[regexp] Port RegExpExecStub to CSA (mostly)

src/arm64/code-stubs-arm64.cc

Index: src/arm64/code-stubs-arm64.cc
diff --git a/src/arm64/code-stubs-arm64.cc b/src/arm64/code-stubs-arm64.cc
index 000a8c30619a6a5d97cb47674fe265b9dce03e83..ec00581566f28e75819e9c2df46fa70dd5342fde 100644
--- a/src/arm64/code-stubs-arm64.cc
+++ b/src/arm64/code-stubs-arm64.cc
@@ -1269,223 +1269,9 @@ void JSEntryStub::Generate(MacroAssembler* masm) {
 
 void RegExpExecStub::Generate(MacroAssembler* masm) {
 #ifdef V8_INTERPRETED_REGEXP
-  __ TailCallRuntime(Runtime::kRegExpExec);
+  // This case is handled prior to the RegExpExecStub call.
+  __ Abort(kUnexpectedRegExpExecCall);
 #else  // V8_INTERPRETED_REGEXP
-
-  // Stack frame on entry.
-  //  jssp[0]: last_match_info (expected JSArray)
-  //  jssp[8]: previous index
-  //  jssp[16]: subject string
-  //  jssp[24]: JSRegExp object
-  Label runtime;
-
-  // Use of registers for this function.
-
-  // Variable registers:
-  //   x10-x13                                  used as scratch registers
-  //   w0       string_type                     type of subject string
-  //   x2       jsstring_length                 subject string length
-  //   x3       jsregexp_object                 JSRegExp object
-  //   w4       string_encoding                 Latin1 or UC16
-  //   w5       sliced_string_offset            if the string is a SlicedString
-  //                                            offset to the underlying string
-  //   w6       string_representation           groups attributes of the string:
-  //                                              - is a string
-  //                                              - type of the string
-  //                                              - is a short external string
-  Register string_type = w0;
-  Register jsstring_length = x2;
-  Register jsregexp_object = x3;
-  Register string_encoding = w4;
-  Register sliced_string_offset = w5;
-  Register string_representation = w6;
-
-  // These are in callee save registers and will be preserved by the call
-  // to the native RegExp code, as this code is called using the normal
-  // C calling convention. When calling directly from generated code the
-  // native RegExp code will not do a GC and therefore the content of
-  // these registers are safe to use after the call.
-
-  //   x19       subject                        subject string
-  //   x20       regexp_data                    RegExp data (FixedArray)
-  //   x21       last_match_info_elements       info relative to the last match
-  //                                            (FixedArray)
-  //   x22       code_object                    generated regexp code
-  Register subject = x19;
-  Register regexp_data = x20;
-  Register last_match_info_elements = x21;
-  Register code_object = x22;
-
-  // Stack frame.
-  //  jssp[00]: last_match_info (JSArray)
-  //  jssp[08]: previous index
-  //  jssp[16]: subject string
-  //  jssp[24]: JSRegExp object
-
-  const int kLastMatchInfoOffset = 0 * kPointerSize;
-  const int kPreviousIndexOffset = 1 * kPointerSize;
-  const int kSubjectOffset = 2 * kPointerSize;
-  const int kJSRegExpOffset = 3 * kPointerSize;
-
-  // Ensure that a RegExp stack is allocated.
-  ExternalReference address_of_regexp_stack_memory_address =
-      ExternalReference::address_of_regexp_stack_memory_address(isolate());
-  ExternalReference address_of_regexp_stack_memory_size =
-      ExternalReference::address_of_regexp_stack_memory_size(isolate());
-  __ Mov(x10, address_of_regexp_stack_memory_size);
-  __ Ldr(x10, MemOperand(x10));
-  __ Cbz(x10, &runtime);
-
-  // Check that the first argument is a JSRegExp object.
-  DCHECK(jssp.Is(__ StackPointer()));
-  __ Peek(jsregexp_object, kJSRegExpOffset);
-  __ JumpIfSmi(jsregexp_object, &runtime);
-  __ JumpIfNotObjectType(jsregexp_object, x10, x10, JS_REGEXP_TYPE, &runtime);
-
-  // Check that the RegExp has been compiled (data contains a fixed array).
-  __ Ldr(regexp_data, FieldMemOperand(jsregexp_object, JSRegExp::kDataOffset));
-  if (FLAG_debug_code) {
-    STATIC_ASSERT(kSmiTag == 0);
-    __ Tst(regexp_data, kSmiTagMask);
-    __ Check(ne, kUnexpectedTypeForRegExpDataFixedArrayExpected);
-    __ CompareObjectType(regexp_data, x10, x10, FIXED_ARRAY_TYPE);
-    __ Check(eq, kUnexpectedTypeForRegExpDataFixedArrayExpected);
-  }
-
-  // Check the type of the RegExp. Only continue if type is JSRegExp::IRREGEXP.
-  __ Ldr(x10, FieldMemOperand(regexp_data, JSRegExp::kDataTagOffset));
-  __ Cmp(x10, Smi::FromInt(JSRegExp::IRREGEXP));
-  __ B(ne, &runtime);
-
-  // Check that the number of captures fit in the static offsets vector buffer.
-  // We have always at least one capture for the whole match, plus additional
-  // ones due to capturing parentheses. A capture takes 2 registers.
-  // The number of capture registers then is (number_of_captures + 1) * 2.
-  __ Ldrsw(x10,
-           UntagSmiFieldMemOperand(regexp_data,
-                                   JSRegExp::kIrregexpCaptureCountOffset));
-  // Check (number_of_captures + 1) * 2 <= offsets vector size
-  //             number_of_captures * 2 <= offsets vector size - 2
-  STATIC_ASSERT(Isolate::kJSRegexpStaticOffsetsVectorSize >= 2);
