From acd9e20cd9d0e6af5680e1870a966d8082a1130a Mon Sep 17 00:00:00 2001 From: Maciej W. Rozycki Date: Fri, 13 Nov 2015 00:48:48 +0000 Subject: MIPS: math-emu: Always propagate sNaN payload in quieting Propagate sNaN payload in quieting in the legacy-NaN mode as well. If clearing the quiet bit would produce infinity, then set the next lower trailing significand field bit, matching the SB-1 and BMIPS5000 hardware implementations. Some other MIPS FPU hardware implementations do produce the default qNaN bit pattern instead. This reverts some changes made for semantics preservation with commit dc3ddf42 [MIPS: math-emu: Update sNaN quieting handlers], consequently bringing back most of the semantics from before commit fdffbafb [Lots of FPU bug fixes from Kjeld Borch Egevang.], except from the qNaN produced in the infinity case. Previously the default qNaN bit pattern was produced in that case. Signed-off-by: Maciej W. Rozycki Cc: Andrew Morton Cc: Matthew Fortune Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/11483/ Signed-off-by: Ralf Baechle --- arch/mips/math-emu/ieee754dp.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'arch/mips/math-emu/ieee754dp.c') diff --git a/arch/mips/math-emu/ieee754dp.c b/arch/mips/math-emu/ieee754dp.c index 47d26c805eac..465a0342ed4c 100644 --- a/arch/mips/math-emu/ieee754dp.c +++ b/arch/mips/math-emu/ieee754dp.c @@ -54,10 +54,13 @@ union ieee754dp __cold ieee754dp_nanxcpt(union ieee754dp r) assert(ieee754dp_issnan(r)); ieee754_setcx(IEEE754_INVALID_OPERATION); - if (ieee754_csr.nan2008) + if (ieee754_csr.nan2008) { DPMANT(r) |= DP_MBIT(DP_FBITS - 1); - else - r = ieee754dp_indef(); + } else { + DPMANT(r) &= ~DP_MBIT(DP_FBITS - 1); + if (!ieee754dp_isnan(r)) + DPMANT(r) |= DP_MBIT(DP_FBITS - 2); + } return r; } -- cgit v1.2.3