1 // Copyright 2011 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
7 #include "src/safepoint-table.h"
9 #include "src/deoptimizer.h"
10 #include "src/disasm.h"
11 #include "src/macro-assembler.h"
12 #include "src/ostreams.h"
13 #include "src/zone-inl.h"
19 bool SafepointEntry::HasRegisters() const {
21 DCHECK(IsAligned(kNumSafepointRegisters, kBitsPerByte));
22 const int num_reg_bytes = kNumSafepointRegisters >> kBitsPerByteLog2;
23 for (int i = 0; i < num_reg_bytes; i++) {
24 if (bits_[i] != SafepointTable::kNoRegisters) return true;
30 bool SafepointEntry::HasRegisterAt(int reg_index) const {
32 DCHECK(reg_index >= 0 && reg_index < kNumSafepointRegisters);
33 int byte_index = reg_index >> kBitsPerByteLog2;
34 int bit_index = reg_index & (kBitsPerByte - 1);
35 return (bits_[byte_index] & (1 << bit_index)) != 0;
39 SafepointTable::SafepointTable(Code* code) {
40 DCHECK(code->is_crankshafted());
42 Address header = code->instruction_start() + code->safepoint_table_offset();
43 length_ = Memory::uint32_at(header + kLengthOffset);
44 entry_size_ = Memory::uint32_at(header + kEntrySizeOffset);
45 pc_and_deoptimization_indexes_ = header + kHeaderSize;
46 entries_ = pc_and_deoptimization_indexes_ +
47 (length_ * kPcAndDeoptimizationIndexSize);
48 DCHECK(entry_size_ > 0);
49 STATIC_ASSERT(SafepointEntry::DeoptimizationIndexField::kMax ==
50 Safepoint::kNoDeoptimizationIndex);
54 SafepointEntry SafepointTable::FindEntry(Address pc) const {
55 unsigned pc_offset = static_cast<unsigned>(pc - code_->instruction_start());
56 for (unsigned i = 0; i < length(); i++) {
57 // TODO(kasperl): Replace the linear search with binary search.
58 if (GetPcOffset(i) == pc_offset) return GetEntry(i);
60 return SafepointEntry();
64 void SafepointTable::PrintEntry(unsigned index,
65 std::ostream& os) const { // NOLINT
66 disasm::NameConverter converter;
67 SafepointEntry entry = GetEntry(index);
68 uint8_t* bits = entry.bits();
70 // Print the stack slot bits.
71 if (entry_size_ > 0) {
72 DCHECK(IsAligned(kNumSafepointRegisters, kBitsPerByte));
73 const int first = kNumSafepointRegisters >> kBitsPerByteLog2;
74 int last = entry_size_ - 1;
75 for (int i = first; i < last; i++) PrintBits(os, bits[i], kBitsPerByte);
76 int last_bits = code_->stack_slots() - ((last - first) * kBitsPerByte);
77 PrintBits(os, bits[last], last_bits);
79 // Print the registers (if any).
80 if (!entry.HasRegisters()) return;
81 for (int j = 0; j < kNumSafepointRegisters; j++) {
82 if (entry.HasRegisterAt(j)) {
83 os << " | " << converter.NameOfCPURegister(j);
90 void SafepointTable::PrintBits(std::ostream& os, // NOLINT
91 uint8_t byte, int digits) {
92 DCHECK(digits >= 0 && digits <= kBitsPerByte);
93 for (int i = 0; i < digits; i++) {
94 os << (((byte & (1 << i)) == 0) ? "0" : "1");
99 void Safepoint::DefinePointerRegister(Register reg, Zone* zone) {
100 registers_->Add(reg.code(), zone);
104 Safepoint SafepointTableBuilder::DefineSafepoint(
105 Assembler* assembler,
106 Safepoint::Kind kind,
108 Safepoint::DeoptMode deopt_mode) {
109 DCHECK(arguments >= 0);
110 DeoptimizationInfo info;
111 info.pc = assembler->pc_offset();
112 info.arguments = arguments;
113 info.has_doubles = (kind & Safepoint::kWithDoubles);
114 deoptimization_info_.Add(info, zone_);
115 deopt_index_list_.Add(Safepoint::kNoDeoptimizationIndex, zone_);
116 if (deopt_mode == Safepoint::kNoLazyDeopt) {
117 last_lazy_safepoint_ = deopt_index_list_.length();
119 indexes_.Add(new(zone_) ZoneList<int>(8, zone_), zone_);
120 registers_.Add((kind & Safepoint::kWithRegisters)
121 ? new(zone_) ZoneList<int>(4, zone_)
124 return Safepoint(indexes_.last(), registers_.last());
128 void SafepointTableBuilder::RecordLazyDeoptimizationIndex(int index) {
129 while (last_lazy_safepoint_ < deopt_index_list_.length()) {
130 deopt_index_list_[last_lazy_safepoint_++] = index;
134 unsigned SafepointTableBuilder::GetCodeOffset() const {
140 void SafepointTableBuilder::Emit(Assembler* assembler, int bits_per_entry) {
141 // Make sure the safepoint table is properly aligned. Pad with nops.
142 assembler->Align(kIntSize);
143 assembler->RecordComment(";;; Safepoint table.");
144 offset_ = assembler->pc_offset();
146 // Take the register bits into account.
147 bits_per_entry += kNumSafepointRegisters;
149 // Compute the number of bytes per safepoint entry.
150 int bytes_per_entry =
151 RoundUp(bits_per_entry, kBitsPerByte) >> kBitsPerByteLog2;
153 // Emit the table header.
154 int length = deoptimization_info_.length();
155 assembler->dd(length);
156 assembler->dd(bytes_per_entry);
158 // Emit sorted table of pc offsets together with deoptimization indexes.
159 for (int i = 0; i < length; i++) {
160 assembler->dd(deoptimization_info_[i].pc);
161 assembler->dd(EncodeExceptPC(deoptimization_info_[i],
162 deopt_index_list_[i]));
165 // Emit table of bitmaps.
166 ZoneList<uint8_t> bits(bytes_per_entry, zone_);
167 for (int i = 0; i < length; i++) {
168 ZoneList<int>* indexes = indexes_[i];
169 ZoneList<int>* registers = registers_[i];
171 bits.AddBlock(0, bytes_per_entry, zone_);
173 // Run through the registers (if any).
174 DCHECK(IsAligned(kNumSafepointRegisters, kBitsPerByte));
175 if (registers == NULL) {
176 const int num_reg_bytes = kNumSafepointRegisters >> kBitsPerByteLog2;
177 for (int j = 0; j < num_reg_bytes; j++) {
178 bits[j] = SafepointTable::kNoRegisters;
181 for (int j = 0; j < registers->length(); j++) {
182 int index = registers->at(j);
183 DCHECK(index >= 0 && index < kNumSafepointRegisters);
184 int byte_index = index >> kBitsPerByteLog2;
185 int bit_index = index & (kBitsPerByte - 1);
186 bits[byte_index] |= (1 << bit_index);
190 // Run through the indexes and build a bitmap.
191 for (int j = 0; j < indexes->length(); j++) {
192 int index = bits_per_entry - 1 - indexes->at(j);
193 int byte_index = index >> kBitsPerByteLog2;
194 int bit_index = index & (kBitsPerByte - 1);
195 bits[byte_index] |= (1U << bit_index);
198 // Emit the bitmap for the current entry.
199 for (int k = 0; k < bytes_per_entry; k++) {
200 assembler->db(bits[k]);
207 uint32_t SafepointTableBuilder::EncodeExceptPC(const DeoptimizationInfo& info,
209 uint32_t encoding = SafepointEntry::DeoptimizationIndexField::encode(index);
210 encoding |= SafepointEntry::ArgumentsField::encode(info.arguments);
211 encoding |= SafepointEntry::SaveDoublesField::encode(info.has_doubles);
217 } } // namespace v8::internal