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2019-10-30softfp: Added hardfloat conversion from float32 to float64Matus Kysel
Reintroduce float32_to_float64 that was removed here: https://lists.gnu.org/archive/html/qemu-devel/2018-04/msg00455.html - nbench test it not actually calling this function at all - SPECS 2006 significat number of tests impoved their runtime, just few of them showed small slowdown Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Matus Kysel <mkysel@tachyum.com> Message-Id: <20191017142133.59439-1-mkysel@tachyum.com> [rth: Add comment about impossible inexact exceptions.] Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-08-19fpu: rename softfloat-specialize.h -> .inc.cAlex Bennée
This is not a normal header and should only be included in the main softfloat.c file to bring in the various target specific specialisations. Indeed as it contains non-inlined C functions it is not even a legal header. Rename it to match our included C convention. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
2019-08-19fpu: replace LIT64 with UINT64_C macrosAlex Bennée
In our quest to eliminate the home rolled LIT64 macro we fixup usage inside the softfloat code. While we are at it we remove some of the extraneous spaces to closer fit the house style. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2019-08-19fpu: use min/max values from stdint.h for integral overflowAlex Bennée
Remove some more use of LIT64 while making the meaning more clear. We also avoid the need of casts as the results by definition fit into the return type. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2019-08-19fpu: convert float[16/32/64]_squash_denormal to new modern styleAlex Bennée
This also allows us to remove the extractFloat16exp/frac helpers. We avoid using the floatXX_pack_raw functions as they are slight overkill for masking out all but the top bit of the number. The generated code is almost exactly the same as makes no difference to the pre-conversion code. Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2019-08-19fpu: replace LIT64 usage with UINT64_C for specialize constantsAlex Bennée
We have a wrapper that does the right thing from stdint.h so lets use it for our constants in softfloat-specialize.h Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2019-03-25hardfloat: fix float32/64 fused multiply-addKito Cheng
Before falling back to softfloat FMA, we do not restore the original values of inputs A and C. Fix it. This bug was caught by running gcc's testsuite on RISC-V qemu. Note that this change gives a small perf increase for fp-bench: Host: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz Command: perf stat -r 3 taskset -c 0 ./fp-bench -o mulAdd -p $prec - $prec = single: - before: 101.71 MFlops 102.18 MFlops 100.96 MFlops - after: 103.63 MFlops 103.05 MFlops 102.96 MFlops - $prec = double: - before: 173.10 MFlops 173.93 MFlops 172.11 MFlops - after: 178.49 MFlops 178.88 MFlops 178.66 MFlops Signed-off-by: Kito Cheng <kito.cheng@gmail.com> Signed-off-by: Emilio G. Cota <cota@braap.org> Message-Id: <20190322204320.17777-1-cota@braap.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2019-03-25target/mips: Fix minor bug in FPUMateja Marjanovic
Wrong type of NaN was generated for IEEE 754-2008 by MADDF.<D|S> and MSUBF.<D|S> instructions when the arguments were (Inf, Zero, NaN) or (Zero, Inf, NaN). The if-else statement establishes if the system conforms to IEEE 754-1985 or IEEE 754-2008, and defines different behaviors depending on that. In case of IEEE 754-2008, in mentioned cases of inputs, <MADDF|MSUBF>.<D|S> returns the input value 'c' [2] (page 53) and raises floating point exception 'Invalid Operation' [1] (pages 349, 350). These scenarios were tested and the results in QEMU emulation match the results obtained on the machine that has a MIPS64R6 CPU. [1] MIPS Architecture for Programmers Volume II-a: The MIPS64 Instruction Set Reference Manual, Revision 6.06 [2] MIPS Architecture for Programmers Volume IV-j: The MIPS64 SIMD Architecture Module, Revision 1.12 Signed-off-by: Mateja Marjanovic <mateja.marjanovic@rt-rk.com> Message-Id: <1553008916-15274-2-git-send-email-mateja.marjanovic@rt-rk.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> [AJB: fixed up commit message] Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2019-02-26softfloat: Support float_round_to_odd more placesRichard Henderson
Previously this was only supported for roundAndPackFloat64. New support in round_canonical, round_to_int, float128_round_to_int, roundAndPackFloat32, roundAndPackInt32, roundAndPackInt64, roundAndPackUint64. This does not include any of the floatx80 routines, as we do not have users for that rounding mode there. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20190215170225.15537-1-richard.henderson@linaro.org> Tested-by: David Hildenbrand <david@redhat.com> [AJB: add missing break] Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2019-02-26softfloat: Implement float128_to_uint32David Hildenbrand
Handling it just like float128_to_uint32_round_to_zero, that hopefully is free of bugs :) Documentation basically copied from float128_to_uint64 Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2019-01-22softfloat: enforce softfloat if the host's FMA is brokenEmilio G. Cota
The added branch to the FMA ops is marked as unlikely and therefore its impact on performance (measured with fp-bench) is within noise range when measured on an Intel(R) Xeon(R) Gold 6142 CPU @ 2.60GHz. Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com> Signed-off-by: Emilio G. Cota <cota@braap.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2018-12-17hardfloat: implement float32/64 comparisonEmilio G. Cota
Performance results for fp-bench: Host: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz - before: cmp-single: 110.98 MFlops cmp-double: 107.12 MFlops - after: cmp-single: 506.28 MFlops cmp-double: 524.77 MFlops Note that flattening both eq and eq_signaling versions would give us extra performance (695v506, 615v524 Mflops for single/double, respectively) but this would emit two essentially identical functions for each eq/signaling pair, which is a waste. Aggregate performance improvement for the last few patches: [ all charts in png: https://imgur.com/a/4yV8p ] 1. Host: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz qemu-aarch64 NBench score; higher is better Host: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz 16 +-+-----------+-------------+----===-------+---===-------+-----------+-+ 14 +-+..........................@@@&&.=.......@@@&&.=...................+-+ 12 +-+..........................@.@.&.=.......@.@.&.=.....+befor=== +-+ 10 +-+..........................@.@.&.=.......@.@.&.=.....+ad@@&& = +-+ 8 +-+.......................$$$%.@.&.=.......@.@.&.=.....+ @@u& = +-+ 6 +-+............@@@&&=+***##.$%.@.&.=***##$$%+@.&.=..###$$%%@i& = +-+ 4 +-+.......###$%%.@.&=.*.*.#.$%.@.&.=*.*.#.$%.@.&.=+**.#+$ +@m& = +-+ 2 +-+.....***.#$.%.@.&=.*.*.#.$%.@.&.=*.*.#.$%.@.&.=.**.#+$+sqr& = +-+ 0 +-+-----***##$%%@@&&=-***##$$%@@&&==***##$$%@@&&==-**##$$%+cmp==-----+-+ FOURIER NEURAL NELU DECOMPOSITION gmean qemu-aarch64 SPEC06fp (test set) speedup over QEMU 4c2c1015905 Host: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz error bars: 95% confidence interval 4.5 +-+---+-----+----+-----+-----+-&---+-----+----+-----+-----+-----+----+-----+-----+-----+-----+----+-----+---+-+ 4 +-+..........................+@@+...........................................................................+-+ 3.5 +-+..............%%@&.........@@..............%%@&............................................+++dsub +-+ 2.5 +-+....&&+.......%%@&.......+%%@..+%%&+..@@&+.%%@&....................................+%%&+.+%@&++%%@& +-+ 2 +-+..+%%&..+%@&+.%%@&...+++..%%@...%%&.+$$@&..%%@&..%%@&.......+%%&+.%%@&+......+%%@&.+%%&++$$@&++d%@& %%@&+-+ 1.5 +-+**#$%&**#$@&**#%@&**$%@**#$%@**#$%&**#$@&**$%@&*#$%@**#$%@**#$%&**#%@&**$%@&*#$%@**#$%&**#$@&*+f%@&**$%@&+-+ 0.5 +-+**#$%&**#$@&**#%@&**$%@**#$%@**#$%&**#$@&**$%@&*#$%@**#$%@**#$%&**#%@&**$%@&*#$%@**#$%&**#$@&+sqr@&**$%@&+-+ 0 +-+**#$%&**#$@&**#%@&**$%@**#$%@**#$%&**#$@&**$%@&*#$%@**#$%@**#$%&**#%@&**$%@&*#$%@**#$%&**#$@&*+cmp&**$%@&+-+ 410.bw416.gam433.434.z435.436.cac437.lesli444.447.de450.so453454.ca459.GemsF465.tont470.lb4482.sphinxgeomean 2. Host: ARM Aarch64 A57 @ 2.4GHz qemu-aarch64 NBench score; higher is better Host: Applied Micro X-Gene, Aarch64 A57 @ 2.4 GHz 5 +-+-----------+-------------+-------------+-------------+-----------+-+ 4.5 +-+........................................@@@&==...................+-+ 3 4 +-+..........................@@@&==........@.@&.=.....+before +-+ 3 +-+..........................@.@&.=........@.@&.=.....+ad@@@&== +-+ 2.5 +-+.....................##$$%%.@&.=........@.@&.=.....+ @m@& = +-+ 2 +-+............@@@&==.***#.$.%.@&.=.***#$$%%.@&.=.***#$$%%d@& = +-+ 1.5 +-+.....***#$$%%.@&.=.*.*#.$.%.@&.=.*.*#.$.%.@&.=.*.*#+$ +f@& = +-+ 0.5 +-+.....*.*#.$.%.@&.=.*.*#.$.%.@&.=.*.*#.$.%.@&.=.*.*#+$+sqr& = +-+ 0 +-+-----***#$$%%@@&==-***#$$%%@@&==-***#$$%%@@&==-***#$$%+cmp==-----+-+ FOURIER NEURAL NLU DECOMPOSITION gmean Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2018-12-17hardfloat: implement float32/64 square rootEmilio G. Cota
