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/MachineFrameInfo.h"
23 #include "llvm/CodeGen/MachineFunction.h"
24 #include "llvm/IR/Function.h"
25 #include "llvm/MC/MCLinkerOptimizationHint.h"
26 #include <cassert>
27 
28 namespace llvm {
29 
30 namespace yaml {
31 struct AArch64FunctionInfo;
32 } // end namespace yaml
33 
34 class MachineInstr;
35 
36 /// AArch64FunctionInfo - This class is derived from MachineFunctionInfo and
37 /// contains private AArch64-specific information for each MachineFunction.
38 class AArch64FunctionInfo final : public MachineFunctionInfo {
39   /// Backreference to the machine function.
40   MachineFunction *MF;
41 
42   /// Number of bytes of arguments this function has on the stack. If the callee
43   /// is expected to restore the argument stack this should be a multiple of 16,
44   /// all usable during a tail call.
45   ///
46   /// The alternative would forbid tail call optimisation in some cases: if we
47   /// want to transfer control from a function with 8-bytes of stack-argument
48   /// space to a function with 16-bytes then misalignment of this value would
49   /// make a stack adjustment necessary, which could not be undone by the
50   /// callee.
51   unsigned BytesInStackArgArea = 0;
52 
53   /// The number of bytes to restore to deallocate space for incoming
54   /// arguments. Canonically 0 in the C calling convention, but non-zero when
55   /// callee is expected to pop the args.
56   unsigned ArgumentStackToRestore = 0;
57 
58   /// Space just below incoming stack pointer reserved for arguments being
59   /// passed on the stack during a tail call. This will be the difference
60   /// between the largest tail call argument space needed in this function and
61   /// what's already available by reusing space of incoming arguments.
62   unsigned TailCallReservedStack = 0;
63 
64   /// HasStackFrame - True if this function has a stack frame. Set by
65   /// determineCalleeSaves().
66   bool HasStackFrame = false;
67 
68   /// Amount of stack frame size, not including callee-saved registers.
69   uint64_t LocalStackSize = 0;
70 
71   /// The start and end frame indices for the SVE callee saves.
72   int MinSVECSFrameIndex = 0;
73   int MaxSVECSFrameIndex = 0;
74 
75   /// Amount of stack frame size used for saving callee-saved registers.
76   unsigned CalleeSavedStackSize = 0;
77   unsigned SVECalleeSavedStackSize = 0;
78   bool HasCalleeSavedStackSize = false;
79 
80   /// Number of TLS accesses using the special (combinable)
81   /// _TLS_MODULE_BASE_ symbol.
82   unsigned NumLocalDynamicTLSAccesses = 0;
83 
84   /// FrameIndex for start of varargs area for arguments passed on the
85   /// stack.
86   int VarArgsStackIndex = 0;
87 
88   /// FrameIndex for start of varargs area for arguments passed in
89   /// general purpose registers.
90   int VarArgsGPRIndex = 0;
91 
92   /// Size of the varargs area for arguments passed in general purpose
93   /// registers.
94   unsigned VarArgsGPRSize = 0;
95 
96   /// FrameIndex for start of varargs area for arguments passed in
97   /// floating-point registers.
98   int VarArgsFPRIndex = 0;
99 
100   /// Size of the varargs area for arguments passed in floating-point
101   /// registers.
102   unsigned VarArgsFPRSize = 0;
103 
104   /// True if this function has a subset of CSRs that is handled explicitly via
105   /// copies.
106   bool IsSplitCSR = false;
107 
108   /// True when the stack gets realigned dynamically because the size of stack
109   /// frame is unknown at compile time. e.g., in case of VLAs.
110   bool StackRealigned = false;
111 
112   /// True when the callee-save stack area has unused gaps that may be used for
113   /// other stack allocations.
114   bool CalleeSaveStackHasFreeSpace = false;
115 
116   /// SRetReturnReg - sret lowering includes returning the value of the
117   /// returned struct in a register. This field holds the virtual register into
118   /// which the sret argument is passed.
