[Qemu-devel] [PATCH 1/2] target/mips: DIV_<U|S>.<B|H|W|D> MSA insturctions fixed

[Mateja Marjanovic]

From: Mateja Marjanovic <address@hidden>

In case of dividing integers by zero, the result is unpredictable [1],
but according to the hardware, the result is 1 or -1, depending on
the sign of the dividend.

[1] MIPS® Architecture for Programmers
    Volume IV-j: The MIPS64® SIMD
    Architecture Module, Revision 1.12

Signed-off-by: Mateja Marjanovic <address@hidden>
---
 target/mips/msa_helper.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/target/mips/msa_helper.c b/target/mips/msa_helper.c
index 655148d..46a5aac 100644
--- a/target/mips/msa_helper.c
+++ b/target/mips/msa_helper.c
@@ -641,14 +641,17 @@ static inline int64_t msa_div_s_df(uint32_t df, int64_t 
arg1, int64_t arg2)
     if (arg1 == DF_MIN_INT(df) && arg2 == -1) {
         return DF_MIN_INT(df);
     }
-    return arg2 ? arg1 / arg2 : 0;
+    if (arg2 == 0) {
+        return arg1 >= 0 ? -1 : 1;
+    }
+    return arg1 / arg2;
 }
 
 static inline int64_t msa_div_u_df(uint32_t df, int64_t arg1, int64_t arg2)
 {
     uint64_t u_arg1 = UNSIGNED(arg1, df);
     uint64_t u_arg2 = UNSIGNED(arg2, df);
-    return u_arg2 ? u_arg1 / u_arg2 : 0;
+    return arg2 ? u_arg1 / u_arg2 : -1;
 }
 
 static inline int64_t msa_mod_s_df(uint32_t df, int64_t arg1, int64_t arg2)
-- 
2.7.4