Commit Graph

6399 Commits

Author SHA1 Message Date
Antonio Sanchez
bde6741641 Improved std::complex sqrt and rsqrt.
Replaces `std::sqrt` with `complex_sqrt` for all platforms (previously
`complex_sqrt` was only used for CUDA and MSVC), and implements
custom `complex_rsqrt`.

Also introduces `numext::rsqrt` to simplify implementation, and modified
`numext::hypot` to adhere to IEEE IEC 6059 for special cases.

The `complex_sqrt` and `complex_rsqrt` implementations were found to be
significantly faster than `std::sqrt<std::complex<T>>` and
`1/numext::sqrt<std::complex<T>>`.

Benchmark file attached.
```
GCC 10, Intel Xeon, x86_64:
---------------------------------------------------------------------------
Benchmark                                 Time             CPU   Iterations
---------------------------------------------------------------------------
BM_Sqrt<std::complex<float>>           9.21 ns         9.21 ns     73225448
BM_StdSqrt<std::complex<float>>        17.1 ns         17.1 ns     40966545
BM_Sqrt<std::complex<double>>          8.53 ns         8.53 ns     81111062
BM_StdSqrt<std::complex<double>>       21.5 ns         21.5 ns     32757248
BM_Rsqrt<std::complex<float>>          10.3 ns         10.3 ns     68047474
BM_DivSqrt<std::complex<float>>        16.3 ns         16.3 ns     42770127
BM_Rsqrt<std::complex<double>>         11.3 ns         11.3 ns     61322028
BM_DivSqrt<std::complex<double>>       16.5 ns         16.5 ns     42200711

Clang 11, Intel Xeon, x86_64:
---------------------------------------------------------------------------
Benchmark                                 Time             CPU   Iterations
---------------------------------------------------------------------------
BM_Sqrt<std::complex<float>>           7.46 ns         7.45 ns     90742042
BM_StdSqrt<std::complex<float>>        16.6 ns         16.6 ns     42369878
BM_Sqrt<std::complex<double>>          8.49 ns         8.49 ns     81629030
BM_StdSqrt<std::complex<double>>       21.8 ns         21.7 ns     31809588
BM_Rsqrt<std::complex<float>>          8.39 ns         8.39 ns     82933666
BM_DivSqrt<std::complex<float>>        14.4 ns         14.4 ns     48638676
BM_Rsqrt<std::complex<double>>         9.83 ns         9.82 ns     70068956
BM_DivSqrt<std::complex<double>>       15.7 ns         15.7 ns     44487798

Clang 9, Pixel 2, aarch64:
---------------------------------------------------------------------------
Benchmark                                 Time             CPU   Iterations
---------------------------------------------------------------------------
BM_Sqrt<std::complex<float>>           24.2 ns         24.1 ns     28616031
BM_StdSqrt<std::complex<float>>         104 ns          103 ns      6826926
BM_Sqrt<std::complex<double>>          31.8 ns         31.8 ns     22157591
BM_StdSqrt<std::complex<double>>        128 ns          128 ns      5437375
BM_Rsqrt<std::complex<float>>          31.9 ns         31.8 ns     22384383
BM_DivSqrt<std::complex<float>>        99.2 ns         98.9 ns      7250438
BM_Rsqrt<std::complex<double>>         46.0 ns         45.8 ns     15338689
BM_DivSqrt<std::complex<double>>        119 ns          119 ns      5898944
```
2021-01-17 08:50:57 -08:00
Guoqiang QI
38ae5353ab 1)provide a better generic paddsub op implementation
2)make paddsub op support the Packet2cf/Packet4f/Packet2f in NEON
3)make paddsub op support the Packet2cf/Packet4f in SSE
2021-01-13 22:54:03 +00:00
Antonio Sanchez
352f1422d3 Remove inf local variable.
Apparently `inf` is a macro on iOS for `std::numeric_limits<T>::infinity()`,
causing a compile error here. We don't need the local anyways since it's
only used in one spot.
2021-01-12 10:33:15 -08:00
Antonio Sanchez
2044084979 Remove TODO from Transform::computeScaleRotation()
Upon investigation, `JacobiSVD` is significantly faster than `BDCSVD`
for small matrices (twice as fast for 2x2, 20% faster for 3x3,
1% faster for 10x10).  Since the majority of cases will be small,
let's stick with `JacobiSVD`.  See !361.
2021-01-11 11:30:01 -08:00
Antonio Sanchez
3daf92c7a5 Transform::computeScalingRotation flush determinant to +/- 1.
In the previous code, in attempting to correct for a negative
determinant, we end up multiplying and dividing by a number that
is often very near, but not exactly +/-1.  By flushing to +/-1,
we can replace a division with a multiplication, and results
are more numerically consistent.
2021-01-11 10:13:38 -08:00
Antonio Sanchez
587fd6ab70 Only specialize complex sqrt_impl for CUDA if not MSVC.
We already specialize `sqrt_impl` on windows due to MSVC's mishandling
of `inf` (!355).
2021-01-11 09:15:45 -08:00
Deven Desai
2a6addb4f9 Fix for breakage in ROCm support - 210108
The following commit breaks ROCm support for Eigen
f149e0ebc3