Performance results for fp-bench: Host: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz - before: sqrt-single: 42.30 MFlops sqrt-double: 22.97 MFlops - after: sqrt-single: 311.42 MFlops sqrt-double: 311.08 MFlops Here USE_FP makes a huge difference for f64's, with throughput going from ~200 MFlops to ~300 MFlops. Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2018-12-17hardfloat: implement float32/64 fused multiply-addEmilio G. Cota
Performance results for fp-bench: 1. Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz - before: fma-single: 74.73 MFlops fma-double: 74.54 MFlops - after: fma-single: 203.37 MFlops fma-double: 169.37 MFlops 2. ARM Aarch64 A57 @ 2.4GHz - before: fma-single: 23.24 MFlops fma-double: 23.70 MFlops - after: fma-single: 66.14 MFlops fma-double: 63.10 MFlops 3. IBM POWER8E @ 2.1 GHz - before: fma-single: 37.26 MFlops fma-double: 37.29 MFlops - after: fma-single: 48.90 MFlops fma-double: 59.51 MFlops Here having 3FP64 set to 1 pays off for x86_64: [1] 170.15 vs [0] 153.12 MFlops Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2018-12-17hardfloat: implement float32/64 divisionEmilio G. Cota
Performance results for fp-bench: 1. Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz - before: div-single: 34.84 MFlops div-double: 34.04 MFlops - after: div-single: 275.23 MFlops div-double: 216.38 MFlops 2. ARM Aarch64 A57 @ 2.4GHz - before: div-single: 9.33 MFlops div-double: 9.30 MFlops - after: div-single: 51.55 MFlops div-double: 15.09 MFlops 3. IBM POWER8E @ 2.1 GHz - before: div-single: 25.65 MFlops div-double: 24.91 MFlops - after: div-single: 96.83 MFlops div-double: 31.01 MFlops Here setting 2FP64_USE_FP to 1 pays off for x86_64: [1] 215.97 vs [0] 62.15 MFlops Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2018-12-17hardfloat: implement float32/64 multiplicationEmilio G. Cota
Performance results for fp-bench: 1. Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz - before: mul-single: 126.91 MFlops mul-double: 118.28 MFlops - after: mul-single: 258.02 MFlops mul-double: 197.96 MFlops 2. ARM Aarch64 A57 @ 2.4GHz - before: mul-single: 37.42 MFlops mul-double: 38.77 MFlops - after: mul-single: 73.41 MFlops mul-double: 76.93 MFlops 3. IBM POWER8E @ 2.1 GHz - before: mul-single: 58.40 MFlops mul-double: 59.33 MFlops - after: mul-single: 60.25 MFlops mul-double: 94.79 MFlops Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2018-12-17hardfloat: implement float32/64 addition and subtractionEmilio G. Cota
Performance results (single and double precision) for fp-bench: 1. Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz - before: add-single: 135.07 MFlops add-double: 131.60 MFlops sub-single: 130.04 MFlops sub-double: 133.01 MFlops - after: add-single: 443.04 MFlops add-double: 301.95 MFlops sub-single: 411.36 MFlops sub-double: 293.15 MFlops 2. ARM Aarch64 A57 @ 2.4GHz - before: add-single: 44.79 MFlops add-double: 49.20 MFlops sub-single: 44.55 MFlops sub-double: 49.06 MFlops - after: add-single: 93.28 MFlops add-double: 88.27 MFlops sub-single: 91.47 MFlops sub-double: 88.27 MFlops 3. IBM POWER8E @ 2.1 GHz - before: add-single: 72.59 MFlops add-double: 72.27 MFlops sub-single: 75.33 MFlops sub-double: 70.54 MFlops - after: add-single: 112.95 MFlops add-double: 201.11 MFlops sub-single: 116.80 MFlops sub-double: 188.72 MFlops Note that the IBM and ARM machines benefit from having HARDFLOAT_2F{32,64}_USE_FP set to 0. Otherwise their performance can suffer significantly: - IBM Power8: add-single: [1] 54.94 vs [0] 116.37 MFlops add-double: [1] 58.92 vs [0] 201.44 MFlops - Aarch64 A57: add-single: [1] 80.72 vs [0] 93.24 MFlops add-double: [1] 82.10 vs [0] 88.18 MFlops On the Intel machine, having 2F64 set to 1 pays off, but it doesn't for 2F32: - Intel i7-6700K: add-single: [1] 285.79 vs [0] 426.70 MFlops add-double: [1] 302.15 vs [0] 278.82 MFlops Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2018-12-17fpu: introduce hardfloatEmilio G. Cota
The appended paves the way for leveraging the host FPU for a subset of guest FP operations. For most guest workloads (e.g. FP flags aren't ever cleared, inexact occurs often and rounding is set to the default [to nearest]) this will yield sizable performance speedups. The approach followed here avoids checking the FP exception flags register. See the added comment for details. This assumes that QEMU is running on an IEEE754-compliant FPU and that the rounding is set to the default (to nearest). The implementation-dependent specifics of the FPU should not matter; things like tininess detection and snan representation are still dealt with in soft-fp. However, this approach will break on most hosts if we compile QEMU with flags that break IEEE compatibility. There is no way to detect all of these flags at compilation time, but at least we check for -ffast-math (which defines __FAST_MATH__) and disable hardfloat (plus emit a #warning) when it is set. This patch just adds common code. Some operations will be migrated to hardfloat in subsequent patches to ease bisection. Note: some architectures (at least PPC, there might be others) clear the status flags passed to softfloat before most FP operations. This precludes the use of hardfloat, so to avoid introducing a performance regression for those targets, we add a flag to disable hardfloat. In the long run though it would be good to fix the targets so that at least the inexact flag passed to softfloat is indeed sticky. Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2018-12-17softfloat: rename canonicalize to sf_canonicalizeEmilio G. Cota
glibc >= 2.25 defines canonicalize in commit eaf5ad0 (Add canonicalize, canonicalizef, canonicalizel., 2016-10-26). Given that we'll be including <math.h> soon, prepare for this by prefixing our canonicalize() with sf_ to avoid clashing with the libc's canonicalize(). Reported-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de> Tested-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2018-10-17qemu/compiler: Wrap __attribute__((flatten)) in a macroThomas Huth
Older versions of Clang (before 3.5) and GCC (before 4.1) do not support the "__attribute__((flatten))" yet. We don't care about such old versions of GCC anymore, but since Clang 3.4 is still used in EPEL for RHEL7 / CentOS 7, we should not use this attribute directly but with a wrapper macro instead. Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Thomas Huth <thuth@redhat.com>
2018-10-05softfloat: Fix divisionRichard Henderson
The __udiv_qrnnd primitive that we nicked from gmp requires its inputs to be normalized. We were not doing that. Because the inputs are nearly normalized already, finishing that is trivial. Replace div128to64 with a "proper" udiv_qrnnd, so that this remains a reusable primitive. Fixes: cf07323d494 Fixes: https://bugs.launchpad.net/qemu/+bug/1793119 Tested-by: Emilio G. Cota <cota@braap.org> 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>
2018-10-05softfloat: Replace countLeadingZeros32/64 with clz32/64Thomas Huth
Our minimum required compiler for compiling QEMU is GCC 4.1 these days, so we can drop the support for compilers which do not provide the __builtin_clz*() functions yet. Since the countLeadingZeros32/64 are then identical to the clz32/64 functions, and we do not have to sync the softloat 2 codebase with upstream anymore (softloat 3 is a complete rewrite) we can simply replace the functions with our QEMU versions. Suggested-by: Peter Maydell <peter.maydell@linaro.org> Acked-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Thomas Huth <thuth@redhat.com> Message-Id: <1538118095-7003-1-git-send-email-thuth@redhat.com> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-05softfloat: remove float64_trunc_to_intEmilio G. Cota
It has not had users since f83311e476 ("target-m68k: use floatx80 internally", 2017-06-21). Note that no other bit-width has floatX_trunc_to_int. Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-08-24softfloat: Add scaling float-to-int routinesRichard Henderson
Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20180814002653.12828-3-richard.henderson@linaro.org Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2018-08-24softfloat: Add scaling int-to-float routinesRichard Henderson
Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20180814002653.12828-2-richard.henderson@linaro.org Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2018-08-16softfloat: Fix missing inexact for floating-point addRichard Henderson
For 0x1.0000000000003p+0 + 0x1.ffffffep+14 = 0x1.0001fffp+15 we dropped the sticky bit and so failed to raise inexact. Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Laurent Desnogues <laurent.desnogues@gmail.com> Tested-by: Laurent Desnogues <laurent.desnogues@gmail.com> Message-id: 20180810193129.1556-7-richard.henderson@linaro.org Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2018-05-17fpu/softfloat: Define floatN_silence_nan in terms of parts_silence_nanRichard Henderson
