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/MIRYamlMapping.h"
22 #include "llvm/CodeGen/MachineFunction.h"
23 #include "llvm/IR/Function.h"
24 #include "llvm/MC/MCLinkerOptimizationHint.h"
25 #include <cassert>
26 
27 namespace llvm {
28 
29 namespace yaml {
30 struct AArch64FunctionInfo;
31 } // end namespace yaml
32 
33 class MachineInstr;
34 
35 /// AArch64FunctionInfo - This class is derived from MachineFunctionInfo and
36 /// contains private AArch64-specific information for each MachineFunction.
37 class AArch64FunctionInfo final : public MachineFunctionInfo {
38   /// Backreference to the machine function.
39   MachineFunction &MF;
40 
41   /// Number of bytes of arguments this function has on the stack. If the callee
42   /// is expected to restore the argument stack this should be a multiple of 16,
43   /// all usable during a tail call.
44   ///
45   /// The alternative would forbid tail call optimisation in some cases: if we
46   /// want to transfer control from a function with 8-bytes of stack-argument
47   /// space to a function with 16-bytes then misalignment of this value would
48   /// make a stack adjustment necessary, which could not be undone by the
49   /// callee.
50   unsigned BytesInStackArgArea = 0;
51 
52   /// The number of bytes to restore to deallocate space for incoming
53   /// arguments. Canonically 0 in the C calling convention, but non-zero when
54   /// callee is expected to pop the args.
55   unsigned ArgumentStackToRestore = 0;
56 
57   /// HasStackFrame - True if this function has a stack frame. Set by
58   /// determineCalleeSaves().
59   bool HasStackFrame = false;
60 
61   /// Amount of stack frame size, not including callee-saved registers.
62   uint64_t LocalStackSize = 0;
63 
64   /// The start and end frame indices for the SVE callee saves.
65   int MinSVECSFrameIndex = 0;
66   int MaxSVECSFrameIndex = 0;
67 
68   /// Amount of stack frame size used for saving callee-saved registers.
69   unsigned CalleeSavedStackSize = 0;
70   unsigned SVECalleeSavedStackSize = 0;
71   bool HasCalleeSavedStackSize = false;
72 
73   /// Number of TLS accesses using the special (combinable)
74   /// _TLS_MODULE_BASE_ symbol.
75   unsigned NumLocalDynamicTLSAccesses = 0;
76 
77   /// FrameIndex for start of varargs area for arguments passed on the
78   /// stack.
79   int VarArgsStackIndex = 0;
80 
81   /// FrameIndex for start of varargs area for arguments passed in
82   /// general purpose registers.
83   int VarArgsGPRIndex = 0;
84 
85   /// Size of the varargs area for arguments passed in general purpose
86   /// registers.
87   unsigned VarArgsGPRSize = 0;
88 
89   /// FrameIndex for start of varargs area for arguments passed in
90   /// floating-point registers.
91   int VarArgsFPRIndex = 0;
92 
93   /// Size of the varargs area for arguments passed in floating-point
94   /// registers.
95   unsigned VarArgsFPRSize = 0;
96 
97   /// True if this function has a subset of CSRs that is handled explicitly via
98   /// copies.
99   bool IsSplitCSR = false;
100 
101   /// True when the stack gets realigned dynamically because the size of stack
102   /// frame is unknown at compile time. e.g., in case of VLAs.
103   bool StackRealigned = false;
104 
105   /// True when the callee-save stack area has unused gaps that may be used for
106   /// other stack allocations.
107   bool CalleeSaveStackHasFreeSpace = false;
108 
109   /// SRetReturnReg - sret lowering includes returning the value of the
110   /// returned struct in a register. This field holds the virtual register into
111   /// which the sret argument is passed.
112   unsigned SRetReturnReg = 0;
113   /// SVE stack size (for predicates and data vectors) are maintained here
114   /// rather than in FrameInfo, as the placement and Stack IDs are target
115   /// specific.
116   uint64_t StackSizeSVE = 0;
117 
118   /// HasCalculatedStackSizeSVE indicates whether StackSizeSVE is valid.
119   bool HasCalculatedStackSizeSVE = false;
120 
121   /// Has a value when it is known whether or not the function uses a
122   /// redzone, and no value otherwise.
123   /// Initialized during frame lowering, unless the function has the noredzone
124   /// attribute, in which case it is set to false at construction.
125   Optional<bool> HasRedZone;
126 
127   /// ForwardedMustTailRegParms - A list of virtual and physical registers
128   /// that must be forwarded to every musttail call.
129   SmallVector<ForwardedRegister, 1> ForwardedMustTailRegParms;
130 
131   /// FrameIndex for the tagged base pointer.
