1//===-- FunctionLoweringInfo.h - Lower functions from LLVM IR to CodeGen --===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This implements routines for translating functions from LLVM IR into
11// Machine IR.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_CODEGEN_FUNCTIONLOWERINGINFO_H
16#define LLVM_CODEGEN_FUNCTIONLOWERINGINFO_H
17
18#include "llvm/ADT/APInt.h"
19#include "llvm/ADT/DenseMap.h"
20#include "llvm/ADT/IndexedMap.h"
21#include "llvm/ADT/Optional.h"
22#include "llvm/ADT/SmallPtrSet.h"
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/CodeGen/ISDOpcodes.h"
25#include "llvm/CodeGen/MachineBasicBlock.h"
26#include "llvm/IR/InlineAsm.h"
27#include "llvm/IR/Instructions.h"
28#include "llvm/Target/TargetRegisterInfo.h"
29#include <vector>
30
31namespace llvm {
32
33class AllocaInst;
34class BasicBlock;
35class BranchProbabilityInfo;
36class CallInst;
37class Function;
38class GlobalVariable;
39class Instruction;
40class MachineInstr;
41class MachineBasicBlock;
42class MachineFunction;
43class MachineModuleInfo;
44class MachineRegisterInfo;
45class SelectionDAG;
46class MVT;
47class TargetLowering;
48class Value;
49
50//===--------------------------------------------------------------------===//
51/// FunctionLoweringInfo - This contains information that is global to a
52/// function that is used when lowering a region of the function.
53///
54class FunctionLoweringInfo {
55public:
56  const Function *Fn;
57  MachineFunction *MF;
58  const TargetLowering *TLI;
59  MachineRegisterInfo *RegInfo;
60  BranchProbabilityInfo *BPI;
61  /// CanLowerReturn - true iff the function's return value can be lowered to
62  /// registers.
63  bool CanLowerReturn;
64
65  /// True if part of the CSRs will be handled via explicit copies.
66  bool SplitCSR;
67
68  /// DemoteRegister - if CanLowerReturn is false, DemoteRegister is a vreg
69  /// allocated to hold a pointer to the hidden sret parameter.
70  unsigned DemoteRegister;
71
72  /// MBBMap - A mapping from LLVM basic blocks to their machine code entry.
73  DenseMap<const BasicBlock*, MachineBasicBlock *> MBBMap;
74
75  typedef SmallVector<unsigned, 1> SwiftErrorVRegs;
76  typedef SmallVector<const Value*, 1> SwiftErrorValues;
77  /// A function can only have a single swifterror argument. And if it does
78  /// have a swifterror argument, it must be the first entry in
79  /// SwiftErrorVals.
80  SwiftErrorValues SwiftErrorVals;
81
82  /// Track the virtual register for each swifterror value in a given basic
83  /// block. Entries in SwiftErrorVRegs have the same ordering as entries
84  /// in SwiftErrorVals.
85  /// Note that another choice that is more straight-forward is to use
86  /// Map<const MachineBasicBlock*, Map<Value*, unsigned/*VReg*/>>. It
87  /// maintains a map from swifterror values to virtual registers for each
88  /// machine basic block. This choice does not require a one-to-one
89  /// correspondence between SwiftErrorValues and SwiftErrorVRegs. But because
90  /// of efficiency concern, we do not choose it.
91  llvm::DenseMap<const MachineBasicBlock*, SwiftErrorVRegs> SwiftErrorMap;
92
93  /// Track the virtual register for each swifterror value at the end of a basic
94  /// block when we need the assignment of a virtual register before the basic
95  /// block is visited. When we actually visit the basic block, we will make
96  /// sure the swifterror value is in the correct virtual register.
97  llvm::DenseMap<const MachineBasicBlock*, SwiftErrorVRegs>
98      SwiftErrorWorklist;
99
100  /// Find the swifterror virtual register in SwiftErrorMap. We will assert
101  /// failure when the value does not exist in swifterror map.
102  unsigned findSwiftErrorVReg(const MachineBasicBlock*, const Value*) const;
103  /// Set the swifterror virtual register in SwiftErrorMap.
104  void setSwiftErrorVReg(const MachineBasicBlock *MBB, const Value*, unsigned);
105
106  /// ValueMap - Since we emit code for the function a basic block at a time,
107  /// we must remember which virtual registers hold the values for
108  /// cross-basic-block values.
109  DenseMap<const Value *, unsigned> ValueMap;
110
111  /// Track virtual registers created for exception pointers.
