Not using builtins doesn't always imply worse code,
but for e. g. isinf, this is 30%+ faster.
Before:
name time/op
BM_isinf 2.14ns ± 2%
After:
name time/op
BM_isinf 1.33ns ± 2%
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D88854
This commit should will break libc++ without local submodule visibility, but
the LLVM+modules bots are now all using this mode. Before the Green Dragon
LLDB bot was failing to compile with a libc++ built with this commit as LSV
was disabled on macOS.
Original summary:
libc++ is careful to not fracture overload sets. When one overload
is visible to a user, all of them should be. Anything less causes
subtle bugs and ODR violations.
Previously, in order to support ::abs and ::div being supplied by
both <cmath> and <cstdlib> we had to do awful things that make
<math.h> and <stdlib.h> have header cycles and be non-modular.
This really breaks with modules.
Specifically the problem was that in C++ ::abs introduces overloads
for floating point numbers, these overloads forward to ::fabs,
which are defined in math.h. Therefore ::abs needed to be in math.h
too. But this required stdlib.h to include math.h and math.h to
include stdlib.h.
To avoid these problems the definitions have been moved to stddef.h
(which math includes), and the floating point overloads of ::abs
have been changed to call __builtin_fabs, which both Clang and GCC
support.
This relands this commit as it broke the LLDB bot the first time it landed.
See also the discussion on https://reviews.llvm.org/rG82b47b2978405f802a33b00d046e6f18ef6a47be
Since D74892 this code should now also work on macOS.
Original description:
libc++ is careful to not fracture overload sets. When one overload
is visible to a user, all of them should be. Anything less causes
subtle bugs and ODR violations.
Previously, in order to support ::abs and ::div being supplied by
both <cmath> and <cstdlib> we had to do awful things that make
<math.h> and <stdlib.h> have header cycles and be non-modular.
This really breaks with modules.
Specifically the problem was that in C++ ::abs introduces overloads
for floating point numbers, these overloads forward to ::fabs,
which are defined in math.h. Therefore ::abs needed to be in math.h
too. But this required stdlib.h to include math.h and math.h to
include stdlib.h.
To avoid these problems the definitions have been moved to stddef.h
(which math includes), and the floating point overloads of ::abs
have been changed to call __builtin_fabs, which both Clang and GCC
support.
This reverts commit 82b47b2978.
This broke Clang and LLDB module builds without -fmodules-local-submodule-visbility.
I'll revert this for now until we have a fix and reland once Clang
can properly handle this code.
See also the discussion in https://reviews.llvm.org/rG82b47b2978405f802a33b00d046e6f18ef6a47be
libc++ is careful to not fracture overload sets. When one overload
is visible to a user, all of them should be. Anything less causes
subtle bugs and ODR violations.
Previously, in order to support ::abs and ::div being supplied by
both <cmath> and <cstdlib> we had to do awful things that make
<math.h> and <stdlib.h> have header cycles and be non-modular.
This really breaks with modules.
Specifically the problem was that in C++ ::abs introduces overloads
for floating point numbers, these overloads forward to ::fabs,
which are defined in math.h. Therefore ::abs needed to be in math.h
too. But this required stdlib.h to include math.h and math.h to
include stdlib.h.
To avoid these problems the definitions have been moved to stddef.h
(which math includes), and the floating point overloads of ::abs
have been changed to call __builtin_fabs, which both Clang and GCC
support.
This is needed anytime we need to clamp an arbitrary floating point
value to an integer type.
Thanks to Eric Fiselier for the patch.
Differential Revision: https://reviews.llvm.org/D66836
llvm-svn: 370891
The new meta-programming primitives are lower cost than the old versions. This patch removes those old versions and switches libc++ to use the new ones.
llvm-svn: 364160
Summary:
All overloads of `::abs` and `std::abs` must be present in both `<cmath>` and `<cstdlib>`. This is problematic to implement because C defines `fabs` in `math.h` and `labs` in `stdlib.h`. This introduces a circular dependency between the two headers.
This patch implements that requirement by moving `abs` into `math.h` and making `stdlib.h` include `math.h`. In order to get the underlying C declarations from the "real" `stdlib.h` inside our `math.h` we need some trickery. Specifically we need to make `stdlib.h` include next itself.
Suggestions for a cleaner implementation are welcome.
Reviewers: mclow.lists, ldionne
Reviewed By: ldionne
Subscribers: krytarowski, fedor.sergeev, dexonsmith, jdoerfert, jsji, libcxx-commits
Differential Revision: https://reviews.llvm.org/D60097
llvm-svn: 359020
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351648
Summary:
We never actually mean to always inline a function -- all the uses of
the macro I could find are actually attempts to control the visibility
of symbols. This is better described by _LIBCPP_INLINE_VISIBILITY, which
is actually always defined the same.
