1 //===-- ARMUnwindOpAsm.cpp - ARM Unwind Opcodes Assembler -------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the unwind opcode assmebler for ARM exception handling
13 //===----------------------------------------------------------------------===//
15 #include "ARMUnwindOpAsm.h"
17 #include "ARMUnwindOp.h"
18 #include "llvm/Support/ErrorHandling.h"
19 #include "llvm/Support/LEB128.h"
24 /// UnwindOpcodeStreamer - The simple wrapper over SmallVector to emit bytes
25 /// with MSB to LSB per uint32_t ordering. For example, the first byte will
26 /// be placed in Vec[3], and the following bytes will be placed in 2, 1, 0,
27 /// 7, 6, 5, 4, 11, 10, 9, 8, and so on.
28 class UnwindOpcodeStreamer {
30 SmallVectorImpl<uint8_t> &Vec;
34 UnwindOpcodeStreamer(SmallVectorImpl<uint8_t> &V) : Vec(V), Pos(3) {
37 /// Emit the byte in MSB to LSB per uint32_t order.
38 inline void EmitByte(uint8_t elem) {
40 Pos = (((Pos ^ 0x3u) + 1) ^ 0x3u);
43 /// Emit the size prefix.
44 inline void EmitSize(size_t Size) {
45 size_t SizeInWords = (Size + 3) / 4;
46 assert(SizeInWords <= 0x100u &&
47 "Only 256 additional words are allowed for unwind opcodes");
48 EmitByte(static_cast<uint8_t>(SizeInWords - 1));
51 /// Emit the personality index prefix.
52 inline void EmitPersonalityIndex(unsigned PI) {
53 assert(PI < NUM_PERSONALITY_INDEX && "Invalid personality prefix");
54 EmitByte(EHT_COMPACT | PI);
57 /// Fill the rest of bytes with FINISH opcode.
58 inline void FillFinishOpcode() {
59 while (Pos < Vec.size())
60 EmitByte(UNWIND_OPCODE_FINISH);
65 void UnwindOpcodeAssembler::EmitRegSave(uint32_t RegSave) {
69 // One byte opcode to save register r14 and r11-r4
70 if (RegSave & (1u << 4)) {
71 // The one byte opcode will always save r4, thus we can't use the one byte
72 // opcode when r4 is not in .save directive.
74 // Compute the consecutive registers from r4 to r11.
76 uint32_t Mask = (1u << 4);
77 for (uint32_t Bit = (1u << 5); Bit < (1u << 12); Bit <<= 1) {
78 if ((RegSave & Bit) == 0u)
84 // Emit this opcode when the mask covers every registers.
85 uint32_t UnmaskedReg = RegSave & 0xfff0u & (~Mask);
86 if (UnmaskedReg == 0u) {
88 EmitInt8(UNWIND_OPCODE_POP_REG_RANGE_R4 | Range);
90 } else if (UnmaskedReg == (1u << 14)) {
91 // Pop r[14] + r[4 : (4 + n)]
92 EmitInt8(UNWIND_OPCODE_POP_REG_RANGE_R4_R14 | Range);
97 // Two bytes opcode to save register r15-r4
98 if ((RegSave & 0xfff0u) != 0)
99 EmitInt16(UNWIND_OPCODE_POP_REG_MASK_R4 | (RegSave >> 4));
101 // Opcode to save register r3-r0
102 if ((RegSave & 0x000fu) != 0)
103 EmitInt16(UNWIND_OPCODE_POP_REG_MASK | (RegSave & 0x000fu));
106 /// Emit unwind opcodes for .vsave directives
107 void UnwindOpcodeAssembler::EmitVFPRegSave(uint32_t VFPRegSave) {
111 uint32_t Bit = 1u << (i - 1);
112 if ((VFPRegSave & Bit) == 0u) {
122 while (i > 16 && (VFPRegSave & Bit)) {
128 EmitInt16(UNWIND_OPCODE_POP_VFP_REG_RANGE_FSTMFDD_D16 |
129 ((i - 16) << 4) | Range);
133 uint32_t Bit = 1u << (i - 1);
134 if ((VFPRegSave & Bit) == 0u) {
144 while (i > 0 && (VFPRegSave & Bit)) {
150 EmitInt16(UNWIND_OPCODE_POP_VFP_REG_RANGE_FSTMFDD | (i << 4) | Range);
154 /// Emit unwind opcodes to copy address from source register to $sp.
155 void UnwindOpcodeAssembler::EmitSetSP(uint16_t Reg) {
156 EmitInt8(UNWIND_OPCODE_SET_VSP | Reg);
159 /// Emit unwind opcodes to add $sp with an offset.
160 void UnwindOpcodeAssembler::EmitSPOffset(int64_t Offset) {
161 if (Offset > 0x200) {
163 Buff[0] = UNWIND_OPCODE_INC_VSP_ULEB128;
164 size_t ULEBSize = encodeULEB128((Offset - 0x204) >> 2, Buff + 1);
165 EmitBytes(Buff, ULEBSize + 1);
166 } else if (Offset > 0) {
167 if (Offset > 0x100) {
168 EmitInt8(UNWIND_OPCODE_INC_VSP | 0x3fu);
171 EmitInt8(UNWIND_OPCODE_INC_VSP | static_cast<uint8_t>((Offset - 4) >> 2));
172 } else if (Offset < 0) {
173 while (Offset < -0x100) {
174 EmitInt8(UNWIND_OPCODE_DEC_VSP | 0x3fu);
177 EmitInt8(UNWIND_OPCODE_DEC_VSP |
178 static_cast<uint8_t>(((-Offset) - 4) >> 2));
182 void UnwindOpcodeAssembler::Finalize(unsigned &PersonalityIndex,
183 SmallVectorImpl<uint8_t> &Result) {
185 UnwindOpcodeStreamer OpStreamer(Result);
187 if (HasPersonality) {
188 // User-specifed personality routine: [ SIZE , OP1 , OP2 , ... ]
189 PersonalityIndex = NUM_PERSONALITY_INDEX;
190 size_t TotalSize = Ops.size() + 1;
191 size_t RoundUpSize = (TotalSize + 3) / 4 * 4;
192 Result.resize(RoundUpSize);
193 OpStreamer.EmitSize(RoundUpSize);
195 if (Ops.size() <= 3) {
196 // __aeabi_unwind_cpp_pr0: [ 0x80 , OP1 , OP2 , OP3 ]
197 PersonalityIndex = AEABI_UNWIND_CPP_PR0;
199 OpStreamer.EmitPersonalityIndex(PersonalityIndex);
201 // __aeabi_unwind_cpp_pr1: [ 0x81 , SIZE , OP1 , OP2 , ... ]
202 PersonalityIndex = AEABI_UNWIND_CPP_PR1;
203 size_t TotalSize = Ops.size() + 2;
204 size_t RoundUpSize = (TotalSize + 3) / 4 * 4;
205 Result.resize(RoundUpSize);
206 OpStreamer.EmitPersonalityIndex(PersonalityIndex);
207 OpStreamer.EmitSize(RoundUpSize);
211 // Copy the unwind opcodes
212 for (size_t i = OpBegins.size() - 1; i > 0; --i)
213 for (size_t j = OpBegins[i - 1], end = OpBegins[i]; j < end; ++j)
214 OpStreamer.EmitByte(Ops[j]);
216 // Emit the padding finish opcodes if the size is not multiple of 4.
217 OpStreamer.FillFinishOpcode();
219 // Reset the assembler state