llvm-6502/lib/Target/SparcV9/LiveVar/FunctionLiveVarInfo.cpp

284 lines
11 KiB
C++

//===-- 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/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();
}
// gets InSet of a BB
const ValueSet &FunctionLiveVarInfo::getInSetOfBB(const BasicBlock *BB) const {
return BBLiveVar::GetFromBB(*BB)->getInSet();
}
//-----------------------------------------------------------------------------
// Performs live var analysis for a function
//-----------------------------------------------------------------------------
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);
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;
}
//-----------------------------------------------------------------------------
// 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();
}
}
//-----------------------------------------------------------------------------
// do one backward pass over the CFG (for iterative analysis)
//-----------------------------------------------------------------------------
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 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
// 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();
}
// true if we need to reiterate over the CFG
return NeedAnotherIteration;
}
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). It
// is sufficient to free up all ValueSet using only one cache since
// both caches refer to the same sets
//
for (std::map<const MachineInstr*, const ValueSet*>::iterator
MI = MInst2LVSetBI.begin(),
ME = MInst2LVSetBI.end(); MI != ME; ++MI)
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 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.
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// Gives live variable information before a machine instruction
//-----------------------------------------------------------------------------
const ValueSet &
FunctionLiveVarInfo::getLiveVarSetBeforeMInst(const MachineInstr *MInst,
const BasicBlock *BB) {
if (const ValueSet *LVSet = MInst2LVSetBI[MInst]) {
return *LVSet; // if found, just return the set
} else {
calcLiveVarSetsForBB(BB); // else, calc for all instrs in BB
return *MInst2LVSetBI[MInst];
}
}
//-----------------------------------------------------------------------------
// Gives live variable information after a machine instruction
//-----------------------------------------------------------------------------
const ValueSet &
FunctionLiveVarInfo::getLiveVarSetAfterMInst(const MachineInstr *MI,
const BasicBlock *BB) {
if (const ValueSet *LVSet = MInst2LVSetAI[MI]) {
return *LVSet; // if found, just return the set
} else {
calcLiveVarSetsForBB(BB); // else, calc for all instrs in BB
return *MInst2LVSetAI[MI];
}
}
// 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.isDef()) // kill only 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->implicitRefIsDefined(i))
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.isDef() || 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->implicitRefIsDefined(i) ||
MInst->implicitRefIsDefinedAndUsed(i))
LVS.insert(MInst->getImplicitRef(i));
}
//-----------------------------------------------------------------------------
// 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();
if (DEBUG_LV >= LV_DEBUG_Instr)
std::cerr << "\n======For BB " << BB->getName()
<< ": Live var sets for instructions======\n";
ValueSet CurSet;
const ValueSet *SetAI = &getOutSetOfBB(BB); // init SetAI with OutSet
set_union(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(); // create a new set and
set_union(*NewSet, CurSet); // copy the set after T/F to it
MInst2LVSetBI[MI] = NewSet; // record in Before Inst map
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;
}
}