Messages in this thread | | | Date | Tue, 31 Oct 2017 10:43:32 +0000 | From | Mark Rutland <> | Subject | Re: CONFIG_ARCH_SUPPORTS_INT128 for AArch64 |
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On Tue, Oct 31, 2017 at 11:17:52AM +0100, Jason A. Donenfeld wrote: > Hi folks, > > Older versions of gcc are horrible for int128_t on aarch64, emitting a > __multi3 call, which is slow and defeats the purpose. However, more > recent versions of gcc (since 5, IIRC), do the right thing and produce > the proper inlined instructions. > > Do we have the infrastructure available to test for this, and > conditionally set CONFIG_ARCH_SUPPORTS_INT128 if we do?
Judging by Documentation/kbuild/makefiles.txt, we could do something like the below in the arm64 Makefile:
cflags-y += $(call cc-ifversion, -ge, 0500, -DCONFIG_ARCH_SUPPORTS_INT128)
Note that I havent tested this at all.
Thanks,
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