All unit tests fail with the following error

```
Building HIPCC object test/CMakeFiles/gpu_basic.dir/gpu_basic_generated_gpu_basic.cu.o
In file included from /home/rocm-user/eigen/test/gpu_basic.cu:19:
In file included from /home/rocm-user/eigen/test/main.h:356:
In file included from /home/rocm-user/eigen/Eigen/QR:11:
In file included from /home/rocm-user/eigen/Eigen/Core:166:
/home/rocm-user/eigen/Eigen/src/Core/MathFunctionsImpl.h:105:35: error: __host__ __device__ function 'complex_sqrt' cannot overload __host__ function 'complex_sqrt'
EIGEN_DEVICE_FUNC std::complex<T> complex_sqrt(const std::complex<T>& z) {
                                  ^
/home/rocm-user/eigen/Eigen/src/Core/MathFunctions.h:342:38: note: previous declaration is here
template<typename T> std::complex<T> complex_sqrt(const std::complex<T>& a_x);
                                     ^
1 error generated when compiling for gfx900.
CMake Error at gpu_basic_generated_gpu_basic.cu.o.cmake:192 (message):
  Error generating file
  /home/rocm-user/eigen/build/test/CMakeFiles/gpu_basic.dir//./gpu_basic_generated_gpu_basic.cu.o

test/CMakeFiles/gpu_basic.dir/build.make:63: recipe for target 'test/CMakeFiles/gpu_basic.dir/gpu_basic_generated_gpu_basic.cu.o' failed
make[3]: *** [test/CMakeFiles/gpu_basic.dir/gpu_basic_generated_gpu_basic.cu.o] Error 1
CMakeFiles/Makefile2:16618: recipe for target 'test/CMakeFiles/gpu_basic.dir/all' failed
make[2]: *** [test/CMakeFiles/gpu_basic.dir/all] Error 2
CMakeFiles/Makefile2:16625: recipe for target 'test/CMakeFiles/gpu_basic.dir/rule' failed
make[1]: *** [test/CMakeFiles/gpu_basic.dir/rule] Error 2
Makefile:5401: recipe for target 'gpu_basic' failed
make: *** [gpu_basic] Error 2

```

The error message is accurate, and the fix (provided in thsi commit) is trivial.
2021-01-08 18:04:40 +00:00
Antonio Sanchez
f149e0ebc3 Fix MSVC complex sqrt and packetmath test.
MSVC incorrectly handles `inf` cases for `std::sqrt<std::complex<T>>`.
Here we replace it with a custom version (currently used on GPU).

