ARM64: remove stack pushes without frame in RegExpExecStub.

src/arm64/code-stubs-arm64.cc

 // Copyright 2013 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.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 2287 matching lines @@
   //   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;
 
-  // TODO(jbramley): Is it necessary to preserve these? I don't think ARM does.
-  CPURegList used_callee_saved_registers(subject,
-                                         regexp_data,
-                                         last_match_info_elements,
-                                         code_object);
-  __ PushCPURegList(used_callee_saved_registers);
+  // Stack frame.
+  //  jssp[00]: last_match_info (JSArray)
+  //  jssp[08]: previous index
+  //  jssp[16]: subject string
+  //  jssp[24]: JSRegExp object
 
-  // Stack frame.
-  //  jssp[0] : x19
-  //  jssp[8] : x20
-  //  jssp[16]: x21
-  //  jssp[24]: x22
-  //  jssp[32]: last_match_info (JSArray)
-  //  jssp[40]: previous index
-  //  jssp[48]: subject string
-  //  jssp[56]: JSRegExp object
-
-  const int kLastMatchInfoOffset = 4 * kPointerSize;
-  const int kPreviousIndexOffset = 5 * kPointerSize;
-  const int kSubjectOffset = 6 * kPointerSize;
-  const int kJSRegExpOffset = 7 * kPointerSize;
+  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);
 
@@ skipping 346 matching lines @@
   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.
   __ Peek(x0, kLastMatchInfoOffset);
-  __ PopCPURegList(used_callee_saved_registers);
   // 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, 4, 1);
 
   __ Bind(&failure);
   __ Mov(x0, Operand(isolate()->factory()->null_value()));
-  __ PopCPURegList(used_callee_saved_registers);
   // Drop the 4 arguments of the stub from the stack.
   __ Drop(4);
   __ Ret();
 
   __ Bind(&runtime);
-  __ PopCPURegList(used_callee_saved_registers);
   __ TailCallRuntime(Runtime::kRegExpExec, 4, 1);
 
   // Deferred code for string handling.
   // (6) Not a long external string?  If yes, go to (8).
   __ Bind(&not_seq_nor_cons);
   // Compare flags are still set.
   __ B(ne, &not_long_external);  // Go to (8).
 
   // (7) External string. Make it, offset-wise, look like a sequential string.
   __ Bind(&external_string);
@@ skipping 3096 matching lines @@
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM64