1 //===-- SelectionDAGBuilder.h - Selection-DAG building --------*- C++ -*---===//
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 routines for translating from LLVM IR into SelectionDAG IR.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_LIB_CODEGEN_SELECTIONDAG_SELECTIONDAGBUILDER_H
15 #define LLVM_LIB_CODEGEN_SELECTIONDAG_SELECTIONDAGBUILDER_H
17 #include "StatepointLowering.h"
18 #include "llvm/ADT/APInt.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/Analysis/AliasAnalysis.h"
21 #include "llvm/CodeGen/SelectionDAG.h"
22 #include "llvm/CodeGen/SelectionDAGNodes.h"
23 #include "llvm/IR/CallSite.h"
24 #include "llvm/IR/Constants.h"
25 #include "llvm/IR/Statepoint.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Target/TargetLowering.h"
33 class AddrSpaceCastInst;
40 class ExtractElementInst;
41 class ExtractValueInst;
48 class FunctionLoweringInfo;
49 class GetElementPtrInst;
55 class InsertElementInst;
56 class InsertValueInst;
59 class MachineBasicBlock;
61 class MachineRegisterInfo;
70 class ShuffleVectorInst;
75 class TargetLibraryInfo;
79 class UnreachableInst;
83 //===----------------------------------------------------------------------===//
84 /// SelectionDAGBuilder - This is the common target-independent lowering
85 /// implementation that is parameterized by a TargetLowering object.
87 class SelectionDAGBuilder {
88 /// CurInst - The current instruction being visited
89 const Instruction *CurInst;
91 DenseMap<const Value*, SDValue> NodeMap;
93 /// UnusedArgNodeMap - Maps argument value for unused arguments. This is used
94 /// to preserve debug information for incoming arguments.
95 DenseMap<const Value*, SDValue> UnusedArgNodeMap;
97 /// DanglingDebugInfo - Helper type for DanglingDebugInfoMap.
98 class DanglingDebugInfo {
99 const DbgValueInst* DI;
101 unsigned SDNodeOrder;
103 DanglingDebugInfo() : DI(nullptr), dl(DebugLoc()), SDNodeOrder(0) { }
104 DanglingDebugInfo(const DbgValueInst *di, DebugLoc DL, unsigned SDNO)
105 : DI(di), dl(std::move(DL)), SDNodeOrder(SDNO) {}
106 const DbgValueInst* getDI() { return DI; }
107 DebugLoc getdl() { return dl; }
108 unsigned getSDNodeOrder() { return SDNodeOrder; }
111 /// DanglingDebugInfoMap - Keeps track of dbg_values for which we have not
112 /// yet seen the referent. We defer handling these until we do see it.
113 DenseMap<const Value*, DanglingDebugInfo> DanglingDebugInfoMap;
116 /// PendingLoads - Loads are not emitted to the program immediately. We bunch
117 /// them up and then emit token factor nodes when possible. This allows us to
118 /// get simple disambiguation between loads without worrying about alias
120 SmallVector<SDValue, 8> PendingLoads;
122 /// State used while lowering a statepoint sequence (gc_statepoint,
123 /// gc_relocate, and gc_result). See StatepointLowering.hpp/cpp for details.
124 StatepointLoweringState StatepointLowering;
127 /// PendingExports - CopyToReg nodes that copy values to virtual registers
128 /// for export to other blocks need to be emitted before any terminator
129 /// instruction, but they have no other ordering requirements. We bunch them
130 /// up and the emit a single tokenfactor for them just before terminator
132 SmallVector<SDValue, 8> PendingExports;
134 /// SDNodeOrder - A unique monotonically increasing number used to order the
135 /// SDNodes we create.
136 unsigned SDNodeOrder;
138 enum CaseClusterKind {
139 /// A cluster of adjacent case labels with the same destination, or just one
142 /// A cluster of cases suitable for jump table lowering.
144 /// A cluster of cases suitable for bit test lowering.
148 /// A cluster of case labels.
150 CaseClusterKind Kind;
151 const ConstantInt *Low, *High;
153 MachineBasicBlock *MBB;
154 unsigned JTCasesIndex;
155 unsigned BTCasesIndex;
157 BranchProbability Prob;
159 static CaseCluster range(const ConstantInt *Low, const ConstantInt *High,
160 MachineBasicBlock *MBB, BranchProbability Prob) {
170 static CaseCluster jumpTable(const ConstantInt *Low,
171 const ConstantInt *High, unsigned JTCasesIndex,
172 BranchProbability Prob) {
174 C.Kind = CC_JumpTable;
177 C.JTCasesIndex = JTCasesIndex;
182 static CaseCluster bitTests(const ConstantInt *Low, const ConstantInt *High,
183 unsigned BTCasesIndex, BranchProbability Prob) {
185 C.Kind = CC_BitTests;
188 C.BTCasesIndex = BTCasesIndex;
194 typedef std::vector<CaseCluster> CaseClusterVector;
195 typedef CaseClusterVector::iterator CaseClusterIt;
199 MachineBasicBlock* BB;
201 BranchProbability ExtraProb;
203 CaseBits(uint64_t mask, MachineBasicBlock* bb, unsigned bits,
204 BranchProbability Prob):
205 Mask(mask), BB(bb), Bits(bits), ExtraProb(Prob) { }
207 CaseBits() : Mask(0), BB(nullptr), Bits(0) {}
210 typedef std::vector<CaseBits> CaseBitsVector;
212 /// Sort Clusters and merge adjacent cases.
213 void sortAndRangeify(CaseClusterVector &Clusters);
215 /// CaseBlock - This structure is used to communicate between
216 /// SelectionDAGBuilder and SDISel for the code generation of additional basic
217 /// blocks needed by multi-case switch statements.
219 CaseBlock(ISD::CondCode cc, const Value *cmplhs, const Value *cmprhs,
220 const Value *cmpmiddle, MachineBasicBlock *truebb,
221 MachineBasicBlock *falsebb, MachineBasicBlock *me,
222 BranchProbability trueprob = BranchProbability::getUnknown(),
223 BranchProbability falseprob = BranchProbability::getUnknown())
224 : CC(cc), CmpLHS(cmplhs), CmpMHS(cmpmiddle), CmpRHS(cmprhs),
225 TrueBB(truebb), FalseBB(falsebb), ThisBB(me), TrueProb(trueprob),
226 FalseProb(falseprob) {}
228 // CC - the condition code to use for the case block's setcc node
231 // CmpLHS/CmpRHS/CmpMHS - The LHS/MHS/RHS of the comparison to emit.
232 // Emit by default LHS op RHS. MHS is used for range comparisons:
233 // If MHS is not null: (LHS <= MHS) and (MHS <= RHS).
234 const Value *CmpLHS, *CmpMHS, *CmpRHS;
236 // TrueBB/FalseBB - the block to branch to if the setcc is true/false.
237 MachineBasicBlock *TrueBB, *FalseBB;
239 // ThisBB - the block into which to emit the code for the setcc and branches
240 MachineBasicBlock *ThisBB;
242 // TrueProb/FalseProb - branch weights.
243 BranchProbability TrueProb, FalseProb;
247 JumpTable(unsigned R, unsigned J, MachineBasicBlock *M,
248 MachineBasicBlock *D): Reg(R), JTI(J), MBB(M), Default(D) {}
250 /// Reg - the virtual register containing the index of the jump table entry
253 /// JTI - the JumpTableIndex for this jump table in the function.
255 /// MBB - the MBB into which to emit the code for the indirect jump.
256 MachineBasicBlock *MBB;
257 /// Default - the MBB of the default bb, which is a successor of the range
258 /// check MBB. This is when updating PHI nodes in successors.
259 MachineBasicBlock *Default;
261 struct JumpTableHeader {
262 JumpTableHeader(APInt F, APInt L, const Value *SV, MachineBasicBlock *H,
264 : First(std::move(F)), Last(std::move(L)), SValue(SV), HeaderBB(H),
269 MachineBasicBlock *HeaderBB;
272 typedef std::pair<JumpTableHeader, JumpTable> JumpTableBlock;
275 BitTestCase(uint64_t M, MachineBasicBlock* T, MachineBasicBlock* Tr,
276 BranchProbability Prob):
277 Mask(M), ThisBB(T), TargetBB(Tr), ExtraProb(Prob) { }
279 MachineBasicBlock *ThisBB;
280 MachineBasicBlock *TargetBB;
281 BranchProbability ExtraProb;
284 typedef SmallVector<BitTestCase, 3> BitTestInfo;
286 struct BitTestBlock {
287 BitTestBlock(APInt F, APInt R, const Value *SV, unsigned Rg, MVT RgVT,
288 bool E, bool CR, MachineBasicBlock *P, MachineBasicBlock *D,
289 BitTestInfo C, BranchProbability Pr)
290 : First(std::move(F)), Range(std::move(R)), SValue(SV), Reg(Rg),
291 RegVT(RgVT), Emitted(E), ContiguousRange(CR), Parent(P), Default(D),
292 Cases(std::move(C)), Prob(Pr) {}
299 bool ContiguousRange;
300 MachineBasicBlock *Parent;
301 MachineBasicBlock *Default;
303 BranchProbability Prob;
304 BranchProbability DefaultProb;
307 /// Check whether a range of clusters is dense enough for a jump table.
308 bool isDense(const CaseClusterVector &Clusters,
309 const SmallVectorImpl<unsigned> &TotalCases,
310 unsigned First, unsigned Last, unsigned MinDensity) const;
312 /// Build a jump table cluster from Clusters[First..Last]. Returns false if it
313 /// decides it's not a good idea.
314 bool buildJumpTable(const CaseClusterVector &Clusters, unsigned First,
315 unsigned Last, const SwitchInst *SI,
316 MachineBasicBlock *DefaultMBB, CaseCluster &JTCluster);
318 /// Find clusters of cases suitable for jump table lowering.
319 void findJumpTables(CaseClusterVector &Clusters, const SwitchInst *SI,
320 MachineBasicBlock *DefaultMBB);
322 /// Check whether the range [Low,High] fits in a machine word.
