[regexp] Remove remainder of native RegExpExecStub

src/regexp/mips64/regexp-macro-assembler-mips64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_MIPS64
 
 #include "src/regexp/mips64/regexp-macro-assembler-mips64.h"
 
 #include "src/code-stubs.h"
 #include "src/log.h"
 #include "src/macro-assembler.h"
 #include "src/regexp/regexp-macro-assembler.h"
 #include "src/regexp/regexp-stack.h"
 #include "src/unicode.h"
 
 namespace v8 {
 namespace internal {
 
 #ifndef V8_INTERPRETED_REGEXP
-/*
+
+/* clang-format off
+ *
  * This assembler uses the following register assignment convention
  * - t3 : Temporarily stores the index of capture start after a matching pass
  *        for a global regexp.
  * - a5 : Pointer to current code object (Code*) including heap object tag.
  * - a6 : Current position in input, as negative offset from end of string.
  *        Please notice that this is the byte offset, not the character offset!
  * - a7 : Currently loaded character. Must be loaded using
  *        LoadCurrentCharacter before using any of the dispatch methods.
  * - t0 : Points to tip of backtrack stack
  * - t1 : Unused.
@@ skipping 36 matching lines @@
  *    string, otherwise 0)
  *  - fp[-32] register 0         (Only positions must be stored in the first
  *  -         register 1          num_saved_registers_ registers)
  *  -         ...
  *  -         register num_registers-1
  *  --- sp ---
  *
  *
  * The N64 stack will have the following structure:
  *
- *  - fp[88]  Isolate* isolate   (address of the current isolate)               kIsolate
- *  - fp[80]  secondary link/return address used by exit frame on native call.  kSecondaryReturnAddress
-                                                                                kStackFrameHeader
+ *  - fp[80]  Isolate* isolate   (address of the current isolate)               kIsolate

[georgia.kouveli, 2017/04/19 15:57:26]

The corresponding comments for arm and arm64 are also out of date now (they also
mention the secondary return address in the frame layout description, in the
signature of "match" and also mention exit frames).

[jgruber, 2017/04/20 09:37:47]

Thanks, good point. I made a pass through the comments for all architectures and
updated all of them (+ some drive-by fixes).

+ *                                                                              kStackFrameHeader
  *  --- sp when called ---
  *  - fp[72]  ra                 Return from RegExp code (ra).                  kReturnAddress
  *  - fp[64]  s9, old-fp         Old fp, callee saved(s9).
  *  - fp[0..63]  s0..s7          Callee-saved registers s0..s7.
  *  --- frame pointer ----
  *  - fp[-8]  direct_call        (1 = direct call from JS, 0 = from runtime)    kDirectCall
  *  - fp[-16] stack_base         (Top of backtracking stack).                   kStackHighEnd
  *  - fp[-24] capture array size (may fit multiple sets of matches)             kNumOutputRegisters
  *  - fp[-32] int* capture_array (int[num_saved_registers_], for output).       kRegisterOutput
  *  - fp[-40] end of input       (address of end of string).                    kInputEnd
@@ skipping 19 matching lines @@
  * code and the remaining arguments are passed in registers, e.g. by calling the
  * code entry as cast to a function with the signature:
  * int (*match)(String* input_string,
  *              int start_index,
  *              Address start,
  *              Address end,
  *              Address secondary_return_address,  // Only used by native call.
  *              int* capture_output_array,
  *              byte* stack_area_base,
  *              bool direct_call = false,
  *              void* return_address,

[georgia.kouveli, 2017/04/19 15:57:26]

return_address is removed now?

[jgruber, 2017/04/20 09:37:47]

Removed.

  *              Isolate* isolate);
  * The call is performed by NativeRegExpMacroAssembler::Execute()
  * (in regexp-macro-assembler.cc) via the CALL_GENERATED_REGEXP_CODE macro
  * in mips/simulator-mips.h.
  * When calling as a non-direct call (i.e., from C++ code), the return address
  * area is overwritten with the ra register by the RegExp code. When doing a
  * direct call from generated code, the return address is placed there by

[georgia.kouveli, 2017/04/19 15:57:26]

Another mention of the return address and exit frames.

[jgruber, 2017/04/20 09:37:47]

Removed this entire paragraph.

  * the calling code, as in a normal exit frame.
+ *
+ * clang-format on
  */
 
 #define __ ACCESS_MASM(masm_)
 
 RegExpMacroAssemblerMIPS::RegExpMacroAssemblerMIPS(Isolate* isolate, Zone* zone,
                                                    Mode mode,
                                                    int registers_to_save)
     : NativeRegExpMacroAssembler(isolate, zone),
       masm_(new MacroAssembler(isolate, NULL, kRegExpCodeSize,
                                CodeObjectRequired::kYes)),
@@ skipping 1190 matching lines @@
 }
 
 #undef __
 
 #endif  // V8_INTERPRETED_REGEXP
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS64