[liveedit] reimplement frame restarting.

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index b35ef3b07a12f80783258adca72b9e90fcf0a7cd..d620fa9c6c60da3c5887b5a4611d7bd59455941c 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -4081,7 +4081,6 @@ void MacroAssembler::DecrementCounter(StatsCounter* counter, int value) {
   }
 }
 
-
 void MacroAssembler::DebugBreak() {
   Set(rax, 0);  // No arguments.
   LoadAddress(rbx,
@@ -4091,6 +4090,15 @@ void MacroAssembler::DebugBreak() {
   Call(ces.GetCode(), RelocInfo::DEBUGGER_STATEMENT);
 }
 
+void MacroAssembler::MaybeDropFrames() {
+  // Check whether we need to drop frames to restart a function on the stack.
+  ExternalReference new_fp = ExternalReference::debug_new_fp_address(isolate());
+  Load(rbx, new_fp);
+  testp(rbx, rbx);
+  j(not_zero, isolate()->builtins()->FrameDropperTrampoline(),
+    RelocInfo::CODE_TARGET);
+}
+
 void MacroAssembler::PrepareForTailCall(const ParameterCount& callee_args_count,
                                         Register caller_args_count_reg,
                                         Register scratch0, Register scratch1,
@@ -4290,6 +4298,7 @@ void MacroAssembler::InvokePrologue(const ParameterCount& expected,
       DCHECK(actual.reg().is(rax));
       DCHECK(expected.reg().is(rbx));
     } else {
+      definitely_matches = true;
       Move(rax, actual.reg());
     }
   }