For "fmax/fmin ft0, ft1, ft2" and if one of the inputs is sNaN,

  The original logic:
    Return NaN and set invalid flag if ft1 == sNaN || ft2 == sNan.

  The alternative path:
    Set invalid flag if ft1 == sNaN || ft2 == sNaN.
    Return NaN only if ft1 == NaN && ft2 == NaN.

The IEEE 754 spec allows both implementation and some architecture such
as riscv choose different defintions in two spec versions.
(riscv-spec-v2.2 use original version, riscv-spec-20191213 changes to
 alternative)

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>
Signed-off-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211021160847.2748577-2-frank.chang@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

In commit a777d603 we added an assertion to parts_silence_nan() that
prohibits calling float*_silence_nan() when in default-NaN mode.
This ties together a property of the output ("do we generate a default
NaN when the result is a NaN?") with an operation on an input ("silence
this input NaN").

It's true that most of the time when in default-NaN mode you won't
need to silence an input NaN, because you can just produce the
default NaN as the result instead.  But some functions like
float*_maxnum() are defined to be able to work with quiet NaNs, so
silencing an input SNaN is still reasonable.  In particular, the
upcoming implementation of MVE VMAXNMV would fall over this assertion
if we didn't delete it.

Delete the assertion.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20210614233143.1221879-3-richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210614233143.1221879-3-richard.henderson@linaro.org>

Typo in the conversion to FloatParts64.

Fixes: 572c4d86
Fixes: Coverity CID 1457457
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210607223812.110596-1-richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

For the normal case of no additional scaling, this reduces the
profile contribution of int64_to_float64 to the testcase in the
linked issue from 0.81% to 0.04%.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/134


Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Rename to parts$N_modrem.  This was the last use of a lot
of the legacy infrastructure, so remove it as required.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Rename to parts$N_log2.  Though this is partly a ruse, since I do not
believe the code will succeed for float128 without work.  Which is ok
for now, because we do not need this for more than float32 and float64.

Since berkeley-testfloat-3 doesn't support log2, compare float64_log2
vs the system log2.  Fix the errors for inputs near 1.0:

test: 3ff00000000000b0  +0x1.00000000000b0p+0
  sf: 3d2fa00000000000  +0x1.fa00000000000p-45
libm: 3d2fbd422b1bd36f  +0x1.fbd422b1bd36fp-45
Error in fraction: 32170028290927 ulp

test: 3feec24f6770b100  +0x1.ec24f6770b100p-1
  sf: bfad3740d13c9ec0  -0x1.d3740d13c9ec0p-5
libm: bfad3740d13c9e98  -0x1.d3740d13c9e98p-5
Error in fraction: 40 ulp

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Keep the intermediate results in FloatParts instead of
converting back and forth between float64.  Use muladd
instead of separate mul+add.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

This is the last use of commonNaNT and all of the routines
that use it, so remove all of them for Werror.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Since this is the first such, this includes all of the
packing and unpacking routines as well.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

With floatx80_precision_x, the rounding happens across
the break between words.  Notice this case with

  frac_lsb = round_mask + 1 -> 0

and check the bits in frac_hi as needed.

In addition, since frac_shift == 0, we won't implicitly clear
round_mask via the right-shift, so explicitly clear those bits.
This fixes rounding for floatx80_precision_[sd].

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Use an enumeration instead of raw 32/64/80 values.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Remove frac_lsb, frac_lsbm1, roundeven_mask.  Compute
these from round_mask in parts$N_uncanon_normal.

With floatx80, round_mask will not be tied to frac_shift.
Everything else is easily computable.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

We will need to treat the non-normal cases of floatx80 specially,
so split out the normal case that we can reuse.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Rename to parts$N_sqrt.
Reimplement float128_sqrt with FloatParts128.

Reimplement with the inverse sqrt newton-raphson algorithm from musl.
This is significantly faster than even the berkeley sqrt n-r algorithm,
because it does not use division instructions, only multiplication.

Ordinarily, changing algorithms at the same time as migrating code is
a bad idea, but this is the only way I found that didn't break one of
the routines at the same time.

Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Rename to parts$N_scalbn.
Reimplement float128_scalbn with FloatParts128.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Rename to parts$N_compare.  Rename all of the intermediate
functions to ftype_do_compare.  Rename the hard-float functions
to ftype_hs_compare.  Convert float128 to FloatParts128.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

The float128 implementation is straight-forward.
Unfortuantely, we don't have any tests we can simply adjust/unlock.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20210517142739.38597-24-david@redhat.com>
[rth: Update for changed parts_minmax return value]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Rename to parts$N_minmax.  Combine 3 bool arguments to a bitmask.
Introduce ftype_minmax functions as a common optimization point.
Fold bfloat16 expansions into the same macro as the other types.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Rename to parts$N_uint_to_float.
Reimplement uint64_to_float128 with FloatParts128.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Rename to parts$N_sint_to_float.
Reimplement int{32,64}_to_float128 with FloatParts128.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Rename to parts$N_float_to_uint.  Reimplement
float128_to_uint{32,64}{_round_to_zero} with FloatParts128.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

For Arm BFDOT and BFMMLA, we need a version of round-to-odd
that overflows to infinity, instead of the max normal number.

Cc: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210525225817.400336-6-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Rename to parts$N_float_to_sint.  Reimplement
float128_to_int{32,64}{_round_to_zero} with FloatParts128.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

At the same time, convert to pointers, split out
parts$N_round_to_int_normal, define a macro for
parts_round_to_int using QEMU_GENERIC.

This necessarily meant some rearrangement to the
rount_to_{,u}int_and_pack routines, so go ahead and
convert to parts_round_to_int_normal, which in turn
allows cleaning up of the raised exception handling.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Introduce parts_float_to_float_widen and parts_float_to_float_narrow.
Use them for float128_to_float{32,64} and float{32,64}_to_float128.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Split out parts_float_to_ahp and parts_float_to_float.
Convert to pointers.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Rename to parts$N_div.
Implement float128_div with FloatParts128.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Have x86_64 assembly for them, with a fallback.
This avoids shuffling values through %cl in the x86 case.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>