Details are scattered across #920, #1000, #1324, #2291.
Summary: some MSVC versions have a bug that requires omitting explicit
`operator=` definitions (leads to duplicate definition errors), and
some MSVC versions require adding explicit `operator=` definitions
(otherwise implicitly deleted errors). This mess tries to cover
all the cases encountered.
Fixes#2291.
For custom scalars, zero is not necessarily represented by
a zeroed-out memory block (e.g. gnu MPFR). We therefore
cannot rely on `memset` if we want to fill a matrix or tensor
with zeroes. Instead, we should rely on `fill`, which for trivial
types does end up getting converted to a `memset` under-the-hood
(at least with gcc/clang).
Requires adding a `fill(begin, end, v)` to `TensorDevice`.
Replaced all potentially bad instances of memset with fill.
Fixes#2245.
- Move constructors can only be defaulted as NOEXCEPT if all members
have NOEXCEPT move constructors.
- gcc 4.8 has some funny parsing bug in `a < b->c`, thinking `b-` is a template parameter.
For empty or single-column matrices, the current `PartialPivLU`
currently dereferences a `nullptr` or accesses memory out-of-bounds.
Here we adjust the checks to avoid this.
We can't make guarantees on alignment for existing calls to `pset`,
so we should default to loading unaligned. But in that case, we should
just use `ploadu` directly. For loading constants, this load should hopefully
get optimized away.
This is causing segfaults in Google Maps.
MinGW spits out version strings like: `x86_64-w64-mingw32-g++ (GCC)
10-win32 20210110`, which causes the version extraction to fail.
Added support for this with tests.
Also added `make_unsigned` for `long long`, since mingw seems to
use that for `uint64_t`.
Related to #2268. CMake and build passes for me after this.
This used to work for non-class types (e.g. raw function pointers) in
Eigen 3.3. This was changed in commit 11f55b29 to optimize the
evaluator:
> `sizeof((A-B).cwiseAbs2())` with A,B Vector4f is now 16 bytes, instead of 48 before this optimization.
though I cannot reproduce the 16 byte result. Both before the change
and after, with multiple compilers/versions, I always get a result of 40 bytes.
https://godbolt.org/z/MsjTc1PGe
This change modifies the code slightly to allow non-class types. The
final generated code is identical, and the expression remains 40 bytes
for the `abs2` sample case.
Fixes#2251
When calling conservativeResize() on a matrix with DontAlign flag, the
temporary variable used to perform the resize should have the same
Options as the original matrix to ensure that the correct override of
swap is called (i.e. PlainObjectBase::swap(DenseBase<OtherDerived> &
other). Calling the base class swap (i.e in DenseBase) results in
assertions errors or memory corruption.
The boost library unfortunately specializes `conj` for various types and
assumes the original two-template-parameter version. This changes
restores the second parameter. This also restores ABI compatibility.
The specialization for `std::complex` is because `std::conj` is not
a device function. For custom complex scalar types, users should provide
their own `conj` implementation.
We may consider removing the unnecessary second parameter in the future - but
this will require modifying boost as well.
Fixes#2112.
The cxx11 path for `numext::arg` incorrectly returned the complex type
instead of the real type, leading to compile errors. Fixed this and
added tests.
Related to !477, which uncovered the issue.
Fixes#2229.
For dynamic matrices with fixed-sized storage, only copy/swap
elements that have been set. Otherwise, this leads to inefficient
copying, and potential UB for non-initialized elements.
Should have been 0.5 to widen the bounds, since this is inverse
precision. Setting to 0.5, however, leads to many more failing
tests at Google, so reverting to 1 for now.
Adjust the relaxation step to use the condition
```
abs(subdiag[i]) <= epsilon * sqrt(abs(diag[i]) + abs(diag[i+1]))
```
for setting the subdiagonal entry to zero.
Also adjust Wilkinson shift for small `e = subdiag[end-1]` -
I couldn't find a reference for the original, and it was not
consistent with the Wilkinson definition.
Fixes#2191.
Some CUDA/HIP constants fail on device with `constexpr` since they
internally rely on non-constexpr functions, e.g.
```
\#define CUDART_INF_F __int_as_float(0x7f800000)
```
This fails for cuda-clang (though passes with nvcc). These constants are
currently used by `device::numeric_limits`. For portability, we
need to remove `constexpr` from the affected functions.
