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| author | Mateja Marjanovic <Mateja.Marjanovic@rt-rk.com> | 2019-04-02 14:11:49 +0200 |
|---|---|---|
| committer | Aleksandar Markovic <amarkovic@wavecomp.com> | 2019-05-26 17:32:31 +0200 |
| commit | d2a40a5f6938f30f44b536e997e1e89bb62b971c (patch) | |
| tree | ea519320aa5f8fbcaca697858aee64fb26d7c00f /target | |
| parent | a7b21f6762a2d6ec08106d8a7ccb11829914523f (diff) | |
| download | qemu-d2a40a5f6938f30f44b536e997e1e89bb62b971c.zip qemu-d2a40a5f6938f30f44b536e997e1e89bb62b971c.tar.gz qemu-d2a40a5f6938f30f44b536e997e1e89bb62b971c.tar.bz2 | |
target/mips: Make the results of DIV_<U|S>.<B|H|W|D> the same as on hardware
MSA instructions DIV_<U|S>.<B|H|W|D> when dividing by zero,
didn't return the same value when executed on a referent hardware
(FPGA MIPS 64 r6, little endian) and when executed on QEMU, which
is not a real bug, because the result when dividing by zero is
UNPREDICTABLE [1] (page 141, 142).
[1] MIPS Architecture for Programmers
Volume IV-j: The MIPS64 SIMD
Architecture Module, Revision 1.12
Signed-off-by: Mateja Marjanovic <mateja.marjanovic@rt-rk.com>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Reviewed-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Message-Id: <1554207110-9113-2-git-send-email-mateja.marjanovic@rt-rk.com>
Diffstat (limited to 'target')
| -rw-r--r-- | target/mips/msa_helper.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/target/mips/msa_helper.c b/target/mips/msa_helper.c index c74e3cd..596190b 100644 --- a/target/mips/msa_helper.c +++ b/target/mips/msa_helper.c @@ -641,14 +641,15 @@ 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; + return arg2 ? arg1 / arg2 + : arg1 >= 0 ? -1 : 1; } 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) |