On Fri, Jul 11, 2025 at 11:03 AM Robin Dapp <rdapp....@gmail.com> wrote:
>
> This patch adds an is_gather_scatter argument to the
> support_vector_misalignment hook. All targets but riscv do not care
> about alignment for gather/scatter so return true for is_gather_scatter.
OK.
> gcc/ChangeLog:
>
> * config/aarch64/aarch64.cc
> (aarch64_builtin_support_vector_misalignment):
> Return true for gather/scatter.
> * config/arm/arm.cc (arm_builtin_support_vector_misalignment):
> Ditto.
> * config/epiphany/epiphany.cc (epiphany_support_vector_misalignment):
> Ditto.
> * config/gcn/gcn.cc (gcn_vectorize_support_vector_misalignment):
> Ditto.
> * config/loongarch/loongarch.cc
> (loongarch_builtin_support_vector_misalignment):
> Ditto.
> * config/riscv/riscv.cc (riscv_support_vector_misalignment):
> Add gather/scatter argument.
> * config/rs6000/rs6000.cc
> (rs6000_builtin_support_vector_misalignment):
> Return true for gather/scatter.
> * config/s390/s390.cc (s390_support_vector_misalignment):
> Ditto.
> * doc/tm.texi: Add argument.
> * target.def: Ditto.
> * targhooks.cc (default_builtin_support_vector_misalignment):
> Ditto.
> * targhooks.h (default_builtin_support_vector_misalignment):
> Ditto.
> * tree-vect-data-refs.cc (vect_supportable_dr_alignment):
> Ditto.
> ---
> gcc/config/aarch64/aarch64.cc | 12 +++++++++---
> gcc/config/arm/arm.cc | 12 +++++++++---
> gcc/config/epiphany/epiphany.cc | 8 ++++++--
> gcc/config/gcn/gcn.cc | 6 +++++-
> gcc/config/loongarch/loongarch.cc | 8 ++++++--
> gcc/config/riscv/riscv.cc | 29 +++++++++++++++++++++++------
> gcc/config/rs6000/rs6000.cc | 6 +++++-
> gcc/config/s390/s390.cc | 6 ++++--
> gcc/doc/tm.texi | 8 +++++---
> gcc/target.def | 14 +++++++++-----
> gcc/targhooks.cc | 2 ++
> gcc/targhooks.h | 2 +-
> gcc/tree-vect-data-refs.cc | 2 +-
> 13 files changed, 85 insertions(+), 30 deletions(-)
>
> diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
> index 10b8ed5d387..0162c724cd2 100644
> --- a/gcc/config/aarch64/aarch64.cc
> +++ b/gcc/config/aarch64/aarch64.cc
> @@ -356,7 +356,8 @@ static int aarch64_address_cost (rtx, machine_mode,
> addr_space_t, bool);
> static bool aarch64_builtin_support_vector_misalignment (machine_mode mode,
> const_tree type,
> int misalignment,
> - bool is_packed);
> + bool is_packed,
> + bool
> is_gather_scatter);
> static machine_mode aarch64_simd_container_mode (scalar_mode, poly_int64);
> static bool aarch64_print_address_internal (FILE*, machine_mode, rtx,
> aarch64_addr_query_type);
> @@ -24401,10 +24402,14 @@ aarch64_simd_vector_alignment_reachable (const_tree
> type, bool is_packed)
> static bool
> aarch64_builtin_support_vector_misalignment (machine_mode mode,
> const_tree type, int
> misalignment,
> - bool is_packed)
> + bool is_packed,
> + bool is_gather_scatter)
> {
> if (TARGET_SIMD && STRICT_ALIGNMENT)
> {
> + if (is_gather_scatter)
> + return true;
> +
> /* Return if movmisalign pattern is not supported for this mode. */
> if (optab_handler (movmisalign_optab, mode) == CODE_FOR_nothing)
> return false;
> @@ -24414,7 +24419,8 @@ aarch64_builtin_support_vector_misalignment
> (machine_mode mode,
> return false;
> }
> return default_builtin_support_vector_misalignment (mode, type,
> misalignment,
> - is_packed);
> + is_packed,
> + is_gather_scatter);
> }
>
> /* If VALS is a vector constant that can be loaded into a register
> diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc
> index bde06f3fa86..29b45ae96bd 100644
> --- a/gcc/config/arm/arm.cc
> +++ b/gcc/config/arm/arm.cc
> @@ -289,7 +289,8 @@ static bool arm_vector_alignment_reachable (const_tree
> type, bool is_packed);
> static bool arm_builtin_support_vector_misalignment (machine_mode mode,
> const_tree type,
> int misalignment,
> - bool is_packed);
> + bool is_packed,
> + bool is_gather_scatter);
> static void arm_conditional_register_usage (void);
> static enum flt_eval_method arm_excess_precision (enum
> excess_precision_type);
