Fix full code generator to not use --debug-code if it is in

src/x64/assembler-x64.cc

 // Copyright 2012 the V8 project authors. 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.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 332 matching lines @@
 // Implementation of Assembler.
 
 #ifdef GENERATED_CODE_COVERAGE
 static void InitCoverageLog();
 #endif
 
 Assembler::Assembler(Isolate* arg_isolate, void* buffer, int buffer_size)
     : AssemblerBase(arg_isolate),
       code_targets_(100),
       positions_recorder_(this),
-      emit_debug_code_(FLAG_debug_code) {
+      emit_debug_code_(FLAG_debug_code),
+      predictable_code_size_(false) {
   if (buffer == NULL) {
     // Do our own buffer management.
     if (buffer_size <= kMinimalBufferSize) {
       buffer_size = kMinimalBufferSize;
 
       if (isolate() != NULL && isolate()->assembler_spare_buffer() != NULL) {
         buffer = isolate()->assembler_spare_buffer();
         isolate()->set_assembler_spare_buffer(NULL);
       }
     }
@@ skipping 863 matching lines @@
   } else if (cc == never) {
     return;
   }
   EnsureSpace ensure_space(this);
   ASSERT(is_uint4(cc));
   if (L->is_bound()) {
     const int short_size = 2;
     const int long_size  = 6;
     int offs = L->pos() - pc_offset();
     ASSERT(offs <= 0);
-    if (is_int8(offs - short_size)) {
+    if (is_int8(offs - short_size) && !predictable_code_size_) {

[Jakob Kummerow, 2012/07/31 14:44:58]

A comment would be nice about why we have to disable automatic near jumps on
x64. Draft based on our offline discussion:
// On x64, when code is recompiled for debugging, some places need to be padded
// out to a certain size. The debugger is keeping track of how often it did
// this, but if the size of jump instructions can also change, that's not
// enough and the calculated offsets would be incorrect.

       // 0111 tttn #8-bit disp.
       emit(0x70 | cc);
       emit((offs - short_size) & 0xFF);
     } else {
       // 0000 1111 1000 tttn #32-bit disp.
       emit(0x0F);
       emit(0x80 | cc);
       emitl(offs - long_size);
     }
   } else if (distance == Label::kNear) {
@@ skipping 36 matching lines @@
 }
 
 
 void Assembler::jmp(Label* L, Label::Distance distance) {
   EnsureSpace ensure_space(this);
   const int short_size = sizeof(int8_t);
   const int long_size = sizeof(int32_t);
   if (L->is_bound()) {
     int offs = L->pos() - pc_offset() - 1;
     ASSERT(offs <= 0);
-    if (is_int8(offs - short_size)) {
+    if (is_int8(offs - short_size) && !predictable_code_size_) {
       // 1110 1011 #8-bit disp.
       emit(0xEB);
       emit((offs - short_size) & 0xFF);
     } else {
       // 1110 1001 #32-bit disp.
       emit(0xE9);
       emitl(offs - long_size);
     }
   } else if (distance == Label::kNear) {
     emit(0xEB);
@@ skipping 1738 matching lines @@
 bool RelocInfo::IsCodedSpecially() {
   // The deserializer needs to know whether a pointer is specially coded.  Being
   // specially coded on x64 means that it is a relative 32 bit address, as used
   // by branch instructions.
   return (1 << rmode_) & kApplyMask;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64