Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame^] | 1 | // Copyright 2013 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 | #if V8_TARGET_ARCH_ARM64 |
| 8 | |
| 9 | #include "src/arm64/simulator-arm64.h" |
| 10 | #include "src/codegen.h" |
| 11 | #include "src/macro-assembler.h" |
| 12 | |
| 13 | namespace v8 { |
| 14 | namespace internal { |
| 15 | |
| 16 | #define __ ACCESS_MASM(masm) |
| 17 | |
| 18 | #if defined(USE_SIMULATOR) |
| 19 | byte* fast_exp_arm64_machine_code = NULL; |
| 20 | double fast_exp_simulator(double x) { |
| 21 | Simulator * simulator = Simulator::current(Isolate::Current()); |
| 22 | Simulator::CallArgument args[] = { |
| 23 | Simulator::CallArgument(x), |
| 24 | Simulator::CallArgument::End() |
| 25 | }; |
| 26 | return simulator->CallDouble(fast_exp_arm64_machine_code, args); |
| 27 | } |
| 28 | #endif |
| 29 | |
| 30 | |
| 31 | UnaryMathFunction CreateExpFunction() { |
| 32 | if (!FLAG_fast_math) return &std::exp; |
| 33 | |
| 34 | // Use the Math.exp implemetation in MathExpGenerator::EmitMathExp() to create |
| 35 | // an AAPCS64-compliant exp() function. This will be faster than the C |
| 36 | // library's exp() function, but probably less accurate. |
| 37 | size_t actual_size; |
| 38 | byte* buffer = |
| 39 | static_cast<byte*>(base::OS::Allocate(1 * KB, &actual_size, true)); |
| 40 | if (buffer == NULL) return &std::exp; |
| 41 | |
| 42 | ExternalReference::InitializeMathExpData(); |
| 43 | MacroAssembler masm(NULL, buffer, static_cast<int>(actual_size)); |
| 44 | masm.SetStackPointer(csp); |
| 45 | |
| 46 | // The argument will be in d0 on entry. |
| 47 | DoubleRegister input = d0; |
| 48 | // Use other caller-saved registers for all other values. |
| 49 | DoubleRegister result = d1; |
| 50 | DoubleRegister double_temp1 = d2; |
| 51 | DoubleRegister double_temp2 = d3; |
| 52 | Register temp1 = x10; |
| 53 | Register temp2 = x11; |
| 54 | Register temp3 = x12; |
| 55 | |
| 56 | MathExpGenerator::EmitMathExp(&masm, input, result, |
| 57 | double_temp1, double_temp2, |
| 58 | temp1, temp2, temp3); |
| 59 | // Move the result to the return register. |
| 60 | masm.Fmov(d0, result); |
| 61 | masm.Ret(); |
| 62 | |
| 63 | CodeDesc desc; |
| 64 | masm.GetCode(&desc); |
| 65 | DCHECK(!RelocInfo::RequiresRelocation(desc)); |
| 66 | |
| 67 | CpuFeatures::FlushICache(buffer, actual_size); |
| 68 | base::OS::ProtectCode(buffer, actual_size); |
| 69 | |
| 70 | #if !defined(USE_SIMULATOR) |
| 71 | return FUNCTION_CAST<UnaryMathFunction>(buffer); |
| 72 | #else |
| 73 | fast_exp_arm64_machine_code = buffer; |
| 74 | return &fast_exp_simulator; |
| 75 | #endif |
| 76 | } |
| 77 | |
| 78 | |
| 79 | UnaryMathFunction CreateSqrtFunction() { |
| 80 | return &std::sqrt; |
| 81 | } |
| 82 | |
| 83 | |
| 84 | // ------------------------------------------------------------------------- |
| 85 | // Platform-specific RuntimeCallHelper functions. |
| 86 | |
| 87 | void StubRuntimeCallHelper::BeforeCall(MacroAssembler* masm) const { |
| 88 | masm->EnterFrame(StackFrame::INTERNAL); |
| 89 | DCHECK(!masm->has_frame()); |
| 90 | masm->set_has_frame(true); |
| 91 | } |
| 92 | |
| 93 | |
| 94 | void StubRuntimeCallHelper::AfterCall(MacroAssembler* masm) const { |
| 95 | masm->LeaveFrame(StackFrame::INTERNAL); |