For C++11 or higher, we should be able to rely on the `std::numeric_limits`
versions anyways, since the methods themselves are now `constexpr`, so
should be supported on device (clang/hipcc natively, nvcc with
`--expr-relaxed-constexpr`).
The Eigen unit-tests started failing on the HIP/ROCm platform, after the following commit
e7b8643d70
```
In file included from /home/rocm-user/eigen/test/main.h:360:
In file included from /home/rocm-user/eigen/Eigen/QR:11:
In file included from /home/rocm-user/eigen/Eigen/Core:162:
/home/rocm-user/eigen/Eigen/src/Core/util/Meta.h:300:17: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
static float (max)() {
^
/home/rocm-user/eigen/Eigen/src/Core/util/Meta.h:304:12: note: non-constexpr function '__int_as_float' cannot be used in a constant expression
return HIPRT_MAX_NORMAL_F;
^
/home/rocm-user/eigen/Eigen/src/Core/arch/HIP/hcc/math_constants.h:14:28: note: expanded from macro 'HIPRT_MAX_NORMAL_F'
#define HIPRT_MAX_NORMAL_F __int_as_float(0x7f7fffff)
^
/opt/rocm/hip/include/hip/hcc_detail/device_functions.h:913:32: note: declared here
__device__ static inline float __int_as_float(int x) {
^
```
The problem seems to that some of the constants defined in the HIP `math_constants.h` have a call to `__int_as_float` routine which is not declared `constexpr` in the HIP runtime header file.
Working around this issue for now, be skipping the const_expr support (enabled via the above commit) on HIP
Replace usage of `std::numeric_limits<...>::min/max_exponent` in
codebase where possible. Also replaced some other `numeric_limits`
usages in affected tests with the `NumTraits` equivalent.
The previous MR !443 failed for c++03 due to lack of `constexpr`.
Because of this, we need to keep around the `std::numeric_limits`
version in enum expressions until the switch to c++11.
Fixes#2148
Replace usage of `std::numeric_limits<...>::min/max_exponent` in
codebase. Also replaced some other `numeric_limits` usages in
affected tests with the `NumTraits` equivalent.
Fixes#2148
This is to resolve an issue for large inputs when +0.5 can
actually lead to +1 if the input doesn't have enough precision
to resolve the addition - leading to an off-by-one error.
See discussion on 9a663973.
NVCC does not understand `__forceinline`, so we need to use `inline`
when compiling for GPU.
ICC specializes `std::complex` operators for `float` and `double`
by default, which cannot be used on device and conflict with Eigen's
workaround in CUDA/Complex.h. This can be prevented by defining
`_OVERRIDE_COMPLEX_SPECIALIZATION_` before including `<complex>`.
Added this define to the tests and to `Eigen/Core`, but this will
not work if the user includes `<complex>` before `<Eigen/Core>`.
ICC also seems to generate a duplicate `Map` symbol in
`PlainObjectBase`:
```
error: "Map" has already been declared in the current scope
static ConstMapType Map(const Scalar *data)
```
I tracked this down to `friend class Eigen::Map`. Putting the `friend`
statements at the bottom of the class seems to resolve this issue.
Fixes#2180
The original swap approach leads to potential undefined behavior (reading
uninitialized memory) and results in unnecessary copying of data for static
storage.
Here we pass down the move assignment to the underlying storage. Static
storage does a one-way copy, dynamic storage does a swap.
Modified the tests to no longer read from the moved-from matrix/tensor,
since that can lead to UB. Added a test to ensure we do not access
uninitialized memory in a move.
Fixes: #2119
Both CUDA and HIP require trivial default constructors for types used
in shared memory. Otherwise failing with
```
error: initialization is not supported for __shared__ variables.
```
Currently, when compiling with HIP, Eigen::half is derived from the `__half_raw` struct that is defined within the hip_fp16.h header file. This is true for both the "host" compile phase and the "device" compile phase. This was causing a very hard to detect bug in the ROCm TensorFlow build.
In the ROCm Tensorflow build,
* files that do not contain ant GPU code get compiled via gcc, and
* files that contnain GPU code get compiled via hipcc.