132   Optional<int> TaggedBasePointerIndex;
133 
134   /// Offset from SP-at-entry to the tagged base pointer.
135   /// Tagged base pointer is set up to point to the first (lowest address)
136   /// tagged stack slot.
137   unsigned TaggedBasePointerOffset;
138 
139   /// OutliningStyle denotes, if a function was outined, how it was outlined,
140   /// e.g. Tail Call, Thunk, or Function if none apply.
141   Optional<std::string> OutliningStyle;
142 
143   // Offset from SP-after-callee-saved-spills (i.e. SP-at-entry minus
144   // CalleeSavedStackSize) to the address of the frame record.
145   int CalleeSaveBaseToFrameRecordOffset = 0;
146 
147   /// SignReturnAddress is true if PAC-RET is enabled for the function with
148   /// defaults being sign non-leaf functions only, with the B key.
149   bool SignReturnAddress = false;
150 
151   /// SignReturnAddressAll modifies the default PAC-RET mode to signing leaf
152   /// functions as well.
153   bool SignReturnAddressAll = false;
154 
155   /// SignWithBKey modifies the default PAC-RET mode to signing with the B key.
156   bool SignWithBKey = false;
157 
158   /// BranchTargetEnforcement enables placing BTI instructions at potential
159   /// indirect branch destinations.
160   bool BranchTargetEnforcement = false;
161 
162   /// Whether this function has an extended frame record [Ctx, FP, LR]. If so,
163   /// bit 60 of the in-memory FP will be 1 to enable other tools to detect the
164   /// extended record.
165   bool HasSwiftAsyncContext = false;
166 
167   /// The stack slot where the Swift asynchronous context is stored.
168   int SwiftAsyncContextFrameIdx = std::numeric_limits<int>::max();
169 
170 public:
171   explicit AArch64FunctionInfo(MachineFunction &MF);
172 
173   void initializeBaseYamlFields(const yaml::AArch64FunctionInfo &YamlMFI);
174 
175   unsigned getBytesInStackArgArea() const { return BytesInStackArgArea; }
176   void setBytesInStackArgArea(unsigned bytes) { BytesInStackArgArea = bytes; }
177 
178   unsigned getArgumentStackToRestore() const { return ArgumentStackToRestore; }
179   void setArgumentStackToRestore(unsigned bytes) {
180     ArgumentStackToRestore = bytes;
181   }
182 
183   bool hasCalculatedStackSizeSVE() const { return HasCalculatedStackSizeSVE; }
184 
185   void setStackSizeSVE(uint64_t S) {
186     HasCalculatedStackSizeSVE = true;
187     StackSizeSVE = S;
188   }
189 
190   uint64_t getStackSizeSVE() const { return StackSizeSVE; }
191 
192   bool hasStackFrame() const { return HasStackFrame; }
193   void setHasStackFrame(bool s) { HasStackFrame = s; }
194 
195   bool isStackRealigned() const { return StackRealigned; }
196   void setStackRealigned(bool s) { StackRealigned = s; }
197 
198   bool hasCalleeSaveStackFreeSpace() const {
199     return CalleeSaveStackHasFreeSpace;
200   }
201   void setCalleeSaveStackHasFreeSpace(bool s) {
202     CalleeSaveStackHasFreeSpace = s;
203   }
204   bool isSplitCSR() const { return IsSplitCSR; }
205   void setIsSplitCSR(bool s) { IsSplitCSR = s; }
206 
207   void setLocalStackSize(uint64_t Size) { LocalStackSize = Size; }
208   uint64_t getLocalStackSize() const { return LocalStackSize; }
209 
210   void setOutliningStyle(std::string Style) { OutliningStyle = Style; }
211   Optional<std::string> getOutliningStyle() const { return OutliningStyle; }
212 
213   void setCalleeSavedStackSize(unsigned Size) {
214     CalleeSavedStackSize = Size;
215     HasCalleeSavedStackSize = true;
216   }
217 
218   // When CalleeSavedStackSize has not been set (for example when
219   // some MachineIR pass is run in isolation), then recalculate
220   // the CalleeSavedStackSize directly from the CalleeSavedInfo.
221   // Note: This information can only be recalculated after PEI
222   // has assigned offsets to the callee save objects.
223   unsigned getCalleeSavedStackSize(const MachineFrameInfo &MFI) const {
224     bool ValidateCalleeSavedStackSize = false;
225 
226 #ifndef NDEBUG
227     // Make sure the calculated size derived from the CalleeSavedInfo
228     // equals the cached size that was calculated elsewhere (e.g. in
229     // determineCalleeSaves).
