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