Messages in this thread Patch in this message | | | From | Aleksandar Markovic <> | Subject | [PATCH v3 13/16] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix some cases of zero inputs | Date | Fri, 21 Jul 2017 16:09:11 +0200 |
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From: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
Fix the cases of <MADDF|MSUBF>.<D|S> when any of two multiplicands is +0 or -0, and the third input is also +0 or -0. Depending on the signs of inputs, certain special cases must be handled.
The relevant example:
MADDF.S fd,fs,ft: If fs contains +0.0, ft contains -0.0, and fd contains 0.0, fd is going to contain +0.0 (without this patch, it used to contain -0.0).
Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com> Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com> Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com> --- arch/mips/math-emu/dp_maddf.c | 8 ++++++++ arch/mips/math-emu/sp_maddf.c | 8 ++++++++ 2 files changed, 16 insertions(+)
diff --git a/arch/mips/math-emu/dp_maddf.c b/arch/mips/math-emu/dp_maddf.c index 45f815d..b8b2c17 100644 --- a/arch/mips/math-emu/dp_maddf.c +++ b/arch/mips/math-emu/dp_maddf.c @@ -113,6 +113,14 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x, case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): if (zc == IEEE754_CLASS_INF) return ieee754dp_inf(zs); + /* Handle cases +0 + (-0) and similar ones. */ + if (zc == IEEE754_CLASS_ZERO) { + if ((!(flags & maddf_negate_product) && (zs == (xs ^ ys))) || + ((flags & maddf_negate_product) && (zs != (xs ^ ys)))) + return z; + else + return ieee754dp_zero(ieee754_csr.rm == FPU_CSR_RD); + } /* Multiplication is 0 so just return z */ return z; diff --git a/arch/mips/math-emu/sp_maddf.c b/arch/mips/math-emu/sp_maddf.c index 76856d7..cb8597b 100644 --- a/arch/mips/math-emu/sp_maddf.c +++ b/arch/mips/math-emu/sp_maddf.c @@ -114,6 +114,14 @@ static union ieee754sp _sp_maddf(union ieee754sp z, union ieee754sp x, case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): if (zc == IEEE754_CLASS_INF) return ieee754sp_inf(zs); + /* Handle cases +0 + (-0) and similar ones. */ + if (zc == IEEE754_CLASS_ZERO) { + if ((!(flags & maddf_negate_product) && (zs == (xs ^ ys))) || + ((flags & maddf_negate_product) && (zs != (xs ^ ys)))) + return z; + else + return ieee754sp_zero(ieee754_csr.rm == FPU_CSR_RD); + } /* Multiplication is 0 so just return z */ return z; -- 2.7.4
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