In certain case, we have a function that is defined in a file that is compiled by hipcc, and is called in a file that is compiled by gcc. If such a function had Eigen::half has a "pass-by-value" argument, its value was getting corrupted, when received by the function.
The reason for this seems to be that for the gcc compile, Eigen::half is derived from a `__half_raw` struct that has `uint16_t` as the data-store, and for hipcc the `__half_raw` implementation uses `_Float16` as the data store. There is some ABI incompatibility between gcc / hipcc (which is essentially latest clang), which results in the Eigen::half value (which is correct at the call-site) getting randomly corrupted when passed to the function.
Changing the Eigen::half argument to be "pass by reference" seems to workaround the error.
In order to fix it such that we do not run into it again in TF, this commit changes the Eigne::half implementation to use the same `__half_raw` implementation as the non-GPU compile, during host compile phase of the hipcc compile.
The macro `__cplusplus` is not defined correctly in MSVC unless building
with the the `/Zc:__cplusplus` flag. Instead, it defines `_MSVC_LANG` to the
specified c++ standard version number.
Here we introduce `EIGEN_CPLUSPLUS` which will contain the c++ version
number both for MSVC and otherwise. This simplifies checks for supported
features.
Also replaced most instances of standard version checking via `__cplusplus`
with the existing `EIGEN_COMP_CXXVER` macro for better clarity.
Fixes: #2170
This is a new version of !423, which failed for MSVC.
Defined `EIGEN_OPTIMIZATION_BARRIER(X)` that uses inline assembly to
prevent operations involving `X` from crossing that barrier. Should
work on most `GNUC` compatible compilers (MSVC doesn't seem to need
this). This is a modified version adapted from what was used in
`psincos_float` and tested on more platforms
(see #1674, https://godbolt.org/z/73ezTG).
Modified `rint` to use the barrier to prevent the add/subtract rounding
trick from being optimized away.
Also fixed an edge case for large inputs that get bumped up a power of two
and ends up rounding away more than just the fractional part. If we are
over `2^digits` then just return the input. This edge case was missed in
the test since the test was comparing approximate equality, which was still
satisfied. Adding a strict equality option catches it.
It seems *sometimes* with aggressive optimizations the combination
`psub(padd(a, b), b)` trick to force rounding is compiled away. Here
we replace with inline assembly to prevent this (I tried `volatile`,
but that leads to additional loads from memory).
Also fixed an edge case for large inputs `a` where adding `b` bumps
the value up a power of two and ends up rounding away more than
just the fractional part. If we are over `2^digits` then just return
the input. This edge case was missed in the test since the test was
comparing approximate equality, which was still satisfied. Adding
a strict equality option catches it.
In SSE, by adding/subtracting 2^MantissaBits, we force rounding according to the
current rounding mode.
For NEON, we use the provided intrinsics for rint/floor/ceil if
available (armv8).
Related to #1969.
Since `numeric_limits<half>::max_exponent` is a static inline constant,
it cannot be directly passed by reference. This triggers a linker error
in recent versions of `g++-powerpc64le`.
Changing `half` to take inputs by value fixes this. Wrapping
`max_exponent` with `int(...)` to make an addressable integer also fixes this
and may help with other custom `Scalar` types down-the-road.
Also eliminated some compile warnings for powerpc.
With !406, we accidentally broke arm 32-bit NEON builds, since
`vsqrt_f32` is only available for 64-bit.
Here we add back the `rsqrt` implementation for 32-bit, relying
on a `prsqrt` implementation with better handling of edge cases.
Note that several of the 32-bit NEON packet tests are currently
failing - either due to denormal handling (NEON versions flush
to zero, but scalar paths don't) or due to accuracy (e.g. sin/cos).
The original will saturate if the input does not fit into an integer
type. Here we fix this, returning the input if it doesn't have
enough precision to have a fractional part.
Also added `pceil` for NEON.
Fixes#1969.
The `std::result_of` meta struct is deprecated in C++17 and removed
in C++20. It was still slipping through due to a faulty definition of
`EIGEN_HAS_STD_RESULT_OF`.
Added a new macro `EIGEN_HAS_STD_INVOKE_RESULT` and
`Eigen::internal::invoke_result` implementation with fallback for
pre C++17.
Replaces the `result_of` definition with one based on `std::invoke_result`
for C++17 and higher.
For completeness, added nullary op support for c++03.