-  __ Add(x10, x10, x10);
-  __ Cmp(x10, Isolate::kJSRegexpStaticOffsetsVectorSize - 2);
-  __ B(hi, &runtime);
-
-  // Initialize offset for possibly sliced string.
-  __ Mov(sliced_string_offset, 0);
-
-  DCHECK(jssp.Is(__ StackPointer()));
-  __ Peek(subject, kSubjectOffset);
-  __ JumpIfSmi(subject, &runtime);
-
-  __ Ldr(jsstring_length, FieldMemOperand(subject, String::kLengthOffset));
-
-  // Handle subject string according to its encoding and representation:
-  // (1) Sequential string?  If yes, go to (4).
-  // (2) Sequential or cons?  If not, go to (5).
-  // (3) Cons string.  If the string is flat, replace subject with first string
-  //     and go to (1). Otherwise bail out to runtime.
-  // (4) Sequential string.  Load regexp code according to encoding.
-  // (E) Carry on.
-  /// [...]
-
-  // Deferred code at the end of the stub:
-  // (5) Long external string?  If not, go to (7).
-  // (6) External string.  Make it, offset-wise, look like a sequential string.
-  //     Go to (4).
-  // (7) Short external string or not a string?  If yes, bail out to runtime.
-  // (8) Sliced or thin string.  Replace subject with parent.  Go to (1).
-
-  Label check_underlying;   // (1)
-  Label seq_string;         // (4)
-  Label not_seq_nor_cons;   // (5)
-  Label external_string;    // (6)
-  Label not_long_external;  // (7)
-
-  __ Bind(&check_underlying);
-  __ Ldr(x10, FieldMemOperand(subject, HeapObject::kMapOffset));
-  __ Ldrb(string_type, FieldMemOperand(x10, Map::kInstanceTypeOffset));
-
-  // (1) Sequential string?  If yes, go to (4).
-  __ And(string_representation,
-         string_type,
-         kIsNotStringMask |
-             kStringRepresentationMask |
-             kShortExternalStringMask);
-  // We depend on the fact that Strings of type
-  // SeqString and not ShortExternalString are defined
-  // by the following pattern:
-  //   string_type: 0XX0 XX00
-  //                ^  ^   ^^
-  //                |  |   ||
-  //                |  |   is a SeqString
-  //                |  is not a short external String
-  //                is a String
-  STATIC_ASSERT((kStringTag | kSeqStringTag) == 0);
-  STATIC_ASSERT(kShortExternalStringTag != 0);
-  __ Cbz(string_representation, &seq_string);  // Go to (4).
-
-  // (2) Sequential or cons?  If not, go to (5).
-  STATIC_ASSERT(kConsStringTag < kExternalStringTag);
-  STATIC_ASSERT(kSlicedStringTag > kExternalStringTag);
-  STATIC_ASSERT(kThinStringTag > kExternalStringTag);
-  STATIC_ASSERT(kIsNotStringMask > kExternalStringTag);
-  STATIC_ASSERT(kShortExternalStringTag > kExternalStringTag);
-  __ Cmp(string_representation, kExternalStringTag);
-  __ B(ge, &not_seq_nor_cons);  // Go to (5).
-
-  // (3) Cons string.  Check that it's flat.
-  __ Ldr(x10, FieldMemOperand(subject, ConsString::kSecondOffset));
-  __ JumpIfNotRoot(x10, Heap::kempty_stringRootIndex, &runtime);
-  // Replace subject with first string.
-  __ Ldr(subject, FieldMemOperand(subject, ConsString::kFirstOffset));
-  __ B(&check_underlying);
-
-  // (4) Sequential string.  Load regexp code according to encoding.
-  __ Bind(&seq_string);
-
-  // Check that the third argument is a positive smi less than the subject
-  // string length. A negative value will be greater (unsigned comparison).
-  DCHECK(jssp.Is(__ StackPointer()));
-  __ Peek(x10, kPreviousIndexOffset);
-  __ JumpIfNotSmi(x10, &runtime);
-  __ Cmp(jsstring_length, x10);
-  __ B(ls, &runtime);
-
-  // Argument 2 (x1): We need to load argument 2 (the previous index) into x1
-  // before entering the exit frame.
-  __ SmiUntag(x1, x10);
-
-  // The fourth bit determines the string encoding in string_type.
-  STATIC_ASSERT(kOneByteStringTag == 0x08);
-  STATIC_ASSERT(kTwoByteStringTag == 0x00);
-  STATIC_ASSERT(kStringEncodingMask == 0x08);
-
-  // Find the code object based on the assumptions above.
-  // kDataOneByteCodeOffset and kDataUC16CodeOffset are adjacent, adds an offset
-  // of kPointerSize to reach the latter.
-  STATIC_ASSERT(JSRegExp::kDataOneByteCodeOffset + kPointerSize ==
-                JSRegExp::kDataUC16CodeOffset);
-  __ Mov(x10, kPointerSize);
-  // We will need the encoding later: Latin1 = 0x08
-  //                                  UC16   = 0x00
-  __ Ands(string_encoding, string_type, kStringEncodingMask);
-  __ CzeroX(x10, ne);
-  __ Add(x10, regexp_data, x10);
-  __ Ldr(code_object, FieldMemOperand(x10, JSRegExp::kDataOneByteCodeOffset));
-
-  // (E) Carry on.  String handling is done.
-
-  // Check that the irregexp code has been generated for the actual string
-  // encoding. If it has, the field contains a code object otherwise it contains
-  // a smi (code flushing support).
-  __ JumpIfSmi(code_object, &runtime);
-
-  // All checks done. Now push arguments for native regexp code.
-  __ IncrementCounter(isolate()->counters()->regexp_entry_native(), 1,
-                      x10,
-                      x11);
-
   // Isolates: note we add an additional parameter here (isolate pointer).
   __ EnterExitFrame(false, x10, 1);
   DCHECK(csp.Is(__ StackPointer()));
@@ -1501,50 +1287,16 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
   __ Mov(x10, ExternalReference::isolate_address(isolate()));
   __ Poke(x10, kPointerSize);
 
