1 //=- AArch64MachineFunctionInfo.h - AArch64 machine function info -*- C++ -*-=//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file declares AArch64-specific per-machine-function information.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_LIB_TARGET_AARCH64_AARCH64MACHINEFUNCTIONINFO_H
14 #define LLVM_LIB_TARGET_AARCH64_AARCH64MACHINEFUNCTIONINFO_H
15 
16 #include "llvm/ADT/ArrayRef.h"
17 #include "llvm/ADT/Optional.h"
18 #include "llvm/ADT/SmallPtrSet.h"
19 #include "llvm/ADT/SmallVector.h"
20 #include "llvm/CodeGen/CallingConvLower.h"
21 #include "llvm/CodeGen/MachineFunction.h"
22 #include "llvm/CodeGen/TargetFrameLowering.h"
23 #include "llvm/IR/Function.h"
24 #include "llvm/MC/MCLinkerOptimizationHint.h"
25 #include <cassert>
26 
27 namespace llvm {
28 
29 class MachineInstr;
30 
31 /// AArch64FunctionInfo - This class is derived from MachineFunctionInfo and
32 /// contains private AArch64-specific information for each MachineFunction.
33 class AArch64FunctionInfo final : public MachineFunctionInfo {
34   /// Number of bytes of arguments this function has on the stack. If the callee
35   /// is expected to restore the argument stack this should be a multiple of 16,
36   /// all usable during a tail call.
37   ///
38   /// The alternative would forbid tail call optimisation in some cases: if we
39   /// want to transfer control from a function with 8-bytes of stack-argument
40   /// space to a function with 16-bytes then misalignment of this value would
41   /// make a stack adjustment necessary, which could not be undone by the
42   /// callee.
43   unsigned BytesInStackArgArea = 0;
44 
45   /// The number of bytes to restore to deallocate space for incoming
46   /// arguments. Canonically 0 in the C calling convention, but non-zero when
47   /// callee is expected to pop the args.
48   unsigned ArgumentStackToRestore = 0;
49 
50   /// HasStackFrame - True if this function has a stack frame. Set by
51   /// determineCalleeSaves().
52   bool HasStackFrame = false;
53 
54   /// Amount of stack frame size, not including callee-saved registers.
55   uint64_t LocalStackSize = 0;
56 
57   /// The start and end frame indices for the SVE callee saves.
58   int MinSVECSFrameIndex = 0;
59   int MaxSVECSFrameIndex = 0;
60 
61   /// Amount of stack frame size used for saving callee-saved registers.
62   unsigned CalleeSavedStackSize = 0;
63   unsigned SVECalleeSavedStackSize = 0;
64   bool HasCalleeSavedStackSize = false;
65 
66   /// Number of TLS accesses using the special (combinable)
67   /// _TLS_MODULE_BASE_ symbol.
68   unsigned NumLocalDynamicTLSAccesses = 0;
69 
70   /// FrameIndex for start of varargs area for arguments passed on the
71   /// stack.
72   int VarArgsStackIndex = 0;
73 
74   /// FrameIndex for start of varargs area for arguments passed in
75   /// general purpose registers.
76   int VarArgsGPRIndex = 0;
77 
78   /// Size of the varargs area for arguments passed in general purpose
79   /// registers.
80   unsigned VarArgsGPRSize = 0;
81 
82   /// FrameIndex for start of varargs area for arguments passed in
83   /// floating-point registers.
84   int VarArgsFPRIndex = 0;
85 
86   /// Size of the varargs area for arguments passed in floating-point
87   /// registers.
88   unsigned VarArgsFPRSize = 0;
89 
90   /// True if this function has a subset of CSRs that is handled explicitly via
91   /// copies.
92   bool IsSplitCSR = false;
93 
94   /// True when the stack gets realigned dynamically because the size of stack
95   /// frame is unknown at compile time. e.g., in case of VLAs.
96   bool StackRealigned = false;
97 
98   /// True when the callee-save stack area has unused gaps that may be used for
99   /// other stack allocations.
100   bool CalleeSaveStackHasFreeSpace = false;
101 
102   /// SRetReturnReg - sret lowering includes returning the value of the
103   /// returned struct in a register. This field holds the virtual register into
104   /// which the sret argument is passed.
105   unsigned SRetReturnReg = 0;
106   /// SVE stack size (for predicates and data vectors) are maintained here
107   /// rather than in FrameInfo, as the placement and Stack IDs are target
108   /// specific.
109   uint64_t StackSizeSVE = 0;
110 
111   /// HasCalculatedStackSizeSVE indicates whether StackSizeSVE is valid.
112   bool HasCalculatedStackSizeSVE = false;
113 
114   /// Has a value when it is known whether or not the function uses a
115   /// redzone, and no value otherwise.
116   /// Initialized during frame lowering, unless the function has the noredzone
117   /// attribute, in which case it is set to false at construction.
118   Optional<bool> HasRedZone;
119 
120   /// ForwardedMustTailRegParms - A list of virtual and physical registers
121   /// that must be forwarded to every musttail call.
122   SmallVector<ForwardedRegister, 1> ForwardedMustTailRegParms;
123 
124   // Offset from SP-at-entry to the tagged base pointer.
125   // Tagged base pointer is set up to point to the first (lowest address) tagged
126   // stack slot.
127   unsigned TaggedBasePointerOffset = 0;
128 
129 public:
130   AArch64FunctionInfo() = default;
131 
132   explicit AArch64FunctionInfo(MachineFunction &MF) {
133     (void)MF;
134 
135     // If we already know that the function doesn't have a redzone, set
136     // HasRedZone here.
137     if (MF.getFunction().hasFnAttribute(Attribute::NoRedZone))
138       HasRedZone = false;
139   }
140 
141   unsigned getBytesInStackArgArea() const { return BytesInStackArgArea; }
142   void setBytesInStackArgArea(unsigned bytes) { BytesInStackArgArea = bytes; }
143 
144   unsigned getArgumentStackToRestore() const { return ArgumentStackToRestore; }
145   void setArgumentStackToRestore(unsigned bytes) {
146     ArgumentStackToRestore = bytes;
147   }
148 
149   bool hasCalculatedStackSizeSVE() const { return HasCalculatedStackSizeSVE; }
150 
151   void setStackSizeSVE(uint64_t S) {
152     HasCalculatedStackSizeSVE = true;
153     StackSizeSVE = S;
154   }
155 
156   uint64_t getStackSizeSVE() const { return StackSizeSVE; }
157 
158   bool hasStackFrame() const { return HasStackFrame; }
159   void setHasStackFrame(bool s) { HasStackFrame = s; }
160 
161   bool isStackRealigned() const { return StackRealigned; }
162   void setStackRealigned(bool s) { StackRealigned = s; }
163 
164   bool hasCalleeSaveStackFreeSpace() const {
165     return CalleeSaveStackHasFreeSpace;
166   }
167   void setCalleeSaveStackHasFreeSpace(bool s) {
168     CalleeSaveStackHasFreeSpace = s;
169   }
170   bool isSplitCSR() const { return IsSplitCSR; }
171   void setIsSplitCSR(bool s) { IsSplitCSR = s; }
172 
173   void setLocalStackSize(uint64_t Size) { LocalStackSize = Size; }
174   uint64_t getLocalStackSize() const { return LocalStackSize; }
175 
176   void setCalleeSavedStackSize(unsigned Size) {
177     CalleeSavedStackSize = Size;
178     HasCalleeSavedStackSize = true;
179   }
180 
181   // When CalleeSavedStackSize has not been set (for example when
182   // some MachineIR pass is run in isolation), then recalculate
183   // the CalleeSavedStackSize directly from the CalleeSavedInfo.
184   // Note: This information can only be recalculated after PEI
185   // has assigned offsets to the callee save objects.
186   unsigned getCalleeSavedStackSize(const MachineFrameInfo &MFI) const {
187     bool ValidateCalleeSavedStackSize = false;
188 
189 #ifndef NDEBUG
190     // Make sure the calculated size derived from the CalleeSavedInfo
191     // equals the cached size that was calculated elsewhere (e.g. in
192     // determineCalleeSaves).
193     ValidateCalleeSavedStackSize = HasCalleeSavedStackSize;
194 #endif
195 
196     if (!HasCalleeSavedStackSize || ValidateCalleeSavedStackSize) {
197       assert(MFI.isCalleeSavedInfoValid() && "CalleeSavedInfo not calculated");
198       if (MFI.getCalleeSavedInfo().empty())
199         return 0;
200 
201       int64_t MinOffset = std::numeric_limits<int64_t>::max();
202       int64_t MaxOffset = std::numeric_limits<int64_t>::min();
203       for (const auto &Info : MFI.getCalleeSavedInfo()) {
204         int FrameIdx = Info.getFrameIdx();
205         if (MFI.getStackID(FrameIdx) != TargetStackID::Default)
206           continue;
207         int64_t Offset = MFI.getObjectOffset(FrameIdx);
208         int64_t ObjSize = MFI.getObjectSize(FrameIdx);
209         MinOffset = std::min<int64_t>(Offset, MinOffset);
210         MaxOffset = std::max<int64_t>(Offset + ObjSize, MaxOffset);
211       }
212 
213       unsigned Size = alignTo(MaxOffset - MinOffset, 16);
214       assert((!HasCalleeSavedStackSize || getCalleeSavedStackSize() == Size) &&
215              "Invalid size calculated for callee saves");
216       return Size;
217     }
218 
219     return getCalleeSavedStackSize();
220   }
221 
222   unsigned getCalleeSavedStackSize() const {
223     assert(HasCalleeSavedStackSize &&
224            "CalleeSavedStackSize has not been calculated");