Fixes#1850.
Added `EIGEN_HAS_STD_HASH` macro, checking for C++11 support and not
running on GPU.
`std::hash<float>` is not a device function, so cannot be used by
`std::hash<bfloat16>`. Removed `EIGEN_DEVICE_FUNC` and only
define if `EIGEN_HAS_STD_HASH`. Same for `half`.
Added `EIGEN_CUDA_HAS_FP16_ARITHMETIC` to improve readability,
eliminate warnings about `EIGEN_CUDA_ARCH` not being defined.
Replaced a couple C-style casts with `reinterpret_cast` for aligned
loading of `half*` to `half2*`. This eliminates `-Wcast-align`
warnings in clang. Although not ideal due to potential type aliasing,
this is how CUDA handles these conversions internally.
macOS defines int64_t as long long even for C++03 and therefore expects
a template specialization
internal::make_unsigned<long long>,
for C++03. Since other platforms define int64_t as long for C++03 we
cannot add the specialization for all cases.
In two places in SuperLUSupport.h, a local variable 'size' is
created that is used only inside an eigen_assert. Remove these,
just fetch the required values inside the assert statements.
This avoids annoying -Wunused warnings (and -Werror=unused errors)
in NDEBUG builds.
The original clamping bounds on `_x` actually produce finite values:
```
exp(88.3762626647950) = 2.40614e+38 < 3.40282e+38
exp(709.437) = 1.27226e+308 < 1.79769e+308
```
so with an accurate `ldexp` implementation, `pexp` fails for large
inputs, producing finite values instead of `inf`.
This adjusts the bounds slightly outside the finite range so that
the output will overflow to +/- `inf` as expected.
The previous implementations produced garbage values if the exponent did
not fit within the exponent bits. See #2131 for a complete discussion,
and !375 for other possible implementations.
Here we implement the 4-factor version. See `pldexp_impl` in
`GenericPacketMathFunctions.h` for a full description.
The SSE `pcmp*` methods were moved down since `pcmp_le<Packet4i>`
requires `por`.
Left as a "TODO" is to delegate to a faster version if we know the
exponent does fit within the exponent bits.
Fixes#2131.
Currently if compiled by NVCC, the `MatrixBase::bdcSvd()` implementation
is skipped, leading to a linker error. This prevents it from running on
the host as well.
Seems it was disabled 6 years ago (5384e891) to match `jacobiSvd`, but
`jacobiSvd` is now enabled on host. Tested and runs fine on host, but
will not compile/run for device (though it's not labelled as a device
function, so this should be fine).
Fixes#2139
We are potentially seeing some accuracy issues with these. Ideally we
would hand off to `float`, but that's not trivial with the current
setup.
We may want to consider adding `ppow<Packet>` and `HasPow`, so
implementations can more easily specialize this.
Clang does a poor job of optimizing the GEBP microkernel on 32-bit ARM,
leading to excessive 16-byte register spills, slowing down basic f32
matrix multiplication by approx 50%.
By specializing `gebp_traits`, we can eliminate the register spills.
Volatile inline ASM both acts as a barrier to prevent reordering and
enforces strict register use. In a simple f32 matrix multiply example,
this modification reduces 16-byte spills from 109 instances to zero,
leading to a 1.5x speed increase (search for `16-byte Spill` in the
assembly in https://godbolt.org/z/chsPbE).
This is a replacement of !379. See there for further discussion.
Also moved `gebp_traits` specializations for NEON to
`Eigen/src/Core/arch/NEON/GeneralBlockPanelKernel.h` to be alongside
other NEON-specific code.
Fixes#2138.
Unfortunately `std::bit_and` and the like are host-only functions prior
to c++14 (since they are not `constexpr`). They also never exist in the
global namespace, so the current implementation always fails to compile via
NVCC - since `EIGEN_USING_STD` tries to import the symbol from the global
namespace on device.
To overcome these limitations, we implement these functionals here.
Allows the altivec packetmath tests to pass. There were a few issues:
- `pstoreu` was missing MSQ on `_BIG_ENDIAN` systems
- `cmp_*` didn't properly handle conversion of bool flags (0x7FC instead
of 0xFFFF)
- `pfrexp` needed to set the `exponent` argument.