323 bool rangeFitsInWord(const APInt &Low, const APInt &High);
325 /// Check whether these clusters are suitable for lowering with bit tests based
326 /// on the number of destinations, comparison metric, and range.
327 bool isSuitableForBitTests(unsigned NumDests, unsigned NumCmps,
328 const APInt &Low, const APInt &High);
330 /// Build a bit test cluster from Clusters[First..Last]. Returns false if it
331 /// decides it's not a good idea.
332 bool buildBitTests(CaseClusterVector &Clusters, unsigned First, unsigned Last,
333 const SwitchInst *SI, CaseCluster &BTCluster);
335 /// Find clusters of cases suitable for bit test lowering.
336 void findBitTestClusters(CaseClusterVector &Clusters, const SwitchInst *SI);
338 struct SwitchWorkListItem {
339 MachineBasicBlock *MBB;
340 CaseClusterIt FirstCluster;
341 CaseClusterIt LastCluster;
342 const ConstantInt *GE;
343 const ConstantInt *LT;
344 BranchProbability DefaultProb;
346 typedef SmallVector<SwitchWorkListItem, 4> SwitchWorkList;
348 /// Determine the rank by weight of CC in [First,Last]. If CC has more weight
349 /// than each cluster in the range, its rank is 0.
350 static unsigned caseClusterRank(const CaseCluster &CC, CaseClusterIt First,
353 /// Emit comparison and split W into two subtrees.
354 void splitWorkItem(SwitchWorkList &WorkList, const SwitchWorkListItem &W,
355 Value *Cond, MachineBasicBlock *SwitchMBB);
358 void lowerWorkItem(SwitchWorkListItem W, Value *Cond,
359 MachineBasicBlock *SwitchMBB,
360 MachineBasicBlock *DefaultMBB);
363 /// A class which encapsulates all of the information needed to generate a
364 /// stack protector check and signals to isel via its state being initialized
365 /// that a stack protector needs to be generated.
367 /// *NOTE* The following is a high level documentation of SelectionDAG Stack
368 /// Protector Generation. The reason that it is placed here is for a lack of
369 /// other good places to stick it.
371 /// High Level Overview of SelectionDAG Stack Protector Generation:
373 /// Previously, generation of stack protectors was done exclusively in the
374 /// pre-SelectionDAG Codegen LLVM IR Pass "Stack Protector". This necessitated
375 /// splitting basic blocks at the IR level to create the success/failure basic
376 /// blocks in the tail of the basic block in question. As a result of this,
377 /// calls that would have qualified for the sibling call optimization were no
378 /// longer eligible for optimization since said calls were no longer right in
379 /// the "tail position" (i.e. the immediate predecessor of a ReturnInst
382 /// Then it was noticed that since the sibling call optimization causes the
383 /// callee to reuse the caller's stack, if we could delay the generation of
384 /// the stack protector check until later in CodeGen after the sibling call
385 /// decision was made, we get both the tail call optimization and the stack
388 /// A few goals in solving this problem were:
390 /// 1. Preserve the architecture independence of stack protector generation.
392 /// 2. Preserve the normal IR level stack protector check for platforms like
393 /// OpenBSD for which we support platform-specific stack protector
396 /// The main problem that guided the present solution is that one can not
397 /// solve this problem in an architecture independent manner at the IR level
398 /// only. This is because:
400 /// 1. The decision on whether or not to perform a sibling call on certain
401 /// platforms (for instance i386) requires lower level information
402 /// related to available registers that can not be known at the IR level.
404 /// 2. Even if the previous point were not true, the decision on whether to
405 /// perform a tail call is done in LowerCallTo in SelectionDAG which
406 /// occurs after the Stack Protector Pass. As a result, one would need to
407 /// put the relevant callinst into the stack protector check success
408 /// basic block (where the return inst is placed) and then move it back
409 /// later at SelectionDAG/MI time before the stack protector check if the
410 /// tail call optimization failed. The MI level option was nixed
411 /// immediately since it would require platform-specific pattern
412 /// matching. The SelectionDAG level option was nixed because
413 /// SelectionDAG only processes one IR level basic block at a time
414 /// implying one could not create a DAG Combine to move the callinst.
416 /// To get around this problem a few things were realized:
418 /// 1. While one can not handle multiple IR level basic blocks at the
419 /// SelectionDAG Level, one can generate multiple machine basic blocks
420 /// for one IR level basic block. This is how we handle bit tests and
423 /// 2. At the MI level, tail calls are represented via a special return
424 /// MIInst called "tcreturn". Thus if we know the basic block in which we
425 /// wish to insert the stack protector check, we get the correct behavior
426 /// by always inserting the stack protector check right before the return
427 /// statement. This is a "magical transformation" since no matter where
428 /// the stack protector check intrinsic is, we always insert the stack
429 /// protector check code at the end of the BB.
431 /// Given the aforementioned constraints, the following solution was devised:
433 /// 1. On platforms that do not support SelectionDAG stack protector check
434 /// generation, allow for the normal IR level stack protector check
435 /// generation to continue.