Isolate the target-specific choice to 3 functions instead of 6. The code in floatx80_default_nan tried to be over-general. There are only two targets that support this format: x86 and m68k. Thus there is no point in inventing a mechanism for snan_bit_is_one. Move routines that no longer have ifdefs out of softfloat-specialize.h. 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>
2018-05-17fpu/softfloat: Clean up parts_default_nanRichard Henderson
Reduce the number of ifdefs. Correct the result for OpenRISC and TriCore (although TriCore fixed in target-specific code). 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>
2018-05-17fpu/softfloat: Define floatN_default_nan in terms of parts_default_nanRichard Henderson
Isolate the target-specific choice to 2 functions instead of 6. The code in float16_default_nan was only correct for ARM, MIPS, and X86. Though float16 support is rare among our targets. The code in float128_default_nan was arguably wrong for Sparc. While QEMU supports the Sparc 128-bit insns, no real cpu enables it. The code in floatx80_default_nan tried to be over-general. There are only two targets that support this format: x86 and m68k. Thus there is no point in inventing a value for snan_bit_is_one. Move routines that no longer have ifdefs out of softfloat-specialize.h. 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>
2018-05-17fpu/softfloat: Pass FloatClass to pickNaNMulAddRichard Henderson
For each operand, pass a single enumeration instead of a pair of booleans. The commit also merges multiple different ifdef-selected implementations of pickNaNMulAdd into a single function whose body is ifdef-selected. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Pass FloatClass to pickNaNRichard Henderson
For each operand, pass a single enumeration instead of a pair of booleans. The commit also merges multiple different ifdef-selected implementations of pickNaN into a single function whose body is ifdef-selected. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Make is_nan et al available to softfloat-specialize.hRichard Henderson
We will need these helpers within softfloat-specialize.h, so move the definitions above the include. After specialization, they will not always be used so mark them to avoid the Werror. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Specialize on snan_bit_is_oneRichard Henderson
Only MIPS requires snan_bit_is_one to be variable. While we are specializing softfloat behaviour, allow other targets to eliminate this runtime check. Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Yongbok Kim <yongbok.kim@mips.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Alexander Graf <agraf@suse.de> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Remove floatX_maybe_silence_nanRichard Henderson
These functions are now unused. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Use float*_silence_nan in propagateFloat*NaNRichard Henderson
We have already checked the arguments for SNaN; we don't need to do it again. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: re-factor float to float conversionsAlex Bennée
This allows us to delete a lot of additional boilerplate code which is no longer needed. Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Partial support for ARM Alternative half-precisionAlex Bennée
For float16 ARM supports an alternative half-precision format which sacrifices the ability to represent NaN/Inf in return for a higher dynamic range. The new FloatFmt flag, arm_althp, is then used to modify the behaviour of canonicalize and round_canonical with respect to representation and exception raising. Usage of this new flag waits until we re-factor float-to-float conversions. Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Replace float_class_msnan with parts_silence_nanRichard Henderson
With a canonical representation of NaNs, we can silence an SNaN immediately rather than delay until the final format is known. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Replace float_class_dnan with parts_default_nanRichard Henderson
With a canonical representation of NaNs, we can return the default nan directly rather than delay the expansion until the final format is known. Note one case where we uselessly assigned to a.sign, which was overwritten/ignored later when expanding float_class_dnan. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Introduce parts_is_snan_fracRichard Henderson
Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Canonicalize NaN fractionRichard Henderson
Shift the NaN fraction to a canonical position, much like we do for the fraction of normal numbers. This will facilitate manipulation of NaNs within the shared code paths. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Move softfloat-specialize.h below FloatParts definitionRichard Henderson
We want to be able to specialize on the canonical representation. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Split floatXX_silence_nan from floatXX_maybe_silence_nanRichard Henderson
The new function assumes that the input is an SNaN and does not double-check. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Merge NO_SIGNALING_NANS definitionsRichard Henderson
Move the ifdef inside the relevant functions instead of duplicating the function declarations. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-17fpu/softfloat: Fix conversion from uint64 to float128Petr Tesarik
The significand is passed to normalizeRoundAndPackFloat128() as high first, low second. The current code passes the integer first, so the result is incorrectly shifted left by 64 bits. This bug affects the emulation of s390x instruction CXLGBR (convert from logical 64-bit binary-integer operand to extended BFP result). Cc: qemu-stable@nongnu.org Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Petr Tesarik <ptesarik@suse.com> Message-Id: <20180511071052.1443-1-ptesarik@suse.com> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-05-15fpu/softfloat: Don't set Invalid for float-to-int(MAXINT)Peter Maydell
In float-to-integer conversion, if the floating point input converts exactly to the largest or smallest integer that fits in to the result type, this is not an overflow. In this situation we were producing the correct result value, but were incorrectly setting the Invalid flag. For example for Arm A64, "FCVTAS w0, d0" on an input of 0x41dfffffffc00000 should produce 0x7fffffff and set no flags. Fix the boundary case to take the right half of the if() statements. This fixes a regression from 2.11 introduced by the softfloat refactoring. Cc: qemu-stable@nongnu.org Fixes: ab52f973a50 Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20180510140141.12120-1-peter.maydell@linaro.org
2018-05-15fpu/softfloat: int_to_float ensure r fully initialisedAlex Bennée
Reported by Coverity (CID1390635). We ensure this for uint_to_float later on so we might as well mirror that. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2018-05-10softfloat: Handle default NaN mode after pickNaNMulAdd, not beforePeter Maydell
It is implementation defined whether a multiply-add of (0,inf,qnan) or (inf,0,qnan) raises InvalidaOperation or not, so we let the target-specific pickNaNMulAdd function handle this. This means that we must do the "return the default NaN in default NaN mode" check after the call, not before. Correct the ordering, and restore the comment from the old propagateFloat64MulAddNaN() that warned about this corner case. This fixes a regression from 2.11 for Arm guests where we would incorrectly fail to set the Invalid flag for these cases. Cc: qemu-stable@nongnu.org Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Tested-by: Alex Bennée <alex.bennee@linaro.org> Message-id: 20180504100547.14621-1-peter.maydell@linaro.org
2018-04-17fpu: Bound increment for scalbnRichard Henderson
Without bounding the increment, we can overflow exp either here in scalbn_decomposed or when adding the bias in round_canonical. This can result in e.g. underflowing to 0 instead of overflowing to infinity. The old softfloat code did bound the increment. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Tested-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2018-04-16fpu/softfloat: check for Inf / x or 0 / x before /0Alex Bennée
The re-factoring of div_floats changed the order of checking meaning an operation like -inf/0 erroneously raises the divbyzero flag. IEEE-754 (2008) specifies this should only occur for operations on finite operands. We fix this by moving the check on the dividend being Inf/0 to before the divisor is zero check. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Message-id: 20180416135442.30606-1-alex.bennee@linaro.org Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de> Reviewed-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de> Tested-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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