1 //===-- SelectionDAGISel.cpp - Implement the SelectionDAGISel class -------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This implements the SelectionDAGISel class.
12 //===----------------------------------------------------------------------===//
14 #define DEBUG_TYPE "isel"
15 #include "ScheduleDAGSDNodes.h"
16 #include "SelectionDAGBuilder.h"
17 #include "FunctionLoweringInfo.h"
18 #include "llvm/CodeGen/SelectionDAGISel.h"
19 #include "llvm/Analysis/AliasAnalysis.h"
20 #include "llvm/Analysis/DebugInfo.h"
21 #include "llvm/Constants.h"
22 #include "llvm/CallingConv.h"
23 #include "llvm/DerivedTypes.h"
24 #include "llvm/Function.h"
25 #include "llvm/GlobalVariable.h"
26 #include "llvm/InlineAsm.h"
27 #include "llvm/Instructions.h"
28 #include "llvm/Intrinsics.h"
29 #include "llvm/IntrinsicInst.h"
30 #include "llvm/LLVMContext.h"
31 #include "llvm/CodeGen/FastISel.h"
32 #include "llvm/CodeGen/GCStrategy.h"
33 #include "llvm/CodeGen/GCMetadata.h"
34 #include "llvm/CodeGen/MachineFunction.h"
35 #include "llvm/CodeGen/MachineFunctionAnalysis.h"
36 #include "llvm/CodeGen/MachineFrameInfo.h"
37 #include "llvm/CodeGen/MachineInstrBuilder.h"
38 #include "llvm/CodeGen/MachineJumpTableInfo.h"
39 #include "llvm/CodeGen/MachineModuleInfo.h"
40 #include "llvm/CodeGen/MachineRegisterInfo.h"
41 #include "llvm/CodeGen/ScheduleHazardRecognizer.h"
42 #include "llvm/CodeGen/SchedulerRegistry.h"
43 #include "llvm/CodeGen/SelectionDAG.h"
44 #include "llvm/CodeGen/DwarfWriter.h"
45 #include "llvm/Target/TargetRegisterInfo.h"
46 #include "llvm/Target/TargetData.h"
47 #include "llvm/Target/TargetFrameInfo.h"
48 #include "llvm/Target/TargetIntrinsicInfo.h"
49 #include "llvm/Target/TargetInstrInfo.h"
50 #include "llvm/Target/TargetLowering.h"
51 #include "llvm/Target/TargetMachine.h"
52 #include "llvm/Target/TargetOptions.h"
53 #include "llvm/Support/Compiler.h"
54 #include "llvm/Support/Debug.h"
55 #include "llvm/Support/ErrorHandling.h"
56 #include "llvm/Support/MathExtras.h"
57 #include "llvm/Support/Timer.h"
58 #include "llvm/Support/raw_ostream.h"
63 DisableLegalizeTypes("disable-legalize-types", cl::Hidden);
65 EnableFastISelVerbose("fast-isel-verbose", cl::Hidden,
66 cl::desc("Enable verbose messages in the \"fast\" "
67 "instruction selector"));
69 EnableFastISelAbort("fast-isel-abort", cl::Hidden,
70 cl::desc("Enable abort calls when \"fast\" instruction fails"));
72 SchedLiveInCopies("schedule-livein-copies", cl::Hidden,
73 cl::desc("Schedule copies of livein registers"),
78 ViewDAGCombine1("view-dag-combine1-dags", cl::Hidden,
79 cl::desc("Pop up a window to show dags before the first "
82 ViewLegalizeTypesDAGs("view-legalize-types-dags", cl::Hidden,
83 cl::desc("Pop up a window to show dags before legalize types"));
85 ViewLegalizeDAGs("view-legalize-dags", cl::Hidden,
86 cl::desc("Pop up a window to show dags before legalize"));
88 ViewDAGCombine2("view-dag-combine2-dags", cl::Hidden,
89 cl::desc("Pop up a window to show dags before the second "
92 ViewDAGCombineLT("view-dag-combine-lt-dags", cl::Hidden,
93 cl::desc("Pop up a window to show dags before the post legalize types"
94 " dag combine pass"));
96 ViewISelDAGs("view-isel-dags", cl::Hidden,
97 cl::desc("Pop up a window to show isel dags as they are selected"));
99 ViewSchedDAGs("view-sched-dags", cl::Hidden,
100 cl::desc("Pop up a window to show sched dags as they are processed"));
102 ViewSUnitDAGs("view-sunit-dags", cl::Hidden,
103 cl::desc("Pop up a window to show SUnit dags after they are processed"));
105 static const bool ViewDAGCombine1 = false,
106 ViewLegalizeTypesDAGs = false, ViewLegalizeDAGs = false,
107 ViewDAGCombine2 = false,
108 ViewDAGCombineLT = false,
109 ViewISelDAGs = false, ViewSchedDAGs = false,
110 ViewSUnitDAGs = false;
113 //===---------------------------------------------------------------------===//
115 /// RegisterScheduler class - Track the registration of instruction schedulers.
117 //===---------------------------------------------------------------------===//
118 MachinePassRegistry RegisterScheduler::Registry;
120 //===---------------------------------------------------------------------===//
122 /// ISHeuristic command line option for instruction schedulers.
124 //===---------------------------------------------------------------------===//
125 static cl::opt<RegisterScheduler::FunctionPassCtor, false,
126 RegisterPassParser<RegisterScheduler> >
127 ISHeuristic("pre-RA-sched",
128 cl::init(&createDefaultScheduler),
129 cl::desc("Instruction schedulers available (before register"
132 static RegisterScheduler
133 defaultListDAGScheduler("default", "Best scheduler for the target",
134 createDefaultScheduler);
137 //===--------------------------------------------------------------------===//
138 /// createDefaultScheduler - This creates an instruction scheduler appropriate
140 ScheduleDAGSDNodes* createDefaultScheduler(SelectionDAGISel *IS,
141 CodeGenOpt::Level OptLevel) {
142 const TargetLowering &TLI = IS->getTargetLowering();
144 if (OptLevel == CodeGenOpt::None)
145 return createFastDAGScheduler(IS, OptLevel);
146 if (TLI.getSchedulingPreference() == TargetLowering::SchedulingForLatency)
147 return createTDListDAGScheduler(IS, OptLevel);
148 assert(TLI.getSchedulingPreference() ==
149 TargetLowering::SchedulingForRegPressure && "Unknown sched type!");
150 return createBURRListDAGScheduler(IS, OptLevel);
154 // EmitInstrWithCustomInserter - This method should be implemented by targets
155 // that mark instructions with the 'usesCustomInserter' flag. These
156 // instructions are special in various ways, which require special support to
157 // insert. The specified MachineInstr is created but not inserted into any
158 // basic blocks, and this method is called to expand it into a sequence of
159 // instructions, potentially also creating new basic blocks and control flow.
160 // When new basic blocks are inserted and the edges from MBB to its successors
161 // are modified, the method should insert pairs of <OldSucc, NewSucc> into the
163 MachineBasicBlock *TargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
164 MachineBasicBlock *MBB,
165 DenseMap<MachineBasicBlock*, MachineBasicBlock*> *EM) const {
167 errs() << "If a target marks an instruction with "
168 "'usesCustomInserter', it must implement "
169 "TargetLowering::EmitInstrWithCustomInserter!";
175 /// EmitLiveInCopy - Emit a copy for a live in physical register. If the
176 /// physical register has only a single copy use, then coalesced the copy
178 static void EmitLiveInCopy(MachineBasicBlock *MBB,
179 MachineBasicBlock::iterator &InsertPos,
180 unsigned VirtReg, unsigned PhysReg,
181 const TargetRegisterClass *RC,
182 DenseMap<MachineInstr*, unsigned> &CopyRegMap,
183 const MachineRegisterInfo &MRI,
184 const TargetRegisterInfo &TRI,
185 const TargetInstrInfo &TII) {
186 unsigned NumUses = 0;
187 MachineInstr *UseMI = NULL;
188 for (MachineRegisterInfo::use_iterator UI = MRI.use_begin(VirtReg),
189 UE = MRI.use_end(); UI != UE; ++UI) {
195 // If the number of uses is not one, or the use is not a move instruction,
196 // don't coalesce. Also, only coalesce away a virtual register to virtual
198 bool Coalesced = false;
199 unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
201 TII.isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubReg, DstSubReg) &&
202 TargetRegisterInfo::isVirtualRegister(DstReg)) {
207 // Now find an ideal location to insert the copy.
208 MachineBasicBlock::iterator Pos = InsertPos;
209 while (Pos != MBB->begin()) {
210 MachineInstr *PrevMI = prior(Pos);
211 DenseMap<MachineInstr*, unsigned>::iterator RI = CopyRegMap.find(PrevMI);
212 // copyRegToReg might emit multiple instructions to do a copy.
213 unsigned CopyDstReg = (RI == CopyRegMap.end()) ? 0 : RI->second;
214 if (CopyDstReg && !TRI.regsOverlap(CopyDstReg, PhysReg))
215 // This is what the BB looks like right now:
220 // We want to insert "r1025 = mov r1". Inserting this copy below the
221 // move to r1024 makes it impossible for that move to be coalesced.
228 break; // Woot! Found a good location.
232 bool Emitted = TII.copyRegToReg(*MBB, Pos, VirtReg, PhysReg, RC, RC);
233 assert(Emitted && "Unable to issue a live-in copy instruction!\n");
236 CopyRegMap.insert(std::make_pair(prior(Pos), VirtReg));
238 if (&*InsertPos == UseMI) ++InsertPos;
243 /// EmitLiveInCopies - If this is the first basic block in the function,
244 /// and if it has live ins that need to be copied into vregs, emit the
245 /// copies into the block.
246 static void EmitLiveInCopies(MachineBasicBlock *EntryMBB,
247 const MachineRegisterInfo &MRI,
248 const TargetRegisterInfo &TRI,
249 const TargetInstrInfo &TII) {
250 if (SchedLiveInCopies) {
251 // Emit the copies at a heuristically-determined location in the block.
252 DenseMap<MachineInstr*, unsigned> CopyRegMap;
253 MachineBasicBlock::iterator InsertPos = EntryMBB->begin();
254 for (MachineRegisterInfo::livein_iterator LI = MRI.livein_begin(),
255 E = MRI.livein_end(); LI != E; ++LI)
257 const TargetRegisterClass *RC = MRI.getRegClass(LI->second);
258 EmitLiveInCopy(EntryMBB, InsertPos, LI->second, LI->first,
259 RC, CopyRegMap, MRI, TRI, TII);
262 // Emit the copies into the top of the block.
263 for (MachineRegisterInfo::livein_iterator LI = MRI.livein_begin(),
264 E = MRI.livein_end(); LI != E; ++LI)
266 const TargetRegisterClass *RC = MRI.getRegClass(LI->second);
267 bool Emitted = TII.copyRegToReg(*EntryMBB, EntryMBB->begin(),
268 LI->second, LI->first, RC, RC);
269 assert(Emitted && "Unable to issue a live-in copy instruction!\n");
275 //===----------------------------------------------------------------------===//
276 // SelectionDAGISel code
277 //===----------------------------------------------------------------------===//
279 SelectionDAGISel::SelectionDAGISel(TargetMachine &tm, CodeGenOpt::Level OL) :
280 MachineFunctionPass(&ID), TM(tm), TLI(*tm.getTargetLowering()),
281 FuncInfo(new FunctionLoweringInfo(TLI)),
282 CurDAG(new SelectionDAG(TLI, *FuncInfo)),
283 SDB(new SelectionDAGBuilder(*CurDAG, TLI, *FuncInfo, OL)),
289 SelectionDAGISel::~SelectionDAGISel() {
295 unsigned SelectionDAGISel::MakeReg(EVT VT) {
296 return RegInfo->createVirtualRegister(TLI.getRegClassFor(VT));
299 void SelectionDAGISel::getAnalysisUsage(AnalysisUsage &AU) const {
300 AU.addRequired<AliasAnalysis>();
301 AU.addPreserved<AliasAnalysis>();
302 AU.addRequired<GCModuleInfo>();
303 AU.addPreserved<GCModuleInfo>();
304 AU.addRequired<DwarfWriter>();
305 AU.addPreserved<DwarfWriter>();
306 MachineFunctionPass::getAnalysisUsage(AU);
309 bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
310 Function &Fn = *mf.getFunction();
312 // Do some sanity-checking on the command-line options.
313 assert((!EnableFastISelVerbose || EnableFastISel) &&
314 "-fast-isel-verbose requires -fast-isel");
315 assert((!EnableFastISelAbort || EnableFastISel) &&
316 "-fast-isel-abort requires -fast-isel");
318 // Get alias analysis for load/store combining.
319 AA = &getAnalysis<AliasAnalysis>();
322 const TargetInstrInfo &TII = *TM.getInstrInfo();
323 const TargetRegisterInfo &TRI = *TM.getRegisterInfo();
326 GFI = &getAnalysis<GCModuleInfo>().getFunctionInfo(Fn);
329 RegInfo = &MF->getRegInfo();
330 DEBUG(errs() << "\n\n\n=== " << Fn.getName() << "\n");
332 MachineModuleInfo *MMI = getAnalysisIfAvailable<MachineModuleInfo>();
333 DwarfWriter *DW = getAnalysisIfAvailable<DwarfWriter>();
334 CurDAG->init(*MF, MMI, DW);
335 FuncInfo->set(Fn, *MF, EnableFastISel);
338 for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
339 if (InvokeInst *Invoke = dyn_cast<InvokeInst>(I->getTerminator()))
341 FuncInfo->MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
343 SelectAllBasicBlocks(Fn, *MF, MMI, DW, TII);
345 // If the first basic block in the function has live ins that need to be
346 // copied into vregs, emit the copies into the top of the block before
347 // emitting the code for the block.
348 EmitLiveInCopies(MF->begin(), *RegInfo, TRI, TII);
350 // Add function live-ins to entry block live-in set.
351 for (MachineRegisterInfo::livein_iterator I = RegInfo->livein_begin(),
352 E = RegInfo->livein_end(); I != E; ++I)
353 MF->begin()->addLiveIn(I->first);
356 assert(FuncInfo->CatchInfoFound.size() == FuncInfo->CatchInfoLost.size() &&
357 "Not all catch info was assigned to a landing pad!");
365 static void copyCatchInfo(BasicBlock *SrcBB, BasicBlock *DestBB,
366 MachineModuleInfo *MMI, FunctionLoweringInfo &FLI) {
367 for (BasicBlock::iterator I = SrcBB->begin(), E = --SrcBB->end(); I != E; ++I)
368 if (EHSelectorInst *EHSel = dyn_cast<EHSelectorInst>(I)) {
369 // Apply the catch info to DestBB.
370 AddCatchInfo(*EHSel, MMI, FLI.MBBMap[DestBB]);
372 if (!FLI.MBBMap[SrcBB]->isLandingPad())
373 FLI.CatchInfoFound.insert(EHSel);
378 void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB,
379 BasicBlock::iterator Begin,
380 BasicBlock::iterator End,
382 SDB->setCurrentBasicBlock(BB);
383 MetadataContext &TheMetadata = LLVMBB->getParent()->getContext().getMetadata();
384 unsigned MDDbgKind = TheMetadata.getMDKind("dbg");
386 // Lower all of the non-terminator instructions. If a call is emitted
387 // as a tail call, cease emitting nodes for this block.
388 for (BasicBlock::iterator I = Begin; I != End && !SDB->HasTailCall; ++I) {
390 // Update DebugLoc if debug information is attached with this
392 if (!isa<DbgInfoIntrinsic>(I))
393 if (MDNode *Dbg = TheMetadata.getMD(MDDbgKind, I)) {
394 DILocation DILoc(Dbg);
395 DebugLoc Loc = ExtractDebugLocation(DILoc, MF->getDebugLocInfo());
396 SDB->setCurDebugLoc(Loc);
397 if (MF->getDefaultDebugLoc().isUnknown())
398 MF->setDefaultDebugLoc(Loc);
401 if (!isa<TerminatorInst>(I))
405 if (!SDB->HasTailCall) {
406 // Ensure that all instructions which are used outside of their defining
407 // blocks are available as virtual registers. Invoke is handled elsewhere.
408 for (BasicBlock::iterator I = Begin; I != End; ++I)
409 if (!isa<PHINode>(I) && !isa<InvokeInst>(I))
410 SDB->CopyToExportRegsIfNeeded(I);
412 // Handle PHI nodes in successor blocks.
413 if (End == LLVMBB->end()) {
414 HandlePHINodesInSuccessorBlocks(LLVMBB);
416 // Lower the terminator after the copies are emitted.
417 SDB->visit(*LLVMBB->getTerminator());
421 // Make sure the root of the DAG is up-to-date.
422 CurDAG->setRoot(SDB->getControlRoot());
424 // Final step, emit the lowered DAG as machine code.
426 HadTailCall = SDB->HasTailCall;
430 void SelectionDAGISel::ComputeLiveOutVRegInfo() {
431 SmallPtrSet<SDNode*, 128> VisitedNodes;
432 SmallVector<SDNode*, 128> Worklist;
434 Worklist.push_back(CurDAG->getRoot().getNode());
440 while (!Worklist.empty()) {
441 SDNode *N = Worklist.back();
444 // If we've already seen this node, ignore it.
445 if (!VisitedNodes.insert(N))
448 // Otherwise, add all chain operands to the worklist.
449 for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
450 if (N->getOperand(i).getValueType() == MVT::Other)
451 Worklist.push_back(N->getOperand(i).getNode());
453 // If this is a CopyToReg with a vreg dest, process it.
454 if (N->getOpcode() != ISD::CopyToReg)
457 unsigned DestReg = cast<RegisterSDNode>(N->getOperand(1))->getReg();
458 if (!TargetRegisterInfo::isVirtualRegister(DestReg))
461 // Ignore non-scalar or non-integer values.
462 SDValue Src = N->getOperand(2);
463 EVT SrcVT = Src.getValueType();
464 if (!SrcVT.isInteger() || SrcVT.isVector())
467 unsigned NumSignBits = CurDAG->ComputeNumSignBits(Src);
468 Mask = APInt::getAllOnesValue(SrcVT.getSizeInBits());
469 CurDAG->ComputeMaskedBits(Src, Mask, KnownZero, KnownOne);
471 // Only install this information if it tells us something.
472 if (NumSignBits != 1 || KnownZero != 0 || KnownOne != 0) {
473 DestReg -= TargetRegisterInfo::FirstVirtualRegister;
474 if (DestReg >= FuncInfo->LiveOutRegInfo.size())
475 FuncInfo->LiveOutRegInfo.resize(DestReg+1);
476 FunctionLoweringInfo::LiveOutInfo &LOI =
477 FuncInfo->LiveOutRegInfo[DestReg];
478 LOI.NumSignBits = NumSignBits;
479 LOI.KnownOne = KnownOne;
480 LOI.KnownZero = KnownZero;
485 void SelectionDAGISel::CodeGenAndEmitDAG() {
486 std::string GroupName;
487 if (TimePassesIsEnabled)
488 GroupName = "Instruction Selection and Scheduling";
489 std::string BlockName;
490 if (ViewDAGCombine1 || ViewLegalizeTypesDAGs || ViewLegalizeDAGs ||
491 ViewDAGCombine2 || ViewDAGCombineLT || ViewISelDAGs || ViewSchedDAGs ||
493 BlockName = MF->getFunction()->getNameStr() + ":" +
494 BB->getBasicBlock()->getNameStr();
496 DEBUG(errs() << "Initial selection DAG:\n");
497 DEBUG(CurDAG->dump());
499 if (ViewDAGCombine1) CurDAG->viewGraph("dag-combine1 input for " + BlockName);
501 // Run the DAG combiner in pre-legalize mode.