437 /// 2. On platforms that do support SelectionDAG stack protector check
440 /// a. Use the IR level stack protector pass to decide if a stack
441 /// protector is required/which BB we insert the stack protector check
442 /// in by reusing the logic already therein. If we wish to generate a
443 /// stack protector check in a basic block, we place a special IR
444 /// intrinsic called llvm.stackprotectorcheck right before the BB's
445 /// returninst or if there is a callinst that could potentially be
446 /// sibling call optimized, before the call inst.
448 /// b. Then when a BB with said intrinsic is processed, we codegen the BB
449 /// normally via SelectBasicBlock. In said process, when we visit the
450 /// stack protector check, we do not actually emit anything into the
451 /// BB. Instead, we just initialize the stack protector descriptor
452 /// class (which involves stashing information/creating the success
453 /// mbbb and the failure mbb if we have not created one for this
454 /// function yet) and export the guard variable that we are going to
457 /// c. After we finish selecting the basic block, in FinishBasicBlock if
458 /// the StackProtectorDescriptor attached to the SelectionDAGBuilder is
459 /// initialized, we produce the validation code with one of these
461 /// 1) with a call to a guard check function
462 /// 2) with inlined instrumentation
464 /// 1) We insert a call to the check function before the terminator.
466 /// 2) We first find a splice point in the parent basic block
467 /// before the terminator and then splice the terminator of said basic
468 /// block into the success basic block. Then we code-gen a new tail for
469 /// the parent basic block consisting of the two loads, the comparison,
470 /// and finally two branches to the success/failure basic blocks. We
471 /// conclude by code-gening the failure basic block if we have not
472 /// code-gened it already (all stack protector checks we generate in
473 /// the same function, use the same failure basic block).
474 class StackProtectorDescriptor {
476 StackProtectorDescriptor()
477 : ParentMBB(nullptr), SuccessMBB(nullptr), FailureMBB(nullptr) {}
479 /// Returns true if all fields of the stack protector descriptor are
480 /// initialized implying that we should/are ready to emit a stack protector.
481 bool shouldEmitStackProtector() const {
482 return ParentMBB && SuccessMBB && FailureMBB;
485 bool shouldEmitFunctionBasedCheckStackProtector() const {
486 return ParentMBB && !SuccessMBB && !FailureMBB;
489 /// Initialize the stack protector descriptor structure for a new basic
491 void initialize(const BasicBlock *BB, MachineBasicBlock *MBB,
492 bool FunctionBasedInstrumentation) {
493 // Make sure we are not initialized yet.
494 assert(!shouldEmitStackProtector() && "Stack Protector Descriptor is "
495 "already initialized!");
497 if (!FunctionBasedInstrumentation) {
498 SuccessMBB = AddSuccessorMBB(BB, MBB, /* IsLikely */ true);
499 FailureMBB = AddSuccessorMBB(BB, MBB, /* IsLikely */ false, FailureMBB);
503 /// Reset state that changes when we handle different basic blocks.
505 /// This currently includes:
507 /// 1. The specific basic block we are generating a
508 /// stack protector for (ParentMBB).
510 /// 2. The successor machine basic block that will contain the tail of
511 /// parent mbb after we create the stack protector check (SuccessMBB). This
512 /// BB is visited only on stack protector check success.
513 void resetPerBBState() {
515 SuccessMBB = nullptr;
518 /// Reset state that only changes when we switch functions.
520 /// This currently includes:
522 /// 1. FailureMBB since we reuse the failure code path for all stack
523 /// protector checks created in an individual function.
525 /// 2.The guard variable since the guard variable we are checking against is
527 void resetPerFunctionState() {
528 FailureMBB = nullptr;
531 MachineBasicBlock *getParentMBB() { return ParentMBB; }
532 MachineBasicBlock *getSuccessMBB() { return SuccessMBB; }
533 MachineBasicBlock *getFailureMBB() { return FailureMBB; }
536 /// The basic block for which we are generating the stack protector.
538 /// As a result of stack protector generation, we will splice the
539 /// terminators of this basic block into the successor mbb SuccessMBB and
540 /// replace it with a compare/branch to the successor mbbs
541 /// SuccessMBB/FailureMBB depending on whether or not the stack protector
543 MachineBasicBlock *ParentMBB;
545 /// A basic block visited on stack protector check success that contains the
546 /// terminators of ParentMBB.
547 MachineBasicBlock *SuccessMBB;
549 /// This basic block visited on stack protector check failure that will
550 /// contain a call to __stack_chk_fail().
551 MachineBasicBlock *FailureMBB;
553 /// Add a successor machine basic block to ParentMBB. If the successor mbb
554 /// has not been created yet (i.e. if SuccMBB = 0), then the machine basic
555 /// block will be created. Assign a large weight if IsLikely is true.
556 MachineBasicBlock *AddSuccessorMBB(const BasicBlock *BB,
557 MachineBasicBlock *ParentMBB,
559 MachineBasicBlock *SuccMBB = nullptr);
563 const TargetMachine &TM;
565 /// Lowest valid SDNodeOrder. The special case 0 is reserved for scheduling
566 /// nodes without a corresponding SDNode.
567 static const unsigned LowestSDNodeOrder = 1;
570 const DataLayout *DL;
572 const TargetLibraryInfo *LibInfo;
574 /// SwitchCases - Vector of CaseBlock structures used to communicate
575 /// SwitchInst code generation information.
