On 11/4/24 6:09 AM, Craig Blackmore wrote:
For fast unaligned access targets, by pieces uses up to UNITS_PER_WORD
size pieces resulting in more store instructions than needed. For
example gcc.target/riscv/rvv/base/setmem-2.c:f1 built with
`-O3 -march=rv64gcv -mtune=thead-c906`:
```
f1:
vsetivli zero,8,e8,mf2,ta,ma
vmv.v.x v1,a1
vsetivli zero,0,e32,mf2,ta,ma
sb a1,14(a0)
vmv.x.s a4,v1
vsetivli zero,8,e16,m1,ta,ma
vmv.x.s a5,v1
vse8.v v1,0(a0)
sw a4,8(a0)
sh a5,12(a0)
ret
```
The slow unaligned access version built with `-O3 -march=rv64gcv` used
15 sb instructions:
```
f1:
sb a1,0(a0)
sb a1,1(a0)
sb a1,2(a0)
sb a1,3(a0)
sb a1,4(a0)
sb a1,5(a0)
sb a1,6(a0)
sb a1,7(a0)
sb a1,8(a0)
sb a1,9(a0)
sb a1,10(a0)
sb a1,11(a0)
sb a1,12(a0)
sb a1,13(a0)
sb a1,14(a0)
ret
```
After this patch, the following is generated in both cases:
```
f1:
vsetivli zero,15,e8,m1,ta,ma
vmv.v.x v1,a1
vse8.v v1,0(a0)
ret
```
gcc/ChangeLog:
* config/riscv/riscv.cc (riscv_use_by_pieces_infrastructure_p):
New function.
(TARGET_USE_BY_PIECES_INFRASTRUCTURE_P): Define.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/rvv/autovec/pr113469.c: Expect mf2 setmem.
* gcc.target/riscv/rvv/base/setmem-2.c: Update f1 to expect
straight-line vector memset.
* gcc.target/riscv/rvv/base/setmem-3.c: Likewise.
Pushed to the trunk.
Now I just need to make a trivial adjustment to my glibc patches and
start blasting them out :-)
jeff
