1 //===-- ARMUnwindOpAsm.h - ARM Unwind Opcodes Assembler ---------*- 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 the unwind opcode assembler for ARM exception handling
10 // table.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_TARGET_ARM_MCTARGETDESC_ARMUNWINDOPASM_H
15 #define LLVM_LIB_TARGET_ARM_MCTARGETDESC_ARMUNWINDOPASM_H
16 
17 #include "llvm/ADT/SmallVector.h"
18 #include <cstddef>
19 #include <cstdint>
20 
21 namespace llvm {
22 
23 class MCSymbol;
24 
25 class UnwindOpcodeAssembler {
26 private:
27   SmallVector<uint8_t, 32> Ops;
28   SmallVector<unsigned, 8> OpBegins;
29   bool HasPersonality = false;
30 
31 public:
32   UnwindOpcodeAssembler() {
33     OpBegins.push_back(0);
34   }
35 
36   /// Reset the unwind opcode assembler.
37   void Reset() {
38     Ops.clear();
39     OpBegins.clear();
40     OpBegins.push_back(0);
41     HasPersonality = false;
42   }
43 
44   /// Set the personality
45   void setPersonality(const MCSymbol *Per) {
46     HasPersonality = true;
47   }
48 
49   /// Emit unwind opcodes for .save directives
50   void EmitRegSave(uint32_t RegSave);
51 
52   /// Emit unwind opcodes for .vsave directives
53   void EmitVFPRegSave(uint32_t VFPRegSave);
54 
55   /// Emit unwind opcodes to copy address from source register to $sp.
56   void EmitSetSP(uint16_t Reg);
57 
58   /// Emit unwind opcodes to add $sp with an offset.
59   void EmitSPOffset(int64_t Offset);
60 
61   /// Emit unwind raw opcodes
62   void EmitRaw(const SmallVectorImpl<uint8_t> &Opcodes) {
63     Ops.insert(Ops.end(), Opcodes.begin(), Opcodes.end());
64     OpBegins.push_back(OpBegins.back() + Opcodes.size());
65   }
66 
67   /// Finalize the unwind opcode sequence for EmitBytes()
68   void Finalize(unsigned &PersonalityIndex,
69                 SmallVectorImpl<uint8_t> &Result);
70 
71 private:
72   void EmitInt8(unsigned Opcode) {
73     Ops.push_back(Opcode & 0xff);
74     OpBegins.push_back(OpBegins.back() + 1);
75   }
76 
77   void EmitInt16(unsigned Opcode) {
78     Ops.push_back((Opcode >> 8) & 0xff);
79     Ops.push_back(Opcode & 0xff);
80     OpBegins.push_back(OpBegins.back() + 2);
81   }
82 
83   void EmitBytes(const uint8_t *Opcode, size_t Size) {
84     Ops.insert(Ops.end(), Opcode, Opcode + Size);
85     OpBegins.push_back(OpBegins.back() + Size);
86   }
87 };
88 
89 } // end namespace llvm
90 
91 #endif // LLVM_LIB_TARGET_ARM_MCTARGETDESC_ARMUNWINDOPASM_H
92