| 96 | DCHECK(masm->has_frame()); |
| 97 | masm->set_has_frame(false); |
| 98 | } |
| 99 | |
| 100 | |
| 101 | // ------------------------------------------------------------------------- |
| 102 | // Code generators |
| 103 | |
| 104 | void ElementsTransitionGenerator::GenerateMapChangeElementsTransition( |
| 105 | MacroAssembler* masm, |
| 106 | Register receiver, |
| 107 | Register key, |
| 108 | Register value, |
| 109 | Register target_map, |
| 110 | AllocationSiteMode mode, |
| 111 | Label* allocation_memento_found) { |
| 112 | ASM_LOCATION( |
| 113 | "ElementsTransitionGenerator::GenerateMapChangeElementsTransition"); |
| 114 | DCHECK(!AreAliased(receiver, key, value, target_map)); |
| 115 | |
| 116 | if (mode == TRACK_ALLOCATION_SITE) { |
| 117 | DCHECK(allocation_memento_found != NULL); |
| 118 | __ JumpIfJSArrayHasAllocationMemento(receiver, x10, x11, |
| 119 | allocation_memento_found); |
| 120 | } |
| 121 | |
| 122 | // Set transitioned map. |
| 123 | __ Str(target_map, FieldMemOperand(receiver, HeapObject::kMapOffset)); |
| 124 | __ RecordWriteField(receiver, |
| 125 | HeapObject::kMapOffset, |
| 126 | target_map, |
| 127 | x10, |
| 128 | kLRHasNotBeenSaved, |
| 129 | kDontSaveFPRegs, |
| 130 | EMIT_REMEMBERED_SET, |
| 131 | OMIT_SMI_CHECK); |
| 132 | } |
| 133 | |
| 134 | |
| 135 | void ElementsTransitionGenerator::GenerateSmiToDouble( |
| 136 | MacroAssembler* masm, |
| 137 | Register receiver, |
| 138 | Register key, |
| 139 | Register value, |
| 140 | Register target_map, |
| 141 | AllocationSiteMode mode, |
| 142 | Label* fail) { |
| 143 | ASM_LOCATION("ElementsTransitionGenerator::GenerateSmiToDouble"); |
| 144 | Label gc_required, only_change_map; |
| 145 | Register elements = x4; |
| 146 | Register length = x5; |
| 147 | Register array_size = x6; |
| 148 | Register array = x7; |
| 149 | |
| 150 | Register scratch = x6; |
| 151 | |
| 152 | // Verify input registers don't conflict with locals. |
| 153 | DCHECK(!AreAliased(receiver, key, value, target_map, |
| 154 | elements, length, array_size, array)); |
| 155 | |
| 156 | if (mode == TRACK_ALLOCATION_SITE) { |
| 157 | __ JumpIfJSArrayHasAllocationMemento(receiver, x10, x11, fail); |
| 158 | } |
| 159 | |
| 160 | // Check for empty arrays, which only require a map transition and no changes |
| 161 | // to the backing store. |
| 162 | __ Ldr(elements, FieldMemOperand(receiver, JSObject::kElementsOffset)); |
| 163 | __ JumpIfRoot(elements, Heap::kEmptyFixedArrayRootIndex, &only_change_map); |
| 164 | |
| 165 | __ Push(lr); |
| 166 | __ Ldrsw(length, UntagSmiFieldMemOperand(elements, |
| 167 | FixedArray::kLengthOffset)); |
| 168 | |
| 169 | // Allocate new FixedDoubleArray. |
| 170 | __ Lsl(array_size, length, kDoubleSizeLog2); |
| 171 | __ Add(array_size, array_size, FixedDoubleArray::kHeaderSize); |
| 172 | __ Allocate(array_size, array, x10, x11, &gc_required, DOUBLE_ALIGNMENT); |
| 173 | // Register array is non-tagged heap object. |
| 174 | |
| 175 | // Set the destination FixedDoubleArray's length and map. |
| 176 | Register map_root = array_size; |
| 177 | __ LoadRoot(map_root, Heap::kFixedDoubleArrayMapRootIndex); |
| 178 | __ SmiTag(x11, length); |
| 179 | __ Str(x11, MemOperand(array, FixedDoubleArray::kLengthOffset)); |