> static reg_class_t arm_preferred_rename_class (reg_class_t rclass);
> @@ -30661,12 +30662,16 @@ arm_vector_alignment_reachable (const_tree type,
> bool is_packed)
> static bool
> arm_builtin_support_vector_misalignment (machine_mode mode,
> const_tree type, int misalignment,
> - bool is_packed)
> + bool is_packed,
> + bool is_gather_scatter)
> {
> if (TARGET_NEON && !BYTES_BIG_ENDIAN && unaligned_access)
> {
> HOST_WIDE_INT align = TYPE_ALIGN_UNIT (type);
>
> + if (is_gather_scatter)
> + return true;
> +
> if (is_packed)
> return align == 1;
>
> @@ -30683,7 +30688,8 @@ arm_builtin_support_vector_misalignment (machine_mode
> mode,
> }
>
> return default_builtin_support_vector_misalignment (mode, type,
> misalignment,
> - is_packed);
> + is_packed,
> + is_gather_scatter);
> }
>
> static void
> diff --git a/gcc/config/epiphany/epiphany.cc b/gcc/config/epiphany/epiphany.cc
> index 16626f85f7e..f53a643575b 100644
> --- a/gcc/config/epiphany/epiphany.cc
> +++ b/gcc/config/epiphany/epiphany.cc
> @@ -2816,12 +2816,16 @@ epiphany_vector_alignment_reachable (const_tree type,
> bool is_packed)
>
> static bool
> epiphany_support_vector_misalignment (machine_mode mode, const_tree type,
> - int misalignment, bool is_packed)
> + int misalignment, bool is_packed,
> + bool is_gather_scatter)
> {
> + if (is_gather_scatter)
> + return true;
> if (GET_MODE_SIZE (mode) == 8 && misalignment % 4 == 0)
> return true;
> return default_builtin_support_vector_misalignment (mode, type,
> misalignment,
> - is_packed);
> + is_packed,
> + is_gather_scatter);
> }
>
> /* STRUCTURE_SIZE_BOUNDARY seems a bit crude in how it enlarges small
> diff --git a/gcc/config/gcn/gcn.cc b/gcc/config/gcn/gcn.cc
> index 0ce5a29fbb5..72203dcccd4 100644
> --- a/gcc/config/gcn/gcn.cc
> +++ b/gcc/config/gcn/gcn.cc
> @@ -5315,8 +5315,12 @@ gcn_preferred_vector_alignment (const_tree type)
> static bool
> gcn_vectorize_support_vector_misalignment (machine_mode ARG_UNUSED (mode),
> const_tree type, int misalignment,
> - bool is_packed)
> + bool is_packed,
> + bool is_gather_scatter)
> {
> + if (is_gather_scatter)
> + return true;
> +
> if (is_packed)
> return false;
>
> diff --git a/gcc/config/loongarch/loongarch.cc
> b/gcc/config/loongarch/loongarch.cc
> index f62e4163c71..39a56dd6d22 100644
> --- a/gcc/config/loongarch/loongarch.cc
> +++ b/gcc/config/loongarch/loongarch.cc
> @@ -11116,17 +11116,21 @@ static bool
> loongarch_builtin_support_vector_misalignment (machine_mode mode,
> const_tree type,
> int misalignment,
> - bool is_packed)
> + bool is_packed,
> + bool is_gather_scatter)
> {
> if ((ISA_HAS_LSX || ISA_HAS_LASX) && STRICT_ALIGNMENT)
> {
> + if (is_gather_scatter)
> + return true;
> if (optab_handler (movmisalign_optab, mode) == CODE_FOR_nothing)
> return false;
> if (misalignment == -1)
> return false;
> }
> return default_builtin_support_vector_misalignment (mode, type,
> misalignment,
> - is_packed);
> + is_packed,
> + is_gather_scatter);
> }
>
> /* Return a PARALLEL containing NELTS elements, with element I equal
> diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
> index a4428f0e96d..dcb0291d79d 100644
> --- a/gcc/config/riscv/riscv.cc
> +++ b/gcc/config/riscv/riscv.cc
> @@ -12608,14 +12608,31 @@ riscv_estimated_poly_value (poly_int64 val,
> /* Return true if the vector misalignment factor is supported by the
> target. */
> bool
> -riscv_support_vector_misalignment (machine_mode mode,
> - const_tree type ATTRIBUTE_UNUSED,
> - int misalignment,
> - bool is_packed ATTRIBUTE_UNUSED)
> +riscv_support_vector_misalignment (machine_mode mode, const_tree type,
> + int misalignment, bool is_packed,
> + bool is_gather_scatter)
> {
> - /* Depend on movmisalign pattern. */
> + /* IS_PACKED is true if the corresponding scalar element is not naturally
> + aligned. If the misalignment is unknown and the the access is packed
> + we defer to the default hook which will check if movmisalign is present.