502 if (TimePassesIsEnabled) {
503 NamedRegionTimer T("DAG Combining 1", GroupName);
504 CurDAG->Combine(Unrestricted, *AA, OptLevel);
506 CurDAG->Combine(Unrestricted, *AA, OptLevel);
509 DEBUG(errs() << "Optimized lowered selection DAG:\n");
510 DEBUG(CurDAG->dump());
512 // Second step, hack on the DAG until it only uses operations and types that
513 // the target supports.
514 if (!DisableLegalizeTypes) {
515 if (ViewLegalizeTypesDAGs) CurDAG->viewGraph("legalize-types input for " +
519 if (TimePassesIsEnabled) {
520 NamedRegionTimer T("Type Legalization", GroupName);
521 Changed = CurDAG->LegalizeTypes();
523 Changed = CurDAG->LegalizeTypes();
526 DEBUG(errs() << "Type-legalized selection DAG:\n");
527 DEBUG(CurDAG->dump());
530 if (ViewDAGCombineLT)
531 CurDAG->viewGraph("dag-combine-lt input for " + BlockName);
533 // Run the DAG combiner in post-type-legalize mode.
534 if (TimePassesIsEnabled) {
535 NamedRegionTimer T("DAG Combining after legalize types", GroupName);
536 CurDAG->Combine(NoIllegalTypes, *AA, OptLevel);
538 CurDAG->Combine(NoIllegalTypes, *AA, OptLevel);
541 DEBUG(errs() << "Optimized type-legalized selection DAG:\n");
542 DEBUG(CurDAG->dump());
545 if (TimePassesIsEnabled) {
546 NamedRegionTimer T("Vector Legalization", GroupName);
547 Changed = CurDAG->LegalizeVectors();
549 Changed = CurDAG->LegalizeVectors();
553 if (TimePassesIsEnabled) {
554 NamedRegionTimer T("Type Legalization 2", GroupName);
555 Changed = CurDAG->LegalizeTypes();
557 Changed = CurDAG->LegalizeTypes();
560 if (ViewDAGCombineLT)
561 CurDAG->viewGraph("dag-combine-lv input for " + BlockName);
563 // Run the DAG combiner in post-type-legalize mode.
564 if (TimePassesIsEnabled) {
565 NamedRegionTimer T("DAG Combining after legalize vectors", GroupName);
566 CurDAG->Combine(NoIllegalOperations, *AA, OptLevel);
568 CurDAG->Combine(NoIllegalOperations, *AA, OptLevel);
571 DEBUG(errs() << "Optimized vector-legalized selection DAG:\n");
572 DEBUG(CurDAG->dump());
576 if (ViewLegalizeDAGs) CurDAG->viewGraph("legalize input for " + BlockName);
578 if (TimePassesIsEnabled) {
579 NamedRegionTimer T("DAG Legalization", GroupName);
580 CurDAG->Legalize(DisableLegalizeTypes, OptLevel);
582 CurDAG->Legalize(DisableLegalizeTypes, OptLevel);
585 DEBUG(errs() << "Legalized selection DAG:\n");
586 DEBUG(CurDAG->dump());
588 if (ViewDAGCombine2) CurDAG->viewGraph("dag-combine2 input for " + BlockName);
590 // Run the DAG combiner in post-legalize mode.
591 if (TimePassesIsEnabled) {
592 NamedRegionTimer T("DAG Combining 2", GroupName);
593 CurDAG->Combine(NoIllegalOperations, *AA, OptLevel);
595 CurDAG->Combine(NoIllegalOperations, *AA, OptLevel);
598 DEBUG(errs() << "Optimized legalized selection DAG:\n");
599 DEBUG(CurDAG->dump());
601 if (ViewISelDAGs) CurDAG->viewGraph("isel input for " + BlockName);
603 if (OptLevel != CodeGenOpt::None)
604 ComputeLiveOutVRegInfo();
606 // Third, instruction select all of the operations to machine code, adding the
607 // code to the MachineBasicBlock.
608 if (TimePassesIsEnabled) {
609 NamedRegionTimer T("Instruction Selection", GroupName);
615 DEBUG(errs() << "Selected selection DAG:\n");
616 DEBUG(CurDAG->dump());
618 if (ViewSchedDAGs) CurDAG->viewGraph("scheduler input for " + BlockName);
620 // Schedule machine code.
621 ScheduleDAGSDNodes *Scheduler = CreateScheduler();
622 if (TimePassesIsEnabled) {
623 NamedRegionTimer T("Instruction Scheduling", GroupName);
624 Scheduler->Run(CurDAG, BB, BB->end());
626 Scheduler->Run(CurDAG, BB, BB->end());
629 if (ViewSUnitDAGs) Scheduler->viewGraph();
631 // Emit machine code to BB. This can change 'BB' to the last block being
633 if (TimePassesIsEnabled) {
634 NamedRegionTimer T("Instruction Creation", GroupName);
635 BB = Scheduler->EmitSchedule(&SDB->EdgeMapping);
637 BB = Scheduler->EmitSchedule(&SDB->EdgeMapping);
640 // Free the scheduler state.
641 if (TimePassesIsEnabled) {
642 NamedRegionTimer T("Instruction Scheduling Cleanup", GroupName);
648 DEBUG(errs() << "Selected machine code:\n");
652 void SelectionDAGISel::SelectAllBasicBlocks(Function &Fn,
654 MachineModuleInfo *MMI,
656 const TargetInstrInfo &TII) {
657 // Initialize the Fast-ISel state, if needed.
658 FastISel *FastIS = 0;
660 FastIS = TLI.createFastISel(MF, MMI, DW,
663 FuncInfo->StaticAllocaMap
665 , FuncInfo->CatchInfoLost
669 MetadataContext &TheMetadata = Fn.getContext().getMetadata();
670 unsigned MDDbgKind = TheMetadata.getMDKind("dbg");
672 // Iterate over all basic blocks in the function.
673 for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
674 BasicBlock *LLVMBB = &*I;
675 BB = FuncInfo->MBBMap[LLVMBB];
677 BasicBlock::iterator const Begin = LLVMBB->begin();
678 BasicBlock::iterator const End = LLVMBB->end();
679 BasicBlock::iterator BI = Begin;
681 // Lower any arguments needed in this block if this is the entry block.
682 bool SuppressFastISel = false;
683 if (LLVMBB == &Fn.getEntryBlock()) {
684 LowerArguments(LLVMBB);
686 // If any of the arguments has the byval attribute, forgo
687 // fast-isel in the entry block.
690 for (Function::arg_iterator I = Fn.arg_begin(), E = Fn.arg_end();
692 if (Fn.paramHasAttr(j, Attribute::ByVal)) {
693 if (EnableFastISelVerbose || EnableFastISelAbort)
694 errs() << "FastISel skips entry block due to byval argument\n";
695 SuppressFastISel = true;
701 if (MMI && BB->isLandingPad()) {
702 // Add a label to mark the beginning of the landing pad. Deletion of the
703 // landing pad can thus be detected via the MachineModuleInfo.