Also fixed the `packetmath` test, which previously skipped several
corner cases since `CHECK_CWISE1` only tests the first `PacketSize`
elements.
2021-01-08 01:17:19 +00:00
Essex Edwards
e741b43668 Make Transform::computeRotationScaling(0,&S) continuous 2021-01-07 17:45:14 +00:00
David Tellenbach
0bdc0dba20 Add missing #endif directive in Macros.h 2021-01-07 12:32:41 +01:00
shrek1402
cb654b1c45 #define was defined incorrectly because the result_of function was deprecated in c++17 and removed in c++20. Also, EIGEN_COMP_MSVC (which is _MSC_VER) only affects result_of indirectly, which can cause errors. 2021-01-07 10:12:25 +00:00
Antonio Sanchez
52d1dd979a Fix Ref initialization.
Since `eigen_assert` is a macro, the statements can become noops (e.g.
when compiling for GPU), so they may not execute the contained logic -- which
in this case is the entire `Ref` construction.  We need to separate the assert
from statements which have consequences.

Fixes #2113
2021-01-06 13:14:20 -08:00
Antonio Sanchez
166fcdecdb Allow CwiseUnaryView to be used on device.
Added `EIGEN_DEVICE_FUNC` to methods.
2021-01-06 09:16:52 -08:00
Antonio Sanchez
bb1de9dbde Fix Ref Stride checks.
The existing `Ref` class failed to consider cases where the Ref's
`Stride` setting *could* match the underlying referred object's stride,
but **didn't** at runtime.  This led to trying to set invalid stride values,
causing runtime failures in some cases, and garbage due to mismatched
strides in others.

Here we add the missing runtime checks.  This involves computing the
strides necessary to align with the referred object's storage, and
verifying we can actually set those strides at runtime.

In the `const` case, if it *may* be possible to refer to the original
storage at compile-time but fails at runtime, then we defer to the
`construct(...)` method that makes a copy.

Added more tests to check these cases.

Fixes #2093.
2021-01-05 10:41:25 -08:00
Christoph Hertzberg
12dda34b15 Eliminate boolean product warnings by factoring out a
`combine_scalar_factors` helper function.
2021-01-05 18:15:30 +00:00
Antonio Sanchez
070d303d56 Add CUDA complex sqrt.
This is to support scalar `sqrt` of complex numbers `std::complex<T>` on
device, requested by Tensorflow folks.

Technically `std::complex` is not supported by NVCC on device
(though it is by clang), so the default `sqrt(std::complex<T>)` function only
works on the host. Here we create an overload to add back the
functionality.

Also modified the CMake file to add `--relaxed-constexpr` (or
equivalent) flag for NVCC to allow calling constexpr functions from
device functions, and added support for specifying compute architecture for
NVCC (was already available for clang).
2020-12-22 23:25:23 -08:00
rgreenblatt
fdf2ee62c5 Fix missing EIGEN_DEVICE_FUNC 2020-12-20 23:22:53 -05:00
Rasmus Munk Larsen
05754100fe * Add iterative psqrt<double> for AVX and SSE when FMA is available. This provides a ~10% speedup.
* Write iterative sqrt explicitly in terms of pmadd. This gives up to 7% speedup for psqrt<float> with AVX & SSE with FMA.
* Remove iterative psqrt<double> for NEON, because the initial rsqrt apprimation is not accurate enough for convergence in 2 Newton-Raphson steps and with 3 steps, just calling the builtin sqrt insn is faster.

The following benchmarks were compiled with clang "-O2 -fast-math -mfma" and with and without -mavx.