112  DenseMap<const Value *, unsigned> CatchPadExceptionPointers;
113
114  /// Keep track of frame indices allocated for statepoints as they could be
115  /// used across basic block boundaries.  This struct is more complex than a
116  /// simple map because the stateopint lowering code de-duplicates gc pointers
117  /// based on their SDValue (so %p and (bitcast %p to T) will get the same
118  /// slot), and we track that here.
119
120  struct StatepointSpillMap {
121    typedef DenseMap<const Value *, Optional<int>> SlotMapTy;
122
123    /// Maps uniqued llvm IR values to the slots they were spilled in.  If a
124    /// value is mapped to None it means we visited the value but didn't spill
125    /// it (because it was a constant, for instance).
126    SlotMapTy SlotMap;
127
128    /// Maps llvm IR values to the values they were de-duplicated to.
129    DenseMap<const Value *, const Value *> DuplicateMap;
130
131    SlotMapTy::const_iterator find(const Value *V) const {
132      auto DuplIt = DuplicateMap.find(V);
133      if (DuplIt != DuplicateMap.end())
134        V = DuplIt->second;
135      return SlotMap.find(V);
136    }
137
138    SlotMapTy::const_iterator end() const { return SlotMap.end(); }
139  };
140
141  /// Maps gc.statepoint instructions to their corresponding StatepointSpillMap
142  /// instances.
143  DenseMap<const Instruction *, StatepointSpillMap> StatepointSpillMaps;
144
145  /// StaticAllocaMap - Keep track of frame indices for fixed sized allocas in
146  /// the entry block.  This allows the allocas to be efficiently referenced
147  /// anywhere in the function.
148  DenseMap<const AllocaInst*, int> StaticAllocaMap;
149
150  /// ByValArgFrameIndexMap - Keep track of frame indices for byval arguments.
151  DenseMap<const Argument*, int> ByValArgFrameIndexMap;
152
153  /// ArgDbgValues - A list of DBG_VALUE instructions created during isel for
154  /// function arguments that are inserted after scheduling is completed.
155  SmallVector<MachineInstr*, 8> ArgDbgValues;
156
157  /// RegFixups - Registers which need to be replaced after isel is done.
158  DenseMap<unsigned, unsigned> RegFixups;
159
160  /// StatepointStackSlots - A list of temporary stack slots (frame indices)
161  /// used to spill values at a statepoint.  We store them here to enable
162  /// reuse of the same stack slots across different statepoints in different
163  /// basic blocks.
164  SmallVector<unsigned, 50> StatepointStackSlots;
165
166  /// MBB - The current block.
167  MachineBasicBlock *MBB;
168
169  /// MBB - The current insert position inside the current block.
170  MachineBasicBlock::iterator InsertPt;
171
172  struct LiveOutInfo {
173    unsigned NumSignBits : 31;
174    unsigned IsValid : 1;
175    APInt KnownOne, KnownZero;
176    LiveOutInfo() : NumSignBits(0), IsValid(true), KnownOne(1, 0),
177                    KnownZero(1, 0) {}
178  };
179
180  /// Record the preferred extend type (ISD::SIGN_EXTEND or ISD::ZERO_EXTEND)
181  /// for a value.
182  DenseMap<const Value *, ISD::NodeType> PreferredExtendType;
183
184  /// VisitedBBs - The set of basic blocks visited thus far by instruction
185  /// selection.
186  SmallPtrSet<const BasicBlock*, 4> VisitedBBs;
187
188  /// PHINodesToUpdate - A list of phi instructions whose operand list will
189  /// be updated after processing the current basic block.
190  /// TODO: This isn't per-function state, it's per-basic-block state. But
191  /// there's no other convenient place for it to live right now.
192  std::vector<std::pair<MachineInstr*, unsigned> > PHINodesToUpdate;
193  unsigned OrigNumPHINodesToUpdate;
194
195  /// If the current MBB is a landing pad, the exception pointer and exception
196  /// selector registers are copied into these virtual registers by
197  /// SelectionDAGISel::PrepareEHLandingPad().
198  unsigned ExceptionPointerVirtReg, ExceptionSelectorVirtReg;
199
200  /// set - Initialize this FunctionLoweringInfo with the given Function
201  /// and its associated MachineFunction.
202  ///
203  void set(const Function &Fn, MachineFunction &MF, SelectionDAG *DAG);
204
205  /// clear - Clear out all the function-specific state. This returns this
206  /// FunctionLoweringInfo to an empty state, ready to be used for a
207  /// different function.
208  void clear();
209
210  /// isExportedInst - Return true if the specified value is an instruction
211  /// exported from its block.
