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/codegen.h"
6 #include "src/deoptimizer.h"
7 #include "src/full-codegen/full-codegen.h"
8 #include "src/register-configuration.h"
9 #include "src/safepoint-table.h"
10
11 namespace v8 {
12 namespace internal {
13
14 const int Deoptimizer::table_entry_size_ = 8;
15
16
patch_size()17 int Deoptimizer::patch_size() {
18 const int kCallInstructionSizeInWords = 3;
19 return kCallInstructionSizeInWords * Assembler::kInstrSize;
20 }
21
22
EnsureRelocSpaceForLazyDeoptimization(Handle<Code> code)23 void Deoptimizer::EnsureRelocSpaceForLazyDeoptimization(Handle<Code> code) {
24 // Empty because there is no need for relocation information for the code
25 // patching in Deoptimizer::PatchCodeForDeoptimization below.
26 }
27
28
PatchCodeForDeoptimization(Isolate * isolate,Code * code)29 void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
30 Address code_start_address = code->instruction_start();
31 // Invalidate the relocation information, as it will become invalid by the
32 // code patching below, and is not needed any more.
33 code->InvalidateRelocation();
34
35 if (FLAG_zap_code_space) {
36 // Fail hard and early if we enter this code object again.
37 byte* pointer = code->FindCodeAgeSequence();
38 if (pointer != NULL) {
39 pointer += kNoCodeAgeSequenceLength;
40 } else {
41 pointer = code->instruction_start();
42 }
43 CodePatcher patcher(isolate, pointer, 1);
44 patcher.masm()->bkpt(0);
45
46 DeoptimizationInputData* data =
47 DeoptimizationInputData::cast(code->deoptimization_data());
48 int osr_offset = data->OsrPcOffset()->value();
49 if (osr_offset > 0) {
50 CodePatcher osr_patcher(isolate, code->instruction_start() + osr_offset,
51 1);
52 osr_patcher.masm()->bkpt(0);
53 }
54 }
55
56 DeoptimizationInputData* deopt_data =
57 DeoptimizationInputData::cast(code->deoptimization_data());
58 #ifdef DEBUG
59 Address prev_call_address = NULL;
60 #endif
61 // For each LLazyBailout instruction insert a call to the corresponding
62 // deoptimization entry.
63 for (int i = 0; i < deopt_data->DeoptCount(); i++) {
64 if (deopt_data->Pc(i)->value() == -1) continue;
65 Address call_address = code_start_address + deopt_data->Pc(i)->value();
66 Address deopt_entry = GetDeoptimizationEntry(isolate, i, LAZY);
67 // We need calls to have a predictable size in the unoptimized code, but
68 // this is optimized code, so we don't have to have a predictable size.
69 int call_size_in_bytes = MacroAssembler::CallDeoptimizerSize();
70 int call_size_in_words = call_size_in_bytes / Assembler::kInstrSize;
71 DCHECK(call_size_in_bytes % Assembler::kInstrSize == 0);
72 DCHECK(call_size_in_bytes <= patch_size());
73 CodePatcher patcher(isolate, call_address, call_size_in_words);
74 patcher.masm()->CallDeoptimizer(deopt_entry);
75 DCHECK(prev_call_address == NULL ||
76 call_address >= prev_call_address + patch_size());
77 DCHECK(call_address + patch_size() <= code->instruction_end());
78 #ifdef DEBUG
79 prev_call_address = call_address;
80 #endif
81 }
82 }
83
84
SetPlatformCompiledStubRegisters(FrameDescription * output_frame,CodeStubDescriptor * descriptor)85 void Deoptimizer::SetPlatformCompiledStubRegisters(
86 FrameDescription* output_frame, CodeStubDescriptor* descriptor) {
87 ApiFunction function(descriptor->deoptimization_handler());
88 ExternalReference xref(&function, ExternalReference::BUILTIN_CALL, isolate_);
89 intptr_t handler = reinterpret_cast<intptr_t>(xref.address());
90 int params = descriptor->GetHandlerParameterCount();
91 output_frame->SetRegister(r0.code(), params);
92 output_frame->SetRegister(r1.code(), handler);
93 }
94
95
CopyDoubleRegisters(FrameDescription * output_frame)96 void Deoptimizer::CopyDoubleRegisters(FrameDescription* output_frame) {
97 for (int i = 0; i < DwVfpRegister::kMaxNumRegisters; ++i) {
98 double double_value = input_->GetDoubleRegister(i);
99 output_frame->SetDoubleRegister(i, double_value);
100 }
101 }
102
103 #define __ masm()->
104
105 // This code tries to be close to ia32 code so that any changes can be
106 // easily ported.