576 std::vector<CaseBlock> SwitchCases;
577 /// JTCases - Vector of JumpTable structures used to communicate
578 /// SwitchInst code generation information.
579 std::vector<JumpTableBlock> JTCases;
580 /// BitTestCases - Vector of BitTestBlock structures used to communicate
581 /// SwitchInst code generation information.
582 std::vector<BitTestBlock> BitTestCases;
583 /// A StackProtectorDescriptor structure used to communicate stack protector
584 /// information in between SelectBasicBlock and FinishBasicBlock.
585 StackProtectorDescriptor SPDescriptor;
587 // Emit PHI-node-operand constants only once even if used by multiple
589 DenseMap<const Constant *, unsigned> ConstantsOut;
591 /// FuncInfo - Information about the function as a whole.
593 FunctionLoweringInfo &FuncInfo;
595 /// GFI - Garbage collection metadata for the function.
598 /// LPadToCallSiteMap - Map a landing pad to the call site indexes.
599 DenseMap<MachineBasicBlock*, SmallVector<unsigned, 4> > LPadToCallSiteMap;
601 /// HasTailCall - This is set to true if a call in the current
602 /// block has been translated as a tail call. In this case,
603 /// no subsequent DAG nodes should be created.
607 LLVMContext *Context;
609 SelectionDAGBuilder(SelectionDAG &dag, FunctionLoweringInfo &funcinfo,
610 CodeGenOpt::Level ol)
611 : CurInst(nullptr), SDNodeOrder(LowestSDNodeOrder), TM(dag.getTarget()),
612 DAG(dag), FuncInfo(funcinfo),
616 void init(GCFunctionInfo *gfi, AliasAnalysis &aa,
617 const TargetLibraryInfo *li);
619 /// Clear out the current SelectionDAG and the associated state and prepare
620 /// this SelectionDAGBuilder object to be used for a new block. This doesn't
621 /// clear out information about additional blocks that are needed to complete
622 /// switch lowering or PHI node updating; that information is cleared out as
626 /// Clear the dangling debug information map. This function is separated from
627 /// the clear so that debug information that is dangling in a basic block can
628 /// be properly resolved in a different basic block. This allows the
629 /// SelectionDAG to resolve dangling debug information attached to PHI nodes.
630 void clearDanglingDebugInfo();
632 /// Return the current virtual root of the Selection DAG, flushing any
633 /// PendingLoad items. This must be done before emitting a store or any other
634 /// node that may need to be ordered after any prior load instructions.
637 /// Similar to getRoot, but instead of flushing all the PendingLoad items,
638 /// flush all the PendingExports items. It is necessary to do this before
639 /// emitting a terminator instruction.
640 SDValue getControlRoot();
642 SDLoc getCurSDLoc() const {
643 return SDLoc(CurInst, SDNodeOrder);
646 DebugLoc getCurDebugLoc() const {
647 return CurInst ? CurInst->getDebugLoc() : DebugLoc();
650 void CopyValueToVirtualRegister(const Value *V, unsigned Reg);
652 void visit(const Instruction &I);
654 void visit(unsigned Opcode, const User &I);
656 /// getCopyFromRegs - If there was virtual register allocated for the value V
657 /// emit CopyFromReg of the specified type Ty. Return empty SDValue() otherwise.
658 SDValue getCopyFromRegs(const Value *V, Type *Ty);
660 // resolveDanglingDebugInfo - if we saw an earlier dbg_value referring to V,
661 // generate the debug data structures now that we've seen its definition.
662 void resolveDanglingDebugInfo(const Value *V, SDValue Val);
663 SDValue getValue(const Value *V);
664 bool findValue(const Value *V) const;
666 SDValue getNonRegisterValue(const Value *V);
667 SDValue getValueImpl(const Value *V);
669 void setValue(const Value *V, SDValue NewN) {
670 SDValue &N = NodeMap[V];
671 assert(!N.getNode() && "Already set a value for this node!");
675 void setUnusedArgValue(const Value *V, SDValue NewN) {
676 SDValue &N = UnusedArgNodeMap[V];
677 assert(!N.getNode() && "Already set a value for this node!");
681 void FindMergedConditions(const Value *Cond, MachineBasicBlock *TBB,
682 MachineBasicBlock *FBB, MachineBasicBlock *CurBB,
683 MachineBasicBlock *SwitchBB,
684 Instruction::BinaryOps Opc, BranchProbability TW,
685 BranchProbability FW, bool InvertCond);
686 void EmitBranchForMergedCondition(const Value *Cond, MachineBasicBlock *TBB,
687 MachineBasicBlock *FBB,
688 MachineBasicBlock *CurBB,
689 MachineBasicBlock *SwitchBB,
690 BranchProbability TW, BranchProbability FW,
692 bool ShouldEmitAsBranches(const std::vector<CaseBlock> &Cases);
693 bool isExportableFromCurrentBlock(const Value *V, const BasicBlock *FromBB);
694 void CopyToExportRegsIfNeeded(const Value *V);
695 void ExportFromCurrentBlock(const Value *V);
696 void LowerCallTo(ImmutableCallSite CS, SDValue Callee, bool IsTailCall,
697 const BasicBlock *EHPadBB = nullptr);
699 // Lower range metadata from 0 to N to assert zext to an integer of nearest
700 // floor power of two.