-  Register length = w11;
-  Register previous_index_in_bytes = w12;
-  Register start = x13;
-
-  // Load start of the subject string.
-  __ Add(start, subject, SeqString::kHeaderSize - kHeapObjectTag);
-  // Load the length from the original subject string from the previous stack
-  // frame. Therefore we have to use fp, which points exactly to two pointer
-  // sizes below the previous sp. (Because creating a new stack frame pushes
-  // the previous fp onto the stack and decrements sp by 2 * kPointerSize.)
-  __ Ldr(subject, MemOperand(fp, kSubjectOffset + 2 * kPointerSize));
-  __ Ldr(length, UntagSmiFieldMemOperand(subject, String::kLengthOffset));
-
-  // Handle UC16 encoding, two bytes make one character.
-  //   string_encoding: if Latin1: 0x08
-  //                    if UC16:   0x00
-  STATIC_ASSERT(kStringEncodingMask == 0x08);
-  __ Ubfx(string_encoding, string_encoding, 3, 1);
-  __ Eor(string_encoding, string_encoding, 1);
-  //   string_encoding: if Latin1: 0
-  //                    if UC16:   1
-
-  // Convert string positions from characters to bytes.
-  // Previous index is in x1.
-  __ Lsl(previous_index_in_bytes, w1, string_encoding);
-  __ Lsl(length, length, string_encoding);
-  __ Lsl(sliced_string_offset, sliced_string_offset, string_encoding);
-
   // Argument 1 (x0): Subject string.
-  __ Mov(x0, subject);
+  CHECK(x0.is(RegExpExecDescriptor::StringRegister()));
 
