-/* Title: MethodLiveVarInfo.cpp
- Author: Ruchira Sasanka
- Date: Jun 30, 01
- Purpose:
+//===-- 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.
+//
+//===----------------------------------------------------------------------===//
- This is the interface for live variable info of a method that is required
- by any other part of the compiler.
+#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));
-#include "llvm/Analysis/LiveVar/MethodLiveVarInfo.h"
-#include "BBLiveVar.h"
-#include "llvm/CodeGen/MachineInstr.h"
-#include "llvm/BasicBlock.h"
-#include "Support/PostOrderIterator.h"
-#include <iostream>
-AnalysisID MethodLiveVarInfo::ID(AnalysisID::create<MethodLiveVarInfo>());
//-----------------------------------------------------------------------------
// Accessor Functions
//-----------------------------------------------------------------------------
// gets OutSet of a BB
-const LiveVarSet *MethodLiveVarInfo::getOutSetOfBB(const BasicBlock *BB) const {
- return BB2BBLVMap.find(BB)->second->getOutSet();
+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 LiveVarSet *MethodLiveVarInfo::getInSetOfBB(const BasicBlock *BB) const {
- return BB2BBLVMap.find(BB)->second->getInSet();
+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 method
+// Performs live var analysis for a function
//-----------------------------------------------------------------------------
-bool MethodLiveVarInfo::runOnMethod(Method *M) {
+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);
- while (doSingleBackwardPass(M))
+ unsigned int iter=0;
+ while (doSingleBackwardPass(M, iter++))
; // Iterate until we are done.
if (DEBUG_LV) std::cerr << "Live Variable Analysis complete!\n";
// constructs BBLiveVars and init Def and In sets
//-----------------------------------------------------------------------------
-void MethodLiveVarInfo::constructBBs(const Method *M) {
- unsigned int POId = 0; // Reverse Depth-first Order ID
-
- for(po_iterator<const Method*> BBI = po_begin(M), BBE = po_end(M);
- BBI != BBE; ++BBI, ++POId) {
- const BasicBlock *BB = *BBI; // get the current BB
-
- if (DEBUG_LV) { std::cerr << " For BB "; printValue(BB); cerr << ":\n"; }
-
- // create a new BBLiveVar
- BBLiveVar *LVBB = new BBLiveVar(BB, POId);
- BB2BBLVMap[BB] = LVBB; // insert the pair to Map
+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);
+ }
- LVBB->calcDefUseSets(); // calculates the def and in set
-
if (DEBUG_LV)
LVBB->printAllSets();
}
-
- // Since the PO iterator does not discover unreachable blocks,
- // go over the random iterator and init those blocks as well.
- // However, LV info is not correct for those blocks (they are not
- // analyzed)
- //
- for (Method::const_iterator BBRI = M->begin(), BBRE = M->end();
- BBRI != BBRE; ++BBRI, ++POId)
- if (!BB2BBLVMap[*BBRI]) // Not yet processed?
- BB2BBLVMap[*BBRI] = new BBLiveVar(*BBRI, POId);
}
// do one backward pass over the CFG (for iterative analysis)
//-----------------------------------------------------------------------------
-bool MethodLiveVarInfo::doSingleBackwardPass(const Method *M) {
- if (DEBUG_LV) std::cerr << "\n After Backward Pass ...\n";
+bool FunctionLiveVarInfo::doSingleBackwardPass(const Function *M,
+ unsigned iter) {
+ if (DEBUG_LV) std::cerr << "\n After Backward Pass " << iter << "...\n";
bool NeedAnotherIteration = false;
- for (po_iterator<const Method*> BBI = po_begin(M); BBI != po_end(M) ; ++BBI) {
- BBLiveVar *LVBB = BB2BBLVMap[*BBI];
+ 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) std::cerr << " For BB " << (*BBI)->getName() << ":\n";
+ // InSets are initialized to "GenSet". Recompute only if OutSet changed.
