4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Aleksandar Markovic <aleksandar.markovic@xxxxxxxxxx> commit ddbfff7429a75d954bf5bdff9f2222bceb4c236a upstream. If accumulator value is zero, just return the value of previously calculated product. This brings logic in MADDF/MSUBF implementation closer to the logic in ADD/SUB case. Signed-off-by: Miodrag Dinic <miodrag.dinic@xxxxxxxxxx> Signed-off-by: Goran Ferenc <goran.ferenc@xxxxxxxxxx> Signed-off-by: Aleksandar Markovic <aleksandar.markovic@xxxxxxxxxx> Cc: James.Hogan@xxxxxxxxxx Cc: Paul.Burton@xxxxxxxxxx Cc: Raghu.Gandham@xxxxxxxxxx Cc: Leonid.Yegoshin@xxxxxxxxxx Cc: Douglas.Leung@xxxxxxxxxx Cc: Petar.Jovanovic@xxxxxxxxxx Cc: linux-mips@xxxxxxxxxxxxxx Patchwork: https://patchwork.linux-mips.org/patch/16512/ Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/mips/math-emu/dp_maddf.c | 5 ++++- arch/mips/math-emu/sp_maddf.c | 5 ++++- 2 files changed, 8 insertions(+), 2 deletions(-) --- a/arch/mips/math-emu/dp_maddf.c +++ b/arch/mips/math-emu/dp_maddf.c @@ -54,7 +54,7 @@ static union ieee754dp _dp_maddf(union i return ieee754dp_nanxcpt(z); case IEEE754_CLASS_DNORM: DPDNORMZ; - /* QNAN is handled separately below */ + /* QNAN and ZERO cases are handled separately below */ } switch (CLPAIR(xc, yc)) { @@ -210,6 +210,9 @@ static union ieee754dp _dp_maddf(union i } assert(rm & (DP_HIDDEN_BIT << 3)); + if (zc == IEEE754_CLASS_ZERO) + return ieee754dp_format(rs, re, rm); + /* And now the addition */ assert(zm & DP_HIDDEN_BIT); --- a/arch/mips/math-emu/sp_maddf.c +++ b/arch/mips/math-emu/sp_maddf.c @@ -54,7 +54,7 @@ static union ieee754sp _sp_maddf(union i return ieee754sp_nanxcpt(z); case IEEE754_CLASS_DNORM: SPDNORMZ; - /* QNAN is handled separately below */ + /* QNAN and ZERO cases are handled separately below */ } switch (CLPAIR(xc, yc)) { @@ -203,6 +203,9 @@ static union ieee754sp _sp_maddf(union i } assert(rm & (SP_HIDDEN_BIT << 3)); + if (zc == IEEE754_CLASS_ZERO) + return ieee754sp_format(rs, re, rm); + /* And now the addition */ assert(zm & SP_HIDDEN_BIT);