> + Movmisalign, in turn, depends on TARGET_VECTOR_MISALIGN_SUPPORTED. */
> + if (misalignment == DR_MISALIGNMENT_UNKNOWN)
> + {
> + if (!is_packed)
> + return true;
> + }
> + else
> + {
> + /* If we know that misalignment is a multiple of the element size,
> we're
> + good. */
> + if (misalignment % TYPE_ALIGN_UNIT (type) == 0)
> + return true;
> + }
> +
> + /* Otherwise fall back to movmisalign again. */
> return default_builtin_support_vector_misalignment (mode, type,
> misalignment,
> - is_packed);
> + is_packed,
> + is_gather_scatter);
> }
>
> /* Implement TARGET_VECTORIZE_GET_MASK_MODE. */
> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
> index 7ee26e52b13..a7a5aa5e289 100644
> --- a/gcc/config/rs6000/rs6000.cc
> +++ b/gcc/config/rs6000/rs6000.cc
> @@ -4951,10 +4951,14 @@ static bool
> rs6000_builtin_support_vector_misalignment (machine_mode mode,
> const_tree type,
> int misalignment,
> - bool is_packed)
> + bool is_packed,
> + bool is_gather_scatter)
> {
> if (TARGET_VSX)
> {
> + if (is_gather_scatter)
> + return true;
> +
> if (TARGET_EFFICIENT_UNALIGNED_VSX)
> return true;
>
> diff --git a/gcc/config/s390/s390.cc b/gcc/config/s390/s390.cc
> index de9c15c7bd4..66e843f2823 100644
> --- a/gcc/config/s390/s390.cc
> +++ b/gcc/config/s390/s390.cc
> @@ -17334,13 +17334,15 @@ static bool
> s390_support_vector_misalignment (machine_mode mode ATTRIBUTE_UNUSED,
> const_tree type ATTRIBUTE_UNUSED,
> int misalignment ATTRIBUTE_UNUSED,
> - bool is_packed ATTRIBUTE_UNUSED)
> + bool is_packed ATTRIBUTE_UNUSED,
> + bool is_gather_scatter ATTRIBUTE_UNUSED)
> {
> if (TARGET_VX)
> return true;
>
> return default_builtin_support_vector_misalignment (mode, type,
> misalignment,
> - is_packed);
> + is_packed,
> + is_gather_scatter);
> }
>
> /* The vector ABI requires vector types to be aligned on an 8 byte
> diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
> index 5e305643b3a..928578bcc03 100644
> --- a/gcc/doc/tm.texi
> +++ b/gcc/doc/tm.texi
> @@ -6382,12 +6382,14 @@ return type of the vectorized function shall be of
> vector type
> @var{vec_type_out} and the argument types should be @var{vec_type_in}.
> @end deftypefn
>
> -@deftypefn {Target Hook} bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT
> (machine_mode @var{mode}, const_tree @var{type}, int @var{misalignment}, bool
> @var{is_packed})
> +@deftypefn {Target Hook} bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT
> (machine_mode @var{mode}, const_tree @var{type}, int @var{misalignment}, bool
> @var{is_packed}, bool @var{is_gather_scatter})
> This hook should return true if the target supports misaligned vector
> store/load of a specific factor denoted in the @var{misalignment}
> parameter. The vector store/load should be of machine mode @var{mode} and
> -the elements in the vectors should be of type @var{type}. @var{is_packed}
> -parameter is true if the memory access is defined in a packed struct.