701 SDValue lowerRangeToAssertZExt(SelectionDAG &DAG, const Instruction &I,
704 void populateCallLoweringInfo(TargetLowering::CallLoweringInfo &CLI,
705 ImmutableCallSite CS, unsigned ArgIdx,
706 unsigned NumArgs, SDValue Callee,
707 Type *ReturnTy, bool IsPatchPoint);
709 std::pair<SDValue, SDValue>
710 lowerInvokable(TargetLowering::CallLoweringInfo &CLI,
711 const BasicBlock *EHPadBB = nullptr);
713 /// UpdateSplitBlock - When an MBB was split during scheduling, update the
714 /// references that need to refer to the last resulting block.
715 void UpdateSplitBlock(MachineBasicBlock *First, MachineBasicBlock *Last);
717 /// Describes a gc.statepoint or a gc.statepoint like thing for the purposes
718 /// of lowering into a STATEPOINT node.
719 struct StatepointLoweringInfo {
720 /// Bases[i] is the base pointer for Ptrs[i]. Together they denote the set
721 /// of gc pointers this STATEPOINT has to relocate.
722 SmallVector<const Value *, 16> Bases;
723 SmallVector<const Value *, 16> Ptrs;
725 /// The set of gc.relocate calls associated with this gc.statepoint.
726 SmallVector<const GCRelocateInst *, 16> GCRelocates;
728 /// The full list of gc arguments to the gc.statepoint being lowered.
729 ArrayRef<const Use> GCArgs;
731 /// The gc.statepoint instruction.
732 const Instruction *StatepointInstr = nullptr;
734 /// The list of gc transition arguments present in the gc.statepoint being
736 ArrayRef<const Use> GCTransitionArgs;
738 /// The ID that the resulting STATEPOINT instruction has to report.
741 /// Information regarding the underlying call instruction.
742 TargetLowering::CallLoweringInfo CLI;
744 /// The deoptimization state associated with this gc.statepoint call, if
746 ArrayRef<const Use> DeoptState;
748 /// Flags associated with the meta arguments being lowered.
749 uint64_t StatepointFlags = -1;
751 /// The number of patchable bytes the call needs to get lowered into.
752 unsigned NumPatchBytes = -1;
754 /// The exception handling unwind destination, in case this represents an
755 /// invoke of gc.statepoint.
756 const BasicBlock *EHPadBB = nullptr;
758 explicit StatepointLoweringInfo(SelectionDAG &DAG) : CLI(DAG) {}
761 /// Lower \p SLI into a STATEPOINT instruction.
762 SDValue LowerAsSTATEPOINT(StatepointLoweringInfo &SLI);
764 // This function is responsible for the whole statepoint lowering process.
765 // It uniformly handles invoke and call statepoints.
766 void LowerStatepoint(ImmutableStatepoint Statepoint,
767 const BasicBlock *EHPadBB = nullptr);
769 void LowerCallSiteWithDeoptBundle(ImmutableCallSite CS, SDValue Callee,
770 const BasicBlock *EHPadBB);
772 void LowerDeoptimizeCall(const CallInst *CI);
773 void LowerDeoptimizingReturn();
775 void LowerCallSiteWithDeoptBundleImpl(ImmutableCallSite CS, SDValue Callee,
776 const BasicBlock *EHPadBB,
777 bool VarArgDisallowed,
778 bool ForceVoidReturnTy);
781 // Terminator instructions.
782 void visitRet(const ReturnInst &I);
783 void visitBr(const BranchInst &I);
784 void visitSwitch(const SwitchInst &I);
785 void visitIndirectBr(const IndirectBrInst &I);
786 void visitUnreachable(const UnreachableInst &I);
787 void visitCleanupRet(const CleanupReturnInst &I);
788 void visitCatchSwitch(const CatchSwitchInst &I);
789 void visitCatchRet(const CatchReturnInst &I);
790 void visitCatchPad(const CatchPadInst &I);
791 void visitCleanupPad(const CleanupPadInst &CPI);
793 BranchProbability getEdgeProbability(const MachineBasicBlock *Src,
794 const MachineBasicBlock *Dst) const;
795 void addSuccessorWithProb(
796 MachineBasicBlock *Src, MachineBasicBlock *Dst,
797 BranchProbability Prob = BranchProbability::getUnknown());
800 void visitSwitchCase(CaseBlock &CB,
801 MachineBasicBlock *SwitchBB);
802 void visitSPDescriptorParent(StackProtectorDescriptor &SPD,
803 MachineBasicBlock *ParentBB);
804 void visitSPDescriptorFailure(StackProtectorDescriptor &SPD);
805 void visitBitTestHeader(BitTestBlock &B, MachineBasicBlock *SwitchBB);
806 void visitBitTestCase(BitTestBlock &BB,
807 MachineBasicBlock* NextMBB,
808 BranchProbability BranchProbToNext,
811 MachineBasicBlock *SwitchBB);
812 void visitJumpTable(JumpTable &JT);
813 void visitJumpTableHeader(JumpTable &JT, JumpTableHeader &JTH,
814 MachineBasicBlock *SwitchBB);
817 // These all get lowered before this pass.
