This patch is depending on LEN_MASK_{LOAD,STORE} patch:
https://gcc.gnu.org/pipermail/gcc-patches/2023-June/622742.html
After enabling the LEN_MASK_{LOAD,STORE}, I notice that there is a case that
VSETVL PASS need to be optimized:
void
f (int32_t *__restrict a,
int32_t *__restrict b,
int32_t *__restrict cond,
int n)
{
for (int i = 0; i < 8; i++)
if (cond[i])
a[i] = b[i];
}
Before this patch:
f:
vsetivli a5,8,e8,mf4,tu,mu --> Propagate "8" to the following
vsetvl
vsetvli zero,a5,e32,m1,ta,ma
vle32.v v0,0(a2)
vsetvli a6,zero,e32,m1,ta,ma
li a3,8
vmsne.vi v0,v0,0
vsetvli zero,a5,e32,m1,ta,ma
vle32.v v1,0(a1),v0.t
vse32.v v1,0(a0),v0.t
sub a4,a3,a5
beq a3,a5,.L6
slli a5,a5,2
add a2,a2,a5
add a1,a1,a5
add a0,a0,a5
vsetvli a5,a4,e8,mf4,tu,mu --> Propagate "a4" to the following
vsetvl
vsetvli zero,a5,e32,m1,ta,ma
vle32.v v0,0(a2)
vsetvli a6,zero,e32,m1,ta,ma
vmsne.vi v0,v0,0
vsetvli zero,a5,e32,m1,ta,ma
vle32.v v1,0(a1),v0.t
vse32.v v1,0(a0),v0.t
.L6:
ret
Current VSETLV PASS only enable AVL propagation of VLMAX AVL ("zero").
Now, we enable AVL propagation of immediate && conservative non-VLMAX.
After this patch:
f:
vsetivli a5,8,e8,mf4,ta,ma
vle32.v v0,0(a2)
vsetvli a6,zero,e32,m1,ta,ma
li a3,8
vmsne.vi v0,v0,0
vsetivli zero,8,e32,m1,ta,ma
vle32.v v1,0(a1),v0.t
vse32.v v1,0(a0),v0.t
sub a4,a3,a5
beq a3,a5,.L6
slli a5,a5,2
vsetvli a4,a4,e8,mf4,ta,ma
add a2,a2,a5
vle32.v v0,0(a2)
add a1,a1,a5
vsetvli a6,zero,e32,m1,ta,ma
add a0,a0,a5
vmsne.vi v0,v0,0
vsetvli zero,a4,e32,m1,ta,ma
vle32.v v1,0(a1),v0.t
vse32.v v1,0(a0),v0.t
.L6:
ret
gcc/ChangeLog:
* config/riscv/riscv-vsetvl.cc (vector_insn_info::parse_insn): Ehance
AVL propagation.
* config/riscv/riscv-vsetvl.h: New function.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/rvv/autovec/partial/select_vl-1.c: Add dump checks.
* gcc.target/riscv/rvv/autovec/partial/select_vl-2.c: New test.
