Hi Tamar, > On 31 Jul 2024, at 18:46, Tamar Christina <tamar.christ...@arm.com> wrote: > > External email: Use caution opening links or attachments > > > Hi Kyrill, > >>> /* True if the vector body contains a store to a decl and if the >>> function is known to have a vld1 from the same decl. >>> >>> @@ -17291,6 +17297,17 @@ aarch64_vector_costs::add_stmt_cost (int count, >> vect_cost_for_stmt kind, >>> stmt_cost = aarch64_detect_vector_stmt_subtype (m_vinfo, kind, >>> stmt_info, vectype, >>> where, stmt_cost); >>> + >>> + /* Check if we've seen an SVE gather/scatter operation and which >>> size. */ >>> + if (kind == scalar_load >>> + && aarch64_sve_mode_p (TYPE_MODE (vectype)) >>> + && STMT_VINFO_MEMORY_ACCESS_TYPE (stmt_info) == >> VMAT_GATHER_SCATTER) >>> + { >>> + if (GET_MODE_UNIT_BITSIZE (TYPE_MODE (vectype)) == 64) >>> + m_sve_gather_scatter_x64 = true; >>> + else >>> + m_sve_gather_scatter_x32 = true; >> >> This is a bit academic at this stage but SVE2.1 adds quadword gather loads. >> I know >> we’re not vectoring for those yet, but maybe it’s worth explicitly checking >> for 32- >> bit size and gcc_unreachable () otherwise? > > To be honest I'm not quite sure how to detect it. If it just > GET_MODE_UNIT_BITSIZE () == 128? > But do we want an assert in the cost model? Happy to do so though but maybe a > debug print is more > appropriate? i.e. make it a missed optimization?
I don’t feel strongly about it. I’d drop my comment here. If and when we add vectorization for 128-bit chunks I’m sure we’ll be revisiting this cost model anyway. > >> >> >>> + } >>> } >>> >>> /* Do any SVE-specific adjustments to the cost. */ >>> @@ -17676,6 +17693,18 @@ aarch64_vector_costs::finish_cost (const >> vector_costs *uncast_scalar_costs) >>> m_costs[vect_body] = adjust_body_cost (loop_vinfo, scalar_costs, >>> m_costs[vect_body]); >>> m_suggested_unroll_factor = determine_suggested_unroll_factor (); >>> + >>> + /* For gather and scatters there's an additional overhead for the >>> first >>> + iteration. For low count loops they're not beneficial so model the >>> + overhead as loop prologue costs. */ >>> + if (m_sve_gather_scatter_x32 || m_sve_gather_scatter_x64) >>> + { >>> + const sve_vec_cost *sve_costs = >>> aarch64_tune_params.vec_costs->sve; >>> + if (m_sve_gather_scatter_x32) >>> + m_costs[vect_prologue] += sve_costs->gather_load_x32_init_cost; >>> + else >>> + m_costs[vect_prologue] += sve_costs->gather_load_x64_init_cost; >> >> Shouldn’t this not be en else but rather: >> If (m_sve_gather_scatter_x64) >> m_costs[vect_prologue] += sve_costs->gather_load_x64_init_cost; >> >> In case the loop has both 32-bit and 64-bit gather/scatter? >> > > This was an interesting comment. After some discussion and more benchmarking > we've changed it to be an additive cost. Ok. > >> >>> + } >>> } >>> >>> /* Apply the heuristic described above m_stp_sequence_cost. Prefer >>> diff --git a/gcc/config/aarch64/tuning_models/a64fx.h >> b/gcc/config/aarch64/tuning_models/a64fx.h >>> index >> 6091289d4c3c66f01d7e4dbf97a85c1f8c40bb0b..378a1b3889ee265859786c1 >> ff6525fce2305b615 100644 >>> --- a/gcc/config/aarch64/tuning_models/a64fx.h >>> +++ b/gcc/config/aarch64/tuning_models/a64fx.h >>> @@ -104,6 +104,8 @@ static const sve_vec_cost a64fx_sve_vector_cost = >>> 13, /* fadda_f64_cost */ >>> 64, /* gather_load_x32_cost */ >>> 