From 048039c49b96875144f67e7789fdea54abf7710b Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Tue, 3 Aug 2021 13:00:49 +0100 Subject: aarch64: Add -mtune=neoverse-512tvb This patch adds an option to tune for Neoverse cores that have a total vector bandwidth of 512 bits (4x128 for Advanced SIMD and a vector-length-dependent equivalent for SVE). This is intended to be a compromise between tuning aggressively for a single core like Neoverse V1 (which can be too narrow) and tuning for AArch64 cores in general (which can be too wide). -mcpu=neoverse-512tvb is equivalent to -mcpu=neoverse-v1 -mtune=neoverse-512tvb. gcc/ * doc/invoke.texi: Document -mtune=neoverse-512tvb and -mcpu=neoverse-512tvb. * config/aarch64/aarch64-cores.def (neoverse-512tvb): New entry. * config/aarch64/aarch64-tune.md: Regenerate. * config/aarch64/aarch64.c (neoverse512tvb_sve_vector_cost) (neoverse512tvb_sve_issue_info, neoverse512tvb_vec_issue_info) (neoverse512tvb_vector_cost, neoverse512tvb_tunings): New structures. (aarch64_adjust_body_cost_sve): Handle -mtune=neoverse-512tvb. (aarch64_adjust_body_cost): Likewise. --- gcc/doc/invoke.texi | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) (limited to 'gcc/doc/invoke.texi') diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 32697e6..65bb998 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -18407,10 +18407,10 @@ performance of the code. Permissible values for this option are: @samp{cortex-a65}, @samp{cortex-a65ae}, @samp{cortex-a34}, @samp{cortex-a78}, @samp{cortex-a78ae}, @samp{cortex-a78c}, @samp{ares}, @samp{exynos-m1}, @samp{emag}, @samp{falkor}, -@samp{neoverse-e1}, @samp{neoverse-n1}, @samp{neoverse-n2}, -@samp{neoverse-v1}, @samp{qdf24xx}, @samp{saphira}, -@samp{phecda}, @samp{xgene1}, @samp{vulcan}, @samp{octeontx}, -@samp{octeontx81}, @samp{octeontx83}, +@samp{neoverse-512tvb}, @samp{neoverse-e1}, @samp{neoverse-n1}, +@samp{neoverse-n2}, @samp{neoverse-v1}, @samp{qdf24xx}, +@samp{saphira}, @samp{phecda}, @samp{xgene1}, @samp{vulcan}, +@samp{octeontx}, @samp{octeontx81}, @samp{octeontx83}, @samp{octeontx2}, @samp{octeontx2t98}, @samp{octeontx2t96} @samp{octeontx2t93}, @samp{octeontx2f95}, @samp{octeontx2f95n}, @samp{octeontx2f95mm}, @@ -18428,6 +18428,15 @@ The values @samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53}, @samp{cortex-a75.cortex-a55}, @samp{cortex-a76.cortex-a55} specify that GCC should tune for a big.LITTLE system. +The value @samp{neoverse-512tvb} specifies that GCC should tune +for Neoverse cores that (a) implement SVE and (b) have a total vector +bandwidth of 512 bits per cycle. In other words, the option tells GCC to +tune for Neoverse cores that can execute 4 128-bit Advanced SIMD arithmetic +instructions a cycle and that can execute an equivalent number of SVE +arithmetic instructions per cycle (2 for 256-bit SVE, 4 for 128-bit SVE). +This is more general than tuning for a specific core like Neoverse V1 +but is more specific than the default tuning described below. + Additionally on native AArch64 GNU/Linux systems the value @samp{native} tunes performance to the host system. This option has no effect if the compiler is unable to recognize the processor of the host system. @@ -18457,6 +18466,16 @@ by @option{-mtune}). Where this option is used in conjunction with @option{-march} or @option{-mtune}, those options take precedence over the appropriate part of this option. +@option{-mcpu=neoverse-512tvb} is special in that it does not refer +to a specific core, but instead refers to all Neoverse cores that +(a) implement SVE and (b) have a total vector bandwidth of 512 bits +a cycle. Unless overridden by @option{-march}, +@option{-mcpu=neoverse-512tvb} generates code that can run on a +Neoverse V1 core, since Neoverse V1 is the first Neoverse core with +these properties. Unless overridden by @option{-mtune}, +@option{-mcpu=neoverse-512tvb} tunes code in the same way as for +@option{-mtune=neoverse-512tvb}. + @item -moverride=@var{string} @opindex moverride Override tuning decisions made by the back-end in response to a -- cgit v1.1