| Message ID | 20250124101452.2519171-1-max.chou@sifive.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | target/riscv: rvv: Fix unexpected behavior of vector reduction instructions when vl is 0 | expand |
On 1/24/25 7:14 AM, Max Chou wrote: > According to the Vector Reduction Operations section in the RISC-V "V" > Vector Extension spec, > "If vl=0, no operation is performed and the destination register is not > updated." > > The vd should be updated when vl is larger than 0. > Fixes: fe5c9ab1fc ("target/riscv: vector single-width integer reduction instructions") Fixes: f714361ed7 ("target/riscv: rvv-1.0: implement vstart CSR") > Signed-off-by: Max Chou <max.chou@sifive.com> Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com> > --- > target/riscv/vector_helper.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c > index 5386e3b97c5..7773df6a7c7 100644 > --- a/target/riscv/vector_helper.c > +++ b/target/riscv/vector_helper.c > @@ -4659,7 +4659,9 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, \ > } \ > s1 = OP(s1, (TD)s2); \ > } \ > - *((TD *)vd + HD(0)) = s1; \ > + if (vl > 0) { \ > + *((TD *)vd + HD(0)) = s1; \ > + } \ > env->vstart = 0; \ > /* set tail elements to 1s */ \ > vext_set_elems_1s(vd, vta, esz, vlenb); \ > @@ -4745,7 +4747,9 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, \ > } \ > s1 = OP(s1, (TD)s2, &env->fp_status); \ > } \ > - *((TD *)vd + HD(0)) = s1; \ > + if (vl > 0) { \ > + *((TD *)vd + HD(0)) = s1; \ > + } \ > env->vstart = 0; \ > /* set tail elements to 1s */ \ > vext_set_elems_1s(vd, vta, esz, vlenb); \
On Fri, Jan 24, 2025 at 8:16 PM Max Chou <max.chou@sifive.com> wrote: > > According to the Vector Reduction Operations section in the RISC-V "V" > Vector Extension spec, > "If vl=0, no operation is performed and the destination register is not > updated." > > The vd should be updated when vl is larger than 0. > > Signed-off-by: Max Chou <max.chou@sifive.com> Thanks! Applied to riscv-to-apply.next Alistair > --- > target/riscv/vector_helper.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c > index 5386e3b97c5..7773df6a7c7 100644 > --- a/target/riscv/vector_helper.c > +++ b/target/riscv/vector_helper.c > @@ -4659,7 +4659,9 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, \ > } \ > s1 = OP(s1, (TD)s2); \ > } \ > - *((TD *)vd + HD(0)) = s1; \ > + if (vl > 0) { \ > + *((TD *)vd + HD(0)) = s1; \ > + } \ > env->vstart = 0; \ > /* set tail elements to 1s */ \ > vext_set_elems_1s(vd, vta, esz, vlenb); \ > @@ -4745,7 +4747,9 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, \ > } \ > s1 = OP(s1, (TD)s2, &env->fp_status); \ > } \ > - *((TD *)vd + HD(0)) = s1; \ > + if (vl > 0) { \ > + *((TD *)vd + HD(0)) = s1; \ > + } \ > env->vstart = 0; \ > /* set tail elements to 1s */ \ > vext_set_elems_1s(vd, vta, esz, vlenb); \ > -- > 2.34.1 > >
diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c index 5386e3b97c5..7773df6a7c7 100644 --- a/target/riscv/vector_helper.c +++ b/target/riscv/vector_helper.c @@ -4659,7 +4659,9 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, \ } \ s1 = OP(s1, (TD)s2); \ } \ - *((TD *)vd + HD(0)) = s1; \ + if (vl > 0) { \ + *((TD *)vd + HD(0)) = s1; \ + } \ env->vstart = 0; \ /* set tail elements to 1s */ \ vext_set_elems_1s(vd, vta, esz, vlenb); \ @@ -4745,7 +4747,9 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, \ } \ s1 = OP(s1, (TD)s2, &env->fp_status); \ } \ - *((TD *)vd + HD(0)) = s1; \ + if (vl > 0) { \ + *((TD *)vd + HD(0)) = s1; \ + } \ env->vstart = 0; \ /* set tail elements to 1s */ \ vext_set_elems_1s(vd, vta, esz, vlenb); \
According to the Vector Reduction Operations section in the RISC-V "V" Vector Extension spec, "If vl=0, no operation is performed and the destination register is not updated." The vd should be updated when vl is larger than 0. Signed-off-by: Max Chou <max.chou@sifive.com> --- target/riscv/vector_helper.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)