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d1eacedc6d
Notice we have this following situation:
vsetivli zero,4,e32,m1,ta,ma
vlseg4e32.v v4,(a5)
vlseg4e32.v v12,(a3)
vsetvli a5,zero,e32,m1,tu,ma ---> This is redundant since VLMAX AVL = 4 when it is fixed-vlmax
vfadd.vf v3,v13,fa0
vfadd.vf v1,v12,fa1
vfmul.vv v17,v3,v5
vfmul.vv v16,v1,v5
The rootcause is that we transform COND_LEN_xxx into VLMAX AVL when len == NUNITS blindly.
However, we don't need to transform all of them since when len is range of [0,31], we don't need to
consume scalar registers.
After this patch:
vsetivli zero,4,e32,m1,tu,ma
addi a4,a5,400
vlseg4e32.v v12,(a3)
vfadd.vf v3,v13,fa0
vfadd.vf v1,v12,fa1
vlseg4e32.v v4,(a4)
vfadd.vf v2,v14,fa1
vfmul.vv v17,v3,v5
vfmul.vv v16,v1,v5
Tested on both RV32 and RV64 no regression.
Ok for trunk ?
gcc/ChangeLog:
* config/riscv/riscv-v.cc (is_vlmax_len_p): New function.
(expand_load_store): Disallow transformation into VLMAX when len is in range of [0,31]
(expand_cond_len_op): Ditto.
(expand_gather_scatter): Ditto.
(expand_lanes_load_store): Ditto.
(expand_fold_extract_last): Ditto.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/rvv/autovec/post-ra-avl.c: Adapt test.
* gcc.target/riscv/rvv/base/vf_avl-2.c: New test.
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