818 void visitInvoke(const InvokeInst &I);
819 void visitResume(const ResumeInst &I);
821 void visitBinary(const User &I, unsigned OpCode);
822 void visitShift(const User &I, unsigned Opcode);
823 void visitAdd(const User &I) { visitBinary(I, ISD::ADD); }
824 void visitFAdd(const User &I) { visitBinary(I, ISD::FADD); }
825 void visitSub(const User &I) { visitBinary(I, ISD::SUB); }
826 void visitFSub(const User &I);
827 void visitMul(const User &I) { visitBinary(I, ISD::MUL); }
828 void visitFMul(const User &I) { visitBinary(I, ISD::FMUL); }
829 void visitURem(const User &I) { visitBinary(I, ISD::UREM); }
830 void visitSRem(const User &I) { visitBinary(I, ISD::SREM); }
831 void visitFRem(const User &I) { visitBinary(I, ISD::FREM); }
832 void visitUDiv(const User &I) { visitBinary(I, ISD::UDIV); }
833 void visitSDiv(const User &I);
834 void visitFDiv(const User &I) { visitBinary(I, ISD::FDIV); }
835 void visitAnd (const User &I) { visitBinary(I, ISD::AND); }
836 void visitOr (const User &I) { visitBinary(I, ISD::OR); }
837 void visitXor (const User &I) { visitBinary(I, ISD::XOR); }
838 void visitShl (const User &I) { visitShift(I, ISD::SHL); }
839 void visitLShr(const User &I) { visitShift(I, ISD::SRL); }
840 void visitAShr(const User &I) { visitShift(I, ISD::SRA); }
841 void visitICmp(const User &I);
842 void visitFCmp(const User &I);
843 // Visit the conversion instructions
844 void visitTrunc(const User &I);
845 void visitZExt(const User &I);
846 void visitSExt(const User &I);
847 void visitFPTrunc(const User &I);
848 void visitFPExt(const User &I);
849 void visitFPToUI(const User &I);
850 void visitFPToSI(const User &I);
851 void visitUIToFP(const User &I);
852 void visitSIToFP(const User &I);
853 void visitPtrToInt(const User &I);
854 void visitIntToPtr(const User &I);
855 void visitBitCast(const User &I);
856 void visitAddrSpaceCast(const User &I);
858 void visitExtractElement(const User &I);
859 void visitInsertElement(const User &I);
860 void visitShuffleVector(const User &I);
862 void visitExtractValue(const ExtractValueInst &I);
863 void visitInsertValue(const InsertValueInst &I);
864 void visitLandingPad(const LandingPadInst &I);
866 void visitGetElementPtr(const User &I);
867 void visitSelect(const User &I);
869 void visitAlloca(const AllocaInst &I);
870 void visitLoad(const LoadInst &I);
871 void visitStore(const StoreInst &I);
872 void visitMaskedLoad(const CallInst &I, bool IsExpanding = false);
873 void visitMaskedStore(const CallInst &I, bool IsCompressing = false);
874 void visitMaskedGather(const CallInst &I);
875 void visitMaskedScatter(const CallInst &I);
876 void visitAtomicCmpXchg(const AtomicCmpXchgInst &I);
877 void visitAtomicRMW(const AtomicRMWInst &I);
878 void visitFence(const FenceInst &I);
879 void visitPHI(const PHINode &I);
880 void visitCall(const CallInst &I);
881 bool visitMemCmpCall(const CallInst &I);
882 bool visitMemPCpyCall(const CallInst &I);
883 bool visitMemChrCall(const CallInst &I);
884 bool visitStrCpyCall(const CallInst &I, bool isStpcpy);
885 bool visitStrCmpCall(const CallInst &I);
886 bool visitStrLenCall(const CallInst &I);
887 bool visitStrNLenCall(const CallInst &I);
888 bool visitUnaryFloatCall(const CallInst &I, unsigned Opcode);
889 bool visitBinaryFloatCall(const CallInst &I, unsigned Opcode);
890 void visitAtomicLoad(const LoadInst &I);
891 void visitAtomicStore(const StoreInst &I);
892 void visitLoadFromSwiftError(const LoadInst &I);
893 void visitStoreToSwiftError(const StoreInst &I);
895 void visitInlineAsm(ImmutableCallSite CS);
896 const char *visitIntrinsicCall(const CallInst &I, unsigned Intrinsic);
897 void visitTargetIntrinsic(const CallInst &I, unsigned Intrinsic);
898 void visitConstrainedFPIntrinsic(const CallInst &I, unsigned Intrinsic);
900 void visitVAStart(const CallInst &I);
901 void visitVAArg(const VAArgInst &I);
902 void visitVAEnd(const CallInst &I);
903 void visitVACopy(const CallInst &I);
904 void visitStackmap(const CallInst &I);
905 void visitPatchpoint(ImmutableCallSite CS,
906 const BasicBlock *EHPadBB = nullptr);
908 // These two are implemented in StatepointLowering.cpp
909 void visitGCRelocate(const GCRelocateInst &I);
910 void visitGCResult(const GCResultInst &I);
912 void visitUserOp1(const Instruction &I) {
913 llvm_unreachable("UserOp1 should not exist at instruction selection time!");
915 void visitUserOp2(const Instruction &I) {
916 llvm_unreachable("UserOp2 should not exist at instruction selection time!");
919 void processIntegerCallValue(const Instruction &I,
920 SDValue Value, bool IsSigned);
922 void HandlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB);
924 void emitInlineAsmError(ImmutableCallSite CS, const Twine &Message);
926 /// EmitFuncArgumentDbgValue - If V is an function argument then create
927 /// corresponding DBG_VALUE machine instruction for it now. At the end of
928 /// instruction selection, they will be inserted to the entry BB.
