X64 implementation: Change argument to relocator to take a 64-bit delta. Cha...

src/ia32/assembler-ia32.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 378 matching lines @@
 #endif
   };
  private:
   static uint64_t supported_;
   static uint64_t enabled_;
 };
 
 
 class Assembler : public Malloced {
  private:
-  // The relocation writer's position is kGap bytes below the end of
+  // We check before assembling an instruction that there is sufficient
+  // space to write an instruction and its relocation information.
+  // The relocation writer's position must be kGap bytes above the end of
   // the generated instructions. This leaves enough space for the
-  // longest possible ia32 instruction (17 bytes as of 9/26/06) and
-  // allows for a single, fast space check per instruction.
+  // longest possible ia32 instruction, 15 bytes, and the longest possible
+  // relocation information encoding, RelocInfoWriter::kMaxLength == 16.
+  // (There is a 15 byte limit on ia32 instruction length that rules out some
+  // otherwise valid instructions.)
+  // This allows for a single, fast space check per instruction.
   static const int kGap = 32;
 
  public:
   // Create an assembler. Instructions and relocation information are emitted
   // into a buffer, with the instructions starting from the beginning and the
   // relocation information starting from the end of the buffer. See CodeDesc
   // 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
@@ skipping 439 matching lines @@
  private:
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_IA32_ASSEMBLER_IA32_H_