Related to !370, #2128
cc: @ChipKerchner @pdrocaldeira
Tested on `_BIG_ENDIAN` running on QEMU with VSX. Couldn't figure out build
flags to get it to work for little endian.
Originating from
[this SO issue](https://stackoverflow.com/questions/65901014/how-to-solve-this-all-error-2-in-this-case),
some win32 compilers define `__int32` as a `long`, but MinGW defines
`std::int32_t` as an `int`, leading to a type conflict.
To avoid this, we remove the custom `typedef` definitions for win32. The
Tensor module requires C++11 anyways, so we are guaranteed to have
included `<cstdint>` already in `Eigen/Core`.
Also re-arranged the headers to only include `<cstdint>` in one place to
avoid this type of error again.
The new `generic_pow` implementation was failing for half/bfloat16 since
their construction from int/float is not `constexpr`. Modified
in `GenericPacketMathFunctions` to remove `constexpr`.
While adding tests for half/bfloat16, found other issues related to
implicit conversions.
Also needed to implement `numext::arg` for non-integer, non-complex,
non-float/double/long double types. These seem to be implicitly
converted to `std::complex<T>`, which then fails for half/bfloat16.
NVCC and older versions of clang do not fully support `std::complex` on device,
leading to either compile errors (Cannot call `__host__` function) or worse,
runtime errors (Illegal instruction). For most functions, we can
implement specialized `numext` versions. Here we specialize the standard
operators (with the exception of stream operators and member function operators
with a scalar that are already specialized in `<complex>`) so they can be used
in device code as well.
To import these operators into the current scope, use
`EIGEN_USING_STD_COMPLEX_OPERATORS`. By default, these are imported into
the `Eigen`, `Eigen:internal`, and `Eigen::numext` namespaces.
This allow us to remove specializations of the
sum/difference/product/quotient ops, and allow us to treat complex
numbers like most other scalars (e.g. in tests).
This patch adds support for Arm's new vector extension SVE (Scalable Vector Extension). In contrast to other vector extensions that are supported by Eigen, SVE types are inherently *sizeless*. For the use in Eigen we fix their size at compile-time (note that this is not necessary in general, SVE is *length agnostic*).
During compilation the flag `-msve-vector-bits=N` has to be set where `N` is a power of two in the range of `128`to `2048`, indicating the length of an SVE vector.
Since SVE is rather young, we decided to disable it by default even if it would be available. A user has to enable it explicitly by defining `EIGEN_ARM64_USE_SVE`.
This patch introduces the packet types `PacketXf` and `PacketXi` for packets of `float` and `int32_t` respectively. The size of these packets depends on the SVE vector length. E.g. if `-msve-vector-bits=512` is set, `PacketXf` will contain `512/32 = 16` elements.
This MR is joint work with Miguel Tairum <miguel.tairum@arm.com>.
The recent addition of vectorized pow (!330) relies on `pfrexp` and
`pldexp`. This was missing for `Eigen::half` and `Eigen::bfloat16`.
Adding tests for these packet ops also exposed an issue with handling
negative values in `pfrexp`, returning an incorrect exponent.
Added the missing implementations, corrected the exponent in `pfrexp1`,
and added `packetmath` tests.
Hex literals are interpreted as unsigned, leading to a comparison between
signed max supported function `abcd[0]` (which was negative) to the unsigned
literal `0x80000006`. Should not change result since signed is
implicitly converted to unsigned for the comparison, but eliminates the
warning.
I ran some testing (comparing to `std::pow(double(x), double(y)))` for `x` in the set of all (positive) floats in the interval `[std::sqrt(std::numeric_limits<float>::min()), std::sqrt(std::numeric_limits<float>::max())]`, and `y` in `{2, sqrt(2), -sqrt(2)}` I get the following error statistics:
```
max_rel_error = 8.34405e-07
rms_rel_error = 2.76654e-07
```
If I widen the range to all normal float I see lower accuracy for arguments where the result is subnormal, e.g. for `y = sqrt(2)`:
```
max_rel_error = 0.666667
rms = 6.8727e-05
count = 1335165689
argmax = 2.56049e-32, 2.10195e-45 != 1.4013e-45
```
which seems reasonable, since these results are subnormals with only couple of significant bits left.
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.
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.
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.
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.
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.
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
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.
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).
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.
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