225     return CalleeSavedStackSize;
226   }
227 
228   // Saves the CalleeSavedStackSize for SVE vectors in 'scalable bytes'
229   void setSVECalleeSavedStackSize(unsigned Size) {
230     SVECalleeSavedStackSize = Size;
231   }
232   unsigned getSVECalleeSavedStackSize() const {
233     return SVECalleeSavedStackSize;
234   }
235 
236   void setMinMaxSVECSFrameIndex(int Min, int Max) {
237     MinSVECSFrameIndex = Min;
238     MaxSVECSFrameIndex = Max;
239   }
240 
241   int getMinSVECSFrameIndex() const { return MinSVECSFrameIndex; }
242   int getMaxSVECSFrameIndex() const { return MaxSVECSFrameIndex; }
243 
244   void incNumLocalDynamicTLSAccesses() { ++NumLocalDynamicTLSAccesses; }
245   unsigned getNumLocalDynamicTLSAccesses() const {
246     return NumLocalDynamicTLSAccesses;
247   }
248 
249   Optional<bool> hasRedZone() const { return HasRedZone; }
250   void setHasRedZone(bool s) { HasRedZone = s; }
251 
252   int getVarArgsStackIndex() const { return VarArgsStackIndex; }
253   void setVarArgsStackIndex(int Index) { VarArgsStackIndex = Index; }
254 
255   int getVarArgsGPRIndex() const { return VarArgsGPRIndex; }
256   void setVarArgsGPRIndex(int Index) { VarArgsGPRIndex = Index; }
257 
258   unsigned getVarArgsGPRSize() const { return VarArgsGPRSize; }
259   void setVarArgsGPRSize(unsigned Size) { VarArgsGPRSize = Size; }
260 
261   int getVarArgsFPRIndex() const { return VarArgsFPRIndex; }
262   void setVarArgsFPRIndex(int Index) { VarArgsFPRIndex = Index; }
263 
264   unsigned getVarArgsFPRSize() const { return VarArgsFPRSize; }
265   void setVarArgsFPRSize(unsigned Size) { VarArgsFPRSize = Size; }
266 
267   unsigned getSRetReturnReg() const { return SRetReturnReg; }
268   void setSRetReturnReg(unsigned Reg) { SRetReturnReg = Reg; }
269 
270   unsigned getJumpTableEntrySize(int Idx) const {
271     auto It = JumpTableEntryInfo.find(Idx);
272     if (It != JumpTableEntryInfo.end())
273       return It->second.first;
274     return 4;
275   }
276   MCSymbol *getJumpTableEntryPCRelSymbol(int Idx) const {
277     return JumpTableEntryInfo.find(Idx)->second.second;
278   }
279   void setJumpTableEntryInfo(int Idx, unsigned Size, MCSymbol *PCRelSym) {
280     JumpTableEntryInfo[Idx] = std::make_pair(Size, PCRelSym);
281   }
282 
283   using SetOfInstructions = SmallPtrSet<const MachineInstr *, 16>;
284 
285   const SetOfInstructions &getLOHRelated() const { return LOHRelated; }
286 
287   // Shortcuts for LOH related types.
288   class MILOHDirective {
289     MCLOHType Kind;
290 
291     /// Arguments of this directive. Order matters.
292     SmallVector<const MachineInstr *, 3> Args;
293 
294   public:
295     using LOHArgs = ArrayRef<const MachineInstr *>;
296 
297     MILOHDirective(MCLOHType Kind, LOHArgs Args)
298         : Kind(Kind), Args(Args.begin(), Args.end()) {
299       assert(isValidMCLOHType(Kind) && "Invalid LOH directive type!");
300     }
301 
302     MCLOHType getKind() const { return Kind; }
303     LOHArgs getArgs() const { return Args; }
304   };
305 
306   using MILOHArgs = MILOHDirective::LOHArgs;
307   using MILOHContainer = SmallVector<MILOHDirective, 32>;
308 
309   const MILOHContainer &getLOHContainer() const { return LOHContainerSet; }
310 
311   /// Add a LOH directive of this @p Kind and this @p Args.
312   void addLOHDirective(MCLOHType Kind, MILOHArgs Args) {
313     LOHContainerSet.push_back(MILOHDirective(Kind, Args));
314     LOHRelated.insert(Args.begin(), Args.end());
315   }
316 
317   SmallVectorImpl<ForwardedRegister> &getForwardedMustTailRegParms() {
318     return ForwardedMustTailRegParms;
319   }
320 
321   unsigned getTaggedBasePointerOffset() const {
322     return TaggedBasePointerOffset;
323   }
324   void setTaggedBasePointerOffset(unsigned Offset) {
325     TaggedBasePointerOffset = Offset;
326   }
327 
328 private:
329   // Hold the lists of LOHs.
330   MILOHContainer LOHContainerSet;
331   SetOfInstructions LOHRelated;
332 
333   DenseMap<int, std::pair<unsigned, MCSymbol *>> JumpTableEntryInfo;
334 };
335 
336 } // end namespace llvm
337 
338 #endif // LLVM_LIB_TARGET_AARCH64_AARCH64MACHINEFUNCTIONINFO_H
339