704 unsigned LabelID = MMI->addLandingPad(BB);
706 const TargetInstrDesc &II = TII.get(TargetInstrInfo::EH_LABEL);
707 BuildMI(BB, SDB->getCurDebugLoc(), II).addImm(LabelID);
709 // Mark exception register as live in.
710 unsigned Reg = TLI.getExceptionAddressRegister();
711 if (Reg) BB->addLiveIn(Reg);
713 // Mark exception selector register as live in.
714 Reg = TLI.getExceptionSelectorRegister();
715 if (Reg) BB->addLiveIn(Reg);
717 // FIXME: Hack around an exception handling flaw (PR1508): the personality
718 // function and list of typeids logically belong to the invoke (or, if you
719 // like, the basic block containing the invoke), and need to be associated
720 // with it in the dwarf exception handling tables. Currently however the
721 // information is provided by an intrinsic (eh.selector) that can be moved
722 // to unexpected places by the optimizers: if the unwind edge is critical,
723 // then breaking it can result in the intrinsics being in the successor of
724 // the landing pad, not the landing pad itself. This results in exceptions
725 // not being caught because no typeids are associated with the invoke.
726 // This may not be the only way things can go wrong, but it is the only way
727 // we try to work around for the moment.
728 BranchInst *Br = dyn_cast<BranchInst>(LLVMBB->getTerminator());
730 if (Br && Br->isUnconditional()) { // Critical edge?
731 BasicBlock::iterator I, E;
732 for (I = LLVMBB->begin(), E = --LLVMBB->end(); I != E; ++I)
733 if (isa<EHSelectorInst>(I))
737 // No catch info found - try to extract some from the successor.
738 copyCatchInfo(Br->getSuccessor(0), LLVMBB, MMI, *FuncInfo);
742 // Before doing SelectionDAG ISel, see if FastISel has been requested.
743 if (FastIS && !SuppressFastISel) {
744 // Emit code for any incoming arguments. This must happen before
745 // beginning FastISel on the entry block.
746 if (LLVMBB == &Fn.getEntryBlock()) {
747 CurDAG->setRoot(SDB->getControlRoot());
751 FastIS->startNewBlock(BB);
752 // Do FastISel on as many instructions as possible.
753 for (; BI != End; ++BI) {
755 // Update DebugLoc if debug information is attached with this
757 if (!isa<DbgInfoIntrinsic>(BI))
758 if (MDNode *Dbg = TheMetadata.getMD(MDDbgKind, BI)) {
759 DILocation DILoc(Dbg);
760 DebugLoc Loc = ExtractDebugLocation(DILoc,
761 MF.getDebugLocInfo());
762 FastIS->setCurDebugLoc(Loc);
763 if (MF.getDefaultDebugLoc().isUnknown())
764 MF.setDefaultDebugLoc(Loc);
768 // Just before the terminator instruction, insert instructions to
769 // feed PHI nodes in successor blocks.
770 if (isa<TerminatorInst>(BI))
771 if (!HandlePHINodesInSuccessorBlocksFast(LLVMBB, FastIS)) {
772 if (EnableFastISelVerbose || EnableFastISelAbort) {
773 errs() << "FastISel miss: ";
776 assert(!EnableFastISelAbort &&
777 "FastISel didn't handle a PHI in a successor");
781 // First try normal tablegen-generated "fast" selection.
782 if (FastIS->SelectInstruction(BI))
785 // Next, try calling the target to attempt to handle the instruction.
786 if (FastIS->TargetSelectInstruction(BI))
789 // Then handle certain instructions as single-LLVM-Instruction blocks.
790 if (isa<CallInst>(BI)) {
791 if (EnableFastISelVerbose || EnableFastISelAbort) {
792 errs() << "FastISel missed call: ";
796 if (BI->getType() != Type::getVoidTy(*CurDAG->getContext())) {
797 unsigned &R = FuncInfo->ValueMap[BI];
799 R = FuncInfo->CreateRegForValue(BI);
802 SDB->setCurDebugLoc(FastIS->getCurDebugLoc());
804 bool HadTailCall = false;
805 SelectBasicBlock(LLVMBB, BI, next(BI), HadTailCall);
807 // If the call was emitted as a tail call, we're done with the block.
813 // If the instruction was codegen'd with multiple blocks,
814 // inform the FastISel object where to resume inserting.
815 FastIS->setCurrentBlock(BB);
819 // Otherwise, give up on FastISel for the rest of the block.
820 // For now, be a little lenient about non-branch terminators.
821 if (!isa<TerminatorInst>(BI) || isa<BranchInst>(BI)) {
822 if (EnableFastISelVerbose || EnableFastISelAbort) {
823 errs() << "FastISel miss: ";
826 if (EnableFastISelAbort)
827 // The "fast" selector couldn't handle something and bailed.
828 // For the purpose of debugging, just abort.
829 llvm_unreachable("FastISel didn't select the entire block");
835 // Run SelectionDAG instruction selection on the remainder of the block
836 // not handled by FastISel. If FastISel is not run, this is the entire
839 // If FastISel is run and it has known DebugLoc then use it.
840 if (FastIS && !FastIS->getCurDebugLoc().isUnknown())
841 SDB->setCurDebugLoc(FastIS->getCurDebugLoc());
843 SelectBasicBlock(LLVMBB, BI, End, HadTailCall);
853 SelectionDAGISel::FinishBasicBlock() {
855 DEBUG(errs() << "Target-post-processed machine code:\n");
858 DEBUG(errs() << "Total amount of phi nodes to update: "
859 << SDB->PHINodesToUpdate.size() << "\n");
860 DEBUG(for (unsigned i = 0, e = SDB->PHINodesToUpdate.size(); i != e; ++i)
861 errs() << "Node " << i << " : ("
862 << SDB->PHINodesToUpdate[i].first
863 << ", " << SDB->PHINodesToUpdate[i].second << ")\n");
865 // Next, now that we know what the last MBB the LLVM BB expanded is, update
866 // PHI nodes in successors.
