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

src/ia32/code-stubs-ia32.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 7456 matching lines @@
                                  edx,
                                  ecx,
                                  edi,
                                  xmm0,
                                  &slow_elements_from_double,
                                  false);
   __ pop(edx);
   __ ret(0);
 }
 
+
+void ProfileEntryHookStub::Generate(MacroAssembler* masm) {
+  // Grab the cycle counter immediately.
+  __ db(0x0F);  // rdtsc();

[danno, 2012/07/10 09:37:13]

Any reason to not add this to assembler-ia32.h?

[Sigurður Ásgeirsson, 2012/07/11 14:50:34]

This is already in the assembler, but under a condition on a flag there. I don't
understand the reason for the condition & flag, so I just did the equivalent of
emit().
Removed now that the hook signature doesn't include a timer.

+  __ db(0x31);
+  
+  // Ecx is the only volatile register we must save.
+  __ push(ecx);  
+
+  // Push the cycle time arg.
+  __ push(edx);
+  __ push(eax);
+
+  // Calculate and push the original stack pointer.
+  __ lea(eax, Operand(esp, 0xC));

[danno, 2012/07/10 09:37:13]

Constants? (maybe from frame-ia32.h, also applies to x64)

[Sigurður Ásgeirsson, 2012/07/11 14:50:34]

Done.

+  __ push(eax);
+
+  // Calculate and push the function address.
+  __ mov(eax, Operand(eax, 0));
+  __ sub(eax, Immediate(5));

[danno, 2012/07/10 09:37:13]

constant?

[Sigurður Ásgeirsson, 2012/07/11 14:50:34]

Done.

+  __ push(eax);
+
+  // Call the entry hook.
+  int32_t hook_location =
+      reinterpret_cast<int32_t>(V8::GetFunctionEntryHookLocation());
+  __ call(Operand(hook_location, RelocInfo::NONE));
+  __ add(esp, Immediate(0x10));
+
+  // Restore ecx.
+  __ pop(ecx);
+  __ ret(0);
+}
+
+
+void ProfileEntryHookStub::GenerateAheadOfTime() {
+  ProfileEntryHookStub stub;
+  Handle<Code> code = stub.GetCode();
+  code->set_is_pregenerated(true);
+}
+
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32