sub rsp,16 vs sub esp,16

flat assembler
Message board for the users of flat assembler.

Index > Linux > sub rsp,16 vs sub esp,16

Author

Thread

mattst88

Joined: 12 May 2006
Posts: 260
Location: South Carolina

mattst88

When allocating space on the stack, is it safe to use sub esp,16? Is there a chance for over/underflow?

The benefit is that it is one byte smaller.

_________________
My x86 Instruction Reference -- includes SSE, SSE2, SSE3, SSSE3, SSE4 instructions.
Assembly Programmer's Journal

16 May 2007, 01:23

Feryno

Joined: 23 Mar 2005
Posts: 474
Location: Czech republic, Slovak republic

Feryno

Hello mattst88
on my Fedora Core 3 x64 and kernel 2.6.xx.xx (I can't remember exactly the number now) the stack is usally above 100000000h (I think it is something like 00007FFFFFFFFxxxh) so every subtraction from ESP causes destroying the upper dword of rsp and losing the stack pointer completely.
Perhaps in your Linux it doesn't matter, but my personal suggestion is to use RSP for keeping compactibility between various kernels and configurations.

16 May 2007, 08:07

mattst88

Joined: 12 May 2006
Posts: 260
Location: South Carolina

mattst88

OK, I'll stick with rsp. Smile

Thanks for your reply.

16 May 2007, 13:28

< Last Thread | Next Thread >

Forum Rules:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum