forked from OSchip/llvm-project
227 lines
6.8 KiB
C++
227 lines
6.8 KiB
C++
//===-- ARMUnwindOpAsm.cpp - ARM Unwind Opcodes Assembler -------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the unwind opcode assmebler for ARM exception handling
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// table.
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//
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//===----------------------------------------------------------------------===//
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#include "ARMUnwindOpAsm.h"
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#include "llvm/Support/ARMEHABI.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/LEB128.h"
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using namespace llvm;
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namespace {
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/// UnwindOpcodeStreamer - The simple wrapper over SmallVector to emit bytes
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/// with MSB to LSB per uint32_t ordering. For example, the first byte will
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/// be placed in Vec[3], and the following bytes will be placed in 2, 1, 0,
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/// 7, 6, 5, 4, 11, 10, 9, 8, and so on.
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class UnwindOpcodeStreamer {
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private:
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SmallVectorImpl<uint8_t> &Vec;
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size_t Pos;
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public:
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UnwindOpcodeStreamer(SmallVectorImpl<uint8_t> &V) : Vec(V), Pos(3) {
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}
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/// Emit the byte in MSB to LSB per uint32_t order.
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inline void EmitByte(uint8_t elem) {
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Vec[Pos] = elem;
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Pos = (((Pos ^ 0x3u) + 1) ^ 0x3u);
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}
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/// Emit the size prefix.
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inline void EmitSize(size_t Size) {
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size_t SizeInWords = (Size + 3) / 4;
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assert(SizeInWords <= 0x100u &&
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"Only 256 additional words are allowed for unwind opcodes");
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EmitByte(static_cast<uint8_t>(SizeInWords - 1));
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}
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/// Emit the personality index prefix.
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inline void EmitPersonalityIndex(unsigned PI) {
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assert(PI < ARM::EHABI::NUM_PERSONALITY_INDEX &&
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"Invalid personality prefix");
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EmitByte(ARM::EHABI::EHT_COMPACT | PI);
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}
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/// Fill the rest of bytes with FINISH opcode.
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inline void FillFinishOpcode() {
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while (Pos < Vec.size())
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EmitByte(ARM::EHABI::UNWIND_OPCODE_FINISH);
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}
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};
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}
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void UnwindOpcodeAssembler::EmitRegSave(uint32_t RegSave) {
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if (RegSave == 0u)
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return;
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// One byte opcode to save register r14 and r11-r4
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if (RegSave & (1u << 4)) {
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// The one byte opcode will always save r4, thus we can't use the one byte
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// opcode when r4 is not in .save directive.
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// Compute the consecutive registers from r4 to r11.
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uint32_t Range = 0;
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uint32_t Mask = (1u << 4);
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for (uint32_t Bit = (1u << 5); Bit < (1u << 12); Bit <<= 1) {
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if ((RegSave & Bit) == 0u)
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break;
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++Range;
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Mask |= Bit;
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}
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// Emit this opcode when the mask covers every registers.
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uint32_t UnmaskedReg = RegSave & 0xfff0u & (~Mask);
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if (UnmaskedReg == 0u) {
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// Pop r[4 : (4 + n)]
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EmitInt8(ARM::EHABI::UNWIND_OPCODE_POP_REG_RANGE_R4 | Range);
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RegSave &= 0x000fu;
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} else if (UnmaskedReg == (1u << 14)) {
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// Pop r[14] + r[4 : (4 + n)]
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EmitInt8(ARM::EHABI::UNWIND_OPCODE_POP_REG_RANGE_R4_R14 | Range);
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RegSave &= 0x000fu;
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}
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}
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// Two bytes opcode to save register r15-r4
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if ((RegSave & 0xfff0u) != 0)
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EmitInt16(ARM::EHABI::UNWIND_OPCODE_POP_REG_MASK_R4 | (RegSave >> 4));
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// Opcode to save register r3-r0
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if ((RegSave & 0x000fu) != 0)
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EmitInt16(ARM::EHABI::UNWIND_OPCODE_POP_REG_MASK | (RegSave & 0x000fu));
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}
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/// Emit unwind opcodes for .vsave directives
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void UnwindOpcodeAssembler::EmitVFPRegSave(uint32_t VFPRegSave) {
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size_t i = 32;
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while (i > 16) {
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uint32_t Bit = 1u << (i - 1);
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if ((VFPRegSave & Bit) == 0u) {
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--i;
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continue;
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}
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uint32_t Range = 0;
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--i;
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Bit >>= 1;
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while (i > 16 && (VFPRegSave & Bit)) {
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--i;
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++Range;
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Bit >>= 1;
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}
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EmitInt16(ARM::EHABI::UNWIND_OPCODE_POP_VFP_REG_RANGE_FSTMFDD_D16 |
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((i - 16) << 4) | Range);
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}
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while (i > 0) {
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uint32_t Bit = 1u << (i - 1);
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if ((VFPRegSave & Bit) == 0u) {
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--i;
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continue;
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}
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uint32_t Range = 0;
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--i;
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Bit >>= 1;
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while (i > 0 && (VFPRegSave & Bit)) {
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--i;
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++Range;
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Bit >>= 1;
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}
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EmitInt16(ARM::EHABI::UNWIND_OPCODE_POP_VFP_REG_RANGE_FSTMFDD | (i << 4) |
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Range);
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}
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}
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/// Emit unwind opcodes to copy address from source register to $sp.