32, /* gather_load_x64_cost */ >>> + 0, /* gather_load_x32_init_cost */ >>> + 0, /* gather_load_x64_init_cost */ >>> 1 /* scatter_store_elt_cost */ >>> }; >>> >>> diff --git a/gcc/config/aarch64/tuning_models/cortexx925.h >> b/gcc/config/aarch64/tuning_models/cortexx925.h >>> index >> fb95e87526985b02410d54a5a3ec8539c1b0ba6d..c4206018a3ff707f89ff33007 >> 00ec7dc2a5bc6b0 100644 >>> --- a/gcc/config/aarch64/tuning_models/cortexx925.h >>> +++ b/gcc/config/aarch64/tuning_models/cortexx925.h >>> @@ -135,6 +135,8 @@ static const sve_vec_cost cortexx925_sve_vector_cost = >>> operation more than a 64-bit gather. */ >>> 14, /* gather_load_x32_cost */ >>> 12, /* gather_load_x64_cost */ >>> + 42, /* gather_load_x32_init_cost */ >>> + 24, /* gather_load_x64_init_cost */ >> >> >> Can you comment on how these numbers are derived? > > They were derived essentially from benchmarking. I did a bunch of runs over > various cores > to determine at which iteration count they become profitable. From that as > you can > probably tell the costs are a multiple of the cost of the operations for the > specific core. > > This because that cost already keeps in mind things like VL differences. > > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues. > > Ok for master? Ok with Richard’s comments addressed. Thanks, Kyrill > > Thanks, > Tamar > > gcc/ChangeLog: > > * config/aarch64/aarch64-protos.h (struct sve_vec_cost): Add > gather_load_x32_init_cost and gather_load_x64_init_cost. > * config/aarch64/aarch64.cc (aarch64_vector_costs): Add > m_sve_gather_scatter_init_cost. > (aarch64_vector_costs::add_stmt_cost): Use them. > (aarch64_vector_costs::finish_cost): Likewise. > * config/aarch64/tuning_models/a64fx.h: Update. > * config/aarch64/tuning_models/cortexx925.h: Update. > * config/aarch64/tuning_models/generic.h: Update. > * config/aarch64/tuning_models/generic_armv8_a.h: Update. > * config/aarch64/tuning_models/generic_armv9_a.h: Update. > * config/aarch64/tuning_models/neoverse512tvb.h: Update. > * config/aarch64/tuning_models/neoversen2.h: Update. > * config/aarch64/tuning_models/neoversen3.h: Update. > * config/aarch64/tuning_models/neoversev1.h: Update. > * config/aarch64/tuning_models/neoversev2.h: Update. > * config/aarch64/tuning_models/neoversev3.h: Update. > * config/aarch64/tuning_models/neoversev3ae.h: Update. > > -- inline copy of patch -- > > diff --git a/gcc/config/aarch64/aarch64-protos.h > b/gcc/config/aarch64/aarch64-protos.h > index > 42639e9efcf1e0f9362f759ae63a31b8eeb0d581..16eb8edab4d9fdfc6e3672c56ef5c9f6962d0c0b > 100644 > --- a/gcc/config/aarch64/aarch64-protos.h > +++ b/gcc/config/aarch64/aarch64-protos.h > @@ -262,6 +262,8 @@ struct sve_vec_cost : simd_vec_cost > unsigned int fadda_f64_cost, > unsigned int gather_load_x32_cost, > unsigned int gather_load_x64_cost, > + unsigned int gather_load_x32_init_cost, > + unsigned int gather_load_x64_init_cost, > unsigned int scatter_store_elt_cost) > : simd_vec_cost (base), > clast_cost (clast_cost), > @@ -270,6 +272,8 @@ struct sve_vec_cost : simd_vec_cost > fadda_f64_cost (fadda_f64_cost), > gather_load_x32_cost (gather_load_x32_cost), > gather_load_x64_cost (gather_load_x64_cost), > + gather_load_x32_init_cost (gather_load_x32_init_cost), > + gather_load_x64_init_cost (gather_load_x64_init_cost), > scatter_store_elt_cost (scatter_store_elt_cost) > {} > > @@ -289,6 +293,12 @@ struct sve_vec_cost : simd_vec_cost > const int gather_load_x32_cost; > const int gather_load_x64_cost; > > + /* Additional loop initialization cost of using a gather load instruction. > The x32 > + value is for loads of 32-bit elements and the x64 value is for loads of > + 64-bit elements. */ > + const int gather_load_x32_init_cost; > + const int gather_load_x64_init_cost; > + > /* The per-element cost of a scatter store. */ > const int scatter_store_elt_cost; > }; > diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc > index > eafa377cb095f49408d8a926fb49ce13e2155ba2..da2feb54ddad9b39db92e0a9ec7c4e40cfa3e4e2 > 100644 > --- a/gcc/config/aarch64/aarch64.cc > +++ b/gcc/config/aarch64/aarch64.cc > @@ -16227,6 +16227,10 @@ private: > supported by Advanced SIMD and SVE2. */ > bool m_has_avg = false; > > + /* Additional initialization costs for using gather or scatter operation in > + the current loop. */ > + unsigned int m_sve_gather_scatter_init_cost = 0; > + > /* True if the vector body contains a store to a decl and if the > function is known to have a vld1 from the same decl. > > @@ -17291,6 +17295,20 @@ aarch64_vector_costs::add_stmt_cost (int count, > vect_cost_for_stmt kind, > stmt_cost = aarch64_detect_vector_stmt_subtype (m_vinfo, kind, > stmt_info, vectype, > where, stmt_cost); > + > + /* Check if we've seen an SVE gather/scatter operation and which size. > */ > + if (kind == scalar_load > + && aarch64_sve_mode_p (TYPE_MODE (vectype)) > + && STMT_VINFO_MEMORY_ACCESS_TYPE (stmt_info) == VMAT_GATHER_SCATTER) > + { > + const sve_vec_cost *sve_costs = aarch64_tune_params.vec_costs->sve; > + if (GET_MODE_UNIT_BITSIZE (TYPE_MODE (vectype)) == 64) > + m_sve_gather_scatter_init_cost > + += sve_costs->gather_load_x64_init_cost; > + else > + m_sve_gather_scatter_init_cost > + += sve_costs->gather_load_x32_init_cost; > + } > } > > /* Do any SVE-specific adjustments to the cost. */ > @@ -17676,6 +17694,12 @@ aarch64_vector_costs::finish_cost (const > vector_costs *uncast_scalar_costs) > m_costs[vect_body] = adjust_body_cost (loop_vinfo, scalar_costs, > m_costs[vect_body]); > m_suggested_unroll_factor = determine_suggested_unroll_factor (); > + > + /* For gather and scatters there's an additional overhead for the first > + iteration. For low count loops they're not beneficial so model the > + overhead as loop prologue costs. */ > + if (m_sve_gather_scatter_init_cost) > + m_costs[vect_prologue] += m_sve_gather_scatter_init_cost; > } > > /* Apply the heuristic described above m_stp_sequence_cost. Prefer > diff --git a/gcc/config/aarch64/tuning_models/a64fx.h > b/gcc/config/aarch64/tuning_models/a64fx.h > index > 6091289d4c3c66f01d7e4dbf97a85c1f8c40bb0b..378a1b3889ee265859786c1ff6525fce2305b615 > 100644 > --- a/gcc/config/aarch64/tuning_models/a64fx.h > +++ b/gcc/config/aarch64/tuning_models/a64fx.h > @@ -104,6 +104,8 @@ static const sve_vec_cost a64fx_sve_vector_cost = > 13, /* fadda_f64_cost */ > 64, /* gather_load_x32_cost */ > 32, /* gather_load_x64_cost */ > + 0, /* gather_load_x32_init_cost */ > + 0, /* gather_load_x64_init_cost */ > 1 /* scatter_store_elt_cost */ > }; > > diff --git a/gcc/config/aarch64/tuning_models/cortexx925.h > b/gcc/config/aarch64/tuning_models/cortexx925.h > index > 6cae5b7de5ca7ffad8a0f683e1285039bb55d159..b509cae758419a415d9067ec751ef1e6528eb09a > 100644 > --- a/gcc/config/aarch64/tuning_models/cortexx925.h > +++ b/gcc/config/aarch64/tuning_models/cortexx925.h > @@ -135,6 +135,8 @@ static const sve_vec_cost cortexx925_sve_vector_cost = > operation more than a 64-bit gather. */ > 14, /* gather_load_x32_cost */ > 12, /* gather_load_x64_cost */ > + 42, /* gather_load_x32_init_cost */ > + 24, /* gather_load_x64_init_cost */ > 1 /* scatter_store_elt_cost */ > }; > > diff --git a/gcc/config/aarch64/tuning_models/generic.h > b/gcc/config/aarch64/tuning_models/generic.h > index > 2b1f68b3052117814161a32f426422736ad6462b..101969bdbb9ccf7eafbd9a1cd6e25f0b584fb261 > 100644 > --- a/gcc/config/aarch64/tuning_models/generic.h > +++ b/gcc/config/aarch64/tuning_models/generic.h > @@ -105,6 +105,8 @@ static const sve_vec_cost generic_sve_vector_cost = > 2, /* fadda_f64_cost */ > 4, /* gather_load_x32_cost */ > 2, /* gather_load_x64_cost */ > + 12, /* gather_load_x32_init_cost */ > + 4, /* gather_load_x64_init_cost */ > 1 /* scatter_store_elt_cost */ > }; > > diff --git a/gcc/config/aarch64/tuning_models/generic_armv8_a.h > b/gcc/config/aarch64/tuning_models/generic_armv8_a.h > index > b38b9a8c5cad7d12aa38afdb610a14a25e755010..b5088afe068aa4be7f9dd614cfdd2a51fa96e524 > 100644 > --- a/gcc/config/aarch64/tuning_models/generic_armv8_a.h > +++ b/gcc/config/aarch64/tuning_models/generic_armv8_a.h > @@ -106,6 +106,8 @@ static const sve_vec_cost generic_armv8_a_sve_vector_cost > = > 2, /* fadda_f64_cost */ > 4, /* gather_load_x32_cost */ > 2, /* gather_load_x64_cost */ > + 12, /* gather_load_x32_init_cost */ > + 4, /* gather_load_x64_init_cost */ > 1 /* scatter_store_elt_cost */ > }; > > diff --git a/gcc/config/aarch64/tuning_models/generic_armv9_a.h > b/gcc/config/aarch64/tuning_models/generic_armv9_a.h > index > 7156dbe5787e831bc4343deb7d7b88e9823fc1bc..999985ed40f694f2681779d940bdb282f289b8e3 > 100644 > --- a/gcc/config/aarch64/tuning_models/generic_armv9_a.h > +++ b/gcc/config/aarch64/tuning_models/generic_armv9_a.h > @@ -136,6 +136,8 @@ static const sve_vec_cost generic_armv9_a_sve_vector_cost > = > operation more than a 64-bit gather. */ > 14, /* gather_load_x32_cost */ > 12, /* gather_load_x64_cost */ > + 42, /* gather_load_x32_init_cost */ > + 24, /* gather_load_x64_init_cost */ > 3 /* scatter_store_elt_cost */ > }; > > diff --git a/gcc/config/aarch64/tuning_models/neoverse512tvb.h > b/gcc/config/aarch64/tuning_models/neoverse512tvb.h > index > 825c6a64990b72cda3641737957dc94d75db1509..d2a0b647791de8fca6d7684849d2ab1e9104b045 > 100644 > --- a/gcc/config/aarch64/tuning_models/neoverse512tvb.h > +++ b/gcc/config/aarch64/tuning_models/neoverse512tvb.h > @@ -79,6 +79,8 @@ static const sve_vec_cost neoverse512tvb_sve_vector_cost = > operation more than a 64-bit gather. */ > 14, /* gather_load_x32_cost */ > 12, /* gather_load_x64_cost */ > + 42, /* gather_load_x32_init_cost */ > + 24, /* gather_load_x64_init_cost */ > 3 /* scatter_store_elt_cost */ > }; > > diff --git a/gcc/config/aarch64/tuning_models/neoversen2.h > b/gcc/config/aarch64/tuning_models/neoversen2.h > index > d41e714aa045266ecae62a36ed02dfbfb7597c3a..1a5b66901b5c3fb78f87fee40236957139644585 > 100644 > --- a/gcc/config/aarch64/tuning_models/neoversen2.h > +++ b/gcc/config/aarch64/tuning_models/neoversen2.h > @@ -135,6 +135,8 @@ static const sve_vec_cost neoversen2_sve_vector_cost = > operation more than a 64-bit gather. */ > 14, /* gather_load_x32_cost */ > 12, /* gather_load_x64_cost */ > + 42, /* gather_load_x32_init_cost */ > + 24, /* gather_load_x64_init_cost */ > 3 /* scatter_store_elt_cost */ > }; > > diff --git a/gcc/config/aarch64/tuning_models/neoversen3.h > b/gcc/config/aarch64/tuning_models/neoversen3.h > index > 36f770c0a14fc127c75a60cd37048d46c3b069c7..cfd5060e6b64a0433de41b03cde886da119d9a1c > 100644 > --- a/gcc/config/aarch64/tuning_models/neoversen3.h > +++ b/gcc/config/aarch64/tuning_models/neoversen3.h > @@ -135,6 +135,8 @@ static const sve_vec_cost neoversen3_sve_vector_cost = > operation more than a 64-bit gather. */ > 14, /* gather_load_x32_cost */ > 12, /* gather_load_x64_cost */ > + 42, /* gather_load_x32_init_cost */ > + 24, /* gather_load_x64_init_cost */ > 1 /* scatter_store_elt_cost */ > }; > > diff --git a/gcc/config/aarch64/tuning_models/neoversev1.h > b/gcc/config/aarch64/tuning_models/neoversev1.h > index > 0fc41ce6a41b3135fa06d2bda1f517fdf4f8dbcf..705ed025730f6683109a4796c6eefa55b437cec9 > 100644 > --- a/gcc/config/aarch64/tuning_models/neoversev1.h > +++ b/gcc/config/aarch64/tuning_models/neoversev1.h > @@ -126,6 +126,8 @@ static const sve_vec_cost neoversev1_sve_vector_cost = > 8, /* fadda_f64_cost */ > 32, /* gather_load_x32_cost */ > 16, /* gather_load_x64_cost */ > + 96, /* gather_load_x32_init_cost */ > + 32, /* gather_load_x64_init_cost */ > 3 /* scatter_store_elt_cost */ > }; > > diff --git a/gcc/config/aarch64/tuning_models/neoversev2.h > b/gcc/config/aarch64/tuning_models/neoversev2.h > index > c9c3019dd01a98bc20a76e8455fb59ff24a9ff6c..47908636b0f4c3eadd5848b590fd079c1c04aa10 > 100644 > --- a/gcc/config/aarch64/tuning_models/neoversev2.h > +++ b/gcc/config/aarch64/tuning_models/neoversev2.h > @@ -135,6 +135,8 @@ static const sve_vec_cost neoversev2_sve_vector_cost = > operation more than a 64-bit gather. */ > 14, /* gather_load_x32_cost */ > 12, /* gather_load_x64_cost */ > + 42, /* gather_load_x32_init_cost */ > + 24, /* gather_load_x64_init_cost */ > 3 /* scatter_store_elt_cost */ > }; > > diff --git a/gcc/config/aarch64/tuning_models/neoversev3.h > b/gcc/config/aarch64/tuning_models/neoversev3.h > index > c602d067c7116cf6b081caeae8d36f9969e06d8d..c91e8c829532f9236de0102770e5c6b94e83da9a > 100644 > --- a/gcc/config/aarch64/tuning_models/neoversev3.h > +++ b/gcc/config/aarch64/tuning_models/neoversev3.h > @@ -135,6 +135,8 @@ static const sve_vec_cost neoversev3_sve_vector_cost = > operation more than a 64-bit gather. */ > 14, /* gather_load_x32_cost */ > 12, /* gather_load_x64_cost */ > + 42, /* gather_load_x32_init_cost */ > + 24, /* gather_load_x64_init_cost */ > 1 /* scatter_store_elt_cost */ > }; > > diff --git a/gcc/config/aarch64/tuning_models/neoversev3ae.h > b/gcc/config/aarch64/tuning_models/neoversev3ae.h > index > 96d7ccf03cd96056d09676d908c63a25e3da6765..61e439326eb6f983abf8574e657cfbb0c2f9bb33 > 100644 > --- a/gcc/config/aarch64/tuning_models/neoversev3ae.h > +++ b/gcc/config/aarch64/tuning_models/neoversev3ae.h > @@ -135,6 +135,8 @@ static const sve_vec_cost neoversev3ae_sve_vector_cost = > operation more than a 64-bit gather. */ > 14, /* gather_load_x32_cost */ > 12, /* gather_load_x64_cost */ > + 42, /* gather_load_x32_init_cost */ > + 24, /* gather_load_x64_init_cost */ > 1 /* scatter_store_elt_cost */ > }; > > <rb18671.patch>