Frame pointer Vs Stack Pointer

Frame pointer Vs Stack Pointer

[Ankit Jain]

Frame pointer, Stack Pointer....i want to understand
this concept w.r.t stack in a program

how a program stores and understand by this

thanks

ankit

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Re: Frame pointer Vs Stack Pointer

[Jagadeesh Bhaskar P]

AFAIK, frame pointer points to the current activation record. Activation
records, for example, are created when a function is called, or the
program enters a different block of code. It can have details of the
return address, local variables etc. Now for getting the variables under
the current scope, a frame pointer is used.

A program will have an associated stack, to store values related to the
program. At times even the activtion records are stored in the stack.
The stack pointer points to the top of this stack.


On Tue, 2004-11-23 at 14:54, Ankit Jain wrote:
> Frame pointer, Stack Pointer....i want to understand
> this concept w.r.t stack in a program
> 
> how a program stores and understand by this
> 
> thanks
> 
> ankit
> 
> ________________________________________________________________________
> Yahoo! Messenger - Communicate instantly..."Ping" 
> your friends today! Download Messenger Now 
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-- 
Jagadeesh Bhaskar P <jbhaskar@hclinsys.com>

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Re: Frame pointer Vs Stack Pointer

[lindax newbie]

Frame pointer is a convenience for referencing local variables in a
subrouting, usually all the args are pushed onto the stack then BP
(the frame, or Base pointer) is pushed , then SP
(the stack pointer) is copied to BP, so all variables can easily be
referenced via BP+x, BP+y, etc.  It is especially useful if you are
debugging since BP will give you an idea of where the parameters to
the current subroutine are located.  It is also useful if you are doing
a stack traceback since the values of BP have been pushed onto the stack
for each stack frame.

On the otherhand, there are otherways of accessing those variables by
referencing off of "SP" and using BP as a general purpose register
to do other things -- this can result in faster code that is less
easy to debug.

If you aren't doing kernel debugging and/or are not expecting to be
generating stack traces, allowing the compiler to use BP (Base/Frame
 Pointer) is usually a good thing for optimizing memory and CPU
execution time.

-linda

Ankit Jain wrote:

>Frame pointer, Stack Pointer....i want to understand
>this concept w.r.t stack in a program
>
>how a program stores and understand by this
>
>thanks
>
>
>  
>
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To unsubscribe from this list: send the line "unsubscribe linux-newbie" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
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