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void UnwindOpcodeAssembler::EmitSetSP(uint16_t Reg) {
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EmitInt8(ARM::EHABI::UNWIND_OPCODE_SET_VSP | Reg);
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}
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/// Emit unwind opcodes to add $sp with an offset.
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void UnwindOpcodeAssembler::EmitSPOffset(int64_t Offset) {
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if (Offset > 0x200) {
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uint8_t Buff[16];
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Buff[0] = ARM::EHABI::UNWIND_OPCODE_INC_VSP_ULEB128;
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size_t ULEBSize = encodeULEB128((Offset - 0x204) >> 2, Buff + 1);
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EmitBytes(Buff, ULEBSize + 1);
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} else if (Offset > 0) {
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if (Offset > 0x100) {
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EmitInt8(ARM::EHABI::UNWIND_OPCODE_INC_VSP | 0x3fu);
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Offset -= 0x100;
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}
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EmitInt8(ARM::EHABI::UNWIND_OPCODE_INC_VSP |
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static_cast<uint8_t>((Offset - 4) >> 2));
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} else if (Offset < 0) {
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while (Offset < -0x100) {
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EmitInt8(ARM::EHABI::UNWIND_OPCODE_DEC_VSP | 0x3fu);
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Offset += 0x100;
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}
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EmitInt8(ARM::EHABI::UNWIND_OPCODE_DEC_VSP |
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static_cast<uint8_t>(((-Offset) - 4) >> 2));
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}
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}
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void UnwindOpcodeAssembler::Finalize(unsigned &PersonalityIndex,
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SmallVectorImpl<uint8_t> &Result) {
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UnwindOpcodeStreamer OpStreamer(Result);
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if (HasPersonality) {
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// User-specifed personality routine: [ SIZE , OP1 , OP2 , ... ]
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PersonalityIndex = ARM::EHABI::NUM_PERSONALITY_INDEX;
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size_t TotalSize = Ops.size() + 1;
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size_t RoundUpSize = (TotalSize + 3) / 4 * 4;
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Result.resize(RoundUpSize);
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OpStreamer.EmitSize(RoundUpSize);
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} else {
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// If no personalityindex is specified, select ane
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if (PersonalityIndex == ARM::EHABI::NUM_PERSONALITY_INDEX)
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PersonalityIndex = (Ops.size() <= 3) ? ARM::EHABI::AEABI_UNWIND_CPP_PR0
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: ARM::EHABI::AEABI_UNWIND_CPP_PR1;
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if (PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0) {
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// __aeabi_unwind_cpp_pr0: [ 0x80 , OP1 , OP2 , OP3 ]
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assert(Ops.size() <= 3 && "too many opcodes for __aeabi_unwind_cpp_pr0");
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Result.resize(4);
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OpStreamer.EmitPersonalityIndex(PersonalityIndex);
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} else {
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// __aeabi_unwind_cpp_pr{1,2}: [ {0x81,0x82} , SIZE , OP1 , OP2 , ... ]
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size_t TotalSize = Ops.size() + 2;
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size_t RoundUpSize = (TotalSize + 3) / 4 * 4;
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Result.resize(RoundUpSize);
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OpStreamer.EmitPersonalityIndex(PersonalityIndex);
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OpStreamer.EmitSize(RoundUpSize);
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}
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}
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// Copy the unwind opcodes
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for (size_t i = OpBegins.size() - 1; i > 0; --i)
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for (size_t j = OpBegins[i - 1], end = OpBegins[i]; j < end; ++j)
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OpStreamer.EmitByte(Ops[j]);
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// Emit the padding finish opcodes if the size is not multiple of 4.
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OpStreamer.FillFinishOpcode();
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// Reset the assembler state
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Reset();
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}
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