Commit Graph

213 Commits

Author SHA1 Message Date
Richard Henderson
aca845275a softfloat: Move mul_floats to softfloat-parts.c.inc
Rename to parts$N_mul.
Reimplement float128_mul with FloatParts128.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
3ff49e56a7 softfloat: Implement float128_add/sub via parts
Replace the existing Berkeley implementation with the
FloatParts implementation.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
da10a9074a softfloat: Move addsub_floats to softfloat-parts.c.inc
In preparation for implementing multiple sizes.  Rename to parts_addsub,
split out parts_add/sub_normal for future reuse with muladd.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
ee6959f277 softfloat: Move round_canonical to softfloat-parts.c.inc
At the same time, convert to pointers, renaming to parts$N_uncanon,
and define a macro for parts_uncanon using QEMU_GENERIC.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
d46975bce1 softfloat: Move sf_canonicalize to softfloat-parts.c.inc
At the same time, convert to pointers, rename to parts$N_canonicalize
and define a macro for parts_canonicalize using QEMU_GENERIC.

Rearrange the cases to recognize float_class_normal as
early as possible.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
979582d071 softfloat: Move pick_nan_muladd to softfloat-parts.c.inc
At the same time, convert to pointers, rename to pick_nan_muladd$N
and define a macro for pick_nan_muladd using QEMU_GENERIC.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
22c355f417 softfloat: Move pick_nan to softfloat-parts.c.inc
At the same time, convert to pointers, rename to parts$N_pick_nan
and define a macro for parts_pick_nan using QEMU_GENERIC.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
7c45bad866 softfloat: Move return_nan to softfloat-parts.c.inc
At the same time, convert to pointers, rename to return_nan$N
and define a macro for return_nan using QEMU_GENERIC.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
e9034ea87e softfloat: Convert float128_default_nan to parts
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
0018b1f41b softfloat: Convert float128_silence_nan to parts
This is the minimal change that also introduces float128_params,
float128_unpack_raw, and float128_pack_raw without running into
unused symbol Werrors.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
4109b9ea8a softfloat: Rearrange FloatParts64
Shuffle the fraction to the end, otherwise sort by size.
Add frac_hi and frac_lo members to alias frac.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
92ff426d7b softfloat: Use pointers with parts_silence_nan
At the same time, rename to parts64_silence_nan, split out
parts_silence_nan_frac, and define a macro for parts_silence_nan.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
e293e927a8 softfloat: Use pointers with ftype_round_pack_canonical
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
98e256fc70 softfloat: Use pointers with ftype_unpack_canonical
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
71fd178eae softfloat: Use pointers with ftype_pack_raw
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
9e4af58c24 softfloat: Use pointers with pack_raw
At the same time, rename to pack_raw64.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
3dddb203bc softfloat: Use pointers with ftype_unpack_raw
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
d8fdd17280 softfloat: Use pointers with unpack_raw
At the same time, rename to unpack_raw64.

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>
2021-05-16 07:13:51 -05:00
Richard Henderson
0fc07cade2 softfloat: Use pointers with parts_default_nan
At the same time, rename to parts64_default_nan and add a
macro for parts_default_nan.  This will be flushed out once
128-bit support is added.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
aaffb7bf1c softfloat: Move type-specific pack/unpack routines
In preparation from moving sf_canonicalize.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
f8155c1d52 softfloat: Rename FloatParts to FloatParts64
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
57547c6023 softfloat: fix return_nan vs default_nan_mode
Do not call parts_silence_nan when default_nan_mode is in
effect.  This will avoid an assert in a later patch.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
0d40cd939a softfloat: Use return_nan in float_to_float
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
134eda00e9 softfloat: Add float_cmask and constants
Testing more than one class at a time is better done with masks.
This reduces the static branch count.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
9793c1e224 softfloat: Tidy a * b + inf return
No reason to set values in 'a', when we already
have float_class_inf in 'c', and can flip that sign.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
d82f3b2dc7 softfloat: Use float_raise in more places
We have been somewhat inconsistent about when to use
float_raise and when to or in the bit by hand.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
Richard Henderson
e99c43735a softfloat: Move the binary point to the msb
Rather than point the binary point at msb-1, put it at the msb.
Use uadd64_overflow to detect when addition overflows instead
of DECOMPOSED_OVERFLOW_BIT.

This reduces the number of special cases within the code, such
as shifting an int64_t either left or right during conversion.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-05-16 07:13:51 -05:00
LIU Zhiwei
34f0c0a98a softfloat: Define convert operations for bfloat16
Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200813071421.2509-3-zhiwei_liu@c-sky.com>
[rth: Use FloatRoundMode for conversion functions.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-08-28 10:48:07 -07:00
LIU Zhiwei
8282310d85 softfloat: Define operations for bfloat16
This patch implements operations for bfloat16 except conversion and some misc
operations. We also add FloatFmt and pack/unpack interfaces for bfloat16.
As they are both static fields, we can't make a sperate patch for them.

Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200813071421.2509-2-zhiwei_liu@c-sky.com>
[rth: Use FloatRelation for comparison operations.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-08-28 10:48:07 -07:00
Frank Chang
0d93d8ec63 softfloat: Add fp16 and uint8/int8 conversion functions
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Frank Chang <frank.chang@sifive.com>
Message-Id: <1596102747-20226-4-git-send-email-chihmin.chao@sifive.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-08-28 10:48:07 -07:00
Max Filippov
913602e3ff softfloat: pass float_status pointer to pickNaN
Pass float_status structure pointer to the pickNaN so that
machine-specific settings are available to NaN selection code.
Add use_first_nan property to float_status and use it in Xtensa-specific
pickNaN.

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: "Alex Bennée" <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2020-08-21 12:48:14 -07:00
Paolo Bonzini
139c1837db meson: rename included C source files to .c.inc
With Makefiles that have automatically generated dependencies, you
generated includes are set as dependencies of the Makefile, so that they
are built before everything else and they are available when first
building the .c files.

Alternatively you can use a fine-grained dependency, e.g.

        target/arm/translate.o: target/arm/decode-neon-shared.inc.c

With Meson you have only one choice and it is a third option, namely
"build at the beginning of the corresponding target"; the way you
express it is to list the includes in the sources of that target.

The problem is that Meson decides if something is a source vs. a
generated include by looking at the extension: '.c', '.cc', '.m', '.C'
are sources, while everything else is considered an include---including
'.inc.c'.

Use '.c.inc' to avoid this, as it is consistent with our other convention
of using '.rst.inc' for included reStructuredText files.  The editorconfig
file is adjusted.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-08-21 06:18:30 -04:00
Joseph Myers
445810ec91 softfloat: return low bits of quotient from floatx80_modrem
Both x87 and m68k need the low parts of the quotient for their
remainder operations.  Arrange for floatx80_modrem to track those bits
and return them via a pointer.

The architectures using float32_rem and float64_rem do not appear to
need this information, so the *_rem interface is left unchanged and
the information returned only from floatx80_modrem.  The logic used to
determine the low 7 bits of the quotient for m68k
(target/m68k/fpu_helper.c:make_quotient) appears completely bogus (it
looks at the result of converting the remainder to integer, the
quotient having been discarded by that point); this patch does not
change that, but the m68k maintainers may wish to do so.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <alpine.DEB.2.21.2006081656500.23637@digraph.polyomino.org.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-26 09:39:38 -04:00
Joseph Myers
566601f1f9 softfloat: do not set denominator high bit for floatx80 remainder
The floatx80 remainder implementation unnecessarily sets the high bit
of bSig explicitly.  By that point in the function, arguments that are
invalid, zero, infinity or NaN have already been handled and
subnormals have been through normalizeFloatx80Subnormal, so the high
bit will already be set.  Remove the unnecessary code.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <alpine.DEB.2.21.2006081656220.23637@digraph.polyomino.org.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-26 09:39:38 -04:00
Joseph Myers
b662495dca softfloat: do not return pseudo-denormal from floatx80 remainder
The floatx80 remainder implementation sometimes returns the numerator
unchanged when the denominator is sufficiently larger than the
numerator.  But if the value to be returned unchanged is a
pseudo-denormal, that is incorrect.  Fix it to normalize the numerator
in that case.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <alpine.DEB.2.21.2006081655520.23637@digraph.polyomino.org.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-26 09:39:38 -04:00
Joseph Myers
499a2f7b55 softfloat: fix floatx80 remainder pseudo-denormal check for zero
The floatx80 remainder implementation ignores the high bit of the
significand when checking whether an operand (numerator) with zero
exponent is zero.  This means it mishandles a pseudo-denormal
representation of 0x1p-16382L by treating it as zero.  Fix this by
checking the whole significand instead.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <alpine.DEB.2.21.2006081655180.23637@digraph.polyomino.org.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-26 09:39:38 -04:00
Joseph Myers
6b8b0136ab softfloat: merge floatx80_mod and floatx80_rem
The m68k-specific softfloat code includes a function floatx80_mod that
is extremely similar to floatx80_rem, but computing the remainder
based on truncating the quotient toward zero rather than rounding it
to nearest integer.  This is also useful for emulating the x87 fprem
and fprem1 instructions.  Change the floatx80_rem implementation into
floatx80_modrem that can perform either operation, with both
floatx80_rem and floatx80_mod as thin wrappers available for all
targets.