867 if (SDB->SwitchCases.empty() &&
868 SDB->JTCases.empty() &&
869 SDB->BitTestCases.empty()) {
870 for (unsigned i = 0, e = SDB->PHINodesToUpdate.size(); i != e; ++i) {
871 MachineInstr *PHI = SDB->PHINodesToUpdate[i].first;
872 assert(PHI->getOpcode() == TargetInstrInfo::PHI &&
873 "This is not a machine PHI node that we are updating!");
874 PHI->addOperand(MachineOperand::CreateReg(SDB->PHINodesToUpdate[i].second,
876 PHI->addOperand(MachineOperand::CreateMBB(BB));
878 SDB->PHINodesToUpdate.clear();
882 for (unsigned i = 0, e = SDB->BitTestCases.size(); i != e; ++i) {
883 // Lower header first, if it wasn't already lowered
884 if (!SDB->BitTestCases[i].Emitted) {
885 // Set the current basic block to the mbb we wish to insert the code into
886 BB = SDB->BitTestCases[i].Parent;
887 SDB->setCurrentBasicBlock(BB);
889 SDB->visitBitTestHeader(SDB->BitTestCases[i]);
890 CurDAG->setRoot(SDB->getRoot());
895 for (unsigned j = 0, ej = SDB->BitTestCases[i].Cases.size(); j != ej; ++j) {
896 // Set the current basic block to the mbb we wish to insert the code into
897 BB = SDB->BitTestCases[i].Cases[j].ThisBB;
898 SDB->setCurrentBasicBlock(BB);
901 SDB->visitBitTestCase(SDB->BitTestCases[i].Cases[j+1].ThisBB,
902 SDB->BitTestCases[i].Reg,
903 SDB->BitTestCases[i].Cases[j]);
905 SDB->visitBitTestCase(SDB->BitTestCases[i].Default,
906 SDB->BitTestCases[i].Reg,
907 SDB->BitTestCases[i].Cases[j]);
910 CurDAG->setRoot(SDB->getRoot());
916 for (unsigned pi = 0, pe = SDB->PHINodesToUpdate.size(); pi != pe; ++pi) {
917 MachineInstr *PHI = SDB->PHINodesToUpdate[pi].first;
918 MachineBasicBlock *PHIBB = PHI->getParent();
919 assert(PHI->getOpcode() == TargetInstrInfo::PHI &&
920 "This is not a machine PHI node that we are updating!");
921 // This is "default" BB. We have two jumps to it. From "header" BB and
922 // from last "case" BB.
923 if (PHIBB == SDB->BitTestCases[i].Default) {
924 PHI->addOperand(MachineOperand::CreateReg(SDB->PHINodesToUpdate[pi].second,
926 PHI->addOperand(MachineOperand::CreateMBB(SDB->BitTestCases[i].Parent));
927 PHI->addOperand(MachineOperand::CreateReg(SDB->PHINodesToUpdate[pi].second,
929 PHI->addOperand(MachineOperand::CreateMBB(SDB->BitTestCases[i].Cases.
932 // One of "cases" BB.
933 for (unsigned j = 0, ej = SDB->BitTestCases[i].Cases.size();
935 MachineBasicBlock* cBB = SDB->BitTestCases[i].Cases[j].ThisBB;
936 if (cBB->succ_end() !=
937 std::find(cBB->succ_begin(),cBB->succ_end(), PHIBB)) {
938 PHI->addOperand(MachineOperand::CreateReg(SDB->PHINodesToUpdate[pi].second,
940 PHI->addOperand(MachineOperand::CreateMBB(cBB));
945 SDB->BitTestCases.clear();
947 // If the JumpTable record is filled in, then we need to emit a jump table.
948 // Updating the PHI nodes is tricky in this case, since we need to determine
949 // whether the PHI is a successor of the range check MBB or the jump table MBB
950 for (unsigned i = 0, e = SDB->JTCases.size(); i != e; ++i) {
951 // Lower header first, if it wasn't already lowered
952 if (!SDB->JTCases[i].first.Emitted) {
953 // Set the current basic block to the mbb we wish to insert the code into
954 BB = SDB->JTCases[i].first.HeaderBB;
955 SDB->setCurrentBasicBlock(BB);
957 SDB->visitJumpTableHeader(SDB->JTCases[i].second, SDB->JTCases[i].first);
958 CurDAG->setRoot(SDB->getRoot());
963 // Set the current basic block to the mbb we wish to insert the code into
964 BB = SDB->JTCases[i].second.MBB;
965 SDB->setCurrentBasicBlock(BB);
967 SDB->visitJumpTable(SDB->JTCases[i].second);
968 CurDAG->setRoot(SDB->getRoot());
973 for (unsigned pi = 0, pe = SDB->PHINodesToUpdate.size(); pi != pe; ++pi) {
974 MachineInstr *PHI = SDB->PHINodesToUpdate[pi].first;
975 MachineBasicBlock *PHIBB = PHI->getParent();
976 assert(PHI->getOpcode() == TargetInstrInfo::PHI &&
977 "This is not a machine PHI node that we are updating!");
978 // "default" BB. We can go there only from header BB.
979 if (PHIBB == SDB->JTCases[i].second.Default) {
981 (MachineOperand::CreateReg(SDB->PHINodesToUpdate[pi].second, false));
983 (MachineOperand::CreateMBB(SDB->JTCases[i].first.HeaderBB));
985 // JT BB. Just iterate over successors here
986 if (BB->succ_end() != std::find(BB->succ_begin(),BB->succ_end(), PHIBB)) {
988 (MachineOperand::CreateReg(SDB->PHINodesToUpdate[pi].second, false));
989 PHI->addOperand(MachineOperand::CreateMBB(BB));
993 SDB->JTCases.clear();
995 // If the switch block involved a branch to one of the actual successors, we
996 // need to update PHI nodes in that block.
997 for (unsigned i = 0, e = SDB->PHINodesToUpdate.size(); i != e; ++i) {
998 MachineInstr *PHI = SDB->PHINodesToUpdate[i].first;
999 assert(PHI->getOpcode() == TargetInstrInfo::PHI &&
1000 "This is not a machine PHI node that we are updating!");
1001 if (BB->isSuccessor(PHI->getParent())) {
1002 PHI->addOperand(MachineOperand::CreateReg(SDB->PHINodesToUpdate[i].second,
1004 PHI->addOperand(MachineOperand::CreateMBB(BB));
1008 // If we generated any switch lowering information, build and codegen any
1009 // additional DAGs necessary.
1010 for (unsigned i = 0, e = SDB->SwitchCases.size(); i != e; ++i) {
1011 // Set the current basic block to the mbb we wish to insert the code into
1012 MachineBasicBlock *ThisBB = BB = SDB->SwitchCases[i].ThisBB;
1013 SDB->setCurrentBasicBlock(BB);
1016 SDB->visitSwitchCase(SDB->SwitchCases[i]);
1017 CurDAG->setRoot(SDB->getRoot());
1018 CodeGenAndEmitDAG();
1020 // Handle any PHI nodes in successors of this chunk, as if we were coming
1021 // from the original BB before switch expansion. Note that PHI nodes can
1022 // occur multiple times in PHINodesToUpdate. We have to be very careful to
1023 // handle them the right number of times.
1024 while ((BB = SDB->SwitchCases[i].TrueBB)) { // Handle LHS and RHS.
