esp is the stack pointer, ebp is/was for a stack frame so that when you entered a function ebp could get a copy of esp at that point, everything on the stack before that happens, return address, passed in parameters, etc and things that are global for that function (local variables) will now be a … Read more
Java requires all classes that are loaded to be verified, in order to maintain the security of the sandbox and ensure that the code is safe to optimize. Note that this is done on the bytecode level, so the verification does not verify invariants of the Java language, it merely verifies that the bytecode makes … Read more
The compilers always generate self consistent code, so disabling the frame pointer is fine as long as you don’t use external/hand crafted code that makes some assumption about it (e.g. by relying on the value of rbp for example). The interrupts don’t use the frame pointer information, they may use the current stack pointer for … Read more
There is a performance difference, especially for enter. On modern processors this decodes to some 10 to 20 µops, while the three instruction sequence is about 4 to 6, depending on the architecture. For details consult Agner Fog’s instruction tables. Additionally the enter instruction usually has a quite high latency, for example 8 clocks on … Read more
This seems to be a reliable, simple way to get the “entry” or main assembly for a web app. If you put controllers in a separate project, you may find that the base class of ApplicationInstance is not in the same assembly as your MVC project that contains the Views – but, this setup seems … Read more
There are lots of resources out there that explain this: Function prologue (Wikipedia) x86 Disassembly/Calling Conventions (WikiBooks) Considerations for Writing Prolog/Epilog Code (MSDN) to name a few. Basically, as you somewhat described, “the stack” serves several purposes in the execution of a program: Keeping track of where to return to, when calling a function Storage … Read more
parent.env is the environment in which a closure (e.g., function) is defined. parent.frame is the environment from which the closure was invoked. f = function() c(f=environment(), defined_in=parent.env(environment()), called_from=parent.frame()) g = function() c(g=environment(), f()) and then > g() $g <environment: 0x14060e8> $f <environment: 0x1405f28> $defined_in <environment: R_GlobalEnv> $called_from <environment: 0x14060e8> I’m not sure when a mere … Read more
Most smaller functions don’t need a frame pointer – larger functions MAY need one. It’s really about how well the compiler manages to track how the stack is used, and where things are on the stack (local variables, arguments passed to the current function and arguments being prepared for a function about to be called). … Read more