[PATCH 03/38] target/riscv: Fixup saturate subtract function

[LIU Zhiwei]

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_...@c-sky.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 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