1025 // If new BB's are created during scheduling, the edges may have been
1026 // updated. That is, the edge from ThisBB to BB may have been split and
1027 // BB's predecessor is now another block.
1028 DenseMap<MachineBasicBlock*, MachineBasicBlock*>::iterator EI =
1029 SDB->EdgeMapping.find(BB);
1030 if (EI != SDB->EdgeMapping.end())
1031 ThisBB = EI->second;
1032 for (MachineBasicBlock::iterator Phi = BB->begin();
1033 Phi != BB->end() && Phi->getOpcode() == TargetInstrInfo::PHI; ++Phi){
1034 // This value for this PHI node is recorded in PHINodesToUpdate, get it.
1035 for (unsigned pn = 0; ; ++pn) {
1036 assert(pn != SDB->PHINodesToUpdate.size() &&
1037 "Didn't find PHI entry!");
1038 if (SDB->PHINodesToUpdate[pn].first == Phi) {
1039 Phi->addOperand(MachineOperand::CreateReg(SDB->PHINodesToUpdate[pn].
1041 Phi->addOperand(MachineOperand::CreateMBB(ThisBB));
1047 // Don't process RHS if same block as LHS.
1048 if (BB == SDB->SwitchCases[i].FalseBB)
1049 SDB->SwitchCases[i].FalseBB = 0;
1051 // If we haven't handled the RHS, do so now. Otherwise, we're done.
1052 SDB->SwitchCases[i].TrueBB = SDB->SwitchCases[i].FalseBB;
1053 SDB->SwitchCases[i].FalseBB = 0;
1055 assert(SDB->SwitchCases[i].TrueBB == 0 && SDB->SwitchCases[i].FalseBB == 0);
1058 SDB->SwitchCases.clear();
1060 SDB->PHINodesToUpdate.clear();
1064 /// Create the scheduler. If a specific scheduler was specified
1065 /// via the SchedulerRegistry, use it, otherwise select the
1066 /// one preferred by the target.
1068 ScheduleDAGSDNodes *SelectionDAGISel::CreateScheduler() {
1069 RegisterScheduler::FunctionPassCtor Ctor = RegisterScheduler::getDefault();
1073 RegisterScheduler::setDefault(Ctor);
1076 return Ctor(this, OptLevel);
1079 ScheduleHazardRecognizer *SelectionDAGISel::CreateTargetHazardRecognizer() {
1080 return new ScheduleHazardRecognizer();
1083 //===----------------------------------------------------------------------===//
1084 // Helper functions used by the generated instruction selector.
1085 //===----------------------------------------------------------------------===//
1086 // Calls to these methods are generated by tblgen.
1088 /// CheckAndMask - The isel is trying to match something like (and X, 255). If
1089 /// the dag combiner simplified the 255, we still want to match. RHS is the
1090 /// actual value in the DAG on the RHS of an AND, and DesiredMaskS is the value
1091 /// specified in the .td file (e.g. 255).
1092 bool SelectionDAGISel::CheckAndMask(SDValue LHS, ConstantSDNode *RHS,
1093 int64_t DesiredMaskS) const {
1094 const APInt &ActualMask = RHS->getAPIntValue();
1095 const APInt &DesiredMask = APInt(LHS.getValueSizeInBits(), DesiredMaskS);
1097 // If the actual mask exactly matches, success!
1098 if (ActualMask == DesiredMask)
1101 // If the actual AND mask is allowing unallowed bits, this doesn't match.
1102 if (ActualMask.intersects(~DesiredMask))
1105 // Otherwise, the DAG Combiner may have proven that the value coming in is
1106 // either already zero or is not demanded. Check for known zero input bits.
1107 APInt NeededMask = DesiredMask & ~ActualMask;
1108 if (CurDAG->MaskedValueIsZero(LHS, NeededMask))
1111 // TODO: check to see if missing bits are just not demanded.
1113 // Otherwise, this pattern doesn't match.
1117 /// CheckOrMask - The isel is trying to match something like (or X, 255). If
1118 /// the dag combiner simplified the 255, we still want to match. RHS is the
1119 /// actual value in the DAG on the RHS of an OR, and DesiredMaskS is the value
1120 /// specified in the .td file (e.g. 255).
1121 bool SelectionDAGISel::CheckOrMask(SDValue LHS, ConstantSDNode *RHS,
1122 int64_t DesiredMaskS) const {
1123 const APInt &ActualMask = RHS->getAPIntValue();
1124 const APInt &DesiredMask = APInt(LHS.getValueSizeInBits(), DesiredMaskS);
1126 // If the actual mask exactly matches, success!
1127 if (ActualMask == DesiredMask)
1130 // If the actual AND mask is allowing unallowed bits, this doesn't match.
1131 if (ActualMask.intersects(~DesiredMask))
1134 // Otherwise, the DAG Combiner may have proven that the value coming in is
1135 // either already zero or is not demanded. Check for known zero input bits.
1136 APInt NeededMask = DesiredMask & ~ActualMask;
1138 APInt KnownZero, KnownOne;
1139 CurDAG->ComputeMaskedBits(LHS, NeededMask, KnownZero, KnownOne);
1141 // If all the missing bits in the or are already known to be set, match!
1142 if ((NeededMask & KnownOne) == NeededMask)
1145 // TODO: check to see if missing bits are just not demanded.
1147 // Otherwise, this pattern doesn't match.
1152 /// SelectInlineAsmMemoryOperands - Calls to this are automatically generated
1153 /// by tblgen. Others should not call it.
1154 void SelectionDAGISel::
1155 SelectInlineAsmMemoryOperands(std::vector<SDValue> &Ops) {
1156 std::vector<SDValue> InOps;
1157 std::swap(InOps, Ops);
1159 Ops.push_back(InOps[0]); // input chain.
1160 Ops.push_back(InOps[1]); // input asm string.
1162 unsigned i = 2, e = InOps.size();
1163 if (InOps[e-1].getValueType() == MVT::Flag)
1164 --e; // Don't process a flag operand if it is here.
1167 unsigned Flags = cast<ConstantSDNode>(InOps[i])->getZExtValue();
1168 if ((Flags & 7) != 4 /*MEM*/) {
1169 // Just skip over this operand, copying the operands verbatim.
1170 Ops.insert(Ops.end(), InOps.begin()+i,
1171 InOps.begin()+i+InlineAsm::getNumOperandRegisters(Flags) + 1);
1172 i += InlineAsm::getNumOperandRegisters(Flags) + 1;
1174 assert(InlineAsm::getNumOperandRegisters(Flags) == 1 &&
1175 "Memory operand with multiple values?");
1176 // Otherwise, this is a memory operand. Ask the target to select it.
