From: Alistair Francis <alistair.francis@wdc.com>
To: peter.maydell@linaro.org
Cc: alistair23@gmail.com, Alistair Francis <alistair.francis@wdc.com>,
Richard Henderson <richard.henderson@linaro.org>,
qemu-devel@nongnu.org, LIU Zhiwei <zhiwei_liu@c-sky.com>
Subject: [PULL v3 18/42] target/riscv: Fixup saturate subtract function
Date: Tue, 11 May 2021 20:19:27 +1000 [thread overview]
Message-ID: <20210511101951.165287-19-alistair.francis@wdc.com> (raw)
In-Reply-To: <20210511101951.165287-1-alistair.francis@wdc.com>
From: LIU Zhiwei <zhiwei_liu@c-sky.com>
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: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210212150256.885-4-zhiwei_liu@c-sky.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
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 a156573d28..356cef8a09 100644
--- a/target/riscv/vector_helper.c
+++ b/target/riscv/vector_helper.c
@@ -2451,7 +2451,7 @@ static inline 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;
@@ -2461,7 +2461,7 @@ static inline 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;
@@ -2471,7 +2471,7 @@ static inline 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;
@@ -2481,7 +2481,7 @@ static inline 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;
--
2.31.1
next prev parent reply other threads:[~2021-05-11 10:38 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 10:19 [PULL v3 00/42] riscv-to-apply queue Alistair Francis
2021-05-11 10:19 ` [PULL v3 01/42] target/riscv: Remove privilege v1.9 specific CSR related code Alistair Francis
2021-05-11 10:19 ` [PULL v3 02/42] docs/system/generic-loader.rst: Fix style Alistair Francis
2021-05-11 10:19 ` [PULL v3 03/42] target/riscv: Align the data type of reset vector address Alistair Francis
2021-05-11 10:19 ` [PULL v3 04/42] hw/riscv: sifive_e: Add 'const' to sifive_e_memmap[] Alistair Francis
2021-05-11 10:19 ` [PULL v3 05/42] target/riscv: Add Shakti C class CPU Alistair Francis
2021-05-11 10:19 ` [PULL v3 06/42] riscv: Add initial support for Shakti C machine Alistair Francis
2021-05-11 10:19 ` [PULL v3 07/42] hw/char: Add Shakti UART emulation Alistair Francis
2021-05-11 10:19 ` [PULL v3 08/42] hw/riscv: Connect Shakti UART to Shakti platform Alistair Francis
2021-05-11 10:19 ` [PULL v3 09/42] target/riscv: Convert the RISC-V exceptions to an enum Alistair Francis
2021-05-11 10:19 ` [PULL v3 10/42] target/riscv: Use the RISCVException enum for CSR predicates Alistair Francis
2021-05-11 10:19 ` [PULL v3 11/42] target/riscv: Fix 32-bit HS mode access permissions Alistair Francis
2021-05-11 10:19 ` [PULL v3 12/42] target/riscv: Use the RISCVException enum for CSR operations Alistair Francis
2021-05-11 10:19 ` [PULL v3 13/42] target/riscv: Use RISCVException enum for CSR access Alistair Francis
2021-05-11 10:19 ` [PULL v3 14/42] MAINTAINERS: Update the RISC-V CPU Maintainers Alistair Francis
2021-05-11 10:19 ` [PULL v3 15/42] hw/opentitan: Update the interrupt layout Alistair Francis
2021-05-11 10:19 ` [PULL v3 16/42] hw/riscv: Enable VIRTIO_VGA for RISC-V virt machine Alistair Francis
2021-05-11 10:19 ` [PULL v3 17/42] riscv: don't look at SUM when accessing memory from a debugger context Alistair Francis
2021-05-11 10:19 ` Alistair Francis [this message]
2021-05-11 10:19 ` [PULL v3 19/42] docs: Add documentation for shakti_c machine Alistair Francis
2021-05-11 10:19 ` [PULL v3 20/42] target/riscv: Fix the PMP is locked check when using TOR Alistair Francis
2021-05-11 10:19 ` [PULL v3 21/42] target/riscv: Define ePMP mseccfg Alistair Francis
2021-05-11 10:19 ` [PULL v3 22/42] target/riscv: Add the ePMP feature Alistair Francis
2021-05-11 10:19 ` [PULL v3 23/42] target/riscv: Add ePMP CSR access functions Alistair Francis
2021-05-11 10:19 ` [PULL v3 24/42] target/riscv: Implementation of enhanced PMP (ePMP) Alistair Francis
2021-05-20 13:51 ` Peter Maydell
2021-05-20 22:38 ` Alistair Francis
2021-05-11 10:19 ` [PULL v3 25/42] target/riscv: Add a config option for ePMP Alistair Francis
2021-05-11 10:19 ` [PULL v3 26/42] target/riscv/pmp: Remove outdated comment Alistair Francis
2021-05-11 10:19 ` [PULL v3 27/42] target/riscv: Add ePMP support for the Ibex CPU Alistair Francis
2021-05-11 10:19 ` [PULL v3 28/42] target/riscv: fix vrgather macro index variable type bug Alistair Francis
2021-05-11 10:19 ` [PULL v3 29/42] target/riscv: fix exception index on instruction access fault Alistair Francis
2021-05-11 10:19 ` [PULL v3 30/42] hw/riscv: Fix OT IBEX reset vector Alistair Francis
2021-05-11 10:19 ` [PULL v3 31/42] fpu/softfloat: set invalid excp flag for RISC-V muladd instructions Alistair Francis
2021-05-11 10:19 ` [PULL v3 32/42] target/riscv: fix a typo with interrupt names Alistair Francis
2021-05-11 10:19 ` [PULL v3 33/42] target/riscv: Remove the hardcoded RVXLEN macro Alistair Francis
2021-05-11 10:19 ` [PULL v3 34/42] target/riscv: Remove the hardcoded SSTATUS_SD macro Alistair Francis
2021-05-11 10:19 ` [PULL v3 35/42] target/riscv: Remove the hardcoded HGATP_MODE macro Alistair Francis
2021-05-11 10:19 ` [PULL v3 36/42] target/riscv: Remove the hardcoded MSTATUS_SD macro Alistair Francis
2021-05-20 13:55 ` Peter Maydell
2021-05-20 22:55 ` Alistair Francis
2021-05-21 2:07 ` LIU Zhiwei
2021-05-25 21:47 ` Alistair Francis
2021-05-11 10:19 ` [PULL v3 37/42] target/riscv: Remove the hardcoded SATP_MODE macro Alistair Francis
2021-05-11 10:19 ` [PULL v3 38/42] target/riscv: Remove the unused HSTATUS_WPRI macro Alistair Francis
2021-05-11 10:19 ` [PULL v3 39/42] target/riscv: Remove an unused CASE_OP_32_64 macro Alistair Francis
2021-05-11 10:19 ` [PULL v3 40/42] target/riscv: Consolidate RV32/64 32-bit instructions Alistair Francis
2021-05-11 10:19 ` [PULL v3 41/42] target/riscv: Consolidate RV32/64 16-bit instructions Alistair Francis
2021-05-11 10:19 ` [PULL v3 42/42] target/riscv: Fix the RV64H decode comment Alistair Francis
2021-05-12 18:46 ` [PULL v3 00/42] riscv-to-apply queue Peter Maydell
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