Generalise gather and scatter optabs

Programming / Compilers / GCC - rsandifo [138bc75d-0d04-0410-961f-82ee72b054a4] - 8 November 2019 08:32 EST

The gather and scatter optabs required the vector offset to be the integer equivalent of the vector mode being loaded or stored. This patch generalises them so that the two vectors can have different element sizes, although they still need to have the same number of elements.

One consequence of this is that it's possible (if unlikely) for two IFN_GATHER_LOADs to have the same arguments but different return types. E.g. the same scalar base and vector of 32-bit offsets could be used to load 8-bit elements and to load 16-bit elements. From just looking at the arguments, we could wrongly deduce that they're equivalent.

I know we saw this happen at one point with IFN_WHILE_ULT, and we dealt with it there by passing a zero of the return type as an extra argument. Doing the same here also makes the load and store functions have the same argument assignment.

For now this patch should be a no-op, but later SVE patches take advantage of the new flexibility.

2019-11-08 Richard Sandiford

- optabs.def (gather_load_optab, mask_gather_load_optab) (scatter_store_optab, mask_scatter_store_optab): Turn into conversion optabs, with the offset mode given explicitly.
- doc/md.texi: Update accordingly.
- config/aarch64/ (svld1_gather_impl::expand): Likewise. (svst1_scatter_impl::expand): Likewise.
- internal-fn.c (gather_load_direct, scatter_store_direct): Likewise. (expand_scatter_store_optab_fn): Likewise. (direct_gather_load_optab_supported_p): Likewise. (direct_scatter_store_optab_supported_p): Likewise. (expand_gather_load_optab_fn): Likewise. Expect the mask argument to be argument 4. (internal_fn_mask_index): Return 4 for IFN_MASK_GATHER_LOAD. (internal_gather_scatter_fn_supported_p): Replace the offset sign argument with the offset vector type. Require the two vector types to have the same number of elements but allow their element sizes to be different. Treat the optabs as conversion optabs.
- internal-fn.h (internal_gather_scatter_fn_supported_p): Update prototype accordingly.
- optabs-query.c (supports_at_least_one_mode_p): Replace with... (supports_vec_convert_optab_p): ...this new function. (supports_vec_gather_load_p): Update accordingly. (supports_vec_scatter_store_p): Likewise.
- tree-vectorizer.h (vect_gather_scatter_fn_p): Take a vec_info. Replace the offset sign and bits parameters with a scalar type tree.
- tree-vect-data-refs.c (vect_gather_scatter_fn_p): Likewise. Pass back the offset vector type instead of the scalar element type. Allow the offset to be wider than the memory elements. Search for an offset type that the target supports, stopping once we've reached the maximum of the element size and pointer size. Update call to internal_gather_scatter_fn_supported_p. (vect_check_gather_scatter): Update calls accordingly. When testing a new scale before knowing the final offset type, check whether the scale is supported for any signed or unsigned offset type. Check whether the target supports the source and target types of a conversion before deciding whether to look through the conversion. Record the chosen offset_vectype.
- tree-vect-patterns.c (vect_get_gather_scatter_offset_type): Delete. (vect_recog_gather_scatter_pattern): Get the scalar offset type directly from the gs_info's offset_vectype instead. Pass a zero of the result type to IFN_GATHER_LOAD and IFN_MASK_GATHER_LOAD.
- tree-vect-stmts.c (check_load_store_masking): Update call to internal_gather_scatter_fn_supported_p, passing the offset vector type recorded in the gs_info. (vect_truncate_gather_scatter_offset): Update call to
vect_check_gather_scatter, leaving it to search for a valid offset vector type. (vect_use_strided_gather_scatters_p): Convert the offset to the element type of the gs_info's offset_vectype. (vect_get_gather_scatter_ops): Get the offset vector type directly from the gs_info. (vect_get_strided_load_store_ops): Likewise. (vectorizable_load): Pass a zero of the result type to IFN_GATHER_LOAD and IFN_MASK_GATHER_LOAD.
- config/aarch64/ (gather_load): Rename to... (gather_load): ...this. (mask_gather_load): Rename to... (mask_gather_load): ...this. (scatter_store): Rename to... (scatter_store): ...this. (mask_scatter_store): Rename to... (mask_scatter_store): ...this.

e0caba1c092 Generalise gather and scatter optabs
gcc/ChangeLog | 66 ++++++++++++++++
gcc/config/aarch64/ | 10 ++-
gcc/config/aarch64/ | 20 ++---
gcc/doc/md.texi | 34 ++++----
gcc/internal-fn.c | 41 +++++-----
gcc/internal-fn.h | 2 +-
gcc/optabs-query.c | 16 ++--
gcc/optabs.def | 9 +--
gcc/tree-vect-data-refs.c | 101 ++++++++++++++----------
gcc/tree-vect-patterns.c | 33 ++------
gcc/tree-vect-stmts.c | 70 +++++++---------
gcc/tree-vectorizer.h | 4 +-
12 files changed, 230 insertions(+), 176 deletions(-)


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