1177 std::vector<SDValue> SelOps;
1178 if (SelectInlineAsmMemoryOperand(InOps[i+1], 'm', SelOps)) {
1179 llvm_report_error("Could not match memory address. Inline asm"
1183 // Add this to the output node.
1184 EVT IntPtrTy = TLI.getPointerTy();
1185 Ops.push_back(CurDAG->getTargetConstant(4/*MEM*/ | (SelOps.size()<< 3),
1187 Ops.insert(Ops.end(), SelOps.begin(), SelOps.end());
1192 // Add the flag input back if present.
1193 if (e != InOps.size())
1194 Ops.push_back(InOps.back());
1197 /// findFlagUse - Return use of EVT::Flag value produced by the specified
1200 static SDNode *findFlagUse(SDNode *N) {
1201 unsigned FlagResNo = N->getNumValues()-1;
1202 for (SDNode::use_iterator I = N->use_begin(), E = N->use_end(); I != E; ++I) {
1203 SDUse &Use = I.getUse();
1204 if (Use.getResNo() == FlagResNo)
1205 return Use.getUser();
1210 /// findNonImmUse - Return true if "Use" is a non-immediate use of "Def".
1211 /// This function recursively traverses up the operand chain, ignoring
1213 static bool findNonImmUse(SDNode *Use, SDNode* Def, SDNode *ImmedUse,
1215 SmallPtrSet<SDNode*, 16> &Visited) {
1216 if (Use->getNodeId() < Def->getNodeId() ||
1217 !Visited.insert(Use))
1220 for (unsigned i = 0, e = Use->getNumOperands(); i != e; ++i) {
1221 SDNode *N = Use->getOperand(i).getNode();
1223 if (Use == ImmedUse || Use == Root)
1224 continue; // We are not looking for immediate use.
1229 // Traverse up the operand chain.
1230 if (findNonImmUse(N, Def, ImmedUse, Root, Visited))
1236 /// isNonImmUse - Start searching from Root up the DAG to check is Def can
1237 /// be reached. Return true if that's the case. However, ignore direct uses
1238 /// by ImmedUse (which would be U in the example illustrated in
1239 /// IsLegalAndProfitableToFold) and by Root (which can happen in the store
1241 /// FIXME: to be really generic, we should allow direct use by any node
1242 /// that is being folded. But realisticly since we only fold loads which
1243 /// have one non-chain use, we only need to watch out for load/op/store
1244 /// and load/op/cmp case where the root (store / cmp) may reach the load via
1245 /// its chain operand.
1246 static inline bool isNonImmUse(SDNode *Root, SDNode *Def, SDNode *ImmedUse) {
1247 SmallPtrSet<SDNode*, 16> Visited;
1248 return findNonImmUse(Root, Def, ImmedUse, Root, Visited);
1251 /// IsLegalAndProfitableToFold - Returns true if the specific operand node N of
1252 /// U can be folded during instruction selection that starts at Root and
1253 /// folding N is profitable.
1254 bool SelectionDAGISel::IsLegalAndProfitableToFold(SDNode *N, SDNode *U,
1255 SDNode *Root) const {
1256 if (OptLevel == CodeGenOpt::None) return false;
1258 // If Root use can somehow reach N through a path that that doesn't contain
1259 // U then folding N would create a cycle. e.g. In the following
1260 // diagram, Root can reach N through X. If N is folded into into Root, then
1261 // X is both a predecessor and a successor of U.
1272 // * indicates nodes to be folded together.
1274 // If Root produces a flag, then it gets (even more) interesting. Since it
1275 // will be "glued" together with its flag use in the scheduler, we need to
1276 // check if it might reach N.
1295 // If FU (flag use) indirectly reaches N (the load), and Root folds N
1296 // (call it Fold), then X is a predecessor of FU and a successor of
1297 // Fold. But since Fold and FU are flagged together, this will create
1298 // a cycle in the scheduling graph.
1300 EVT VT = Root->getValueType(Root->getNumValues()-1);
1301 while (VT == MVT::Flag) {
1302 SDNode *FU = findFlagUse(Root);
1306 VT = Root->getValueType(Root->getNumValues()-1);
1309 return !isNonImmUse(Root, N, U);
1312 SDNode *SelectionDAGISel::Select_INLINEASM(SDValue N) {
1313 std::vector<SDValue> Ops(N.getNode()->op_begin(), N.getNode()->op_end());
1314 SelectInlineAsmMemoryOperands(Ops);
1316 std::vector<EVT> VTs;
1317 VTs.push_back(MVT::Other);
1318 VTs.push_back(MVT::Flag);
1319 SDValue New = CurDAG->getNode(ISD::INLINEASM, N.getDebugLoc(),
1320 VTs, &Ops[0], Ops.size());
1321 return New.getNode();
1324 SDNode *SelectionDAGISel::Select_UNDEF(const SDValue &N) {
1325 return CurDAG->SelectNodeTo(N.getNode(), TargetInstrInfo::IMPLICIT_DEF,
1329 SDNode *SelectionDAGISel::Select_DBG_LABEL(const SDValue &N) {
1330 SDValue Chain = N.getOperand(0);
1331 unsigned C = cast<LabelSDNode>(N)->getLabelID();
1332 SDValue Tmp = CurDAG->getTargetConstant(C, MVT::i32);
1333 return CurDAG->SelectNodeTo(N.getNode(), TargetInstrInfo::DBG_LABEL,
1334 MVT::Other, Tmp, Chain);
1337 SDNode *SelectionDAGISel::Select_EH_LABEL(const SDValue &N) {
1338 SDValue Chain = N.getOperand(0);
1339 unsigned C = cast<LabelSDNode>(N)->getLabelID();
1340 SDValue Tmp = CurDAG->getTargetConstant(C, MVT::i32);
1341 return CurDAG->SelectNodeTo(N.getNode(), TargetInstrInfo::EH_LABEL,
1342 MVT::Other, Tmp, Chain);
1345 void SelectionDAGISel::CannotYetSelect(SDValue N) {
1347 raw_string_ostream Msg(msg);
1348 Msg << "Cannot yet select: ";
1349 N.getNode()->print(Msg, CurDAG);
1350 llvm_report_error(Msg.str());
1353 void SelectionDAGISel::CannotYetSelectIntrinsic(SDValue N) {
1354 errs() << "Cannot yet select: ";
1356 cast<ConstantSDNode>(N.getOperand(N.getOperand(0).getValueType() == MVT::Other))->getZExtValue();
1357 if (iid < Intrinsic::num_intrinsics)
1358 llvm_report_error("Cannot yet select: intrinsic %" + Intrinsic::getName((Intrinsic::ID)iid));
1359 else if (const TargetIntrinsicInfo *tii = TM.getIntrinsicInfo())
1360 llvm_report_error(Twine("Cannot yet select: target intrinsic %") +
1364 char SelectionDAGISel::ID = 0;