This change is orthogonal to the decision of what we're actually going
to do with _LIBCPP_INLINE_VISIBILITY -- it just simplifies things by
having one canonical way of doing things.
Note that this commit had originally been applied in r336369 and then
reverted in r336382 because of unforeseen problems. Both of these problems
have now been fixed.
Reviewers: EricWF, mclow.lists
Subscribers: christof, dexonsmith, erikvanderpoel
Differential Revision: https://reviews.llvm.org/D48892
llvm-svn: 336866
This reverts commit r336369. The commit had two problems:
1. __pbump was marked as _LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY instead of
_LIBCPP_INLINE_VISIBILITY, which lead to two symbols being added in the
dylib and the check-cxx-abilist failing.
2. The LLDB tests started failing because they undefine
`_LIBCPP_INLINE_VISIBILITY`. I need to figure out why they do that and
fix the tests before we can go forward with this change.
llvm-svn: 336382
Summary:
We never actually mean to always inline a function -- all the uses of
the macro I could find are actually attempts to control the visibility
of symbols. This is better described by _LIBCPP_INLINE_VISIBILITY, which
is actually always defined the same.
This change is orthogonal to the decision of what we're actually going
to do with _LIBCPP_INLINE_VISIBILITY -- it just simplifies things by
having one canonical way of doing things.
Reviewers: EricWF
Subscribers: christof, llvm-commits, dexonsmith, erikvanderpoel, mclow.lists
Differential Revision: https://reviews.llvm.org/D48892
llvm-svn: 336369
When using an old version of glibc, a ::isinf(double) and ::isnan(double)
function is provided, rather than just the macro required by C and C++.
Displace this function using _LIBCPP_PREFERRED_OVERLOAD where possible.
The only remaining case where we should get the wrong return type is now
glibc + libc++ + a non-clang compiler.
llvm-svn: 331241
Summary:
Certain C libraries require configuration macros defined in __config
to provide the correct functionality for libc++. This patch ensures
that the C header math.h is always included after the __config
header. It also adds a Windows-specific #if guard for the case when
the C math.h file is included the second time, as suggested by
Marshall in https://reviews.llvm.org/rL323490.
Fixes PR36382.
Reviewers: mclow.lists, EricWF
Reviewed By: mclow.lists
Subscribers: cfe-commits, pcc, christof, rogfer01
Differential Revision: https://reviews.llvm.org/D43579
llvm-svn: 325760
Code on Windows expects to be able to do:
#define _USE_MATH_DEFINES
#include <math.h>
and receive the definitions of mathematical constants, even if <math.h>
has previously been included. To support this scenario, re-include
<math.h> every time the wrapper header is included.
Differential Revision: https://reviews.llvm.org/D42403
llvm-svn: 323490
For std::isinf, the standard requires effectively calling isinf as
double from Libc for integral types. But integral types are never
infinite; we don't need to call Libc to return false.
Also short-circuit other functions where Libc won't have interesting
answers: signbit, fpclassify, isfinite, isnan, and isnormal.
I added correctness tests for integral types since we're no longer
deferring to Libc.
In review it was pointed out that in future revisions of the C++
standard we may add more types to std::is_arithmetic (e.g.,
std::is_fixed_point). I'll leave it to a future commit to hack this to
allow using math functions on those. We'll need to change things like
__libcpp_fpclassify anyway, so I'm not sure anything here would really
be future-proof.
https://reviews.llvm.org/D31561
rdar://problem/31361223
llvm-svn: 301060
LLVM dropped support for Visual Studio versions older than 2015 quite
some time ago, so I consider it safe to drop libc++'s support for older
CRTs. The CRT in Visual Studio 2015 provides a lot of previously missing
functions, so targeting it requires less special casing.
Differential Revision: https://reviews.llvm.org/D31798
llvm-svn: 299743
When building with MSVCRT, we need to manually provide the type
promoting overloads to allow the correct type deduced invocation for
signbit(Int) and fpclassify(int).
llvm-svn: 295559
Pull in the math functions from ucrt 14+ after auditing the library. It
seems that they are now complete for C99 math. Fixes more windows
tests!
llvm-svn: 294918
Visual Studio 2013 and onward have all the required functions in their
CRT headers, and we don't support older versions anymore.
Differential Revision: https://reviews.llvm.org/D24879
llvm-svn: 282328
Ilya Tokar