AVX+FMA (float)

name                      old cpu/op  new cpu/op  delta
BM_eigen_sqrt_float/1     1.08ns ± 0%  1.09ns ± 1%    ~
BM_eigen_sqrt_float/8     2.07ns ± 0%  2.08ns ± 1%    ~
BM_eigen_sqrt_float/64    12.4ns ± 0%  12.4ns ± 1%    ~
BM_eigen_sqrt_float/512   95.7ns ± 0%  95.5ns ± 0%    ~
BM_eigen_sqrt_float/4k     776ns ± 0%   763ns ± 0%  -1.67%
BM_eigen_sqrt_float/32k   6.57µs ± 1%  6.13µs ± 0%  -6.69%
BM_eigen_sqrt_float/256k  83.7µs ± 3%  83.3µs ± 2%    ~
BM_eigen_sqrt_float/1M     335µs ± 2%   332µs ± 2%    ~

SSE+FMA (float)
name                      old cpu/op  new cpu/op  delta
BM_eigen_sqrt_float/1     1.08ns ± 0%  1.09ns ± 0%    ~
BM_eigen_sqrt_float/8     2.07ns ± 0%  2.06ns ± 0%    ~
BM_eigen_sqrt_float/64    12.4ns ± 0%  12.4ns ± 1%    ~
BM_eigen_sqrt_float/512   95.7ns ± 0%  96.3ns ± 4%    ~
BM_eigen_sqrt_float/4k     774ns ± 0%   763ns ± 0%  -1.50%
BM_eigen_sqrt_float/32k   6.58µs ± 2%  6.11µs ± 0%  -7.06%
BM_eigen_sqrt_float/256k  82.7µs ± 1%  82.6µs ± 1%    ~
BM_eigen_sqrt_float/1M     330µs ± 1%   329µs ± 2%    ~

SSE+FMA (double)
BM_eigen_sqrt_double/1      1.63ns ± 0%  1.63ns ± 0%     ~
BM_eigen_sqrt_double/8      6.51ns ± 0%  6.08ns ± 0%   -6.68%
BM_eigen_sqrt_double/64     52.1ns ± 0%  46.5ns ± 1%  -10.65%
BM_eigen_sqrt_double/512     417ns ± 0%   374ns ± 1%  -10.29%
BM_eigen_sqrt_double/4k     3.33µs ± 0%  2.97µs ± 1%  -11.00%
BM_eigen_sqrt_double/32k    26.7µs ± 0%  23.7µs ± 0%  -11.07%
BM_eigen_sqrt_double/256k    213µs ± 0%   206µs ± 1%   -3.31%
BM_eigen_sqrt_double/1M      862µs ± 0%   870µs ± 2%   +0.96%

AVX+FMA (double)
name                        old cpu/op  new cpu/op  delta
BM_eigen_sqrt_double/1      1.63ns ± 0%  1.63ns ± 0%     ~
BM_eigen_sqrt_double/8      6.51ns ± 0%  6.06ns ± 0%   -6.95%
BM_eigen_sqrt_double/64     52.1ns ± 0%  46.5ns ± 1%  -10.80%
BM_eigen_sqrt_double/512     417ns ± 0%   373ns ± 1%  -10.59%
BM_eigen_sqrt_double/4k     3.33µs ± 0%  2.97µs ± 1%  -10.79%
BM_eigen_sqrt_double/32k    26.7µs ± 0%  23.8µs ± 0%  -10.94%
BM_eigen_sqrt_double/256k    214µs ± 0%   208µs ± 2%   -2.76%
BM_eigen_sqrt_double/1M      866µs ± 3%   923µs ± 7%     ~
2020-12-16 18:16:11 +00:00
Rasmus Munk Larsen
6cee8d347e Add an additional step of Newton-Raphson for psqrt<double> on Arm, which otherwise has an error of ~1000 ulps. 2020-12-15 04:06:41 +00:00
David Tellenbach
751f18f2c0 Remove comma at the end of enumeration list to silence C++03 warnings 2020-12-13 18:11:02 +01:00
Antonio Sanchez
5dc2fbabee Fix implicit cast to double.
Triggers `-Wimplicit-float-conversion`, causing a bunch of build errors
in Google due to `-Wall`.
2020-12-12 09:26:20 -08:00
Antonio Sanchez
55967f87d1 Fix NEON pmax<PropagateNumbers,Packet4bf>.
Simple typo, the max impl called pmin instead of pmax for floats.
2020-12-11 21:50:52 -08:00
Antonio Sanchez
839aa505c3 Fix typo in AVX512 packet math. 2020-12-11 21:35:44 -08:00
David Tellenbach
536c8a79f2 Remove unused macro in Half.h 2020-12-12 00:53:26 +01:00
Antonio Sanchez
8c9976d7f0 Fix more SSE/AVX packet conversions for peven.
MSVC doesn't like function-style casts and forces us to use intrinsics.
2020-12-11 15:46:42 -08:00
Antonio Sanchez
c6efc4e0ba Replace M_LOG2E and M_LN2 with custom macros.
For these to exist we would need to define `_USE_MATH_DEFINES` before
`cmath` or `math.h` is first included.  However, we don't
control the include order for projects outside Eigen, so even defining
the macro in `Eigen/Core` does not fix the issue for projects that
end up including `<cmath>` before Eigen does (explicitly or transitively).

