1 //=- AArch64MachineFunctionInfo.h - AArch64 machine function info -*- C++ -*-=//
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 file declares AArch64-specific per-machine-function information.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_TARGET_AARCH64_AARCH64MACHINEFUNCTIONINFO_H
15 #define LLVM_LIB_TARGET_AARCH64_AARCH64MACHINEFUNCTIONINFO_H
16 
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/Optional.h"
19 #include "llvm/ADT/SmallPtrSet.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/CodeGen/MachineFunction.h"
22 #include "llvm/MC/MCLinkerOptimizationHint.h"
23 #include <cassert>
24 
25 namespace llvm {
26 
27 class MachineInstr;
28 
29 /// AArch64FunctionInfo - This class is derived from MachineFunctionInfo and
30 /// contains private AArch64-specific information for each MachineFunction.
31 class AArch64FunctionInfo final : public MachineFunctionInfo {
32   /// Number of bytes of arguments this function has on the stack. If the callee
33   /// is expected to restore the argument stack this should be a multiple of 16,
34   /// all usable during a tail call.
35   ///
36   /// The alternative would forbid tail call optimisation in some cases: if we
37   /// want to transfer control from a function with 8-bytes of stack-argument
38   /// space to a function with 16-bytes then misalignment of this value would
39   /// make a stack adjustment necessary, which could not be undone by the
40   /// callee.
41   unsigned BytesInStackArgArea = 0;
42 
43   /// The number of bytes to restore to deallocate space for incoming
44   /// arguments. Canonically 0 in the C calling convention, but non-zero when
45   /// callee is expected to pop the args.
46   unsigned ArgumentStackToRestore = 0;
47 
48   /// HasStackFrame - True if this function has a stack frame. Set by
49   /// determineCalleeSaves().
50   bool HasStackFrame = false;
51 
52   /// Amount of stack frame size, not including callee-saved registers.
53   unsigned LocalStackSize;
54 
55   /// Amount of stack frame size used for saving callee-saved registers.
56   unsigned CalleeSavedStackSize;
57 
58   /// Number of TLS accesses using the special (combinable)
59   /// _TLS_MODULE_BASE_ symbol.
60   unsigned NumLocalDynamicTLSAccesses = 0;
61 
62   /// FrameIndex for start of varargs area for arguments passed on the
63   /// stack.
64   int VarArgsStackIndex = 0;
65 
66   /// FrameIndex for start of varargs area for arguments passed in
67   /// general purpose registers.
68   int VarArgsGPRIndex = 0;
69 
70   /// Size of the varargs area for arguments passed in general purpose
71   /// registers.
72   unsigned VarArgsGPRSize = 0;
73 
74   /// FrameIndex for start of varargs area for arguments passed in
75   /// floating-point registers.
76   int VarArgsFPRIndex = 0;
77 
78   /// Size of the varargs area for arguments passed in floating-point
79   /// registers.
80   unsigned VarArgsFPRSize = 0;
81 
82   /// True if this function has a subset of CSRs that is handled explicitly via
83   /// copies.
84   bool IsSplitCSR = false;
85 
86   /// True when the stack gets realigned dynamically because the size of stack
87   /// frame is unknown at compile time. e.g., in case of VLAs.
88   bool StackRealigned = false;
89 
90   /// True when the callee-save stack area has unused gaps that may be used for
91   /// other stack allocations.
92   bool CalleeSaveStackHasFreeSpace = false;
93 
94   /// Has a value when it is known whether or not the function uses a
95   /// redzone, and no value otherwise.
96   /// Initialized during frame lowering, unless the function has the noredzone
97   /// attribute, in which case it is set to false at construction.
98   Optional<bool> HasRedZone;
99 
100 public:
101   AArch64FunctionInfo() = default;
102 
103   explicit AArch64FunctionInfo(MachineFunction &MF) {
104     (void)MF;
105 
106     // If we already know that the function doesn't have a redzone, set
107     // HasRedZone here.
