On 8/5/2020 5:45 PM, Bruce Richardson wrote: > On Wed, Aug 05, 2020 at 05:15:31PM +0200, Thomas Monjalon wrote: >> 05/08/2020 17:07, Bruce Richardson: >>> On Wed, Aug 05, 2020 at 04:57:42PM +0200, Thomas Monjalon wrote: >>>> 05/08/2020 16:21, Bruce Richardson: >>>>> The RTE_MACHINE_CPUFLAGS_* macros in DPDK build just duplicate info from >>>>> the compiler macros, so we can remove them and just use the compiler >>>>> versions directly. >>>>> >>>>> Signed-off-by: Bruce Richardson <bruce.richard...@intel.com> >>>>> --- >>>>> --- a/doc/guides/rel_notes/deprecation.rst >>>>> +++ b/doc/guides/rel_notes/deprecation.rst >>>>> +* build macros: The macros defining RTE_MACHINE_CPUFLAG_* will be removed >>>>> + from the build. The information provided by these macros is available >>>>> + through standard compiler macros. For example, RTE_MACHINE_CPUFLAG_SSE3 >>>>> + duplicates the compiler-provided macro __SSE3__. >>>> >>>> I see 2 advantages of having alias: >>>> - if 2 compilers differ, we can manage >>>> - we can find all such macros with grep RTE_MACHINE_CPUFLAG >>>> >>> >>> Sure, if you think it's worthwhile keeping them, we can do so. It's just >>> right now they seem to be largely a waste of space. For #2, I'm not sure >>> when we would want to grep for them all, except possibly to remove them. >>> :-) >> >> For instance, in a lib, I grep where we have CPU specific code. >> >> We probably need more opinions, I can change my mind. >> > Yes, we need some more opinions here. > > For the above point, yes it's useful to be able to grep for these things, > but it does assume that everybody uses the DPDK-defines and doesn't use the > compiler ones directly. There are a few instances where there seems to be > x86, ARM or PPC compiler flags already directly used in the code. > > As well as brevity, the other big reason I see for removing them is to > avoid having to maintain these lists of flags for future use. Right now, > with -march=skylake-avx512, gcc will define 7 different AVX feature flags. > DPDK, on the other hand, only provides equivalent defines for 3 of them. > We have no automatic way of pulling all newly added flags from gcc/clang > into our build, so we just add them on an as-needed basis, which makes it > more awkward for those adding new features that may depend on the flags. If > we always try to add in all flags to keep things in sync, we are just > duplicating the efforts the compiler authors have already done for us, and > wasting the effort for those flags that are unused. >
Sounds reasonable, Acked-by: Ferruh Yigit <ferruh.yi...@intel.com>
