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

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
===================================================================
--- src/arm/macro-assembler-arm.cc	(revision 3824)
+++ src/arm/macro-assembler-arm.cc	(working copy)
@@ -37,7 +37,6 @@
 
 MacroAssembler::MacroAssembler(void* buffer, int size)
     : Assembler(buffer, size),
-      unresolved_(0),
       generating_stub_(false),
       allow_stub_calls_(true),
       code_object_(Heap::undefined_value()) {
@@ -1233,58 +1232,29 @@
 }
 
 
-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);
+    Jump(r2);
   }
-
-  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);
-  }
 }
 
 
 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));
 }