Re: [PATCH v4 4/5] RISC-V: Add macro-fusion pair recog nition

Hi Jeff,

> On 7/29/2026 1:17 AM, Jin Ma wrote:
> > Add recognition for the following macro-fusion pairs:
> >
> >    RISCV_FUSE_SUB_SEQZ        - sub/subw + seqz/snez
> >    RISCV_FUSE_ADD_LD          - add type + integer load
> >    RISCV_FUSE_ADD_ST          - add type + integer store
> >    RISCV_FUSE_ADD_ANDI        - add/addi type + andi type
> >    RISCV_FUSE_ANDI_ADD        - andi type + add/addi type
> >    RISCV_FUSE_LOGIC_LOGIC     - logic + logic
> >    RISCV_FUSE_SLLI_SRLI       - slli/slliw + srli/srliw
> >    RISCV_FUSE_SRLI_ADD        - srli/srliw + add type
> >    RISCV_FUSE_PREINDEX_LD     - addi type + load
> >    RISCV_FUSE_PREINDEX_ST     - addi type + store
> >    RISCV_FUSE_POSTINDEX_LD    - load + addi type
> >    RISCV_FUSE_POSTINDEX_ST    - store + addi type
> >    RISCV_FUSE_LDST_PAIR_INC   - ascending integer load/store pair
> >    RISCV_FUSE_LDST_PAIR_DEC   - descending integer load/store pair
> >    RISCV_FUSE_FLDFST_PAIR_INC - ascending FP load/store pair
> >    RISCV_FUSE_FLDFST_PAIR_DEC - descending FP load/store pair
> >
> > Leave the pairs disabled by default and mark positive checks as XFAIL.
> >
> > gcc/ChangeLog:
> >
> >  * config/riscv/riscv-fusion.cc: Include insn-attr.h.
> >  (riscv_fusion_same_source_p, riscv_set_is_addw_p,
> >  riscv_set_is_word_add_p, riscv_set_is_addiw_p, riscv_insn_is_mv_li_p,
> >  riscv_insn_is_addi_type_p, riscv_insn_is_nonword_addi_type_p,
> >  riscv_insn_is_add_type_p, riscv_insn_is_add_addi_p,
> >  riscv_insn_is_sub_type_p, riscv_insn_is_andi_type_p,
> >  riscv_insn_is_logical_type_p, riscv_set_is_slli_p,
> >  riscv_set_is_slliw_p, riscv_set_is_srli_p, riscv_set_is_srliw_p,
> >  riscv_set_is_word_shift_p, riscv_fusion_extract_address,
> >  riscv_fusion_load_store, riscv_insn_is_load_store_type_p): New
> >  helper functions.
> >  (riscv_fuse_sub_seqz, riscv_fuse_add_andi, riscv_fuse_add_ldst_1,
> >  riscv_fuse_add_ld, riscv_fuse_add_st, riscv_fuse_andi_add,
> >  riscv_fuse_logic_logic, riscv_fuse_slli_srli, riscv_fuse_srli_add,
> >  riscv_fuse_preindex_ldst_1, riscv_fuse_preindex_ld,
> >  riscv_fuse_preindex_st, riscv_fuse_postindex_ldst_1,
> >  riscv_fuse_postindex_ld, riscv_fuse_postindex_st,
> >  riscv_fuse_ldst_pair_1, riscv_fuse_ldst_pair_inc,
> >  riscv_fuse_ldst_pair_dec, riscv_fuse_fldfst_pair_inc,
> >  riscv_fuse_fldfst_pair_dec): New function implementing the
> >  corresponding RISCV_FUSE_* pair.
> >  (riscv_fusion_table): Add entries for the new pairs.
> >  * config/riscv/riscv-protos.h (enum riscv_fusion_pairs): Add pair
> >  flags.
> This is getting pretty large and tedious to try and work through from a 
> review standpoint.  I hate to ask, but can we break this down into 
> individual cases to aid review?
>
> jeff

Yes, certainly.  I am sorry that this patch made the review harder.  I
had assumed that fewer patches would reduce the overall review work,
but overlooked that putting all the recognizers in one patch makes each
individual case harder to review.

I will split the patch by individual fusion case or closely related
fusion family, and place the necessary common helpers before the
relevant features.  This should make each patch independently
understandable and reviewable.  I apologize again for the extra work.

Thanks,
Jin