230     ValidateCalleeSavedStackSize = HasCalleeSavedStackSize;
231 #endif
232 
233     if (!HasCalleeSavedStackSize || ValidateCalleeSavedStackSize) {
234       assert(MFI.isCalleeSavedInfoValid() && "CalleeSavedInfo not calculated");
235       if (MFI.getCalleeSavedInfo().empty())
236         return 0;
237 
238       int64_t MinOffset = std::numeric_limits<int64_t>::max();
239       int64_t MaxOffset = std::numeric_limits<int64_t>::min();
240       for (const auto &Info : MFI.getCalleeSavedInfo()) {
241         int FrameIdx = Info.getFrameIdx();
242         if (MFI.getStackID(FrameIdx) != TargetStackID::Default)
243           continue;
244         int64_t Offset = MFI.getObjectOffset(FrameIdx);
245         int64_t ObjSize = MFI.getObjectSize(FrameIdx);
246         MinOffset = std::min<int64_t>(Offset, MinOffset);
247         MaxOffset = std::max<int64_t>(Offset + ObjSize, MaxOffset);
248       }
249 
250       if (SwiftAsyncContextFrameIdx != std::numeric_limits<int>::max()) {
251         int64_t Offset = MFI.getObjectOffset(getSwiftAsyncContextFrameIdx());
252         int64_t ObjSize = MFI.getObjectSize(getSwiftAsyncContextFrameIdx());
253         MinOffset = std::min<int64_t>(Offset, MinOffset);
254         MaxOffset = std::max<int64_t>(Offset + ObjSize, MaxOffset);
255       }
256 
257       unsigned Size = alignTo(MaxOffset - MinOffset, 16);
258       assert((!HasCalleeSavedStackSize || getCalleeSavedStackSize() == Size) &&
259              "Invalid size calculated for callee saves");
260       return Size;
261     }
262 
263     return getCalleeSavedStackSize();
264   }
265 
266   unsigned getCalleeSavedStackSize() const {
267     assert(HasCalleeSavedStackSize &&
268            "CalleeSavedStackSize has not been calculated");
269     return CalleeSavedStackSize;
270   }
271 
272   // Saves the CalleeSavedStackSize for SVE vectors in 'scalable bytes'
273   void setSVECalleeSavedStackSize(unsigned Size) {
274     SVECalleeSavedStackSize = Size;
275   }
276   unsigned getSVECalleeSavedStackSize() const {
277     return SVECalleeSavedStackSize;
278   }
279 
280   void setMinMaxSVECSFrameIndex(int Min, int Max) {
281     MinSVECSFrameIndex = Min;
282     MaxSVECSFrameIndex = Max;
283   }
284 
285   int getMinSVECSFrameIndex() const { return MinSVECSFrameIndex; }
286   int getMaxSVECSFrameIndex() const { return MaxSVECSFrameIndex; }
287 
288   void incNumLocalDynamicTLSAccesses() { ++NumLocalDynamicTLSAccesses; }
289   unsigned getNumLocalDynamicTLSAccesses() const {
290     return NumLocalDynamicTLSAccesses;
291   }
292 
293   Optional<bool> hasRedZone() const { return HasRedZone; }
294   void setHasRedZone(bool s) { HasRedZone = s; }
295 
296   int getVarArgsStackIndex() const { return VarArgsStackIndex; }
297   void setVarArgsStackIndex(int Index) { VarArgsStackIndex = Index; }
298 
299   int getVarArgsGPRIndex() const { return VarArgsGPRIndex; }
300   void setVarArgsGPRIndex(int Index) { VarArgsGPRIndex = Index; }
301 
302   unsigned getVarArgsGPRSize() const { return VarArgsGPRSize; }
303   void setVarArgsGPRSize(unsigned Size) { VarArgsGPRSize = Size; }
304 
305   int getVarArgsFPRIndex() const { return VarArgsFPRIndex; }
306   void setVarArgsFPRIndex(int Index) { VarArgsFPRIndex = Index; }
307 
308   unsigned getVarArgsFPRSize() const { return VarArgsFPRSize; }
309   void setVarArgsFPRSize(unsigned Size) { VarArgsFPRSize = Size; }
310 
311   unsigned getSRetReturnReg() const { return SRetReturnReg; }
312   void setSRetReturnReg(unsigned Reg) { SRetReturnReg = Reg; }
313 
314   unsigned getJumpTableEntrySize(int Idx) const {
315     return JumpTableEntryInfo[Idx].first;
316   }
317   MCSymbol *getJumpTableEntryPCRelSymbol(int Idx) const {
318     return JumpTableEntryInfo[Idx].second;
319   }
320   void setJumpTableEntryInfo(int Idx, unsigned Size, MCSymbol *PCRelSym) {
321     if ((unsigned)Idx >= JumpTableEntryInfo.size())
322       JumpTableEntryInfo.resize(Idx+1);
323     JumpTableEntryInfo[Idx] = std::make_pair(Size, PCRelSym);
324   }
325 
326   using SetOfInstructions = SmallPtrSet<const MachineInstr *, 16>;
327 
328   const SetOfInstructions &getLOHRelated() const { return LOHRelated; }
329 
330   // Shortcuts for LOH related types.
331   class MILOHDirective {
332     MCLOHType Kind;
333 
334     /// Arguments of this directive. Order matters.
335     SmallVector<const MachineInstr *, 3> Args;
336 
337   public:
338     using LOHArgs = ArrayRef<const MachineInstr *>;
339 
340     MILOHDirective(MCLOHType Kind, LOHArgs Args)
341         : Kind(Kind), Args(Args.begin(), Args.end()) {
342       assert(isValidMCLOHType(Kind) && "Invalid LOH directive type!");
343     }
344 
345     MCLOHType getKind() const { return Kind; }
346     LOHArgs getArgs() const { return Args; }
347   };
348 
349   using MILOHArgs = MILOHDirective::LOHArgs;
350   using MILOHContainer = SmallVector<MILOHDirective, 32>;
351 
352   const MILOHContainer &getLOHContainer() const { return LOHContainerSet; }
353 
354   /// Add a LOH directive of this @p Kind and this @p Args.
355   void addLOHDirective(MCLOHType Kind, MILOHArgs Args) {
356     LOHContainerSet.push_back(MILOHDirective(Kind, Args));
357     LOHRelated.insert(Args.begin(), Args.end());
358   }
359 
360   SmallVectorImpl<ForwardedRegister> &getForwardedMustTailRegParms() {
361     return ForwardedMustTailRegParms;
362   }
363 
364   Optional<int> getTaggedBasePointerIndex() const {
365     return TaggedBasePointerIndex;
366   }
367   void setTaggedBasePointerIndex(int Index) { TaggedBasePointerIndex = Index; }
368 
369   unsigned getTaggedBasePointerOffset() const {
370     return TaggedBasePointerOffset;
371   }
372   void setTaggedBasePointerOffset(unsigned Offset) {
373     TaggedBasePointerOffset = Offset;
374   }
375 
376   int getCalleeSaveBaseToFrameRecordOffset() const {
377     return CalleeSaveBaseToFrameRecordOffset;
378   }
379   void setCalleeSaveBaseToFrameRecordOffset(int Offset) {
380     CalleeSaveBaseToFrameRecordOffset = Offset;
381   }
382 
383   bool shouldSignReturnAddress() const;
384   bool shouldSignReturnAddress(bool SpillsLR) const;
385 
386   bool shouldSignWithBKey() const { return SignWithBKey; }
387 
388   bool branchTargetEnforcement() const { return BranchTargetEnforcement; }
389 
390   void setHasSwiftAsyncContext(bool HasContext) {
391     HasSwiftAsyncContext = HasContext;
392   }
393   bool hasSwiftAsyncContext() const { return HasSwiftAsyncContext; }
394 
395   void setSwiftAsyncContextFrameIdx(int FI) {
396     SwiftAsyncContextFrameIdx = FI;
397   }
398   int getSwiftAsyncContextFrameIdx() const { return SwiftAsyncContextFrameIdx; }
399 
400 private:
401   // Hold the lists of LOHs.
402   MILOHContainer LOHContainerSet;
403   SetOfInstructions LOHRelated;
404 
405   SmallVector<std::pair<unsigned, MCSymbol *>, 2> JumpTableEntryInfo;
406 };
407 
408 namespace yaml {
409 struct AArch64FunctionInfo final : public yaml::MachineFunctionInfo {
410   Optional<bool> HasRedZone;
411 
412   AArch64FunctionInfo() = default;
413   AArch64FunctionInfo(const llvm::AArch64FunctionInfo &MFI);
414 
415   void mappingImpl(yaml::IO &YamlIO) override;
416   ~AArch64FunctionInfo() = default;
417 };
418 
419 template <> struct MappingTraits<AArch64FunctionInfo> {
420   static void mapping(IO &YamlIO, AArch64FunctionInfo &MFI) {
421     YamlIO.mapOptional("hasRedZone", MFI.HasRedZone);
422   }
423 };
424 
425 } // end namespace yaml
426 
427 } // end namespace llvm
428 
429 #endif // LLVM_LIB_TARGET_AARCH64_AARCH64MACHINEFUNCTIONINFO_H
430