1 #include "llvm/CodeGen/LiveRangeInfo.h"
3 LiveRangeInfo::LiveRangeInfo(const Method *const M,
4 const TargetMachine& tm,
5 vector<RegClass *> &RCL)
6 : Meth(M), LiveRangeMap(),
7 TM(tm), RegClassList(RCL),
13 // union two live ranges into one. The 2nd LR is deleted. Used for coalescing.
14 // Note: the caller must make sure that L1 and L2 are distinct and both
15 // LRs don't have suggested colors
17 void LiveRangeInfo::unionAndUpdateLRs(LiveRange *const L1, LiveRange *L2)
20 L1->setUnion( L2 ); // add elements of L2 to L1
21 ValueSet::iterator L2It;
23 for( L2It = L2->begin() ; L2It != L2->end(); ++L2It) {
25 //assert(( L1->getTypeID() == L2->getTypeID()) && "Merge:Different types");
27 L1->add( *L2It ); // add the var in L2 to L1
28 LiveRangeMap[ *L2It ] = L1; // now the elements in L2 should map to L1
32 // Now if LROfDef(L1) has a suggested color, it will remain.
33 // But, if LROfUse(L2) has a suggested color, the new range
34 // must have the same color.
36 if(L2->hasSuggestedColor())
37 L1->setSuggestedColor( L2->getSuggestedColor() );
39 delete ( L2 ); // delete L2 as it is no longer needed
45 void LiveRangeInfo::constructLiveRanges()
49 cout << "Consturcting Live Ranges ..." << endl;
51 // first find the live ranges for all incoming args of the method since
52 // those LRs start from the start of the method
54 // get the argument list
55 const Method::ArgumentListType& ArgList = Meth->getArgumentList();
56 // get an iterator to arg list
57 Method::ArgumentListType::const_iterator ArgIt = ArgList.begin();
60 for( ; ArgIt != ArgList.end() ; ++ArgIt) { // for each argument
62 LiveRange * ArgRange = new LiveRange(); // creates a new LR and
63 const Value *const Val = (const Value *) *ArgIt;
67 ArgRange->add( Val ); // add the arg (def) to it
68 LiveRangeMap[ Val ] = ArgRange;
70 // create a temp machine op to find the register class of value
71 //const MachineOperand Op(MachineOperand::MO_VirtualRegister);
73 unsigned rcid = MRI.getRegClassIDOfValue( Val );
74 ArgRange->setRegClass(RegClassList[ rcid ] );
78 cout << " adding LiveRange for argument ";
79 printValue( (const Value *) *ArgIt); cout << endl;
83 // Now suggest hardware registers for these method args
84 MRI.suggestRegs4MethodArgs(Meth, *this);
88 // Now find speical LLVM instructions (CALL, RET) and LRs in machine
92 Method::const_iterator BBI = Meth->begin(); // random iterator for BBs
94 for( ; BBI != Meth->end(); ++BBI) { // go thru BBs in random order
96 // Now find all LRs for machine the instructions. A new LR will be created
97 // only for defs in the machine instr since, we assume that all Values are
98 // defined before they are used. However, there can be multiple defs for
99 // the same Value in machine instructions.
101 // get the iterator for machine instructions
102 const MachineCodeForBasicBlock& MIVec = (*BBI)->getMachineInstrVec();
103 MachineCodeForBasicBlock::const_iterator
104 MInstIterator = MIVec.begin();
106 // iterate over all the machine instructions in BB
107 for( ; MInstIterator != MIVec.end(); MInstIterator++) {
109 const MachineInstr * MInst = *MInstIterator;
111 // Now if the machine instruction has special operands that must be
112 // set with a "suggested color", do it here.
113 // This will be true for call/return instructions
116 if( MRI.handleSpecialMInstr(MInst, *this, RegClassList) )
120 // iterate over MI operands to find defs
121 for( MachineInstr::val_op_const_iterator OpI(MInst);!OpI.done(); ++OpI) {
124 // delete later from here ************
125 MachineOperand::MachineOperandType OpTyp =
126 OpI.getMachineOperand().getOperandType();
128 if (DEBUG_RA && OpTyp == MachineOperand::MO_CCRegister) {
129 cout << "\n**CC reg found. Is Def=" << OpI.isDef() << " Val:";
130 printValue( OpI.getMachineOperand().getVRegValue() );
133 // ************* to here
136 // create a new LR iff this operand is a def
139 const Value *const Def = *OpI;
142 // Only instruction values are accepted for live ranges here
144 if( Def->getValueType() != Value::InstructionVal ) {
145 cout << "\n**%%Error: Def is not an instruction val. Def=";
146 printValue( Def ); cout << endl;
151 LiveRange *DefRange = LiveRangeMap[Def];
153 // see LR already there (because of multiple defs)
155 if( !DefRange) { // if it is not in LiveRangeMap
157 DefRange = new LiveRange(); // creates a new live range and
158 DefRange->add( Def ); // add the instruction (def) to it
159 LiveRangeMap[ Def ] = DefRange; // update the map
162 cout << " creating a LR for def: ";
163 printValue(Def); cout << endl;
166 // set the register class of the new live range
167 //assert( RegClassList.size() );
168 MachineOperand::MachineOperandType OpTy =
169 OpI.getMachineOperand().getOperandType();
171 bool isCC = ( OpTy == MachineOperand::MO_CCRegister);
172 unsigned rcid = MRI.getRegClassIDOfValue(
173 OpI.getMachineOperand().getVRegValue(), isCC );
176 if(isCC && DEBUG_RA) {
177 cout << "\a**created a LR for a CC reg:";
178 printValue( OpI.getMachineOperand().getVRegValue() );
181 DefRange->setRegClass( RegClassList[ rcid ] );
185 DefRange->add( Def ); // add the opearand to def range
186 // update the map - Operand points
188 LiveRangeMap[ Def ] = DefRange;
191 cout << " added to an existing LR for def: ";
192 printValue( Def ); cout << endl;
201 } // for all opereands in machine instructions
203 } // for all machine instructions in the BB
206 } // for all BBs in method
208 // go thru LLVM instructions in the basic block and suggest colors
209 // for their args. Also record all CALL
210 // instructions and Return instructions in the CallRetInstrList
211 // This is done because since there are no reverse pointers in machine
212 // instructions to find the llvm instruction, when we encounter a call
213 // or a return whose args must be specailly colored (e.g., %o's for args)
214 // We have to makes sure that all LRs of call/ret args are added before
215 // doing this. But return value of call will not have a LR.