108     if (MF.getFunction().hasFnAttribute(Attribute::NoRedZone))
109       HasRedZone = false;
110   }
111 
112   unsigned getBytesInStackArgArea() const { return BytesInStackArgArea; }
113   void setBytesInStackArgArea(unsigned bytes) { BytesInStackArgArea = bytes; }
114 
115   unsigned getArgumentStackToRestore() const { return ArgumentStackToRestore; }
116   void setArgumentStackToRestore(unsigned bytes) {
117     ArgumentStackToRestore = bytes;
118   }
119 
120   bool hasStackFrame() const { return HasStackFrame; }
121   void setHasStackFrame(bool s) { HasStackFrame = s; }
122 
123   bool isStackRealigned() const { return StackRealigned; }
124   void setStackRealigned(bool s) { StackRealigned = s; }
125 
126   bool hasCalleeSaveStackFreeSpace() const {
127     return CalleeSaveStackHasFreeSpace;
128   }
129   void setCalleeSaveStackHasFreeSpace(bool s) {
130     CalleeSaveStackHasFreeSpace = s;
131   }
132 
133   bool isSplitCSR() const { return IsSplitCSR; }
134   void setIsSplitCSR(bool s) { IsSplitCSR = s; }
135 
136   void setLocalStackSize(unsigned Size) { LocalStackSize = Size; }
137   unsigned getLocalStackSize() const { return LocalStackSize; }
138 
139   void setCalleeSavedStackSize(unsigned Size) { CalleeSavedStackSize = Size; }
140   unsigned getCalleeSavedStackSize() const { return CalleeSavedStackSize; }
141 
142   void incNumLocalDynamicTLSAccesses() { ++NumLocalDynamicTLSAccesses; }
143   unsigned getNumLocalDynamicTLSAccesses() const {
144     return NumLocalDynamicTLSAccesses;
145   }
146 
147   Optional<bool> hasRedZone() const { return HasRedZone; }
148   void setHasRedZone(bool s) { HasRedZone = s; }
149 
150   int getVarArgsStackIndex() const { return VarArgsStackIndex; }
151   void setVarArgsStackIndex(int Index) { VarArgsStackIndex = Index; }
152 
153   int getVarArgsGPRIndex() const { return VarArgsGPRIndex; }
154   void setVarArgsGPRIndex(int Index) { VarArgsGPRIndex = Index; }
155 
156   unsigned getVarArgsGPRSize() const { return VarArgsGPRSize; }
157   void setVarArgsGPRSize(unsigned Size) { VarArgsGPRSize = Size; }
158 
159   int getVarArgsFPRIndex() const { return VarArgsFPRIndex; }
160   void setVarArgsFPRIndex(int Index) { VarArgsFPRIndex = Index; }
161 
162   unsigned getVarArgsFPRSize() const { return VarArgsFPRSize; }
163   void setVarArgsFPRSize(unsigned Size) { VarArgsFPRSize = Size; }
164 
165   unsigned getJumpTableEntrySize(int Idx) const {
166     auto It = JumpTableEntryInfo.find(Idx);
167     if (It != JumpTableEntryInfo.end())
168       return It->second.first;
169     return 4;
170   }
171   MCSymbol *getJumpTableEntryPCRelSymbol(int Idx) const {
172     return JumpTableEntryInfo.find(Idx)->second.second;
173   }
174   void setJumpTableEntryInfo(int Idx, unsigned Size, MCSymbol *PCRelSym) {
175     JumpTableEntryInfo[Idx] = std::make_pair(Size, PCRelSym);
176   }
177 
178   using SetOfInstructions = SmallPtrSet<const MachineInstr *, 16>;
179 
180   const SetOfInstructions &getLOHRelated() const { return LOHRelated; }
181 
182   // Shortcuts for LOH related types.
183   class MILOHDirective {
184     MCLOHType Kind;
185 
186     /// Arguments of this directive. Order matters.
187     SmallVector<const MachineInstr *, 3> Args;
188 
189   public:
190     using LOHArgs = ArrayRef<const MachineInstr *>;
191 
192     MILOHDirective(MCLOHType Kind, LOHArgs Args)
193         : Kind(Kind), Args(Args.begin(), Args.end()) {
194       assert(isValidMCLOHType(Kind) && "Invalid LOH directive type!");
195     }
196 
197     MCLOHType getKind() const { return Kind; }
198     LOHArgs getArgs() const { return Args; }
199   };
200 
201   using MILOHArgs = MILOHDirective::LOHArgs;
202   using MILOHContainer = SmallVector<MILOHDirective, 32>;
203 
204   const MILOHContainer &getLOHContainer() const { return LOHContainerSet; }
205 
206   /// Add a LOH directive of this @p Kind and this @p Args.
207   void addLOHDirective(MCLOHType Kind, MILOHArgs Args) {
208     LOHContainerSet.push_back(MILOHDirective(Kind, Args));
209     LOHRelated.insert(Args.begin(), Args.end());
210   }
211 
212 private:
213   // Hold the lists of LOHs.
214   MILOHContainer LOHContainerSet;
215   SetOfInstructions LOHRelated;
216 
217   DenseMap<int, std::pair<unsigned, MCSymbol *>> JumpTableEntryInfo;
218 };
219 
220 } // end namespace llvm
221 
222 #endif // LLVM_LIB_TARGET_AARCH64_AARCH64MACHINEFUNCTIONINFO_H
223