1// Copyright 2012 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.
4
5#include "src/v8.h"
6
7#include "src/codegen.h"
8#include "src/deoptimizer.h"
9#include "src/full-codegen.h"
10#include "src/safepoint-table.h"
11
12namespace v8 {
13namespace internal {
14
15const int Deoptimizer::table_entry_size_ = 8;
16
17
18int Deoptimizer::patch_size() {
19  const int kCallInstructionSizeInWords = 3;
20  return kCallInstructionSizeInWords * Assembler::kInstrSize;
21}
22
23
24void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
25  Address code_start_address = code->instruction_start();
26  // Invalidate the relocation information, as it will become invalid by the
27  // code patching below, and is not needed any more.
28  code->InvalidateRelocation();
29
30  if (FLAG_zap_code_space) {
31    // Fail hard and early if we enter this code object again.
32    byte* pointer = code->FindCodeAgeSequence();
33    if (pointer != NULL) {
34      pointer += kNoCodeAgeSequenceLength;
35    } else {
36      pointer = code->instruction_start();
37    }
38    CodePatcher patcher(pointer, 1);
39    patcher.masm()->bkpt(0);
40
41    DeoptimizationInputData* data =
42        DeoptimizationInputData::cast(code->deoptimization_data());
43    int osr_offset = data->OsrPcOffset()->value();
44    if (osr_offset > 0) {
45      CodePatcher osr_patcher(code->instruction_start() + osr_offset, 1);
46      osr_patcher.masm()->bkpt(0);
47    }
48  }
49
50  DeoptimizationInputData* deopt_data =
51      DeoptimizationInputData::cast(code->deoptimization_data());
52#ifdef DEBUG
53  Address prev_call_address = NULL;
54#endif
55  // For each LLazyBailout instruction insert a call to the corresponding
56  // deoptimization entry.
57  for (int i = 0; i < deopt_data->DeoptCount(); i++) {
58    if (deopt_data->Pc(i)->value() == -1) continue;
59    Address call_address = code_start_address + deopt_data->Pc(i)->value();
60    Address deopt_entry = GetDeoptimizationEntry(isolate, i, LAZY);
61    // We need calls to have a predictable size in the unoptimized code, but
62    // this is optimized code, so we don't have to have a predictable size.
63    int call_size_in_bytes =
64        MacroAssembler::CallSizeNotPredictableCodeSize(isolate,
65                                                       deopt_entry,
66                                                       RelocInfo::NONE32);
67    int call_size_in_words = call_size_in_bytes / Assembler::kInstrSize;
68    DCHECK(call_size_in_bytes % Assembler::kInstrSize == 0);
69    DCHECK(call_size_in_bytes <= patch_size());
70    CodePatcher patcher(call_address, call_size_in_words);
71    patcher.masm()->Call(deopt_entry, RelocInfo::NONE32);
72    DCHECK(prev_call_address == NULL ||
73           call_address >= prev_call_address + patch_size());
74    DCHECK(call_address + patch_size() <= code->instruction_end());
75#ifdef DEBUG
76    prev_call_address = call_address;
77#endif
78  }
79}
80
81
82void Deoptimizer::FillInputFrame(Address tos, JavaScriptFrame* frame) {
83  // Set the register values. The values are not important as there are no
84  // callee saved registers in JavaScript frames, so all registers are
85  // spilled. Registers fp and sp are set to the correct values though.
86
87  for (int i = 0; i < Register::kNumRegisters; i++) {
88    input_->SetRegister(i, i * 4);
89  }
90  input_->SetRegister(sp.code(), reinterpret_cast<intptr_t>(frame->sp()));
91  input_->SetRegister(fp.code(), reinterpret_cast<intptr_t>(frame->fp()));
92  for (int i = 0; i < DoubleRegister::NumAllocatableRegisters(); i++) {
93    input_->SetDoubleRegister(i, 0.0);
94  }
95
96  // Fill the frame content from the actual data on the frame.
97  for (unsigned i = 0; i < input_->GetFrameSize(); i += kPointerSize) {
98    input_->SetFrameSlot(i, Memory::uint32_at(tos + i));
99  }
100}
101
102
103void Deoptimizer::SetPlatformCompiledStubRegisters(
104    FrameDescription* output_frame, CodeStubDescriptor* descriptor) {
105  ApiFunction function(descriptor->deoptimization_handler());
106  ExternalReference xref(&function, ExternalReference::BUILTIN_CALL, isolate_);
107  intptr_t handler = reinterpret_cast<intptr_t>(xref.address());
108  int params = descriptor->GetHandlerParameterCount();
109  output_frame->SetRegister(r0.code(), params);
110  output_frame->SetRegister(r1.code(), handler);
111}
112
113
114void Deoptimizer::CopyDoubleRegisters(FrameDescription* output_frame) {
115  for (int i = 0; i < DwVfpRegister::kMaxNumRegisters; ++i) {
116    double double_value = input_->GetDoubleRegister(i);
117    output_frame->SetDoubleRegister(i, double_value);
118  }
119}
120
121
122bool Deoptimizer::HasAlignmentPadding(JSFunction* function) {
123  // There is no dynamic alignment padding on ARM in the input frame.
124  return false;
125}
126
127
128#define __ masm()->
129
130// This code tries to be close to ia32 code so that any changes can be
131// easily ported.
132void Deoptimizer::EntryGenerator::Generate() {
133  GeneratePrologue();
134
135  // Save all general purpose registers before messing with them.
136  const int kNumberOfRegisters = Register::kNumRegisters;
137
138  // Everything but pc, lr and ip which will be saved but not restored.
139  RegList restored_regs = kJSCallerSaved | kCalleeSaved | ip.bit();
140
141  const int kDoubleRegsSize =
142      kDoubleSize * DwVfpRegister::kMaxNumAllocatableRegisters;
143
144  // Save all allocatable VFP registers before messing with them.
145  DCHECK(kDoubleRegZero.code() == 14);
146  DCHECK(kScratchDoubleReg.code() == 15);
147
148  // Check CPU flags for number of registers, setting the Z condition flag.
149  __ CheckFor32DRegs(ip);
150
151  // Push registers d0-d13, and possibly d16-d31, on the stack.
152  // If d16-d31 are not pushed, decrease the stack pointer instead.
153  __ vstm(db_w, sp, d16, d31, ne);
154  __ sub(sp, sp, Operand(16 * kDoubleSize), LeaveCC, eq);
155  __ vstm(db_w, sp, d0, d13);
156
157  // Push all 16 registers (needed to populate FrameDescription::registers_).
158  // TODO(1588) Note that using pc with stm is deprecated, so we should perhaps
159  // handle this a bit differently.
160  __ stm(db_w, sp, restored_regs  | sp.bit() | lr.bit() | pc.bit());
161
162  const int kSavedRegistersAreaSize =
163      (kNumberOfRegisters * kPointerSize) + kDoubleRegsSize;
164
165  // Get the bailout id from the stack.
166  __ ldr(r2, MemOperand(sp, kSavedRegistersAreaSize));
167
168  // Get the address of the location in the code object (r3) (return
169  // address for lazy deoptimization) and compute the fp-to-sp delta in
170  // register r4.
171  __ mov(r3, lr);
172  // Correct one word for bailout id.
173  __ add(r4, sp, Operand(kSavedRegistersAreaSize + (1 * kPointerSize)));
174  __ sub(r4, fp, r4);
175
176  // Allocate a new deoptimizer object.
177  // Pass four arguments in r0 to r3 and fifth argument on stack.
178  __ PrepareCallCFunction(6, r5);
179  __ ldr(r0, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
180  __ mov(r1, Operand(type()));  // bailout type,
181  // r2: bailout id already loaded.
182  // r3: code address or 0 already loaded.
183  __ str(r4, MemOperand(sp, 0 * kPointerSize));  // Fp-to-sp delta.
184  __ mov(r5, Operand(ExternalReference::isolate_address(isolate())));
185  __ str(r5, MemOperand(sp, 1 * kPointerSize));  // Isolate.
186  // Call Deoptimizer::New().
187  {
188    AllowExternalCallThatCantCauseGC scope(masm());
189    __ CallCFunction(ExternalReference::new_deoptimizer_function(isolate()), 6);
190  }
191
192  // Preserve "deoptimizer" object in register r0 and get the input
193  // frame descriptor pointer to r1 (deoptimizer->input_);
194  __ ldr(r1, MemOperand(r0, Deoptimizer::input_offset()));
195
196  // Copy core registers into FrameDescription::registers_[kNumRegisters].
197  DCHECK(Register::kNumRegisters == kNumberOfRegisters);
198  for (int i = 0; i < kNumberOfRegisters; i++) {
199    int offset = (i * kPointerSize) + FrameDescription::registers_offset();
200    __ ldr(r2, MemOperand(sp, i * kPointerSize));
201    __ str(r2, MemOperand(r1, offset));
202  }
203
204  // Copy VFP registers to
205  // double_registers_[DoubleRegister::kMaxNumAllocatableRegisters]
206  int double_regs_offset = FrameDescription::double_registers_offset();
207  for (int i = 0; i < DwVfpRegister::kMaxNumAllocatableRegisters; ++i) {
208    int dst_offset = i * kDoubleSize + double_regs_offset;
209    int src_offset = i * kDoubleSize + kNumberOfRegisters * kPointerSize;
210    __ vldr(d0, sp, src_offset);
211    __ vstr(d0, r1, dst_offset);
212  }
213
214  // Remove the bailout id and the saved registers from the stack.
215  __ add(sp, sp, Operand(kSavedRegistersAreaSize + (1 * kPointerSize)));
216
217  // Compute a pointer to the unwinding limit in register r2; that is
218  // the first stack slot not part of the input frame.
219  __ ldr(r2, MemOperand(r1, FrameDescription::frame_size_offset()));
220  __ add(r2, r2, sp);
221
222  // Unwind the stack down to - but not including - the unwinding
223  // limit and copy the contents of the activation frame to the input
224  // frame description.
225  __ add(r3,  r1, Operand(FrameDescription::frame_content_offset()));
226  Label pop_loop;
227  Label pop_loop_header;
228  __ b(&pop_loop_header);
229  __ bind(&pop_loop);
230  __ pop(r4);
231  __ str(r4, MemOperand(r3, 0));
232  __ add(r3, r3, Operand(sizeof(uint32_t)));
233  __ bind(&pop_loop_header);
234  __ cmp(r2, sp);
235  __ b(ne, &pop_loop);
236
237  // Compute the output frame in the deoptimizer.
238  __ push(r0);  // Preserve deoptimizer object across call.
239  // r0: deoptimizer object; r1: scratch.
240  __ PrepareCallCFunction(1, r1);
241  // Call Deoptimizer::ComputeOutputFrames().
242  {
243    AllowExternalCallThatCantCauseGC scope(masm());
244    __ CallCFunction(
245        ExternalReference::compute_output_frames_function(isolate()), 1);
246  }
247  __ pop(r0);  // Restore deoptimizer object (class Deoptimizer).
248
249  // Replace the current (input) frame with the output frames.
250  Label outer_push_loop, inner_push_loop,
251      outer_loop_header, inner_loop_header;
252  // Outer loop state: r4 = current "FrameDescription** output_",
253  // r1 = one past the last FrameDescription**.
254  __ ldr(r1, MemOperand(r0, Deoptimizer::output_count_offset()));
255  __ ldr(r4, MemOperand(r0, Deoptimizer::output_offset()));  // r4 is output_.
256  __ add(r1, r4, Operand(r1, LSL, 2));
257  __ jmp(&outer_loop_header);
258  __ bind(&outer_push_loop);
259  // Inner loop state: r2 = current FrameDescription*, r3 = loop index.
260  __ ldr(r2, MemOperand(r4, 0));  // output_[ix]
261  __ ldr(r3, MemOperand(r2, FrameDescription::frame_size_offset()));
262  __ jmp(&inner_loop_header);
263  __ bind(&inner_push_loop);
264  __ sub(r3, r3, Operand(sizeof(uint32_t)));
265  __ add(r6, r2, Operand(r3));
266  __ ldr(r6, MemOperand(r6, FrameDescription::frame_content_offset()));
267  __ push(r6);
268  __ bind(&inner_loop_header);
269  __ cmp(r3, Operand::Zero());
270  __ b(ne, &inner_push_loop);  // test for gt?
271  __ add(r4, r4, Operand(kPointerSize));
272  __ bind(&outer_loop_header);
273  __ cmp(r4, r1);
274  __ b(lt, &outer_push_loop);
275
276  // Check CPU flags for number of registers, setting the Z condition flag.
277  __ CheckFor32DRegs(ip);
278
279  __ ldr(r1, MemOperand(r0, Deoptimizer::input_offset()));
280  int src_offset = FrameDescription::double_registers_offset();
281  for (int i = 0; i < DwVfpRegister::kMaxNumRegisters; ++i) {
282    if (i == kDoubleRegZero.code()) continue;
283    if (i == kScratchDoubleReg.code()) continue;
284
285    const DwVfpRegister reg = DwVfpRegister::from_code(i);
286    __ vldr(reg, r1, src_offset, i < 16 ? al : ne);
287    src_offset += kDoubleSize;
288  }
289
290  // Push state, pc, and continuation from the last output frame.
291  __ ldr(r6, MemOperand(r2, FrameDescription::state_offset()));
292  __ push(r6);
293  __ ldr(r6, MemOperand(r2, FrameDescription::pc_offset()));
294  __ push(r6);
295  __ ldr(r6, MemOperand(r2, FrameDescription::continuation_offset()));
296  __ push(r6);
297
298  // Push the registers from the last output frame.
299  for (int i = kNumberOfRegisters - 1; i >= 0; i--) {
300    int offset = (i * kPointerSize) + FrameDescription::registers_offset();
301    __ ldr(r6, MemOperand(r2, offset));
302    __ push(r6);
303  }
304
305  // Restore the registers from the stack.
306  __ ldm(ia_w, sp, restored_regs);  // all but pc registers.
307  __ pop(ip);  // remove sp
308  __ pop(ip);  // remove lr
309
310  __ InitializeRootRegister();
311
312  __ pop(ip);  // remove pc
313  __ pop(ip);  // get continuation, leave pc on stack
314  __ pop(lr);
315  __ Jump(ip);
316  __ stop("Unreachable.");
317}
318
319
320void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
321  // Create a sequence of deoptimization entries.
322  // Note that registers are still live when jumping to an entry.
323  Label done;
324  for (int i = 0; i < count(); i++) {
325    int start = masm()->pc_offset();
326    USE(start);
327    __ mov(ip, Operand(i));
328    __ b(&done);
329    DCHECK(masm()->pc_offset() - start == table_entry_size_);
330  }
331  __ bind(&done);
332  __ push(ip);
333}
334
335
336void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
337  SetFrameSlot(offset, value);
338}
339
340
341void FrameDescription::SetCallerFp(unsigned offset, intptr_t value) {
342  SetFrameSlot(offset, value);
343}
344
345
346void FrameDescription::SetCallerConstantPool(unsigned offset, intptr_t value) {
347  DCHECK(FLAG_enable_ool_constant_pool);
348  SetFrameSlot(offset, value);
349}
350
351
352#undef __
353
354} }  // namespace v8::internal
355