212  bool isExportedInst(const Value *V) {
213    return ValueMap.count(V);
214  }
215
216  unsigned CreateReg(MVT VT);
217
218  unsigned CreateRegs(Type *Ty);
219
220  unsigned InitializeRegForValue(const Value *V) {
221    // Tokens never live in vregs.
222    if (V->getType()->isTokenTy())
223      return 0;
224    unsigned &R = ValueMap[V];
225    assert(R == 0 && "Already initialized this value register!");
226    return R = CreateRegs(V->getType());
227  }
228
229  /// GetLiveOutRegInfo - Gets LiveOutInfo for a register, returning NULL if the
230  /// register is a PHI destination and the PHI's LiveOutInfo is not valid.
231  const LiveOutInfo *GetLiveOutRegInfo(unsigned Reg) {
232    if (!LiveOutRegInfo.inBounds(Reg))
233      return nullptr;
234
235    const LiveOutInfo *LOI = &LiveOutRegInfo[Reg];
236    if (!LOI->IsValid)
237      return nullptr;
238
239    return LOI;
240  }
241
242  /// GetLiveOutRegInfo - Gets LiveOutInfo for a register, returning NULL if the
243  /// register is a PHI destination and the PHI's LiveOutInfo is not valid. If
244  /// the register's LiveOutInfo is for a smaller bit width, it is extended to
245  /// the larger bit width by zero extension. The bit width must be no smaller
246  /// than the LiveOutInfo's existing bit width.
247  const LiveOutInfo *GetLiveOutRegInfo(unsigned Reg, unsigned BitWidth);
248
249  /// AddLiveOutRegInfo - Adds LiveOutInfo for a register.
250  void AddLiveOutRegInfo(unsigned Reg, unsigned NumSignBits,
251                         const APInt &KnownZero, const APInt &KnownOne) {
252    // Only install this information if it tells us something.
253    if (NumSignBits == 1 && KnownZero == 0 && KnownOne == 0)
254      return;
255
256    LiveOutRegInfo.grow(Reg);
257    LiveOutInfo &LOI = LiveOutRegInfo[Reg];
258    LOI.NumSignBits = NumSignBits;
259    LOI.KnownOne = KnownOne;
260    LOI.KnownZero = KnownZero;
261  }
262
263  /// ComputePHILiveOutRegInfo - Compute LiveOutInfo for a PHI's destination
264  /// register based on the LiveOutInfo of its operands.
265  void ComputePHILiveOutRegInfo(const PHINode*);
266
267  /// InvalidatePHILiveOutRegInfo - Invalidates a PHI's LiveOutInfo, to be
268  /// called when a block is visited before all of its predecessors.
269  void InvalidatePHILiveOutRegInfo(const PHINode *PN) {
270    // PHIs with no uses have no ValueMap entry.
271    DenseMap<const Value*, unsigned>::const_iterator It = ValueMap.find(PN);
272    if (It == ValueMap.end())
273      return;
274
275    unsigned Reg = It->second;
276    if (Reg == 0)
277      return;
278
279    LiveOutRegInfo.grow(Reg);
280    LiveOutRegInfo[Reg].IsValid = false;
281  }
282
283  /// setArgumentFrameIndex - Record frame index for the byval
284  /// argument.
285  void setArgumentFrameIndex(const Argument *A, int FI);
286
287  /// getArgumentFrameIndex - Get frame index for the byval argument.
288  int getArgumentFrameIndex(const Argument *A);
289
290  unsigned getCatchPadExceptionPointerVReg(const Value *CPI,
291                                           const TargetRegisterClass *RC);
292
293private:
294  void addSEHHandlersForLPads(ArrayRef<const LandingPadInst *> LPads);
295
296  /// LiveOutRegInfo - Information about live out vregs.
297  IndexedMap<LiveOutInfo, VirtReg2IndexFunctor> LiveOutRegInfo;
298};
299
300/// ComputeUsesVAFloatArgument - Determine if any floating-point values are
301/// being passed to this variadic function, and set the MachineModuleInfo's
302/// usesVAFloatArgument flag if so. This flag is used to emit an undefined
303/// reference to _fltused on Windows, which will link in MSVCRT's
304/// floating-point support.
305void ComputeUsesVAFloatArgument(const CallInst &I, MachineModuleInfo *MMI);
306
307/// AddLandingPadInfo - Extract the exception handling information from the
308/// landingpad instruction and add them to the specified machine module info.
309void AddLandingPadInfo(const LandingPadInst &I, MachineModuleInfo &MMI,
310                       MachineBasicBlock *MBB);
311
312} // end namespace llvm
313
314#endif
315