a union. These don't actually work for by-value function arguments, and
MSVC warns if they exist even while (we hope) it aligns the argument
correctly due to the other union member.
This means MSVC will miss out on optimizations based on the alignment of
the buffer, but really, there aren't that many for x86 and MSVC is
likely not doing a great job of optimizing LLVM and Clang anyways.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171328 91177308-0d34-0410-b5e6-96231b3b80d8
This adds AlignedCharArray<Alignment, Size>. A templated struct that contains
a member named buffer of type char[Size] that is aligned to Alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171319 91177308-0d34-0410-b5e6-96231b3b80d8
MSVC doesn't support passing by-value parameters with alignment of
16-bytes or higher apparantly. What is deeply confusing is that it seems
to *sometimes* (but not always) apply this to any type whose alignment
is set using __declspec(align(...)). This caused lots of errors when we switch
SmallVector over to use the automatically aligned character array
utilities as they used __declspec(align(...)) heavily.
As a pretty horrible but effective work-around, we instead cherry pick
the smallest alignment sizes with specific types that happen to have the
correct alignment, and then fall back to the attribute solution past
them. This should resolve the MSVC build errors folks have been hitting.
Sorry for that. In good news, it will do this without introducing other
UB I hope. =]
Thanks to Timur Iskhodzhanov for helping me test this!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162549 91177308-0d34-0410-b5e6-96231b3b80d8
advertising complete support w/o alignas implemented, and its
implementation of alignas in the latest versions is so convoluted as to
be unusable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159125 91177308-0d34-0410-b5e6-96231b3b80d8
There is a pretty staggering amount of this in LLVM's header files, this
is not all of the instances I'm afraid. These include all of the
functions that (in my build) are used by a non-static inline (or
external) function. Specifically, these issues were caught by the new
'-Winternal-linkage-in-inline' warning.
I'll try to just clean up the remainder of the clearly redundant "static
inline" cases on functions (not methods!) defined within headers if
I can do so in a reliable way.
There were even several cases of a missing 'inline' altogether, or my
personal favorite "static bool inline". Go figure. ;]
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158800 91177308-0d34-0410-b5e6-96231b3b80d8
array of a suitable size and alignment for any of a number of different
types to be stored into the character array.
The mechanisms for producing an explicitly aligned type are fairly
complex because this operation is poorly supported on all compilers.
We've spent a fairly significant amount of time experimenting with
different implementations inside of Google, and the one using explicitly
expanded templates has been the most robust.
Credit goes to Nick Lewycky for writing the first 20 versions or so of
this logic we had inside of Google. I based this on the only one to
actually survive. In case anyone is worried, yes we are both explicitly
re-contributing and re-licensing it for LLVM. =]
Once the issues with actually specifying the alignment are finished, it
turns out that most compilers don't in turn align anything the way they
are instructed. Testing of this logic against both Clang and GCC
indicate that the alignment constraints are largely ignored by both
compilers! I've come up with and used a work-around by wrapping each
alignment-hinted type directly in a struct, and using that struct to
align the character array through a union. This elaborate hackery is
terrifying, but I've included testing that caught a terrifying number of
bugs in every other technique I've tried.
All of this in order to implement a poor C++98 programmers emulation of
C++11 unrestricted unions in classes such as SmallDenseMap.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158597 91177308-0d34-0410-b5e6-96231b3b80d8
Added member template "Add" to FoldingSetNodeID that allows "adding" arbitrary
objects to a profile via dispatch to FoldingSetTrait<T>::Profile().
Removed FoldingSetNodeID::AddAPFloat and FoldingSetNodeID::APInt, as their
functionality is now replaced using the above mentioned member template.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46957 91177308-0d34-0410-b5e6-96231b3b80d8