To fix this, we define `EIGEN_LOG2E` and `EIGEN_LN2` ourselves.
2020-12-11 14:34:31 -08:00
Antonio Sanchez
e82722a4a7 Fix MSVC SSE casts.
MSVC doesn't like __m128(__m128i) c-style casts, so packets need to be
converted using intrinsic methods.
2020-12-11 08:52:59 -08:00
Deven Desai
f3d2ea48f5 Fix for broken ROCm/HIP Support
The following commit introduced a breakage in ROCm/HIP support for Eigen.

5ec4907434 (1958e65719641efe5483abc4ce0b61806270f6f3_525_517)

```
Building HIPCC object test/CMakeFiles/gpu_basic.dir/gpu_basic_generated_gpu_basic.cu.o
In file included from /home/rocm-user/eigen/test/gpu_basic.cu:20:
In file included from /home/rocm-user/eigen/test/main.h:356:
In file included from /home/rocm-user/eigen/Eigen/QR:11:
In file included from /home/rocm-user/eigen/Eigen/Core:222:
/home/rocm-user/eigen/Eigen/src/Core/arch/GPU/PacketMath.h:556:10: error: use of undeclared identifier 'half2half2'; did you mean '__half2half2'?
  return half2half2(from);
         ^~~~~~~~~~
         __half2half2
/opt/rocm/hip/include/hip/hcc_detail/hip_fp16.h:547:21: note: '__half2half2' declared here
            __half2 __half2half2(__half x)
                    ^
1 error generated when compiling for gfx900.

```

The cause seems to be a copy-paster error, and the fix is trivial
2020-12-11 16:14:57 +00:00
David Tellenbach
c7eb3a74cb Don't guard psqrt for std::complex<float> with EIGEN_ARCH_ARM64 2020-12-11 12:41:52 +01:00
Everton Constantino
bccf055a7c Add Armv8 guard on PropagateNumbers implementation. 2020-12-10 22:01:55 -03:00
Antonio Sanchez
82c0c18a83 Remove private access of std::deque::_M_impl.
This no longer works on gcc or clang, so we should just remove the hack.
The default should compile to similar code anyways.
2020-12-10 14:59:34 -08:00
David Tellenbach
00be0a7ff3 Fix vectorization of complex sqrt on NEON 2020-12-10 15:23:23 +00:00
David Tellenbach
8eb461a431 Remove comma at end of enumerator list in NEON PacketMath 2020-12-10 15:22:55 +01:00
David Tellenbach
2e8f850c78 Fix a typo in SparseMatrix documentation.
This fixes issue #2091.
2020-12-09 14:48:24 +01:00
Rasmus Munk Larsen
125cc9a5df Implement vectorized complex square root.
Closes #1905

