Implements a new API to set a function entry hook for profiling.

src/arm/code-stubs-arm.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 7495 matching lines @@
   __ Ret();
 
   // Array literal has ElementsKind of FAST_DOUBLE_ELEMENTS.
   __ bind(&double_elements);
   __ ldr(r5, FieldMemOperand(r1, JSObject::kElementsOffset));
   __ StoreNumberToDoubleElements(r0, r3, r1, r5, r6, r7, r9, r2,
                                  &slow_elements);
   __ Ret();
 }
 
+
+void ProfileEntryHookStub::MaybeCallEntryHook(MacroAssembler* masm) {
+  if (entry_hook_ != NULL) {
+    ProfileEntryHookStub stub;
+    __ push(lr);
+    __ CallStub(&stub);
+    __ pop(lr);
+  }
+}
+
+
+void ProfileEntryHookStub::Generate(MacroAssembler* masm) {
+  // The entry hook is a "push lr" instruction, followed by a call.
+  const int32_t kReturnAddressDistanceFromFunctionStart =
+      Assembler::kCallTargetAddressOffset + Assembler::kInstrSize;
+
+  // Save live volatile registers.
+  __ Push(lr, r5, r1);
+  const int32_t kNumSavedRegs = 3;
+
+  // Compute the function's address for the first argument.
+  __ sub(r0, lr, Operand(kReturnAddressDistanceFromFunctionStart));
+
+  // The caller's return address is above the saved temporaries.
+  // Grab that for the second argument to the hook.
+  __ add(r1, sp, Operand(kNumSavedRegs * kPointerSize));
+
+  // Align the stack if necessary.
+  int frame_alignment = masm->ActivationFrameAlignment();
+  if (frame_alignment > kPointerSize) {
+    __ mov(r5, sp);
+    ASSERT(IsPowerOf2(frame_alignment));
+    __ and_(sp, sp, Operand(-frame_alignment));
+  }
+
+#if defined(V8_HOST_ARCH_ARM)
+  __ mov(ip, Operand(reinterpret_cast<int32_t>(&entry_hook_)));
+  __ ldr(ip, MemOperand(ip));
+#else
+  // Under the simulator we need to indirect the entry hook through a
+  // trampoline function at a known address.
+  ApiFunction dispatcher(reinterpret_cast<Address>(EntryHookTrampoline));
+  __ mov(ip, Operand(ExternalReference(&dispatcher,
+                                       ExternalReference::BUILTIN_CALL,
+                                       masm->isolate())));
+#endif
+  __ Call(ip);
+
+  // Restore the stack pointer if needed.
+  if (frame_alignment > kPointerSize)

[danno, 2012/07/12 15:23:11]

nit: in V8 we always surround if code that can't requires a line break with {} 

[Sigurður Ásgeirsson, 2012/07/12 15:38:54]

Done.

+    __ mov(sp, r5);
+
+  __ Pop(lr, r5, r1);
+  __ Ret();
+}
+
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM