thank you very much for the reply yes and I am using gcc 3.2.2 if you "gdb" the executable and "disassemble main" you will see the line like that but if you use gcc -S something.s something.c it won't appear in the assembly code
and I google around, I think it does the alignment for optimization purpose, in that case the memory access will be faster according to the article. best regards, Chungwei --- Cordula's Web <[EMAIL PROTECTED]> wrote: > > I compile a test C file. I notice there are a few lines at the > > beginning of the assembly code. I want to know what it means, but > > can't figure out one of them. Can anyone tell me what the > > following line does please? > > > > and $0xfffffff0,%esp > > Hmmm, when I compile the simplest possible C file: > > ------------------------------- > int > main (int argc, char *argv[]) > { > return 0; > } > -------------------------------- > > I get this: > > -------------------------------- > .file "test1.c" > .version "01.01" > gcc2_compiled.: > .text > .p2align 2,0x90 > .globl main > .type main,@function > main: > pushl %ebp > movl %esp,%ebp > xorl %eax,%eax > jmp .L2 > .p2align 2,0x90 > .L2: > leave > ret > .Lfe1: > .size main,.Lfe1-main > .ident "GCC: (GNU) c 2.95.4 20020320 [FreeBSD]" > > -------------------------------- > > No such thing as: > > and $0xfffffff0,%esp > > Are you using gcc 3.3.x? > > Anyway, this code looks like it would align the stack > the stack pointer... > > > best regards > > Chungwei > > -- > Cordula's Web. http://www.cordula.ws/ > ===== bear _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"