   // Argument 2 (x1): Previous index, already there.
+  CHECK(x1.is(RegExpExecDescriptor::LastIndexRegister()));
 
-  // Argument 3 (x2): Get the start of input.
-  // Start of input = start of string + previous index + substring offset
-  //                                                     (0 if the string
-  //                                                      is not sliced).
-  __ Add(w10, previous_index_in_bytes, sliced_string_offset);
-  __ Add(x2, start, Operand(w10, UXTW));
-
-  // Argument 4 (x3):
-  // End of input = start of input + (length of input - previous index)
-  __ Sub(w10, length, previous_index_in_bytes);
-  __ Add(x3, x2, Operand(w10, UXTW));
+  // Argument 3 (x2): Input start.
+  // Argument 4 (x3): Input end.
+  CHECK(x2.is(RegExpExecDescriptor::StringStartRegister()));
+  CHECK(x3.is(RegExpExecDescriptor::StringEndRegister()));
 
   // Argument 5 (x4): static offsets vector buffer.
   __ Mov(x4, ExternalReference::address_of_static_offsets_vector(isolate()));
@@ -1555,6 +1307,10 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
   __ Mov(x5, 0);
 
   // Argument 7 (x6): Start (high end) of backtracking stack memory area.
+  ExternalReference address_of_regexp_stack_memory_address =
+      ExternalReference::address_of_regexp_stack_memory_address(isolate());
+  ExternalReference address_of_regexp_stack_memory_size =
+      ExternalReference::address_of_regexp_stack_memory_size(isolate());
   __ Mov(x10, address_of_regexp_stack_memory_address);
   __ Ldr(x10, MemOperand(x10));
   __ Mov(x11, address_of_regexp_stack_memory_size);
@@ -1565,184 +1321,16 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
   __ Mov(x7, 1);
 
   // Locate the code entry and call it.
+  Register code_object = RegExpExecDescriptor::CodeRegister();
   __ Add(code_object, code_object, Code::kHeaderSize - kHeapObjectTag);
   DirectCEntryStub stub(isolate());
   stub.GenerateCall(masm, code_object);
 
   __ LeaveExitFrame(false, x10, true);
 
-  // The generated regexp code returns an int32 in w0.
-  Label failure, exception;
-  __ CompareAndBranch(w0, NativeRegExpMacroAssembler::FAILURE, eq, &failure);
-  __ CompareAndBranch(w0,
-                      NativeRegExpMacroAssembler::EXCEPTION,
-                      eq,
-                      &exception);
-  __ CompareAndBranch(w0, NativeRegExpMacroAssembler::RETRY, eq, &runtime);
-
-  // Success: process the result from the native regexp code.
-  Register number_of_capture_registers = x12;
-
-  // Calculate number of capture registers (number_of_captures + 1) * 2
-  // and store it in the last match info.
-  __ Ldrsw(x10,
-           UntagSmiFieldMemOperand(regexp_data,
-                                   JSRegExp::kIrregexpCaptureCountOffset));
-  __ Add(x10, x10, x10);
-  __ Add(number_of_capture_registers, x10, 2);
-
-  // Check that the last match info is a FixedArray.
-  DCHECK(jssp.Is(__ StackPointer()));
-  __ Peek(last_match_info_elements, kLastMatchInfoOffset);
-  __ JumpIfSmi(last_match_info_elements, &runtime);
-
-  // Check that the object has fast elements.
-  __ Ldr(x10,
-         FieldMemOperand(last_match_info_elements, HeapObject::kMapOffset));
-  __ JumpIfNotRoot(x10, Heap::kFixedArrayMapRootIndex, &runtime);
-
-  // Check that the last match info has space for the capture registers and the
-  // additional information (overhead).
-  //     (number_of_captures + 1) * 2 + overhead <= last match info size
-  //     (number_of_captures * 2) + 2 + overhead <= last match info size
-  //      number_of_capture_registers + overhead <= last match info size
-  __ Ldrsw(x10,
-           UntagSmiFieldMemOperand(last_match_info_elements,
-                                   FixedArray::kLengthOffset));
-  __ Add(x11, number_of_capture_registers, RegExpMatchInfo::kLastMatchOverhead);
-  __ Cmp(x11, x10);
-  __ B(gt, &runtime);
-
-  // Store the capture count.
-  __ SmiTag(x10, number_of_capture_registers);
-  __ Str(x10, FieldMemOperand(last_match_info_elements,
-                              RegExpMatchInfo::kNumberOfCapturesOffset));
-  // Store last subject and last input.
-  __ Str(subject, FieldMemOperand(last_match_info_elements,
-                                  RegExpMatchInfo::kLastSubjectOffset));
-  // Use x10 as the subject string in order to only need
-  // one RecordWriteStub.
-  __ Mov(x10, subject);
-  __ RecordWriteField(last_match_info_elements,
-                      RegExpMatchInfo::kLastSubjectOffset, x10, x11,
-                      kLRHasNotBeenSaved, kDontSaveFPRegs);
-  __ Str(subject, FieldMemOperand(last_match_info_elements,
-                                  RegExpMatchInfo::kLastInputOffset));
-  __ Mov(x10, subject);
-  __ RecordWriteField(last_match_info_elements,
-                      RegExpMatchInfo::kLastInputOffset, x10, x11,
-                      kLRHasNotBeenSaved, kDontSaveFPRegs);
-
-  Register last_match_offsets = x13;
-  Register offsets_vector_index = x14;
-  Register current_offset = x15;
-
-  // Get the static offsets vector filled by the native regexp code
-  // and fill the last match info.
-  ExternalReference address_of_static_offsets_vector =
-      ExternalReference::address_of_static_offsets_vector(isolate());
-  __ Mov(offsets_vector_index, address_of_static_offsets_vector);
-
-  Label next_capture, done;
-  // Capture register counter starts from number of capture registers and
-  // iterates down to zero (inclusive).
-  __ Add(last_match_offsets, last_match_info_elements,
-         RegExpMatchInfo::kFirstCaptureOffset - kHeapObjectTag);
-  __ Bind(&next_capture);
-  __ Subs(number_of_capture_registers, number_of_capture_registers, 2);
-  __ B(mi, &done);
