On Mon, 2007-07-23 at 23:30 +0200, Andi Kleen wrote: > > gcc also tries to count the number of instructions, to guess how large in > > bytes the asm block is, as it could make a difference for near vs short > > jumps, etc. > > Are you sure? I doubt it. It would need a full asm parser to do this > properly and then even it could be wrong > (e.g. when the sections are switched like Linux does extensively) > > gcc doesn't have such a parser. > > Also on x86 gcc doesn't need to care about long/short anyways because > the assembler takes care of this and the other instructions who cared > about this (loop) isn't generated anymore. > > You're probably confusing it with some other compiler, who sometimes > do this. e.g. the Microsoft inline asm syntax requires assembler parsing > in the compiler. > > > I wonder it it also affects the instruction count the inline heuristics > > use? > > AFAIK it counts like one operand. > > -Andi
GCC counts newlines and semicolons and uses that number as the likely instruction count. See asm_insn_count() in gcc/gcc/final.c -- Nicholas Miell <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
