Disentangle assembler from isolate.

src/x64/assembler-x64.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 467 matching lines @@
   // for a detailed comment on the layout (globals.h).
   //
   // If the provided buffer is NULL, the assembler allocates and grows its own
   // buffer, and buffer_size determines the initial buffer size. The buffer is
   // owned by the assembler and deallocated upon destruction of the assembler.
   //
   // If the provided buffer is not NULL, the assembler uses the provided buffer
   // for code generation and assumes its size to be buffer_size. If the buffer
   // is too small, a fatal error occurs. No deallocation of the buffer is done
   // upon destruction of the assembler.
-  Assembler(Isolate* isolate, void* buffer, int buffer_size);
+  Assembler(Isolate* isolate, void* buffer, int buffer_size)
+      : Assembler(IsolateData(isolate), buffer, buffer_size) {}
+  Assembler(IsolateData isolate_data, void* buffer, int buffer_size);
   virtual ~Assembler() { }
 
   // GetCode emits any pending (non-emitted) code and fills the descriptor
   // desc. GetCode() is idempotent; it returns the same result if no other
   // Assembler functions are invoked in between GetCode() calls.
   void GetCode(CodeDesc* desc);
 
   // Read/Modify the code target in the relative branch/call instruction at pc.
   // On the x64 architecture, we use relative jumps with a 32-bit displacement
   // to jump to other Code objects in the Code space in the heap.
   // Jumps to C functions are done indirectly through a 64-bit register holding
   // the absolute address of the target.
   // These functions convert between absolute Addresses of Code objects and
   // the relative displacements stored in the code.
+  // The isolate argument is unused (and may be nullptr) when skipping flushing.
   static inline Address target_address_at(Address pc, Address constant_pool);
   static inline void set_target_address_at(
       Isolate* isolate, Address pc, Address constant_pool, Address target,
       ICacheFlushMode icache_flush_mode = FLUSH_ICACHE_IF_NEEDED);
   static inline Address target_address_at(Address pc, Code* code);
   static inline void set_target_address_at(
       Isolate* isolate, Address pc, Code* code, Address target,
       ICacheFlushMode icache_flush_mode = FLUSH_ICACHE_IF_NEEDED);
 
   // Return the code target address at a call site from the return address
@@ skipping 2003 matching lines @@
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_X64_ASSEMBLER_X64_H_