119   Register SRetReturnReg;
120 
121   /// SVE stack size (for predicates and data vectors) are maintained here
122   /// rather than in FrameInfo, as the placement and Stack IDs are target
123   /// specific.
124   uint64_t StackSizeSVE = 0;
125 
126   /// HasCalculatedStackSizeSVE indicates whether StackSizeSVE is valid.
127   bool HasCalculatedStackSizeSVE = false;
128 
129   /// Has a value when it is known whether or not the function uses a
130   /// redzone, and no value otherwise.
131   /// Initialized during frame lowering, unless the function has the noredzone
132   /// attribute, in which case it is set to false at construction.
133   Optional<bool> HasRedZone;
134 
135   /// ForwardedMustTailRegParms - A list of virtual and physical registers
136   /// that must be forwarded to every musttail call.
137   SmallVector<ForwardedRegister, 1> ForwardedMustTailRegParms;
138 
139   /// FrameIndex for the tagged base pointer.
140   Optional<int> TaggedBasePointerIndex;
141 
142   /// Offset from SP-at-entry to the tagged base pointer.
143   /// Tagged base pointer is set up to point to the first (lowest address)
144   /// tagged stack slot.
145   unsigned TaggedBasePointerOffset;
146 
147   /// OutliningStyle denotes, if a function was outined, how it was outlined,
148   /// e.g. Tail Call, Thunk, or Function if none apply.
149   Optional<std::string> OutliningStyle;
150 
151   // Offset from SP-after-callee-saved-spills (i.e. SP-at-entry minus
152   // CalleeSavedStackSize) to the address of the frame record.
153   int CalleeSaveBaseToFrameRecordOffset = 0;
154 
155   /// SignReturnAddress is true if PAC-RET is enabled for the function with
156   /// defaults being sign non-leaf functions only, with the B key.
157   bool SignReturnAddress = false;
158 
159   /// SignReturnAddressAll modifies the default PAC-RET mode to signing leaf
160   /// functions as well.
161   bool SignReturnAddressAll = false;
162 
163   /// SignWithBKey modifies the default PAC-RET mode to signing with the B key.
164   bool SignWithBKey = false;
165 
166   /// BranchTargetEnforcement enables placing BTI instructions at potential
167   /// indirect branch destinations.
168   bool BranchTargetEnforcement = false;
169 
170   /// Whether this function has an extended frame record [Ctx, FP, LR]. If so,
171   /// bit 60 of the in-memory FP will be 1 to enable other tools to detect the
172   /// extended record.
173   bool HasSwiftAsyncContext = false;
174 
175   /// The stack slot where the Swift asynchronous context is stored.
176   int SwiftAsyncContextFrameIdx = std::numeric_limits<int>::max();
177 
178   bool IsMTETagged = false;
179 
180   /// The function has Scalable Vector or Scalable Predicate register argument
181   /// or return type
182   bool IsSVECC = false;
183 
184   /// True if the function need unwind information.
185   mutable Optional<bool> NeedsDwarfUnwindInfo;
186 
187   /// True if the function need asynchronous unwind information.
188   mutable Optional<bool> NeedsAsyncDwarfUnwindInfo;
189 
190 public:
191   explicit AArch64FunctionInfo(MachineFunction &MF);
192 
193   MachineFunctionInfo *
194   clone(BumpPtrAllocator &Allocator, MachineFunction &DestMF,
195         const DenseMap<MachineBasicBlock *, MachineBasicBlock *> &Src2DstMBB)
196       const override;
197 
198   bool isSVECC() const { return IsSVECC; };
199   void setIsSVECC(bool s) { IsSVECC = s; };
200 
201   void initializeBaseYamlFields(const yaml::AArch64FunctionInfo &YamlMFI);
202 
203   unsigned getBytesInStackArgArea() const { return BytesInStackArgArea; }
204   void setBytesInStackArgArea(unsigned bytes) { BytesInStackArgArea = bytes; }
205 
206   unsigned getArgumentStackToRestore() const { return ArgumentStackToRestore; }
207   void setArgumentStackToRestore(unsigned bytes) {
208     ArgumentStackToRestore = bytes;
209   }
210 
211   unsigned getTailCallReservedStack() const { return TailCallReservedStack; }
212   void setTailCallReservedStack(unsigned bytes) {
213     TailCallReservedStack = bytes;
214   }
215 
216   bool hasCalculatedStackSizeSVE() const { return HasCalculatedStackSizeSVE; }
217 
218   void setStackSizeSVE(uint64_t S) {
219     HasCalculatedStackSizeSVE = true;
220     StackSizeSVE = S;
221   }
222 
223   uint64_t getStackSizeSVE() const { return StackSizeSVE; }
224 
225   bool hasStackFrame() const { return HasStackFrame; }
226   void setHasStackFrame(bool s) { HasStackFrame = s; }
227 
228   bool isStackRealigned() const { return StackRealigned; }
229   void setStackRealigned(bool s) { StackRealigned = s; }
230 
231   bool hasCalleeSaveStackFreeSpace() const {
232     return CalleeSaveStackHasFreeSpace;
233   }
234   void setCalleeSaveStackHasFreeSpace(bool s) {
235     CalleeSaveStackHasFreeSpace = s;
236   }
237   bool isSplitCSR() const { return IsSplitCSR; }
238   void setIsSplitCSR(bool s) { IsSplitCSR = s; }
239 
240   void setLocalStackSize(uint64_t Size) { LocalStackSize = Size; }
241   uint64_t getLocalStackSize() const { return LocalStackSize; }
242 
243   void setOutliningStyle(std::string Style) { OutliningStyle = Style; }
244   Optional<std::string> getOutliningStyle() const { return OutliningStyle; }
245 
246   void setCalleeSavedStackSize(unsigned Size) {
247     CalleeSavedStackSize = Size;
248     HasCalleeSavedStackSize = true;
249   }
250 
251   // When CalleeSavedStackSize has not been set (for example when
252   // some MachineIR pass is run in isolation), then recalculate
253   // the CalleeSavedStackSize directly from the CalleeSavedInfo.
254   // Note: This information can only be recalculated after PEI
255   // has assigned offsets to the callee save objects.
256   unsigned getCalleeSavedStackSize(const MachineFrameInfo &MFI) const {
257     bool ValidateCalleeSavedStackSize = false;
258 
259 #ifndef NDEBUG
260     // Make sure the calculated size derived from the CalleeSavedInfo
261     // equals the cached size that was calculated elsewhere (e.g. in
262     // determineCalleeSaves).
263     ValidateCalleeSavedStackSize = HasCalleeSavedStackSize;
264 #endif
265 
266     if (!HasCalleeSavedStackSize || ValidateCalleeSavedStackSize) {
267       assert(MFI.isCalleeSavedInfoValid() && "CalleeSavedInfo not calculated");
268       if (MFI.getCalleeSavedInfo().empty())
269         return 0;
270 
271       int64_t MinOffset = std::numeric_limits<int64_t>::max();
272       int64_t MaxOffset = std::numeric_limits<int64_t>::min();
273       for (const auto &Info : MFI.getCalleeSavedInfo()) {
274         int FrameIdx = Info.getFrameIdx();
275         if (MFI.getStackID(FrameIdx) != TargetStackID::Default)
276           continue;
277         int64_t Offset = MFI.getObjectOffset(FrameIdx);
278         int64_t ObjSize = MFI.getObjectSize(FrameIdx);
279         MinOffset = std::min<int64_t>(Offset, MinOffset);
280         MaxOffset = std::max<int64_t>(Offset + ObjSize, MaxOffset);
281       }
282 
283       if (SwiftAsyncContextFrameIdx != std::numeric_limits<int>::max()) {
284         int64_t Offset = MFI.getObjectOffset(getSwiftAsyncContextFrameIdx());
285         int64_t ObjSize = MFI.getObjectSize(getSwiftAsyncContextFrameIdx());
286         MinOffset = std::min<int64_t>(Offset, MinOffset);
287         MaxOffset = std::max<int64_t>(Offset + ObjSize, MaxOffset);
288       }
289 
290       unsigned Size = alignTo(MaxOffset - MinOffset, 16);
291       assert((!HasCalleeSavedStackSize || getCalleeSavedStackSize() == Size) &&
292              "Invalid size calculated for callee saves");
293       return Size;
294     }
295 
296     return getCalleeSavedStackSize();
297   }
298 
299   unsigned getCalleeSavedStackSize() const {
300     assert(HasCalleeSavedStackSize &&
301            "CalleeSavedStackSize has not been calculated");
302     return CalleeSavedStackSize;
303   }
304 
305   // Saves the CalleeSavedStackSize for SVE vectors in 'scalable bytes'
306   void setSVECalleeSavedStackSize(unsigned Size) {
307     SVECalleeSavedStackSize = Size;
308   }
309   unsigned getSVECalleeSavedStackSize() const {
310     return SVECalleeSavedStackSize;
311   }
312 
313   void setMinMaxSVECSFrameIndex(int Min, int Max) {
314     MinSVECSFrameIndex = Min;
315     MaxSVECSFrameIndex = Max;
316   }
317 
318   int getMinSVECSFrameIndex() const { return MinSVECSFrameIndex; }
319   int getMaxSVECSFrameIndex() const { return MaxSVECSFrameIndex; }
320 
321   void incNumLocalDynamicTLSAccesses() { ++NumLocalDynamicTLSAccesses; }
322   unsigned getNumLocalDynamicTLSAccesses() const {
323     return NumLocalDynamicTLSAccesses;
324   }
325 
326   Optional<bool> hasRedZone() const { return HasRedZone; }
327   void setHasRedZone(bool s) { HasRedZone = s; }
328 
329   int getVarArgsStackIndex() const { return VarArgsStackIndex; }
330   void setVarArgsStackIndex(int Index) { VarArgsStackIndex = Index; }
331 
332   int getVarArgsGPRIndex() const { return VarArgsGPRIndex; }
333   void setVarArgsGPRIndex(int Index) { VarArgsGPRIndex = Index; }
334 
335   unsigned getVarArgsGPRSize() const { return VarArgsGPRSize; }
336   void setVarArgsGPRSize(unsigned Size) { VarArgsGPRSize = Size; }
337 
338   int getVarArgsFPRIndex() const { return VarArgsFPRIndex; }
339   void setVarArgsFPRIndex(int Index) { VarArgsFPRIndex = Index; }
340 
341   unsigned getVarArgsFPRSize() const { return VarArgsFPRSize; }
342   void setVarArgsFPRSize(unsigned Size) { VarArgsFPRSize = Size; }
343 
344   unsigned getSRetReturnReg() const { return SRetReturnReg; }
345   void setSRetReturnReg(unsigned Reg) { SRetReturnReg = Reg; }
346 
347   unsigned getJumpTableEntrySize(int Idx) const {
348     return JumpTableEntryInfo[Idx].first;
349   }
350   MCSymbol *getJumpTableEntryPCRelSymbol(int Idx) const {
351     return JumpTableEntryInfo[Idx].second;
352   }
353   void setJumpTableEntryInfo(int Idx, unsigned Size, MCSymbol *PCRelSym) {
354     if ((unsigned)Idx >= JumpTableEntryInfo.size())
355       JumpTableEntryInfo.resize(Idx+1);
356     JumpTableEntryInfo[Idx] = std::make_pair(Size, PCRelSym);
357   }
358 
359   using SetOfInstructions = SmallPtrSet<const MachineInstr *, 16>;
360 
361   const SetOfInstructions &getLOHRelated() const { return LOHRelated; }
362 
363   // Shortcuts for LOH related types.
364   class MILOHDirective {
365     MCLOHType Kind;
366 
367     /// Arguments of this directive. Order matters.
368     SmallVector<const MachineInstr *, 3> Args;
369 
370   public:
371     using LOHArgs = ArrayRef<const MachineInstr *>;
372 
373     MILOHDirective(MCLOHType Kind, LOHArgs Args)
374         : Kind(Kind), Args(Args.begin(), Args.end()) {
375       assert(isValidMCLOHType(Kind) && "Invalid LOH directive type!");
376     }
377 
378     MCLOHType getKind() const { return Kind; }
379     LOHArgs getArgs() const { return Args; }
380   };
381 
382   using MILOHArgs = MILOHDirective::LOHArgs;
383   using MILOHContainer = SmallVector<MILOHDirective, 32>;
384 
385   const MILOHContainer &getLOHContainer() const { return LOHContainerSet; }
386 
387   /// Add a LOH directive of this @p Kind and this @p Args.
388   void addLOHDirective(MCLOHType Kind, MILOHArgs Args) {
389     LOHContainerSet.push_back(MILOHDirective(Kind, Args));
390     LOHRelated.insert(Args.begin(), Args.end());
391   }
392 
393   SmallVectorImpl<ForwardedRegister> &getForwardedMustTailRegParms() {
394     return ForwardedMustTailRegParms;
395   }
396 
397   Optional<int> getTaggedBasePointerIndex() const {
398     return TaggedBasePointerIndex;
399   }
400   void setTaggedBasePointerIndex(int Index) { TaggedBasePointerIndex = Index; }
401 
402   unsigned getTaggedBasePointerOffset() const {
403     return TaggedBasePointerOffset;
404   }
405   void setTaggedBasePointerOffset(unsigned Offset) {
406     TaggedBasePointerOffset = Offset;
407   }
408 
409   int getCalleeSaveBaseToFrameRecordOffset() const {
410     return CalleeSaveBaseToFrameRecordOffset;
411   }
412   void setCalleeSaveBaseToFrameRecordOffset(int Offset) {
413     CalleeSaveBaseToFrameRecordOffset = Offset;
414   }
415 
416   bool shouldSignReturnAddress() const;
417   bool shouldSignReturnAddress(bool SpillsLR) const;
418 
419   bool shouldSignWithBKey() const { return SignWithBKey; }
420   bool isMTETagged() const { return IsMTETagged; }
421 
422   bool branchTargetEnforcement() const { return BranchTargetEnforcement; }
423 
424   void setHasSwiftAsyncContext(bool HasContext) {
425     HasSwiftAsyncContext = HasContext;
426   }
427   bool hasSwiftAsyncContext() const { return HasSwiftAsyncContext; }
428 
429   void setSwiftAsyncContextFrameIdx(int FI) {
430     SwiftAsyncContextFrameIdx = FI;
431   }
432   int getSwiftAsyncContextFrameIdx() const { return SwiftAsyncContextFrameIdx; }
433 
434   bool needsDwarfUnwindInfo() const;
435   bool needsAsyncDwarfUnwindInfo() const;
436 
437 private:
438   // Hold the lists of LOHs.
439   MILOHContainer LOHContainerSet;
440   SetOfInstructions LOHRelated;
441 
442   SmallVector<std::pair<unsigned, MCSymbol *>, 2> JumpTableEntryInfo;
443 };
444 
445 namespace yaml {
446 struct AArch64FunctionInfo final : public yaml::MachineFunctionInfo {
447   Optional<bool> HasRedZone;
448 
449   AArch64FunctionInfo() = default;
450   AArch64FunctionInfo(const llvm::AArch64FunctionInfo &MFI);
451 
452   void mappingImpl(yaml::IO &YamlIO) override;
453   ~AArch64FunctionInfo() = default;
454 };
455 
456 template <> struct MappingTraits<AArch64FunctionInfo> {
457   static void mapping(IO &YamlIO, AArch64FunctionInfo &MFI) {
458     YamlIO.mapOptional("hasRedZone", MFI.HasRedZone);
459   }
460 };
461 
462 } // end namespace yaml
463 
464 } // end namespace llvm
465 
466 #endif // LLVM_LIB_TARGET_AARCH64_AARCH64MACHINEFUNCTIONINFO_H
467