On Sat, Jan 10, 2015 at 12:42 PM, Borislav Petkov <b...@alien8.de> wrote: > On Sat, Jan 10, 2015 at 12:17:13PM -0800, Andy Lutomirski wrote: >> I asked this once, and someone told me that push/pop has lower >> throughput. I find this surprising. > > Implicit dependency on %rsp probably. The MOVs allow you to start more > stuff out-of-order I'd guess...
AIUI modern CPUs have fancy stack engines that match call/ret pairs, and presumably they can speculate rsp values across multiple pushes and pops very quickly. Also, don't compilers generally use push and pop to save and restore callee-saved registers? I think that function calls are common enough that the CPU vendors would have made these sequences fast. --Andy > >> Tt could be worth adding a macro along the lines of pushq_cfi_save >> that does the pushq_cfi and the CFI_REL_OFFSET. > > Yep, for balance. > > -- > Regards/Gruss, > Boris. > > Sent from a fat crate under my desk. Formatting is fine. > -- -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