| 180 | __ Str(map_root, MemOperand(array, HeapObject::kMapOffset)); |
| 181 | |
| 182 | __ Str(target_map, FieldMemOperand(receiver, HeapObject::kMapOffset)); |
| 183 | __ RecordWriteField(receiver, HeapObject::kMapOffset, target_map, scratch, |
| 184 | kLRHasBeenSaved, kDontSaveFPRegs, OMIT_REMEMBERED_SET, |
| 185 | OMIT_SMI_CHECK); |
| 186 | |
| 187 | // Replace receiver's backing store with newly created FixedDoubleArray. |
| 188 | __ Add(x10, array, kHeapObjectTag); |
| 189 | __ Str(x10, FieldMemOperand(receiver, JSObject::kElementsOffset)); |
| 190 | __ RecordWriteField(receiver, JSObject::kElementsOffset, x10, |
| 191 | scratch, kLRHasBeenSaved, kDontSaveFPRegs, |
| 192 | EMIT_REMEMBERED_SET, OMIT_SMI_CHECK); |
| 193 | |
| 194 | // Prepare for conversion loop. |
| 195 | Register src_elements = x10; |
| 196 | Register dst_elements = x11; |
| 197 | Register dst_end = x12; |
| 198 | __ Add(src_elements, elements, FixedArray::kHeaderSize - kHeapObjectTag); |
| 199 | __ Add(dst_elements, array, FixedDoubleArray::kHeaderSize); |
| 200 | __ Add(dst_end, dst_elements, Operand(length, LSL, kDoubleSizeLog2)); |
| 201 | |
| 202 | FPRegister nan_d = d1; |
| 203 | __ Fmov(nan_d, rawbits_to_double(kHoleNanInt64)); |
| 204 | |
| 205 | Label entry, done; |
| 206 | __ B(&entry); |
| 207 | |
| 208 | __ Bind(&only_change_map); |
| 209 | __ Str(target_map, FieldMemOperand(receiver, HeapObject::kMapOffset)); |
| 210 | __ RecordWriteField(receiver, HeapObject::kMapOffset, target_map, scratch, |
| 211 | kLRHasNotBeenSaved, kDontSaveFPRegs, OMIT_REMEMBERED_SET, |
| 212 | OMIT_SMI_CHECK); |
| 213 | __ B(&done); |
| 214 | |
| 215 | // Call into runtime if GC is required. |
| 216 | __ Bind(&gc_required); |
| 217 | __ Pop(lr); |
| 218 | __ B(fail); |
| 219 | |
| 220 | // Iterate over the array, copying and coverting smis to doubles. If an |
| 221 | // element is non-smi, write a hole to the destination. |
| 222 | { |
| 223 | Label loop; |
| 224 | __ Bind(&loop); |
| 225 | __ Ldr(x13, MemOperand(src_elements, kPointerSize, PostIndex)); |
| 226 | __ SmiUntagToDouble(d0, x13, kSpeculativeUntag); |
| 227 | __ Tst(x13, kSmiTagMask); |
| 228 | __ Fcsel(d0, d0, nan_d, eq); |
| 229 | __ Str(d0, MemOperand(dst_elements, kDoubleSize, PostIndex)); |
| 230 | |
| 231 | __ Bind(&entry); |
| 232 | __ Cmp(dst_elements, dst_end); |
| 233 | __ B(lt, &loop); |
| 234 | } |
| 235 | |
| 236 | __ Pop(lr); |
| 237 | __ Bind(&done); |
| 238 | } |
| 239 | |
| 240 | |
| 241 | void ElementsTransitionGenerator::GenerateDoubleToObject( |
| 242 | MacroAssembler* masm, |
| 243 | Register receiver, |
| 244 | Register key, |
| 245 | Register value, |
| 246 | Register target_map, |
| 247 | AllocationSiteMode mode, |
| 248 | Label* fail) { |
| 249 | ASM_LOCATION("ElementsTransitionGenerator::GenerateDoubleToObject"); |
| 250 | Register elements = x4; |
| 251 | Register array_size = x6; |
| 252 | Register array = x7; |
| 253 | Register length = x5; |
| 254 | |
| 255 | // Verify input registers don't conflict with locals. |
| 256 | DCHECK(!AreAliased(receiver, key, value, target_map, |
| 257 | elements, array_size, array, length)); |
| 258 | |
| 259 | if (mode == TRACK_ALLOCATION_SITE) { |
| 260 | __ JumpIfJSArrayHasAllocationMemento(receiver, x10, x11, fail); |
| 261 | } |
| 262 | |
