From 9c108bb84d3a2447dac730c455df658be0a2c751 Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Tue, 17 Aug 2021 15:15:27 +0100 Subject: [PATCH] aarch64: Add -mtune=neoverse-512tvb To: gcc-patches@gcc.gnu.org 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. (cherry picked from commit 048039c49b96875144f67e7789fdea54abf7710b) --- gcc/config/aarch64/aarch64-cores.def | 1 + gcc/config/aarch64/aarch64-tune.md | 2 +- gcc/doc/invoke.texi | 25 ++++++++++++++++++++++--- 3 files changed, 24 insertions(+), 4 deletions(-) diff --git a/gcc/config/aarch64/aarch64-cores.def b/gcc/config/aarch64/aarch64-cores.def index dfb839c01cc..f348d31e22e 100644 --- a/gcc/config/aarch64/aarch64-cores.def +++ b/gcc/config/aarch64/aarch64-cores.def @@ -99,6 +99,7 @@ AARCH64_CORE("saphira", saphira, falkor, 8_3A, AARCH64_FL_FOR_ARCH8_3 /* ARM ('A') cores. */ AARCH64_CORE("zeus", zeus, cortexa57, 8_4A, AARCH64_FL_FOR_ARCH8_4 | AARCH64_FL_F16 | AARCH64_FL_RCPC | AARCH64_FL_SVE | AARCH64_FL_RNG, neoversev1, 0x41, 0xd40, -1) AARCH64_CORE("neoverse-v1", neoversev1, cortexa57, 8_4A, AARCH64_FL_FOR_ARCH8_4 | AARCH64_FL_F16 | AARCH64_FL_RCPC | AARCH64_FL_SVE | AARCH64_FL_RNG, neoversev1, 0x41, 0xd40, -1) +AARCH64_CORE("neoverse-512tvb", neoverse512tvb, cortexa57, 8_4A, AARCH64_FL_FOR_ARCH8_4 | AARCH64_FL_F16 | AARCH64_FL_RCPC | AARCH64_FL_SVE | AARCH64_FL_RNG, neoversev1, INVALID_IMP, INVALID_CORE, -1) /* Armv8.5-A Architecture Processors. */ AARCH64_CORE("neoverse-n2", neoversen2, cortexa57, 8_4A, AARCH64_FL_FOR_ARCH8_4 | AARCH64_FL_F16 | AARCH64_FL_SVE | AARCH64_FL_RNG, neoversen2, 0x41, 0xd49, -1) diff --git a/gcc/config/aarch64/aarch64-tune.md b/gcc/config/aarch64/aarch64-tune.md index 2d7c9aa4740..09b76480f0b 100644 --- a/gcc/config/aarch64/aarch64-tune.md +++ b/gcc/config/aarch64/aarch64-tune.md @@ -1,5 +1,5 @@ ;; -*- buffer-read-only: t -*- ;; Generated automatically by gentune.sh from aarch64-cores.def (define_attr "tune" - "cortexa35,cortexa53,cortexa57,cortexa72,cortexa73,thunderx,thunderxt88p1,thunderxt88,thunderxt81,thunderxt83,xgene1,falkor,qdf24xx,exynosm1,thunderx2t99p1,vulcan,thunderx2t99,cortexa55,cortexa75,cortexa76,ares,neoversen1,saphira,zeus,neoversev1,neoversen2,cortexa57cortexa53,cortexa72cortexa53,cortexa73cortexa35,cortexa73cortexa53,cortexa75cortexa55" + "cortexa35,cortexa53,cortexa57,cortexa72,cortexa73,thunderx,thunderxt88p1,thunderxt88,thunderxt81,thunderxt83,xgene1,falkor,qdf24xx,exynosm1,thunderx2t99p1,vulcan,thunderx2t99,cortexa55,cortexa75,cortexa76,ares,neoversen1,saphira,zeus,neoversev1,neoverse512tvb,neoversen2,cortexa57cortexa53,cortexa72cortexa53,cortexa73cortexa35,cortexa73cortexa53,cortexa75cortexa55" (const (symbol_ref "((enum attr_tune) aarch64_tune)"))) diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 78ca7738df2..68fda03281a 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -14772,9 +14772,9 @@ performance of the code. Permissible values for this option are: @samp{generic}, @samp{cortex-a35}, @samp{cortex-a53}, @samp{cortex-a55}, @samp{cortex-a57}, @samp{cortex-a72}, @samp{cortex-a73}, @samp{cortex-a75}, @samp{cortex-a76}, @samp{ares}, @samp{neoverse-n1}, @samp{neoverse-n2}, -@samp{neoverse-v1}, @samp{zeus}, @samp{exynos-m1}, @samp{falkor}, -@samp{qdf24xx}, @samp{saphira}, @samp{xgene1}, @samp{vulcan}, @samp{thunderx}, -@samp{thunderxt88}, @samp{thunderxt88p1}, @samp{thunderxt81}, +@samp{neoverse-v1}, @samp{zeus}, @samp{neoverse-512tvb}, @samp{exynos-m1}, +@samp{falkor}, @samp{qdf24xx}, @samp{saphira}, @samp{xgene1}, @samp{vulcan}, +@samp{thunderx}, @samp{thunderxt88}, @samp{thunderxt88p1}, @samp{thunderxt81}, @samp{thunderxt83}, @samp{thunderx2t99}, @samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53}, @samp{cortex-a73.cortex-a35}, @samp{cortex-a73.cortex-a53}, @samp{cortex-a75.cortex-a55}, @@ -14785,6 +14785,15 @@ The values @samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53}, @samp{cortex-a75.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. @@ -14814,6 +14823,16 @@ 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 -- 2.25.1