lib/Target/ARM/MCTargetDesc/ARMUnwindOpAsm.h

   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 assmebler 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