDelaySlots(MI->getOpCode())) {
+ MachineBasicBlock::const_iterator fwdMII = MII.base(); // ptr to *next* MI
+ for (unsigned i = 0; i < DS; ++i, ++fwdMII) {
+ assert(fwdMII != MIVec.end() && "Missing instruction in delay slot?");
+ MachineInstr* DelaySlotMI = *fwdMII;
+ if (! TM.getInstrInfo().isNop(DelaySlotMI->getOpCode())) {
+ set_union(*MInst2LVSetBI[DelaySlotMI], *NewSet);
+ if (i+1 == DS)
+ set_union(*MInst2LVSetAI[DelaySlotMI], *NewSet);
+ }
+ }
+ }
+
+ if (DEBUG_LV >= LV_DEBUG_Instr) {
+ std::cerr << "\nLive var sets before/after instruction " << *MI;
+ std::cerr << " Before: "; printSet(*NewSet); std::cerr << "\n";
+ std::cerr << " After : "; printSet(*SetAI); std::cerr << "\n";
+ }
+
+ // SetAI will be used in the next iteration
+ SetAI = NewSet;
+ }
+}
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