929 bool EmitFuncArgumentDbgValue(const Value *V, DILocalVariable *Variable,
930 DIExpression *Expr, DILocation *DL,
931 int64_t Offset, bool IsDbgDeclare,
934 /// Return the next block after MBB, or nullptr if there is none.
935 MachineBasicBlock *NextBlock(MachineBasicBlock *MBB);
937 /// Update the DAG and DAG builder with the relevant information after
938 /// a new root node has been created which could be a tail call.
939 void updateDAGForMaybeTailCall(SDValue MaybeTC);
941 /// Return the appropriate SDDbgValue based on N.
942 SDDbgValue *getDbgValue(SDValue N, DILocalVariable *Variable,
943 DIExpression *Expr, int64_t Offset,
944 const DebugLoc &dl, unsigned DbgSDNodeOrder);
947 /// RegsForValue - This struct represents the registers (physical or virtual)
948 /// that a particular set of values is assigned, and the type information about
949 /// the value. The most common situation is to represent one value at a time,
950 /// but struct or array values are handled element-wise as multiple values. The
951 /// splitting of aggregates is performed recursively, so that we never have
952 /// aggregate-typed registers. The values at this point do not necessarily have
953 /// legal types, so each value may require one or more registers of some legal
956 struct RegsForValue {
957 /// The value types of the values, which may not be legal, and
958 /// may need be promoted or synthesized from one or more registers.
959 SmallVector<EVT, 4> ValueVTs;
961 /// The value types of the registers. This is the same size as ValueVTs and it
962 /// records, for each value, what the type of the assigned register or
963 /// registers are. (Individual values are never synthesized from more than one
964 /// type of register.)
966 /// With virtual registers, the contents of RegVTs is redundant with TLI's
967 /// getRegisterType member function, however when with physical registers
968 /// it is necessary to have a separate record of the types.
969 SmallVector<MVT, 4> RegVTs;
971 /// This list holds the registers assigned to the values.
972 /// Each legal or promoted value requires one register, and each
973 /// expanded value requires multiple registers.
974 SmallVector<unsigned, 4> Regs;
978 RegsForValue(const SmallVector<unsigned, 4> ®s, MVT regvt, EVT valuevt);
980 RegsForValue(LLVMContext &Context, const TargetLowering &TLI,
981 const DataLayout &DL, unsigned Reg, Type *Ty);
983 /// Add the specified values to this one.
984 void append(const RegsForValue &RHS) {
985 ValueVTs.append(RHS.ValueVTs.begin(), RHS.ValueVTs.end());
986 RegVTs.append(RHS.RegVTs.begin(), RHS.RegVTs.end());
987 Regs.append(RHS.Regs.begin(), RHS.Regs.end());
990 /// Emit a series of CopyFromReg nodes that copies from this value and returns
991 /// the result as a ValueVTs value. This uses Chain/Flag as the input and
992 /// updates them for the output Chain/Flag. If the Flag pointer is NULL, no
994 SDValue getCopyFromRegs(SelectionDAG &DAG, FunctionLoweringInfo &FuncInfo,
995 const SDLoc &dl, SDValue &Chain, SDValue *Flag,
996 const Value *V = nullptr) const;
998 /// Emit a series of CopyToReg nodes that copies the specified value into the
999 /// registers specified by this object. This uses Chain/Flag as the input and
1000 /// updates them for the output Chain/Flag. If the Flag pointer is nullptr, no
1001 /// flag is used. If V is not nullptr, then it is used in printing better
1002 /// diagnostic messages on error.
1003 void getCopyToRegs(SDValue Val, SelectionDAG &DAG, const SDLoc &dl,
1004 SDValue &Chain, SDValue *Flag, const Value *V = nullptr,
1005 ISD::NodeType PreferredExtendType = ISD::ANY_EXTEND) const;
1007 /// Add this value to the specified inlineasm node operand list. This adds the
1008 /// code marker, matching input operand index (if applicable), and includes
1009 /// the number of values added into it.
1010 void AddInlineAsmOperands(unsigned Kind, bool HasMatching,
1011 unsigned MatchingIdx, const SDLoc &dl,
1012 SelectionDAG &DAG, std::vector<SDValue> &Ops) const;
1015 } // end namespace llvm