| 263 | // Check for empty arrays, which only require a map transition and no changes |
| 264 | // to the backing store. |
| 265 | Label only_change_map; |
| 266 | |
| 267 | __ Ldr(elements, FieldMemOperand(receiver, JSObject::kElementsOffset)); |
| 268 | __ JumpIfRoot(elements, Heap::kEmptyFixedArrayRootIndex, &only_change_map); |
| 269 | |
| 270 | __ Push(lr); |
| 271 | // TODO(all): These registers may not need to be pushed. Examine |
| 272 | // RecordWriteStub and check whether it's needed. |
| 273 | __ Push(target_map, receiver, key, value); |
| 274 | __ Ldrsw(length, UntagSmiFieldMemOperand(elements, |
| 275 | FixedArray::kLengthOffset)); |
| 276 | // Allocate new FixedArray. |
| 277 | Label gc_required; |
| 278 | __ Mov(array_size, FixedDoubleArray::kHeaderSize); |
| 279 | __ Add(array_size, array_size, Operand(length, LSL, kPointerSizeLog2)); |
| 280 | __ Allocate(array_size, array, x10, x11, &gc_required, NO_ALLOCATION_FLAGS); |
| 281 | |
| 282 | // Set destination FixedDoubleArray's length and map. |
| 283 | Register map_root = array_size; |
| 284 | __ LoadRoot(map_root, Heap::kFixedArrayMapRootIndex); |
| 285 | __ SmiTag(x11, length); |
| 286 | __ Str(x11, MemOperand(array, FixedDoubleArray::kLengthOffset)); |
| 287 | __ Str(map_root, MemOperand(array, HeapObject::kMapOffset)); |
| 288 | |
| 289 | // Prepare for conversion loop. |
| 290 | Register src_elements = x10; |
| 291 | Register dst_elements = x11; |
| 292 | Register dst_end = x12; |
| 293 | __ Add(src_elements, elements, |
| 294 | FixedDoubleArray::kHeaderSize - kHeapObjectTag); |
| 295 | __ Add(dst_elements, array, FixedArray::kHeaderSize); |
| 296 | __ Add(array, array, kHeapObjectTag); |
| 297 | __ Add(dst_end, dst_elements, Operand(length, LSL, kPointerSizeLog2)); |
| 298 | |
| 299 | Register the_hole = x14; |
| 300 | Register heap_num_map = x15; |
| 301 | __ LoadRoot(the_hole, Heap::kTheHoleValueRootIndex); |
| 302 | __ LoadRoot(heap_num_map, Heap::kHeapNumberMapRootIndex); |
| 303 | |
| 304 | Label entry; |
| 305 | __ B(&entry); |
| 306 | |
| 307 | // Call into runtime if GC is required. |
| 308 | __ Bind(&gc_required); |
| 309 | __ Pop(value, key, receiver, target_map); |
| 310 | __ Pop(lr); |
| 311 | __ B(fail); |
| 312 | |
| 313 | { |
| 314 | Label loop, convert_hole; |
| 315 | __ Bind(&loop); |
| 316 | __ Ldr(x13, MemOperand(src_elements, kPointerSize, PostIndex)); |
| 317 | __ Cmp(x13, kHoleNanInt64); |
| 318 | __ B(eq, &convert_hole); |
| 319 | |
| 320 | // Non-hole double, copy value into a heap number. |
| 321 | Register heap_num = length; |
| 322 | Register scratch = array_size; |
| 323 | Register scratch2 = elements; |
| 324 | __ AllocateHeapNumber(heap_num, &gc_required, scratch, scratch2, |
| 325 | x13, heap_num_map); |
| 326 | __ Mov(x13, dst_elements); |
| 327 | __ Str(heap_num, MemOperand(dst_elements, kPointerSize, PostIndex)); |
| 328 | __ RecordWrite(array, x13, heap_num, kLRHasBeenSaved, kDontSaveFPRegs, |
| 329 | EMIT_REMEMBERED_SET, OMIT_SMI_CHECK); |
| 330 | |
| 331 | __ B(&entry); |
| 332 | |
| 333 | // Replace the-hole NaN with the-hole pointer. |
| 334 | __ Bind(&convert_hole); |
| 335 | __ Str(the_hole, MemOperand(dst_elements, kPointerSize, PostIndex)); |
| 336 | |
| 337 | __ Bind(&entry); |
| 338 | __ Cmp(dst_elements, dst_end); |
| 339 | __ B(lt, &loop); |
| 340 | } |
| 341 | |
| 342 | __ Pop(value, key, receiver, target_map); |
| 343 | // Replace receiver's backing store with newly created and filled FixedArray. |
| 344 | __ Str(array, FieldMemOperand(receiver, JSObject::kElementsOffset)); |
| 345 | __ RecordWriteField(receiver, JSObject::kElementsOffset, array, x13, |
| 346 | kLRHasBeenSaved, kDontSaveFPRegs, EMIT_REMEMBERED_SET, |
| 347 | OMIT_SMI_CHECK); |
| 348 | __ Pop(lr); |
| 349 | |
| 350 | __ Bind(&only_change_map); |
| 351 | __ Str(target_map, FieldMemOperand(receiver, HeapObject::kMapOffset)); |
| 352 | __ RecordWriteField(receiver, HeapObject::kMapOffset, target_map, x13, |
| 353 | kLRHasNotBeenSaved, kDontSaveFPRegs, OMIT_REMEMBERED_SET, |
| 354 | OMIT_SMI_CHECK); |
| 355 | } |
| 356 | |
| 357 | |
| 358 | CodeAgingHelper::CodeAgingHelper() { |
| 359 | DCHECK(young_sequence_.length() == kNoCodeAgeSequenceLength); |
| 360 | // The sequence of instructions that is patched out for aging code is the |
| 361 | // following boilerplate stack-building prologue that is found both in |
| 362 | // FUNCTION and OPTIMIZED_FUNCTION code: |
| 363 | PatchingAssembler patcher(young_sequence_.start(), |
| 364 | young_sequence_.length() / kInstructionSize); |
| 365 | // The young sequence is the frame setup code for FUNCTION code types. It is |
| 366 | // generated by FullCodeGenerator::Generate. |
| 367 | MacroAssembler::EmitFrameSetupForCodeAgePatching(&patcher); |
| 368 | |
| 369 | #ifdef DEBUG |
| 370 | const int length = kCodeAgeStubEntryOffset / kInstructionSize; |
| 371 | DCHECK(old_sequence_.length() >= kCodeAgeStubEntryOffset); |
| 372 | PatchingAssembler patcher_old(old_sequence_.start(), length); |
| 373 | MacroAssembler::EmitCodeAgeSequence(&patcher_old, NULL); |
| 374 | #endif |
| 375 | } |
| 376 | |
| 377 | |
| 378 | #ifdef DEBUG |
| 379 | bool CodeAgingHelper::IsOld(byte* candidate) const { |
| 380 | return memcmp(candidate, old_sequence_.start(), kCodeAgeStubEntryOffset) == 0; |
| 381 | } |
| 382 | #endif |
| 383 | |
| 384 | |
| 385 | bool Code::IsYoungSequence(Isolate* isolate, byte* sequence) { |
| 386 | return MacroAssembler::IsYoungSequence(isolate, sequence); |
| 387 | } |
| 388 | |
| 389 | |
| 390 | void Code::GetCodeAgeAndParity(Isolate* isolate, byte* sequence, Age* age, |
| 391 | MarkingParity* parity) { |
| 392 | if (IsYoungSequence(isolate, sequence)) { |
| 393 | *age = kNoAgeCodeAge; |
| 394 | *parity = NO_MARKING_PARITY; |
| 395 | } else { |
| 396 | byte* target = sequence + kCodeAgeStubEntryOffset; |
| 397 | Code* stub = GetCodeFromTargetAddress(Memory::Address_at(target)); |
| 398 | GetCodeAgeAndParity(stub, age, parity); |
| 399 | } |
| 400 | } |
| 401 | |
| 402 | |
| 403 | void Code::PatchPlatformCodeAge(Isolate* isolate, |
| 404 | byte* sequence, |
| 405 | Code::Age age, |
| 406 | MarkingParity parity) { |
| 407 | PatchingAssembler patcher(sequence, |
| 408 | kNoCodeAgeSequenceLength / kInstructionSize); |
| 409 | if (age == kNoAgeCodeAge) { |
| 410 | MacroAssembler::EmitFrameSetupForCodeAgePatching(&patcher); |
| 411 | } else { |
| 412 | Code * stub = GetCodeAgeStub(isolate, age, parity); |
| 413 | MacroAssembler::EmitCodeAgeSequence(&patcher, stub); |
| 414 | } |
| 415 | } |
| 416 | |
| 417 | |
