| Message ID | 20210212150256.885-4-zhiwei_liu@c-sky.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | target/riscv: support packed extension v0.9.2 | expand |
On 2/12/21 7:02 AM, LIU Zhiwei wrote: > The overflow predication ((a - b) ^ a) & (a ^ b) & INT64_MIN is right. > However, when the predication is ture and a is 0, it should return maximum. > > Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com> > --- > target/riscv/vector_helper.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
On Fri, Feb 12, 2021 at 10:10 AM LIU Zhiwei <zhiwei_liu@c-sky.com> wrote: > > The overflow predication ((a - b) ^ a) & (a ^ b) & INT64_MIN is right. > However, when the predication is ture and a is 0, it should return maximum. > > Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com> Reviewed-by: Alistair Francis <alistair.francis@wdc.com> Alistair > --- > target/riscv/vector_helper.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c > index 9371d70f6b..9786f630b4 100644 > --- a/target/riscv/vector_helper.c > +++ b/target/riscv/vector_helper.c > @@ -2425,7 +2425,7 @@ int8_t ssub8(CPURISCVState *env, int vxrm, int8_t a, int8_t b) > { > int8_t res = a - b; > if ((res ^ a) & (a ^ b) & INT8_MIN) { > - res = a > 0 ? INT8_MAX : INT8_MIN; > + res = a >= 0 ? INT8_MAX : INT8_MIN; > env->vxsat = 0x1; > } > return res; > @@ -2435,7 +2435,7 @@ int16_t ssub16(CPURISCVState *env, int vxrm, int16_t a, int16_t b) > { > int16_t res = a - b; > if ((res ^ a) & (a ^ b) & INT16_MIN) { > - res = a > 0 ? INT16_MAX : INT16_MIN; > + res = a >= 0 ? INT16_MAX : INT16_MIN; > env->vxsat = 0x1; > } > return res; > @@ -2445,7 +2445,7 @@ int32_t ssub32(CPURISCVState *env, int vxrm, int32_t a, int32_t b) > { > int32_t res = a - b; > if ((res ^ a) & (a ^ b) & INT32_MIN) { > - res = a > 0 ? INT32_MAX : INT32_MIN; > + res = a >= 0 ? INT32_MAX : INT32_MIN; > env->vxsat = 0x1; > } > return res; > @@ -2455,7 +2455,7 @@ int64_t ssub64(CPURISCVState *env, int vxrm, int64_t a, int64_t b) > { > int64_t res = a - b; > if ((res ^ a) & (a ^ b) & INT64_MIN) { > - res = a > 0 ? INT64_MAX : INT64_MIN; > + res = a >= 0 ? INT64_MAX : INT64_MIN; > env->vxsat = 0x1; > } > return res; > -- > 2.17.1 >
diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c index 9371d70f6b..9786f630b4 100644 --- a/target/riscv/vector_helper.c +++ b/target/riscv/vector_helper.c @@ -2425,7 +2425,7 @@ int8_t ssub8(CPURISCVState *env, int vxrm, int8_t a, int8_t b) { int8_t res = a - b; if ((res ^ a) & (a ^ b) & INT8_MIN) { - res = a > 0 ? INT8_MAX : INT8_MIN; + res = a >= 0 ? INT8_MAX : INT8_MIN; env->vxsat = 0x1; } return res; @@ -2435,7 +2435,7 @@ int16_t ssub16(CPURISCVState *env, int vxrm, int16_t a, int16_t b) { int16_t res = a - b; if ((res ^ a) & (a ^ b) & INT16_MIN) { - res = a > 0 ? INT16_MAX : INT16_MIN; + res = a >= 0 ? INT16_MAX : INT16_MIN; env->vxsat = 0x1; } return res; @@ -2445,7 +2445,7 @@ int32_t ssub32(CPURISCVState *env, int vxrm, int32_t a, int32_t b) { int32_t res = a - b; if ((res ^ a) & (a ^ b) & INT32_MIN) { - res = a > 0 ? INT32_MAX : INT32_MIN; + res = a >= 0 ? INT32_MAX : INT32_MIN; env->vxsat = 0x1; } return res; @@ -2455,7 +2455,7 @@ int64_t ssub64(CPURISCVState *env, int vxrm, int64_t a, int64_t b) { int64_t res = a - b; if ((res ^ a) & (a ^ b) & INT64_MIN) { - res = a > 0 ? INT64_MAX : INT64_MIN; + res = a >= 0 ? INT64_MAX : INT64_MIN; env->vxsat = 0x1; } return res;
The overflow predication ((a - b) ^ a) & (a ^ b) & INT64_MIN is right. However, when the predication is ture and a is 0, it should return maximum. Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com> --- target/riscv/vector_helper.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)