> > > 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 > > > > 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: > > 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
Ah, so it's being introduced by the assembler, not the compiler. That is perhaps the effect of alignement instructions like > > .text > > .p2align 2,0x90 this and similar defaults. > 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. That may very well be the case. Considering that a cache line is also a few words worth, it may be sensible to start with an aligned stack frame too. > best regards, > Chungwei -- Cordula's Web. http://www.cordula.ws/ _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