Generate()107 void Deoptimizer::TableEntryGenerator::Generate() {
108 GeneratePrologue();
109
110 // Save all general purpose registers before messing with them.
111 const int kNumberOfRegisters = Register::kNumRegisters;
112
113 // Everything but pc, lr and ip which will be saved but not restored.
114 RegList restored_regs = kJSCallerSaved | kCalleeSaved | ip.bit();
115
116 const int kDoubleRegsSize = kDoubleSize * DwVfpRegister::kMaxNumRegisters;
117
118 // Save all allocatable VFP registers before messing with them.
119 DCHECK(kDoubleRegZero.code() == 14);
120 DCHECK(kScratchDoubleReg.code() == 15);
121
122 {
123 // We use a run-time check for VFP32DREGS.
124 CpuFeatureScope scope(masm(), VFP32DREGS,
125 CpuFeatureScope::kDontCheckSupported);
126
127 // Check CPU flags for number of registers, setting the Z condition flag.
128 __ CheckFor32DRegs(ip);
129
130 // Push registers d0-d15, and possibly d16-d31, on the stack.
131 // If d16-d31 are not pushed, decrease the stack pointer instead.
132 __ vstm(db_w, sp, d16, d31, ne);
133 __ sub(sp, sp, Operand(16 * kDoubleSize), LeaveCC, eq);
134 __ vstm(db_w, sp, d0, d15);
135 }
136
137 // Push all 16 registers (needed to populate FrameDescription::registers_).
138 // TODO(1588) Note that using pc with stm is deprecated, so we should perhaps
139 // handle this a bit differently.
140 __ stm(db_w, sp, restored_regs | sp.bit() | lr.bit() | pc.bit());
141
142 __ mov(ip, Operand(ExternalReference(Isolate::kCEntryFPAddress, isolate())));
143 __ str(fp, MemOperand(ip));
144
145 const int kSavedRegistersAreaSize =
146 (kNumberOfRegisters * kPointerSize) + kDoubleRegsSize;
147
148 // Get the bailout id from the stack.
149 __ ldr(r2, MemOperand(sp, kSavedRegistersAreaSize));
150
151 // Get the address of the location in the code object (r3) (return
152 // address for lazy deoptimization) and compute the fp-to-sp delta in
153 // register r4.
154 __ mov(r3, lr);
155 // Correct one word for bailout id.
156 __ add(r4, sp, Operand(kSavedRegistersAreaSize + (1 * kPointerSize)));
157 __ sub(r4, fp, r4);
158
159 // Allocate a new deoptimizer object.
160 // Pass four arguments in r0 to r3 and fifth argument on stack.
161 __ PrepareCallCFunction(6, r5);
162 __ mov(r0, Operand(0));
163 Label context_check;
164 __ ldr(r1, MemOperand(fp, CommonFrameConstants::kContextOrFrameTypeOffset));
165 __ JumpIfSmi(r1, &context_check);
166 __ ldr(r0, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
167 __ bind(&context_check);
168 __ mov(r1, Operand(type())); // bailout type,
169 // r2: bailout id already loaded.
170 // r3: code address or 0 already loaded.
171 __ str(r4, MemOperand(sp, 0 * kPointerSize)); // Fp-to-sp delta.
172 __ mov(r5, Operand(ExternalReference::isolate_address(isolate())));
173 __ str(r5, MemOperand(sp, 1 * kPointerSize)); // Isolate.
174 // Call Deoptimizer::New().
175 {
176 AllowExternalCallThatCantCauseGC scope(masm());
177 __ CallCFunction(ExternalReference::new_deoptimizer_function(isolate()), 6);
178 }
179
180 // Preserve "deoptimizer" object in register r0 and get the input
181 // frame descriptor pointer to r1 (deoptimizer->input_);
182 __ ldr(r1, MemOperand(r0, Deoptimizer::input_offset()));
183
184 // Copy core registers into FrameDescription::registers_[kNumRegisters].
185 DCHECK(Register::kNumRegisters == kNumberOfRegisters);
186 for (int i = 0; i < kNumberOfRegisters; i++) {
187 int offset = (i * kPointerSize) + FrameDescription::registers_offset();
188 __ ldr(r2, MemOperand(sp, i * kPointerSize));
189 __ str(r2, MemOperand(r1, offset));
190 }
191
192 // Copy VFP registers to
193 // double_registers_[DoubleRegister::kMaxNumAllocatableRegisters]
194 int double_regs_offset = FrameDescription::double_registers_offset();
195 const RegisterConfiguration* config = RegisterConfiguration::Crankshaft();
196 for (int i = 0; i < config->num_allocatable_double_registers(); ++i) {
197 int code = config->GetAllocatableDoubleCode(i);
198 int dst_offset = code * kDoubleSize + double_regs_offset;
199 int src_offset = code * kDoubleSize + kNumberOfRegisters * kPointerSize;
200 __ vldr(d0, sp, src_offset);
201 __ vstr(d0, r1, dst_offset);
202 }
203
204 // Remove the bailout id and the saved registers from the stack.
205 __ add(sp, sp, Operand(kSavedRegistersAreaSize + (1 * kPointerSize)));
206
207 // Compute a pointer to the unwinding limit in register r2; that is
208 // the first stack slot not part of the input frame.
209 __ ldr(r2, MemOperand(r1, FrameDescription::frame_size_offset()));
210 __ add(r2, r2, sp);
211
212 // Unwind the stack down to - but not including - the unwinding
213 // limit and copy the contents of the activation frame to the input
214 // frame description.
215 __ add(r3, r1, Operand(FrameDescription::frame_content_offset()));
216 Label pop_loop;
217 Label pop_loop_header;
218 __ b(&pop_loop_header);
219 __ bind(&pop_loop);
220 __ pop(r4);
221 __ str(r4, MemOperand(r3, 0));
222 __ add(r3, r3, Operand(sizeof(uint32_t)));
223 __ bind(&pop_loop_header);
224 __ cmp(r2, sp);
225 __ b(ne, &pop_loop);
226
227 // Compute the output frame in the deoptimizer.
228 __ push(r0); // Preserve deoptimizer object across call.
229 // r0: deoptimizer object; r1: scratch.
230 __ PrepareCallCFunction(1, r1);
231 // Call Deoptimizer::ComputeOutputFrames().
232 {
233 AllowExternalCallThatCantCauseGC scope(masm());
234 __ CallCFunction(
235 ExternalReference::compute_output_frames_function(isolate()), 1);
236 }
237 __ pop(r0); // Restore deoptimizer object (class Deoptimizer).
238
239 __ ldr(sp, MemOperand(r0, Deoptimizer::caller_frame_top_offset()));
240
241 // Replace the current (input) frame with the output frames.
242 Label outer_push_loop, inner_push_loop,
243 outer_loop_header, inner_loop_header;
244 // Outer loop state: r4 = current "FrameDescription** output_",
245 // r1 = one past the last FrameDescription**.
246 __ ldr(r1, MemOperand(r0, Deoptimizer::output_count_offset()));
247 __ ldr(r4, MemOperand(r0, Deoptimizer::output_offset())); // r4 is output_.
248 __ add(r1, r4, Operand(r1, LSL, 2));
249 __ jmp(&outer_loop_header);
250 __ bind(&outer_push_loop);
251 // Inner loop state: r2 = current FrameDescription*, r3 = loop index.
252 __ ldr(r2, MemOperand(r4, 0)); // output_[ix]
253 __ ldr(r3, MemOperand(r2, FrameDescription::frame_size_offset()));
254 __ jmp(&inner_loop_header);
255 __ bind(&inner_push_loop);
256 __ sub(r3, r3, Operand(sizeof(uint32_t)));
257 __ add(r6, r2, Operand(r3));
258 __ ldr(r6, MemOperand(r6, FrameDescription::frame_content_offset()));
259 __ push(r6);
260 __ bind(&inner_loop_header);
261 __ cmp(r3, Operand::Zero());
262 __ b(ne, &inner_push_loop); // test for gt?
263 __ add(r4, r4, Operand(kPointerSize));
264 __ bind(&outer_loop_header);
265 __ cmp(r4, r1);
266 __ b(lt, &outer_push_loop);
267
268 __ ldr(r1, MemOperand(r0, Deoptimizer::input_offset()));
269 for (int i = 0; i < config->num_allocatable_double_registers(); ++i) {
270 int code = config->GetAllocatableDoubleCode(i);
271 DwVfpRegister reg = DwVfpRegister::from_code(code);
272 int src_offset = code * kDoubleSize + double_regs_offset;
273 __ vldr(reg, r1, src_offset);
274 }
275
276 // Push state, pc, and continuation from the last output frame.