if(LVBB->isOutSetChanged())
LVBB->applyTransferFunc(); // apply the Tran Func to calc InSet
-
- if (LVBB->isInSetChanged()) // to calc Outsets of preds
- NeedAnotherIteration |= LVBB->applyFlowFunc(BB2BBLVMap);
-
+
+ // 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();
+
if (DEBUG_LV) LVBB->printInOutSets();
}
}
-void MethodLiveVarInfo::releaseMemory() {
- // First delete all BBLiveVar objects created in constructBBs(). A new object
- // of type BBLiveVar is created for every BasicBlock in the method
- //
- for (std::map<const BasicBlock *, BBLiveVar *>::iterator
- HMI = BB2BBLVMap.begin(),
- HME = BB2BBLVMap.end(); HMI != HME; ++HMI)
- delete HMI->second; // delete all BBLiveVar in BB2BBLVMap
-
- BB2BBLVMap.clear();
-
- // Then delete all objects of type LiveVarSet created in calcLiveVarSetsForBB
- // and entered into MInst2LVSetBI and MInst2LVSetAI (these are caches
- // to return LiveVarSet's before/after a machine instruction quickly). It
- // is sufficient to free up all LiveVarSet using only one cache since
- // both caches refer to the same sets
+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 (std::map<const MachineInstr*, const LiveVarSet*>::iterator
+ for (hash_map<const MachineInstr*, ValueSet*>::iterator
MI = MInst2LVSetBI.begin(),
ME = MInst2LVSetBI.end(); MI != ME; ++MI)
- delete MI->second; // delete all LiveVarSets in MInst2LVSetBI
+ delete MI->second; // delete all ValueSets in MInst2LVSetBI
MInst2LVSetBI.clear();
MInst2LVSetAI.clear();
//-----------------------------------------------------------------------------
// Following functions will give the LiveVar info for any machine instr in
-// a method. It should be called after a call to analyze().
+// 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 method does not require specific
+// block. Also, the arguments to this function does not require specific
// iterators.
//-----------------------------------------------------------------------------
// Gives live variable information before a machine instruction
//-----------------------------------------------------------------------------
-const LiveVarSet *
-MethodLiveVarInfo::getLiveVarSetBeforeMInst(const MachineInstr *MInst,
- const BasicBlock *BB) {
- if (const LiveVarSet *LVSet = MInst2LVSetBI[MInst]) {
- return LVSet; // if found, just return the set
- } else {
- calcLiveVarSetsForBB(BB); // else, calc for all instrs in BB
- return MInst2LVSetBI[MInst];
+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 *LVSet;
}
//-----------------------------------------------------------------------------
// Gives live variable information after a machine instruction
//-----------------------------------------------------------------------------
-const LiveVarSet *
-MethodLiveVarInfo::getLiveVarSetAfterMInst(const MachineInstr *MI,
- const BasicBlock *BB) {
- if (const LiveVarSet *LVSet = MInst2LVSetAI[MI]) {
- return LVSet; // if found, just return the set
- } else {
- calcLiveVarSetsForBB(BB); // else, calc for all instrs in BB
- return MInst2LVSetAI[MI];
+const ValueSet &
+FunctionLiveVarInfo::getLiveVarSetAfterMInst(const MachineInstr *MI,
+ const BasicBlock *BB) {
+
+ 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));
+ }
+
+ 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
+ }
+ // 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));
+}
//-----------------------------------------------------------------------------
// This method calculates the live variable information for all the
// variable sets into a the caches (MInst2LVSetAI, MInst2LVSetBI)
//-----------------------------------------------------------------------------
-void MethodLiveVarInfo::calcLiveVarSetsForBB(const BasicBlock *BB) {
- const MachineCodeForBasicBlock &MIVec = BB->getMachineInstrVec();
+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();
- LiveVarSet *CurSet = new LiveVarSet();
- const LiveVarSet *SetAI = getOutSetOfBB(BB); // init SetAI with OutSet
- CurSet->setUnion(SetAI); // CurSet now contains OutSet
+ 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 (MachineCodeForBasicBlock::const_reverse_iterator MII = MIVec.rbegin(),
+ 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
- CurSet->applyTranferFuncForMInst(MI); // apply the transfer Func
- LiveVarSet *NewSet = new LiveVarSet(); // create a new set and
- NewSet->setUnion(CurSet); // copy the set after T/F to it
-
+ 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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