Always load the JavaScript builtins code entry from the JavaScript...

src/arm/macro-assembler-arm.cc

 // Copyright 2006-2009 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 19 matching lines @@
 #include "bootstrapper.h"
 #include "codegen-inl.h"
 #include "debug.h"
 #include "runtime.h"
 
 namespace v8 {
 namespace internal {
 
 MacroAssembler::MacroAssembler(void* buffer, int size)
     : Assembler(buffer, size),
-      unresolved_(0),
       generating_stub_(false),
       allow_stub_calls_(true),
       code_object_(Heap::undefined_value()) {
 }
 
 
 // We always generate arm code, never thumb code, even if V8 is compiled to
 // thumb, so we require inter-working support
 #if defined(__thumb__) && !defined(USE_THUMB_INTERWORK)
 #error "flag -mthumb-interwork missing"
@@ skipping 1175 matching lines @@
 #if defined(__thumb__)
   // Thumb mode builtin.
   ASSERT((reinterpret_cast<intptr_t>(builtin.address()) & 1) == 1);
 #endif
   mov(r1, Operand(builtin));
   CEntryStub stub(1);
   Jump(stub.GetCode(), RelocInfo::CODE_TARGET);
 }
 
 
-Handle<Code> MacroAssembler::ResolveBuiltin(Builtins::JavaScript id,
-                                            bool* resolved) {
-  // Contract with compiled functions is that the function is passed in r1.
-  int builtins_offset =
-      JSBuiltinsObject::kJSBuiltinsOffset + (id * kPointerSize);
-  ldr(r1, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
-  ldr(r1, FieldMemOperand(r1, GlobalObject::kBuiltinsOffset));
-  ldr(r1, FieldMemOperand(r1, builtins_offset));
-
-  return Builtins::GetCode(id, resolved);
-}
-
-
 void MacroAssembler::InvokeBuiltin(Builtins::JavaScript id,
                                    InvokeJSFlags flags) {
-  bool resolved;
-  Handle<Code> code = ResolveBuiltin(id, &resolved);
-
+  GetBuiltinEntry(r2, id);
   if (flags == CALL_JS) {
-    Call(code, RelocInfo::CODE_TARGET);
+    Call(r2);
   } else {
     ASSERT(flags == JUMP_JS);
-    Jump(code, RelocInfo::CODE_TARGET);
-  }
-
-  if (!resolved) {
-    const char* name = Builtins::GetName(id);
-    int argc = Builtins::GetArgumentsCount(id);
-    uint32_t flags =
-        Bootstrapper::FixupFlagsArgumentsCount::encode(argc) |
-        Bootstrapper::FixupFlagsUseCodeObject::encode(false);
-    Unresolved entry = { pc_offset() - kInstrSize, flags, name };
-    unresolved_.Add(entry);
+    Jump(r2);
   }
 }
 
 
 void MacroAssembler::GetBuiltinEntry(Register target, Builtins::JavaScript id) {
-  bool resolved;
-  Handle<Code> code = ResolveBuiltin(id, &resolved);
-
-  mov(target, Operand(code));
-  if (!resolved) {
-    const char* name = Builtins::GetName(id);
-    int argc = Builtins::GetArgumentsCount(id);
-    uint32_t flags =
-        Bootstrapper::FixupFlagsArgumentsCount::encode(argc) |
-        Bootstrapper::FixupFlagsUseCodeObject::encode(true);
-    Unresolved entry = { pc_offset() - kInstrSize, flags, name };
-    unresolved_.Add(entry);
-  }
-
+  // Load the JavaScript builtin function from the builtins object
+  // using the target register as a scratch register.
+  ldr(target, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  ldr(target, FieldMemOperand(target, GlobalObject::kBuiltinsOffset));
+  int builtins_offset =
+      JSBuiltinsObject::kJSBuiltinsOffset + (id * kPointerSize);
+  ldr(r1, FieldMemOperand(target, builtins_offset));

[Erik Corry, 2010/02/10 17:22:49]

Seems like you might as well just use r1 throughout instead of having a hidden
scratch register here.

[Mads Ager (chromium), 2010/02/11 07:58:30]

Yes, done on all platforms.

+  // Load the code entry point from the function into the target register.
+  ldr(target, FieldMemOperand(r1, JSFunction::kSharedFunctionInfoOffset));
+  ldr(target, FieldMemOperand(target, SharedFunctionInfo::kCodeOffset));

[Erik Corry, 2010/02/10 17:22:49]

A chain of 5 dependent loads!  If this turns out to be slow we should consider
putting the builtins array in the root array instead of accessing it through the
context.  Since you showed it's no slower on Intel perhaps it doesn't matter.

   add(target, target, Operand(Code::kHeaderSize - kHeapObjectTag));
 }
 
 
 void MacroAssembler::SetCounter(StatsCounter* counter, int value,
                                 Register scratch1, Register scratch2) {
   if (FLAG_native_code_counters && counter->Enabled()) {
     mov(scratch1, Operand(value));
     mov(scratch2, Operand(ExternalReference(counter)));
     str(scratch1, MemOperand(scratch2));
@@ skipping 175 matching lines @@
 }
 
 
 void CodePatcher::Emit(Address addr) {
   masm()->emit(reinterpret_cast<Instr>(addr));
 }
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 } }  // namespace v8::internal