277 __ ldr(r6, MemOperand(r2, FrameDescription::state_offset()));
278 __ push(r6);
279 __ ldr(r6, MemOperand(r2, FrameDescription::pc_offset()));
280 __ push(r6);
281 __ ldr(r6, MemOperand(r2, FrameDescription::continuation_offset()));
282 __ push(r6);
283
284 // Push the registers from the last output frame.
285 for (int i = kNumberOfRegisters - 1; i >= 0; i--) {
286 int offset = (i * kPointerSize) + FrameDescription::registers_offset();
287 __ ldr(r6, MemOperand(r2, offset));
288 __ push(r6);
289 }
290
291 // Restore the registers from the stack.
292 __ ldm(ia_w, sp, restored_regs); // all but pc registers.
293 __ pop(ip); // remove sp
294 __ pop(ip); // remove lr
295
296 __ InitializeRootRegister();
297
298 __ pop(ip); // remove pc
299 __ pop(ip); // get continuation, leave pc on stack
300 __ pop(lr);
301 __ Jump(ip);
302 __ stop("Unreachable.");
303 }
304
305
GeneratePrologue()306 void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
307 // Create a sequence of deoptimization entries.
308 // Note that registers are still live when jumping to an entry.
309
310 // We need to be able to generate immediates up to kMaxNumberOfEntries. On
311 // ARMv7, we can use movw (with a maximum immediate of 0xffff). On ARMv6, we
312 // need two instructions.
313 STATIC_ASSERT((kMaxNumberOfEntries - 1) <= 0xffff);
314 if (CpuFeatures::IsSupported(ARMv7)) {
315 CpuFeatureScope scope(masm(), ARMv7);
316 Label done;
317 for (int i = 0; i < count(); i++) {
318 int start = masm()->pc_offset();
319 USE(start);
320 __ movw(ip, i);
321 __ b(&done);
322 DCHECK_EQ(table_entry_size_, masm()->pc_offset() - start);
323 }
324 __ bind(&done);
325 } else {
326 // We want to keep table_entry_size_ == 8 (since this is the common case),
327 // but we need two instructions to load most immediates over 0xff. To handle
328 // this, we set the low byte in the main table, and then set the high byte
329 // in a separate table if necessary.
330 Label high_fixes[256];
331 int high_fix_max = (count() - 1) >> 8;
332 DCHECK_GT(arraysize(high_fixes), static_cast<size_t>(high_fix_max));
333 for (int i = 0; i < count(); i++) {
334 int start = masm()->pc_offset();
335 USE(start);
336 __ mov(ip, Operand(i & 0xff)); // Set the low byte.
337 __ b(&high_fixes[i >> 8]); // Jump to the secondary table.
338 DCHECK_EQ(table_entry_size_, masm()->pc_offset() - start);
339 }
340 // Generate the secondary table, to set the high byte.
341 for (int high = 1; high <= high_fix_max; high++) {
342 __ bind(&high_fixes[high]);
343 __ orr(ip, ip, Operand(high << 8));
344 // If this isn't the last entry, emit a branch to the end of the table.
345 // The last entry can just fall through.
346 if (high < high_fix_max) __ b(&high_fixes[0]);
347 }
348 // Bind high_fixes[0] last, for indices like 0x00**. This case requires no
349 // fix-up, so for (common) small tables we can jump here, then just fall
350 // through with no additional branch.
351 __ bind(&high_fixes[0]);
352 }
353 __ push(ip);
354 }
355
356
SetCallerPc(unsigned offset,intptr_t value)357 void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
358 SetFrameSlot(offset, value);
359 }
360
361
SetCallerFp(unsigned offset,intptr_t value)362 void FrameDescription::SetCallerFp(unsigned offset, intptr_t value) {
363 SetFrameSlot(offset, value);
364 }
365
366
SetCallerConstantPool(unsigned offset,intptr_t value)367 void FrameDescription::SetCallerConstantPool(unsigned offset, intptr_t value) {
368 DCHECK(FLAG_enable_embedded_constant_pool);
369 SetFrameSlot(offset, value);
370 }
371
372
373 #undef __
374
375 } // namespace internal
376 } // namespace v8
377