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Re: [Qemu-devel] [PATCH] target/mips: Fix minor bug in FPU
From: |
Aleksandar Markovic |
Subject: |
Re: [Qemu-devel] [PATCH] target/mips: Fix minor bug in FPU |
Date: |
Mon, 18 Mar 2019 18:55:56 +0000 |
Hi, Mateja,
> From: Mateja Marjanovic <address@hidden>
> Subject: [PATCH] target/mips: Fix minor bug in FPU
>
> From: Mateja Marjanovic <address@hidden>
>
> Wrong type of NaN was generated for IEEE754-2008 by maddf and
> msubf insturctions when the arguments were inf, zero, nan or
> zero, inf, nan respectively.
>
> Signed-off-by: Mateja Marjanovic <address@hidden>
> ---
> fpu/softfloat-specialize.h | 24 ++++++++++++++++--------
> 1 file changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/fpu/softfloat-specialize.h b/fpu/softfloat-specialize.h
> index 16c0bcb..56256be 100644
> --- a/fpu/softfloat-specialize.h
> +++ b/fpu/softfloat-specialize.h
> @@ -495,15 +495,15 @@ static int pickNaNMulAdd(FloatClass a_cls, FloatClass
> b_cls, > FloatClass c_cls,
> return 1;
> }
> #elif defined(TARGET_MIPS)
> - /* For MIPS, the (inf,zero,qnan) case sets InvalidOp and returns
> - * the default NaN
> - */
> - if (infzero) {
> - float_raise(float_flag_invalid, status);
> - return 3;
> - }
> -
> if (snan_bit_is_one(status)) {
> + /*
> + * For MIPS systems that conform to IEEE754-1985, the (inf,zero,qnan)
"IEEE754-1985" should be "IEEE 754-1985".
"(inf,zero,qnan)" should be "(inf,zero,nan)" (the "c" can be both kinds of NaN
at
the moment of execution of this block, as it is visible from the code
surrounding
invocations of pickNaNMulAdd()).
> + * case sets InvalidOp and returns the default NaN
> + */
> + if (infzero) {
> + float_raise(float_flag_invalid, status);
> + return 3;
> + }
> /* Prefer sNaN over qNaN, in the a, b, c order. */
> if (is_snan(a_cls)) {
> return 0;
> @@ -519,6 +519,14 @@ static int pickNaNMulAdd(FloatClass a_cls, FloatClass
> b_cls, > FloatClass c_cls,
> return 2;
> }
> } else {
> + /*
> + * For MIPS systems that conform to IEEE754-2008, the (inf,zero,qnan)
A similar comment applies, like for the block above.
> + * case sets InvalidOp and returns the default NaN
This line is incorrect, and, instead of "the default NaN", there should be "c".
> + */
> + if (infzero) {
> + float_raise(float_flag_invalid, status);
> + return 2;
> + }
> /* Prefer sNaN over qNaN, in the c, a, b order. */
> if (is_snan(c_cls)) {
> return 2;
> --
> 2.7.4
Reference to the justification in documentation in the commit message would be
useful and nice.
Thanks,
Aleksandar
- Re: [Qemu-devel] [PATCH] target/mips: Fix minor bug in FPU, (continued)
[Qemu-devel] [PATCH] target/mips: Fix minor bug in FPU, Mateja Marjanovic, 2019/03/18
Re: [Qemu-devel] [PATCH] target/mips: Fix minor bug in FPU,
Aleksandar Markovic <=
Re: [Qemu-devel] [PATCH] target/mips: Fix minor bug in FPU, Mateja Marjanovic, 2019/03/19
Re: [Qemu-devel] [PATCH] target/mips: Fix minor bug in FPU, Aleksandar Markovic, 2019/03/18
Re: [Qemu-devel] [PATCH] target/mips: Fix minor bug in FPU, Mateja Marjanovic, 2019/03/19