There does not appear to be any use for the _mod operation for other
floating-point formats in QEMU (the only other architectures using
_rem at all are linux-user/arm/nwfpe, for FPA emulation, and openrisc,
for instructions that have been removed in the latest version of the
architecture), so no change is made to the code for other formats.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <alpine.DEB.2.21.2006081654280.23637@digraph.polyomino.org.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-26 09:39:37 -04:00
Philippe Mathieu-Daudé
4066288694 fpu/softfloat: Silence 'bitwise negation of boolean expression' warning
When building with clang version 10.0.0-4ubuntu1, we get:

    CC      lm32-softmmu/fpu/softfloat.o
  fpu/softfloat.c:3365:13: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
      absZ &= ~ ( ( ( roundBits ^ 0x40 ) == 0 ) & roundNearestEven );
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  fpu/softfloat.c:3423:18: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
          absZ0 &= ~ ( ( (uint64_t) ( absZ1<<1 ) == 0 ) & roundNearestEven );
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  ...

  fpu/softfloat.c:4273:18: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
          zSig1 &= ~ ( ( zSig2 + zSig2 == 0 ) & roundNearestEven );
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix by rewriting the fishy bitwise AND of two bools as an int.

Suggested-by: Eric Blake <eblake@redhat.com>
Buglink: https://bugs.launchpad.net/bugs/1881004
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200617201309.1640952-2-richard.henderson@linaro.org
Message-Id: <20200528155420.9802-1-philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2020-06-18 10:26:02 +01:00
Richard Henderson
c6baf65000 softfloat: Inline floatx80 compare specializations
Replace the floatx80 compare specializations with inline functions
that call the standard floatx80_compare{,_quiet} functions.
Use bool as the return type.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-05-19 08:42:57 -07:00
Richard Henderson
b7b1ac684f softfloat: Inline float128 compare specializations
Replace the float128 compare specializations with inline functions
that call the standard float128_compare{,_quiet} functions.
Use bool as the return type.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-05-19 08:42:49 -07:00
Richard Henderson
0673ecdf6c softfloat: Inline float64 compare specializations
Replace the float64 compare specializations with inline functions
that call the standard float64_compare{,_quiet} functions.
Use bool as the return type.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-05-19 08:42:45 -07:00
Richard Henderson
5da2d2d8e5 softfloat: Inline float32 compare specializations
Replace the float32 compare specializations with inline functions
that call the standard float32_compare{,_quiet} functions.
Use bool as the return type.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-05-19 08:42:26 -07:00
Richard Henderson
71bfd65c5f softfloat: Name compare relation enum
Give the previously unnamed enum a typedef name.  Use it in the
prototypes of compare functions.  Use it to hold the results
of the compare functions.

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>
2020-05-19 08:41:45 -07:00
Richard Henderson
3dede407cc softfloat: Name rounding mode enum
Give the previously unnamed enum a typedef name.  Use the packed
attribute so that we do not affect the layout of the float_status
struct.  Use it in the prototypes of relevant functions.

Adjust switch statements as necessary to avoid compiler warnings.

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>
2020-05-19 08:41:26 -07:00
Richard Henderson
a828b373bd softfloat: Change tininess_before_rounding to bool
Slightly tidies the usage within softfloat.c and the
representation in float_status.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-05-19 08:41:16 -07:00
Richard Henderson
c120391c00 softfloat: Replace flag with bool
We have had this on the to-do list for quite some time.

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>
2020-05-19 08:40:50 -07:00
Richard Henderson
b240c9c497 softfloat: Use post test for floatN_mul
The existing f{32,64}_addsub_post test, which checks for zero
inputs, is identical to f{32,64}_mul_fast_test.  Which means
we can eliminate the fast_test/fast_op hooks in favor of
reusing the same post hook.

This means we have one fewer test along the fast path for multiply.

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>
2020-05-19 08:40:33 -07:00
Joseph Myers
9ecaf5ccec softfloat: fix floatx80 pseudo-denormal round to integer
The softfloat function floatx80_round_to_int incorrectly handles the
case of a pseudo-denormal where only the high bit of the significand
is set, ignoring that bit (treating the number as an exact zero)
rather than treating the number as an alternative representation of
+/- 2^-16382 (which may round to +/- 1 depending on the rounding mode)
as hardware does.  Fix this check (simplifying the code in the
process).

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Message-Id: <alpine.DEB.2.21.2005042339420.22972@digraph.polyomino.org.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-05-15 11:04:50 -07:00
Joseph Myers
be53fa785a softfloat: fix floatx80 pseudo-denormal comparisons
The softfloat floatx80 comparisons fail to allow for pseudo-denormals,
which should compare equal to corresponding values with biased
exponent 1 rather than 0.  Add an adjustment for that case when
comparing numbers with the same sign.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Message-Id: <alpine.DEB.2.21.2005042338470.22972@digraph.polyomino.org.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-05-15 11:04:50 -07:00
Joseph Myers
4160280776 softfloat: fix floatx80 pseudo-denormal addition / subtraction
The softfloat function addFloatx80Sigs, used for addition of values
with the same sign and subtraction of values with opposite sign, fails
to handle the case where the two values both have biased exponent zero
and there is a carry resulting from adding the significands, which can
occur if one or both values are pseudo-denormals (biased exponent
zero, explicit integer bit 1).  Add a check for that case, so making
the results match those seen on x86 hardware for pseudo-denormals.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Message-Id: <alpine.DEB.2.21.2005042337570.22972@digraph.polyomino.org.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-05-15 11:04:50 -07:00