| 418 | void StringCharLoadGenerator::Generate(MacroAssembler* masm, |
| 419 | Register string, |
| 420 | Register index, |
| 421 | Register result, |
| 422 | Label* call_runtime) { |
| 423 | DCHECK(string.Is64Bits() && index.Is32Bits() && result.Is64Bits()); |
| 424 | // Fetch the instance type of the receiver into result register. |
| 425 | __ Ldr(result, FieldMemOperand(string, HeapObject::kMapOffset)); |
| 426 | __ Ldrb(result, FieldMemOperand(result, Map::kInstanceTypeOffset)); |
| 427 | |
| 428 | // We need special handling for indirect strings. |
| 429 | Label check_sequential; |
| 430 | __ TestAndBranchIfAllClear(result, kIsIndirectStringMask, &check_sequential); |
| 431 | |
| 432 | // Dispatch on the indirect string shape: slice or cons. |
| 433 | Label cons_string; |
| 434 | __ TestAndBranchIfAllClear(result, kSlicedNotConsMask, &cons_string); |
| 435 | |
| 436 | // Handle slices. |
| 437 | Label indirect_string_loaded; |
| 438 | __ Ldr(result.W(), |
| 439 | UntagSmiFieldMemOperand(string, SlicedString::kOffsetOffset)); |
| 440 | __ Ldr(string, FieldMemOperand(string, SlicedString::kParentOffset)); |
| 441 | __ Add(index, index, result.W()); |
| 442 | __ B(&indirect_string_loaded); |
| 443 | |
| 444 | // Handle cons strings. |
| 445 | // Check whether the right hand side is the empty string (i.e. if |
| 446 | // this is really a flat string in a cons string). If that is not |
| 447 | // the case we would rather go to the runtime system now to flatten |
| 448 | // the string. |
| 449 | __ Bind(&cons_string); |
| 450 | __ Ldr(result, FieldMemOperand(string, ConsString::kSecondOffset)); |
| 451 | __ JumpIfNotRoot(result, Heap::kempty_stringRootIndex, call_runtime); |
| 452 | // Get the first of the two strings and load its instance type. |
| 453 | __ Ldr(string, FieldMemOperand(string, ConsString::kFirstOffset)); |
| 454 | |
| 455 | __ Bind(&indirect_string_loaded); |
| 456 | __ Ldr(result, FieldMemOperand(string, HeapObject::kMapOffset)); |
| 457 | __ Ldrb(result, FieldMemOperand(result, Map::kInstanceTypeOffset)); |
| 458 | |
| 459 | // Distinguish sequential and external strings. Only these two string |
| 460 | // representations can reach here (slices and flat cons strings have been |
| 461 | // reduced to the underlying sequential or external string). |
| 462 | Label external_string, check_encoding; |
| 463 | __ Bind(&check_sequential); |
| 464 | STATIC_ASSERT(kSeqStringTag == 0); |
| 465 | __ TestAndBranchIfAnySet(result, kStringRepresentationMask, &external_string); |
| 466 | |
| 467 | // Prepare sequential strings |
| 468 | STATIC_ASSERT(SeqTwoByteString::kHeaderSize == SeqOneByteString::kHeaderSize); |
| 469 | __ Add(string, string, SeqTwoByteString::kHeaderSize - kHeapObjectTag); |
| 470 | __ B(&check_encoding); |
| 471 | |
| 472 | // Handle external strings. |
| 473 | __ Bind(&external_string); |
| 474 | if (FLAG_debug_code) { |
| 475 | // Assert that we do not have a cons or slice (indirect strings) here. |
| 476 | // Sequential strings have already been ruled out. |
| 477 | __ Tst(result, kIsIndirectStringMask); |
| 478 | __ Assert(eq, kExternalStringExpectedButNotFound); |
| 479 | } |
| 480 | // Rule out short external strings. |
| 481 | STATIC_ASSERT(kShortExternalStringTag != 0); |
| 482 | // TestAndBranchIfAnySet can emit Tbnz. Do not use it because call_runtime |
| 483 | // can be bound far away in deferred code. |
| 484 | __ Tst(result, kShortExternalStringMask); |
| 485 | __ B(ne, call_runtime); |
| 486 | __ Ldr(string, FieldMemOperand(string, ExternalString::kResourceDataOffset)); |
| 487 | |
| 488 | Label one_byte, done; |
| 489 | __ Bind(&check_encoding); |
| 490 | STATIC_ASSERT(kTwoByteStringTag == 0); |
| 491 | __ TestAndBranchIfAnySet(result, kStringEncodingMask, &one_byte); |
| 492 | // Two-byte string. |
| 493 | __ Ldrh(result, MemOperand(string, index, SXTW, 1)); |
| 494 | __ B(&done); |
| 495 | __ Bind(&one_byte); |
| 496 | // One-byte string. |
| 497 | __ Ldrb(result, MemOperand(string, index, SXTW)); |
| 498 | __ Bind(&done); |
| 499 | } |
| 500 | |
| 501 | |
| 502 | static MemOperand ExpConstant(Register base, int index) { |
| 503 | return MemOperand(base, index * kDoubleSize); |
| 504 | } |
| 505 | |
| 506 | |
| 507 | void MathExpGenerator::EmitMathExp(MacroAssembler* masm, |
| 508 | DoubleRegister input, |
| 509 | DoubleRegister result, |
| 510 | DoubleRegister double_temp1, |
| 511 | DoubleRegister double_temp2, |
| 512 | Register temp1, |
| 513 | Register temp2, |
| 514 | Register temp3) { |
| 515 | // TODO(jbramley): There are several instances where fnmsub could be used |
| 516 | // instead of fmul and fsub. Doing this changes the result, but since this is |
| 517 | // an estimation anyway, does it matter? |
| 518 | |
| 519 | DCHECK(!AreAliased(input, result, |
| 520 | double_temp1, double_temp2, |
| 521 | temp1, temp2, temp3)); |
| 522 | DCHECK(ExternalReference::math_exp_constants(0).address() != NULL); |
| 523 | DCHECK(!masm->serializer_enabled()); // External references not serializable. |
| 524 | |
| 525 | Label done; |
| 526 | DoubleRegister double_temp3 = result; |
| 527 | Register constants = temp3; |
| 528 | |
| 529 | // The algorithm used relies on some magic constants which are initialized in |
| 530 | // ExternalReference::InitializeMathExpData(). |
| 531 | |
| 532 | // Load the address of the start of the array. |
| 533 | __ Mov(constants, ExternalReference::math_exp_constants(0)); |
| 534 | |
| 535 | // We have to do a four-way split here: |
| 536 | // - If input <= about -708.4, the output always rounds to zero. |
| 537 | // - If input >= about 709.8, the output always rounds to +infinity. |
| 538 | // - If the input is NaN, the output is NaN. |
| 539 | // - Otherwise, the result needs to be calculated. |
| 540 | Label result_is_finite_non_zero; |
| 541 | // Assert that we can load offset 0 (the small input threshold) and offset 1 |
| 542 | // (the large input threshold) with a single ldp. |
| 543 | DCHECK(kDRegSize == (ExpConstant(constants, 1).offset() - |
| 544 | ExpConstant(constants, 0).offset())); |
| 545 | __ Ldp(double_temp1, double_temp2, ExpConstant(constants, 0)); |
| 546 | |
| 547 | __ Fcmp(input, double_temp1); |
| 548 | __ Fccmp(input, double_temp2, NoFlag, hi); |
| 549 | // At this point, the condition flags can be in one of five states: |
| 550 | // NZCV |
| 551 | // 1000 -708.4 < input < 709.8 result = exp(input) |
| 552 | // 0110 input == 709.8 result = +infinity |
| 553 | // 0010 input > 709.8 result = +infinity |
| 554 | // 0011 input is NaN result = input |
| 555 | // 0000 input <= -708.4 result = +0.0 |
| 556 | |
| 557 | // Continue the common case first. 'mi' tests N == 1. |
| 558 | __ B(&result_is_finite_non_zero, mi); |
| 559 | |
| 560 | // TODO(jbramley): Consider adding a +infinity register for ARM64. |
| 561 | __ Ldr(double_temp2, ExpConstant(constants, 2)); // Synthesize +infinity. |
| 562 | |
| 563 | // Select between +0.0 and +infinity. 'lo' tests C == 0. |
| 564 | __ Fcsel(result, fp_zero, double_temp2, lo); |
| 565 | // Select between {+0.0 or +infinity} and input. 'vc' tests V == 0. |
| 566 | __ Fcsel(result, result, input, vc); |
| 567 | __ B(&done); |
| 568 | |
| 569 | // The rest is magic, as described in InitializeMathExpData(). |
| 570 | __ Bind(&result_is_finite_non_zero); |
| 571 | |
| 572 | // Assert that we can load offset 3 and offset 4 with a single ldp. |
| 573 | DCHECK(kDRegSize == (ExpConstant(constants, 4).offset() - |
| 574 | ExpConstant(constants, 3).offset())); |
| 575 | __ Ldp(double_temp1, double_temp3, ExpConstant(constants, 3)); |
| 576 | __ Fmadd(double_temp1, double_temp1, input, double_temp3); |
| 577 | __ Fmov(temp2.W(), double_temp1.S()); |
| 578 | __ Fsub(double_temp1, double_temp1, double_temp3); |
| 579 | |
| 580 | // Assert that we can load offset 5 and offset 6 with a single ldp. |
| 581 | DCHECK(kDRegSize == (ExpConstant(constants, 6).offset() - |
| 582 | ExpConstant(constants, 5).offset())); |
| 583 | __ Ldp(double_temp2, double_temp3, ExpConstant(constants, 5)); |
| 584 | // TODO(jbramley): Consider using Fnmsub here. |
| 585 | __ Fmul(double_temp1, double_temp1, double_temp2); |
| 586 | __ Fsub(double_temp1, double_temp1, input); |
| 587 | |
| 588 | __ Fmul(double_temp2, double_temp1, double_temp1); |
| 589 | __ Fsub(double_temp3, double_temp3, double_temp1); |
| 590 | __ Fmul(double_temp3, double_temp3, double_temp2); |
| 591 | |
| 592 | __ Mov(temp1.W(), Operand(temp2.W(), LSR, 11)); |
| 593 | |
| 594 | __ Ldr(double_temp2, ExpConstant(constants, 7)); |
| 595 | // TODO(jbramley): Consider using Fnmsub here. |
| 596 | __ Fmul(double_temp3, double_temp3, double_temp2); |
| 597 | __ Fsub(double_temp3, double_temp3, double_temp1); |
| 598 | |
| 599 | // The 8th constant is 1.0, so use an immediate move rather than a load. |
| 600 | // We can't generate a runtime assertion here as we would need to call Abort |
| 601 | // in the runtime and we don't have an Isolate when we generate this code. |
| 602 | __ Fmov(double_temp2, 1.0); |
| 603 | __ Fadd(double_temp3, double_temp3, double_temp2); |
| 604 | |
| 605 | __ And(temp2, temp2, 0x7ff); |
| 606 | __ Add(temp1, temp1, 0x3ff); |
| 607 | |
| 608 | // Do the final table lookup. |
| 609 | __ Mov(temp3, ExternalReference::math_exp_log_table()); |
| 610 | |
| 611 | __ Add(temp3, temp3, Operand(temp2, LSL, kDRegSizeLog2)); |
| 612 | __ Ldp(temp2.W(), temp3.W(), MemOperand(temp3)); |
| 613 | __ Orr(temp1.W(), temp3.W(), Operand(temp1.W(), LSL, 20)); |
| 614 | __ Bfi(temp2, temp1, 32, 32); |
| 615 | __ Fmov(double_temp1, temp2); |
| 616 | |
| 617 | __ Fmul(result, double_temp3, double_temp1); |
| 618 | |
| 619 | __ Bind(&done); |
| 620 | } |
| 621 | |
| 622 | #undef __ |
| 623 | |
| 624 | } } // namespace v8::internal |
| 625 | |
| 626 | #endif // V8_TARGET_ARCH_ARM64 |