217 BBI = Meth->begin(); // random iterator for BBs
219 for( ; BBI != Meth->end(); ++BBI) { // go thru BBs in random order
221 BasicBlock::const_iterator InstIt = (*BBI)->begin();
223 for( ; InstIt != (*BBI)->end() ; ++InstIt) {
225 const Instruction *const CallRetI = *InstIt;
226 unsigned OpCode = (CallRetI)->getOpcode();
228 if( (OpCode == Instruction::Call) ) {
229 CallRetInstrList.push_back(CallRetI );
230 MRI.suggestRegs4CallArgs( (CallInst *) CallRetI, *this, RegClassList );
233 else if (OpCode == Instruction::Ret ) {
234 CallRetInstrList.push_back( CallRetI );
235 MRI.suggestReg4RetValue( (ReturnInst *) CallRetI, *this);
239 } // for each llvm instr in BB
241 } // for all BBs in method
244 cout << "Initial Live Ranges constructed!" << endl;
250 void LiveRangeInfo::coalesceLRs()
254 for each BB in method
255 for each machine instruction (inst)
256 for each definition (def) in inst
257 for each operand (op) of inst that is a use
258 if the def and op are of the same register class
259 if the def and op do not interfere //i.e., not simultaneously live
260 if (degree(LR of def) + degree(LR of op)) <= # avail regs
261 if both LRs do not have suggested colors
262 merge2IGNodes(def, op) // i.e., merge 2 LRs
267 cout << endl << "Coalscing LRs ..." << endl;
269 Method::const_iterator BBI = Meth->begin(); // random iterator for BBs
271 for( ; BBI != Meth->end(); ++BBI) { // traverse BBs in random order
273 // get the iterator for machine instructions
274 const MachineCodeForBasicBlock& MIVec = (*BBI)->getMachineInstrVec();
275 MachineCodeForBasicBlock::const_iterator
276 MInstIterator = MIVec.begin();
278 // iterate over all the machine instructions in BB
279 for( ; MInstIterator != MIVec.end(); ++MInstIterator) {
281 const MachineInstr * MInst = *MInstIterator;
284 cout << " *Iterating over machine instr ";
290 // iterate over MI operands to find defs
291 for(MachineInstr::val_op_const_iterator DefI(MInst);!DefI.done();++DefI){
293 if( DefI.isDef() ) { // iff this operand is a def
295 LiveRange *const LROfDef = getLiveRangeForValue( *DefI );
297 RegClass *const RCOfDef = LROfDef->getRegClass();
299 MachineInstr::val_op_const_iterator UseI(MInst);
300 for( ; !UseI.done(); ++UseI){ // for all uses
302 LiveRange *const LROfUse = getLiveRangeForValue( *UseI );
304 if( ! LROfUse ) { // if LR of use is not found
306 //don't warn about labels
307 if (!((*UseI)->getType())->isLabelType() && DEBUG_RA) {
308 cout<<" !! Warning: No LR for use "; printValue(*UseI);
311 continue; // ignore and continue
314 if( LROfUse == LROfDef) // nothing to merge if they are same
317 RegClass *const RCOfUse = LROfUse->getRegClass();
319 if( RCOfDef == RCOfUse ) { // if the reg classes are the same
321 // if( LROfUse->getTypeID() == LROfDef->getTypeID() ) {
323 if( ! RCOfDef->getInterference(LROfDef, LROfUse) ) {
325 unsigned CombinedDegree =
326 LROfDef->getUserIGNode()->getNumOfNeighbors() +
327 LROfUse->getUserIGNode()->getNumOfNeighbors();
329 if( CombinedDegree <= RCOfDef->getNumOfAvailRegs() ) {
331 // if both LRs do not have suggested colors
332 if( ! (LROfDef->hasSuggestedColor() &&
333 LROfUse->hasSuggestedColor() ) ) {
335 RCOfDef->mergeIGNodesOfLRs(LROfDef, LROfUse);
336 unionAndUpdateLRs(LROfDef, LROfUse);
340 } // if combined degree is less than # of regs
342 } // if def and use do not interfere
344 }// if reg classes are the same
352 } // for all machine instructions
357 cout << endl << "Coalscing Done!" << endl;
365 /*--------------------------- Debug code for printing ---------------*/
368 void LiveRangeInfo::printLiveRanges()
370 LiveRangeMapType::iterator HMI = LiveRangeMap.begin(); // hash map iterator
371 cout << endl << "Printing Live Ranges from Hash Map:" << endl;
372 for( ; HMI != LiveRangeMap.end() ; HMI ++ ) {
373 if( (*HMI).first && (*HMI).second ) {
374 cout <<" "; printValue((*HMI).first); cout << "\t: ";
375 ((*HMI).second)->printSet(); cout << endl;