-  // Read two 32 bit values from the static offsets vector buffer into
-  // an X register
-  __ Ldr(current_offset,
-         MemOperand(offsets_vector_index, kWRegSize * 2, PostIndex));
-  // Store the smi values in the last match info.
-  __ SmiTag(x10, current_offset);
-  // Clearing the 32 bottom bits gives us a Smi.
-  STATIC_ASSERT(kSmiTag == 0);
-  __ Bic(x11, current_offset, kSmiShiftMask);
-  __ Stp(x10,
-         x11,
-         MemOperand(last_match_offsets, kXRegSize * 2, PostIndex));
-  __ B(&next_capture);
-  __ Bind(&done);
-
-  // Return last match info.
-  __ Mov(x0, last_match_info_elements);
-  // Drop the 4 arguments of the stub from the stack.
-  __ Drop(4);
-  __ Ret();
-
-  __ Bind(&exception);
-  Register exception_value = x0;
-  // A stack overflow (on the backtrack stack) may have occured
-  // in the RegExp code but no exception has been created yet.
-  // If there is no pending exception, handle that in the runtime system.
-  __ Mov(x10, Operand(isolate()->factory()->the_hole_value()));
-  __ Mov(x11,
-         Operand(ExternalReference(Isolate::kPendingExceptionAddress,
-                                   isolate())));
-  __ Ldr(exception_value, MemOperand(x11));
-  __ Cmp(x10, exception_value);
-  __ B(eq, &runtime);
-
-  // For exception, throw the exception again.
-  __ TailCallRuntime(Runtime::kRegExpExecReThrow);
-
-  __ Bind(&failure);
-  __ Mov(x0, Operand(isolate()->factory()->null_value()));
-  // Drop the 4 arguments of the stub from the stack.
-  __ Drop(4);
+  // Return the smi-tagged result.
+  __ SmiTag(x0);
   __ Ret();
-
-  __ Bind(&runtime);
-  __ TailCallRuntime(Runtime::kRegExpExec);
-
-  // Deferred code for string handling.
-  // (5) Long external string?  If not, go to (7).
-  __ Bind(&not_seq_nor_cons);
-  // Compare flags are still set.
-  __ B(ne, &not_long_external);  // Go to (7).
-
-  // (6) External string. Make it, offset-wise, look like a sequential string.
-  __ Bind(&external_string);
-  if (masm->emit_debug_code()) {
-    // Assert that we do not have a cons or slice (indirect strings) here.
-    // Sequential strings have already been ruled out.
-    __ Ldr(x10, FieldMemOperand(subject, HeapObject::kMapOffset));
-    __ Ldrb(x10, FieldMemOperand(x10, Map::kInstanceTypeOffset));
-    __ Tst(x10, kIsIndirectStringMask);
-    __ Check(eq, kExternalStringExpectedButNotFound);
-    __ And(x10, x10, kStringRepresentationMask);
-    __ Cmp(x10, 0);
-    __ Check(ne, kExternalStringExpectedButNotFound);
-  }
-  __ Ldr(subject,
-         FieldMemOperand(subject, ExternalString::kResourceDataOffset));
-  // Move the pointer so that offset-wise, it looks like a sequential string.
-  STATIC_ASSERT(SeqTwoByteString::kHeaderSize == SeqOneByteString::kHeaderSize);
-  __ Sub(subject, subject, SeqTwoByteString::kHeaderSize - kHeapObjectTag);
-  __ B(&seq_string);  // Go to (4).
-
-  // (7) If this is a short external string or not a string, bail out to
-  // runtime.
-  __ Bind(&not_long_external);
-  STATIC_ASSERT(kShortExternalStringTag != 0);
-  __ TestAndBranchIfAnySet(string_representation,
-                           kShortExternalStringMask | kIsNotStringMask,
-                           &runtime);
-
-  // (8) Sliced or thin string. Replace subject with parent.
-  Label thin_string;
-  __ Cmp(string_representation, kThinStringTag);
-  __ B(eq, &thin_string);
-  __ Ldr(sliced_string_offset,
-         UntagSmiFieldMemOperand(subject, SlicedString::kOffsetOffset));
-  __ Ldr(subject, FieldMemOperand(subject, SlicedString::kParentOffset));
-  __ B(&check_underlying);  // Go to (1).
-
-  __ bind(&thin_string);
-  __ Ldr(subject, FieldMemOperand(subject, ThinString::kActualOffset));
-  __ B(&check_underlying);  // Go to (1).
 #endif
 }