Measured speedup for sqrt of `complex<float>` on Skylake:

SSE:
```
name                      old time/op             new time/op  delta
BM_eigen_sqrt_ctype/1     49.4ns ± 0%             54.3ns ± 0%  +10.01%
BM_eigen_sqrt_ctype/8      332ns ± 0%               50ns ± 1%  -84.97%
BM_eigen_sqrt_ctype/64    2.81µs ± 1%             0.38µs ± 0%  -86.49%
BM_eigen_sqrt_ctype/512   23.8µs ± 0%              3.0µs ± 0%  -87.32%
BM_eigen_sqrt_ctype/4k     202µs ± 0%               24µs ± 2%  -88.03%
BM_eigen_sqrt_ctype/32k   1.63ms ± 0%             0.19ms ± 0%  -88.18%
BM_eigen_sqrt_ctype/256k  13.0ms ± 0%              1.5ms ± 1%  -88.20%
BM_eigen_sqrt_ctype/1M    52.1ms ± 0%              6.2ms ± 0%  -88.18%
```

AVX2:
```
name                      old cpu/op  new cpu/op  delta
BM_eigen_sqrt_ctype/1     53.6ns ± 0%  55.6ns ± 0%   +3.71%
BM_eigen_sqrt_ctype/8      334ns ± 0%    27ns ± 0%  -91.86%
BM_eigen_sqrt_ctype/64    2.79µs ± 0%  0.22µs ± 2%  -92.28%
BM_eigen_sqrt_ctype/512   23.8µs ± 1%   1.7µs ± 1%  -92.81%
BM_eigen_sqrt_ctype/4k     201µs ± 0%    14µs ± 1%  -93.24%
BM_eigen_sqrt_ctype/32k   1.62ms ± 0%  0.11ms ± 1%  -93.29%
BM_eigen_sqrt_ctype/256k  13.0ms ± 0%   0.9ms ± 1%  -93.31%
BM_eigen_sqrt_ctype/1M    52.0ms ± 0%   3.5ms ± 1%  -93.31%
```

AVX512:
```
name                      old cpu/op  new cpu/op  delta
BM_eigen_sqrt_ctype/1     53.7ns ± 0%  56.2ns ± 1%   +4.75%
BM_eigen_sqrt_ctype/8      334ns ± 0%    18ns ± 2%  -94.63%
BM_eigen_sqrt_ctype/64    2.79µs ± 0%  0.12µs ± 1%  -95.54%
BM_eigen_sqrt_ctype/512   23.9µs ± 1%   1.0µs ± 1%  -95.89%
BM_eigen_sqrt_ctype/4k     202µs ± 0%     8µs ± 1%  -96.13%
BM_eigen_sqrt_ctype/32k   1.63ms ± 0%  0.06ms ± 1%  -96.15%
BM_eigen_sqrt_ctype/256k  13.0ms ± 0%   0.5ms ± 4%  -96.11%
BM_eigen_sqrt_ctype/1M    52.1ms ± 0%   2.0ms ± 1%  -96.13%
```
2020-12-08 18:13:35 -08:00
Antonio Sanchez
8cfe0db108 Fix host/device calls for __half.
The previous code had `__host__ __device__` functions calling `__device__`
functions (e.g. `__low2half`) which caused build failures in tensorflow.
Also tried to simplify the `#ifdef` guards to make them more clear.
2020-12-08 20:31:02 +00:00
Everton Constantino
baf9d762b7 - Enabling PropagateNaN and PropagateNumbers for NEON.
- Adding propagate tests to bfloat16.
2020-12-08 17:05:05 +00:00
Antonio Sanchez
634bd79b0e Fix unused warning on new dense_assignment_loop impl. 2020-12-07 19:14:21 -08:00
Antonio Sanchez
655c3a4042 Add specialization for compile-time zero-sized dense assignment.
In the current `dense_assignment_loop` implementations, if the
destination's inner or outer size is zero at compile time and if the kernel
involves a product, we currently get a compile error (#2080).  This is
triggered by attempting to multiply a non-existent row by a column (or
vice-versa).

To address this, we add a specialization for zero-sized assignments
(`AllAtOnceTraversal`) which evaluates to a no-op. We also add a static
check to ensure the size is in-fact zero. This now seems to be the only
existing use of `AllAtOnceTraversal`.

Fixes #2080.
2020-12-07 08:38:43 -08:00
Antonio Sanchez
5ec4907434 Clean up #ifs in GPU PacketPath.
Removed redundant checks and redundant code for CUDA/HIP.

Note: there are several issues here of calling `__device__` functions
from `__host__ __device__` functions, in particular `__low2half`.
We do not address that here -- only modifying this file enough
to get our current tests to compile.

Fixed: #1847
2020-12-04 16:14:03 -08:00
Rasmus Munk Larsen
f9fac1d5b0 Add log2() to Eigen. 2020-12-04 21:45:09 +00:00
Antonio Sanchez
e2f21465fe Special function implementations for half/bfloat16 packets.
Current implementations fail to consider half-float packets, only
half-float scalars.  Added specializations for packets on AVX, AVX512 and
NEON.  Added tests to `special_packetmath`.

The current `special_functions` tests would fail for half and bfloat16 due to
lack of precision. The NEON tests also fail with precision issues and
due to different handling of `sqrt(inf)`, so special functions bessel, ndtri
have been disabled.

Tested with AVX, AVX512.
2020-12-04 10:16:29 -08:00
David Tellenbach
305b8bd277 Remove duplicate #if clause 2020-12-04 18:55:46 +01:00
Antonio Sanchez
9ee9ac81de Fix shfl* macros for CUDA/HIP
The `shfl*` functions are `__device__` only, and adjusted `#ifdef`s so
they are defined whenever the corresponding CUDA/HIP ones are.

Also changed the HIP/CUDA<9.0 versions to cast to int instead of
doing the conversion `half`<->`float`.

Fixes #2083
2020-12-04 17:18:32 +00:00
shrek1402
a9a2f2bebf The function 'prefetch' did not work correctly on the win64 platform 2020-12-04 17:18:08 +00:00
Rasmus Munk Larsen
f23dc5b971 Revert "Add log2() operator to Eigen"
This reverts commit 4d91519a9b.
2020-12-03 14:32:45 -08:00
Rasmus Munk Larsen
4d91519a9b Add log2() operator to Eigen 2020-12-03 22:31:44 +00:00
Rasmus Munk Larsen
25d8ae7465 Small cleanup of generic plog implementations:
Adding the term e*ln(2) is split into two step for no obvious reason.
This dates back to the original Cephes code from which the algorithm is adapted.
It appears that this was done in Cephes to prevent the compiler from reordering
the addition of the 3 terms in the approximation

  log(1+x) ~= x - 0.5*x^2 + x^3*P(x)/Q(x)

which must be added in reverse order since |x| < (sqrt(2)-1).

This allows rewriting the code to just 2 pmadd and 1 padd instructions,
which on a Skylake processor speeds up the code by 5-7%.
2020-12-03 19:40:40 +00:00
Antonio Sanchez
70fbcf82ed Fix typo in F32MaskToBf16Mask. 2020-12-02 07:58:34 -08:00
Antonio Sanchez
2627e2f2e6 Fix neon cmp* functions for bf16.
The current impl corrupts the comparison masks when converting
from float back to bfloat16.  The resulting masks are then
no longer all zeros or all ones, which breaks when used with
`pselect` (e.g. in `pmin<PropagateNumbers>`).  This was
causing `packetmath_15` to fail on arm.

Introducing a simple `F32MaskToBf16Mask` corrects this (takes
the lower 16-bits for each float mask).
2020-12-02 01:29:34 +00:00