> +the elements in the vectors should be of type @var{type}. The
> +@var{is_packed} parameter is true if the misalignment is unknown and the
> +memory access is defined in a packed struct. @var{is_gather_scatter} is true
> +if the load/store is a gather or scatter.
> @end deftypefn
>
> @deftypefn {Target Hook} machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE
> (scalar_mode @var{mode})
> diff --git a/gcc/target.def b/gcc/target.def
> index 38903eb567a..273a2f2e6bb 100644
> --- a/gcc/target.def
> +++ b/gcc/target.def
> @@ -1918,17 +1918,21 @@ implementation approaches itself.",
> NULL)
>
> /* Return true if the target supports misaligned store/load of a
> - specific factor denoted in the third parameter. The last parameter
> - is true if the access is defined in a packed struct. */
> + specific factor denoted in the third parameter. The second to the last
> + parameter is true if the access is defined in a packed struct and
> + the last parameter is true if the access is a gather/scatter. */
> DEFHOOK
> (support_vector_misalignment,
> "This hook should return true if the target supports misaligned vector\n\
> store/load of a specific factor denoted in the @var{misalignment}\n\
> parameter. The vector store/load should be of machine mode @var{mode} and\n\
> -the elements in the vectors should be of type @var{type}. @var{is_packed}\n\
> -parameter is true if the memory access is defined in a packed struct.",
> +the elements in the vectors should be of type @var{type}. The\n\
> +@var{is_packed} parameter is true if the misalignment is unknown and the\n\
> +memory access is defined in a packed struct. @var{is_gather_scatter} is
> true\n\
> +if the load/store is a gather or scatter.",
> bool,
> - (machine_mode mode, const_tree type, int misalignment, bool is_packed),
> + (machine_mode mode, const_tree type, int misalignment, bool is_packed,
> + bool is_gather_scatter),
> default_builtin_support_vector_misalignment)
>
> /* Returns the preferred mode for SIMD operations for the specified
> diff --git a/gcc/targhooks.cc b/gcc/targhooks.cc
> index c79458e374e..e723bbbc4df 100644
> --- a/gcc/targhooks.cc
> +++ b/gcc/targhooks.cc
> @@ -1556,6 +1556,8 @@ default_builtin_support_vector_misalignment
> (machine_mode mode,
> int misalignment
> ATTRIBUTE_UNUSED,
> bool is_packed
> + ATTRIBUTE_UNUSED,
> + bool is_gather_scatter
> ATTRIBUTE_UNUSED)
> {
> if (optab_handler (movmisalign_optab, mode) != CODE_FOR_nothing)
> diff --git a/gcc/targhooks.h b/gcc/targhooks.h
> index f16b58798c2..3fa20af0e11 100644
> --- a/gcc/targhooks.h
> +++ b/gcc/targhooks.h
> @@ -114,7 +114,7 @@ extern bool default_builtin_vector_alignment_reachable
> (const_tree, bool);
> extern bool
> default_builtin_support_vector_misalignment (machine_mode mode,
> const_tree,
> - int, bool);
> + int, bool, bool);
> extern machine_mode default_preferred_simd_mode (scalar_mode mode);
> extern machine_mode default_split_reduction (machine_mode);
> extern unsigned int default_autovectorize_vector_modes (vector_modes *,
> bool);
> diff --git a/gcc/tree-vect-data-refs.cc b/gcc/tree-vect-data-refs.cc
> index 5b2cb537438..019f0b6ca36 100644
> --- a/gcc/tree-vect-data-refs.cc
> +++ b/gcc/tree-vect-data-refs.cc
> @@ -7490,7 +7490,7 @@ vect_supportable_dr_alignment (vec_info *vinfo,
> dr_vec_info *dr_info,
> if (misalignment == DR_MISALIGNMENT_UNKNOWN)
> is_packed = not_size_aligned (DR_REF (dr));
> if (targetm.vectorize.support_vector_misalignment (mode, type,
> misalignment,
> - is_packed))
> + is_packed, false))
> return dr_unaligned_supported;
>
> /* Unsupported. */
> --
> 2.50.0
>
