diff mbox series

[PULL,v2,18/42] target/riscv: Fixup saturate subtract function

Message ID 20210505232312.4175486-19-alistair.francis@wdc.com
State New
Headers show
Series [PULL,v2,01/42] target/riscv: Remove privilege v1.9 specific CSR related code | expand

Commit Message

Alistair Francis May 5, 2021, 11:22 p.m. UTC 
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 mbox series

Patch

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;