From: Alistair Francis <alistair23@gmail.com>
To: LIU Zhiwei <zhiwei_liu@c-sky.com>
Cc: Richard Henderson <richard.henderson@linaro.org>,
Palmer Dabbelt <palmer@dabbelt.com>,
"open list:RISC-V" <qemu-riscv@nongnu.org>,
"qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>
Subject: Re: [PATCH 03/38] target/riscv: Fixup saturate subtract function
Date: Tue, 9 Mar 2021 09:11:26 -0500 [thread overview]
Message-ID: <CAKmqyKNhnVLNNuNVPFjjvM4OMFekJSu_dn3-sB6Ph7PAkvfTXg@mail.gmail.com> (raw)
In-Reply-To: <20210212150256.885-4-zhiwei_liu@c-sky.com>
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
>
next prev parent reply other threads:[~2021-03-09 14:15 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-12 15:02 [PATCH 00/38] target/riscv: support packed extension v0.9.2 LIU Zhiwei
2021-02-12 15:02 ` [PATCH 01/38] target/riscv: implementation-defined constant parameters LIU Zhiwei
2021-03-09 14:08 ` Alistair Francis
2021-02-12 15:02 ` [PATCH 02/38] target/riscv: Hoist vector functions LIU Zhiwei
2021-03-09 14:10 ` Alistair Francis
2021-02-12 15:02 ` [PATCH 03/38] target/riscv: Fixup saturate subtract function LIU Zhiwei
2021-02-12 18:52 ` Richard Henderson
2021-03-09 14:11 ` Alistair Francis [this message]
2021-02-12 15:02 ` [PATCH 04/38] target/riscv: 16-bit Addition & Subtraction Instructions LIU Zhiwei
2021-02-12 18:03 ` Richard Henderson
2021-02-18 8:39 ` LIU Zhiwei
2021-02-18 16:20 ` Richard Henderson
2021-02-12 19:02 ` Richard Henderson
2021-02-18 8:47 ` LIU Zhiwei
2021-02-18 16:21 ` Richard Henderson
2021-02-12 15:02 ` [PATCH 05/38] target/riscv: 8-bit Addition & Subtraction Instruction LIU Zhiwei
2021-03-15 21:22 ` Alistair Francis
2021-05-24 1:00 ` Palmer Dabbelt
2021-05-26 5:43 ` LIU Zhiwei
2021-05-26 6:15 ` Palmer Dabbelt
2021-02-12 15:02 ` [PATCH 06/38] target/riscv: SIMD 16-bit Shift Instructions LIU Zhiwei
2021-03-15 21:25 ` Alistair Francis
2021-03-16 2:40 ` LIU Zhiwei
2021-03-16 19:54 ` Alistair Francis
2021-03-17 2:30 ` LIU Zhiwei
2021-03-17 20:39 ` Alistair Francis
2021-02-12 15:02 ` [PATCH 07/38] target/riscv: SIMD 8-bit " LIU Zhiwei
2021-03-15 21:27 ` Alistair Francis
2021-05-24 4:46 ` Palmer Dabbelt
2021-02-12 15:02 ` [PATCH 08/38] target/riscv: SIMD 16-bit Compare Instructions LIU Zhiwei
2021-03-15 21:28 ` Alistair Francis
2021-05-26 5:30 ` Palmer Dabbelt
2021-05-26 5:31 ` Palmer Dabbelt
2021-02-12 15:02 ` [PATCH 09/38] target/riscv: SIMD 8-bit " LIU Zhiwei
2021-03-15 21:31 ` Alistair Francis
2021-02-12 15:02 ` [PATCH 10/38] target/riscv: SIMD 16-bit Multiply Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 11/38] target/riscv: SIMD 8-bit " LIU Zhiwei
2021-03-15 21:33 ` Alistair Francis
2021-02-12 15:02 ` [PATCH 12/38] target/riscv: SIMD 16-bit Miscellaneous Instructions LIU Zhiwei
2021-03-15 21:35 ` Alistair Francis
2021-02-12 15:02 ` [PATCH 13/38] target/riscv: SIMD 8-bit " LIU Zhiwei
2021-03-16 14:38 ` Alistair Francis
2021-02-12 15:02 ` [PATCH 14/38] target/riscv: 8-bit Unpacking Instructions LIU Zhiwei
2021-03-16 14:40 ` Alistair Francis
2021-02-12 15:02 ` [PATCH 15/38] target/riscv: 16-bit Packing Instructions LIU Zhiwei
2021-03-16 14:42 ` Alistair Francis
2021-02-12 15:02 ` [PATCH 16/38] target/riscv: Signed MSW 32x32 Multiply and Add Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 17/38] target/riscv: Signed MSW 32x16 " LIU Zhiwei
2021-03-16 16:01 ` Alistair Francis
2021-02-12 15:02 ` [PATCH 18/38] target/riscv: Signed 16-bit Multiply 32-bit Add/Subtract Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 19/38] target/riscv: Signed 16-bit Multiply 64-bit " LIU Zhiwei
2021-02-12 15:02 ` [PATCH 20/38] target/riscv: Partial-SIMD Miscellaneous Instructions LIU Zhiwei
2021-03-16 19:44 ` Alistair Francis
2021-02-12 15:02 ` [PATCH 21/38] target/riscv: 8-bit Multiply with 32-bit Add Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 22/38] target/riscv: 64-bit Add/Subtract Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 23/38] target/riscv: 32-bit Multiply " LIU Zhiwei
2021-02-12 15:02 ` [PATCH 24/38] target/riscv: Signed 16-bit Multiply with " LIU Zhiwei
2021-02-12 15:02 ` [PATCH 25/38] target/riscv: Non-SIMD Q15 saturation ALU Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 26/38] target/riscv: Non-SIMD Q31 " LIU Zhiwei
2021-02-12 15:02 ` [PATCH 27/38] target/riscv: 32-bit Computation Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 28/38] target/riscv: Non-SIMD Miscellaneous Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 29/38] target/riscv: RV64 Only SIMD 32-bit Add/Subtract Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 30/38] target/riscv: RV64 Only SIMD 32-bit Shift Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 31/38] target/riscv: RV64 Only SIMD 32-bit Miscellaneous Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 32/38] target/riscv: RV64 Only SIMD Q15 saturating Multiply Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 33/38] target/riscv: RV64 Only 32-bit " LIU Zhiwei
2021-02-12 15:02 ` [PATCH 34/38] target/riscv: RV64 Only 32-bit Multiply & Add Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 35/38] target/riscv: RV64 Only 32-bit Parallel " LIU Zhiwei
2021-02-12 15:02 ` [PATCH 36/38] target/riscv: RV64 Only Non-SIMD 32-bit Shift Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 37/38] target/riscv: RV64 Only 32-bit Packing Instructions LIU Zhiwei
2021-02-12 15:02 ` [PATCH 38/38] target/riscv: configure and turn on packed extension from command line LIU Zhiwei
2021-03-05 6:14 ` [PATCH 00/38] target/riscv: support packed extension v0.9.2 LIU Zhiwei
2021-04-13 3:27 ` LIU Zhiwei
2021-04-15 4:46 ` Alistair Francis
2021-04-15 5:50 ` LIU Zhiwei
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