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[Qemu-devel] [PATCH 2/2] target/mips: MOD_<U|S>.<B|H|W|D> MSA insturctio


From: Mateja Marjanovic
Subject: [Qemu-devel] [PATCH 2/2] target/mips: MOD_<U|S>.<B|H|W|D> MSA insturctions fixed
Date: Mon, 1 Apr 2019 16:38:21 +0200

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 not zero, but 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 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target/mips/msa_helper.c b/target/mips/msa_helper.c
index 46a5aac..bdfbc95 100644
--- a/target/mips/msa_helper.c
+++ b/target/mips/msa_helper.c
@@ -659,14 +659,14 @@ static inline int64_t msa_mod_s_df(uint32_t df, int64_t 
arg1, int64_t arg2)
     if (arg1 == DF_MIN_INT(df) && arg2 == -1) {
         return 0;
     }
-    return arg2 ? arg1 % arg2 : 0;
+    return arg2 ? arg1 % arg2 : arg1;
 }
 
 static inline int64_t msa_mod_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 u_arg2 ? u_arg1 % u_arg2 : u_arg1;
 }
 
 #define SIGNED_EVEN(a, df) \
-- 
2.7.4




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