Add `SmallVectorImpl::truncate()`, a variant of `resize()` that cannot
increase the size.
- Compared to `resize()`, this has no code path for growing the
allocation and can be better optimized.
- Compared to `set_size()`, this formally calls destructors, and does
not skip any constructors.
- Compared to `pop_back_n()`, this takes the new desired size, which in
many contexts is more intuitive than the number of elements to remove.
The immediate motivation is to pair this with `resize_for_overwrite()`
to remove uses of `set_size()`, which can then be made private.
Differential Revision: https://reviews.llvm.org/D115383
Rather than reimplement, use a `using` declaration to bring in
`SmallVectorImpl<char>`'s assign and append implementations in
`SmallString`.
The `SmallString` versions were missing reference invalidation
assertions from `SmallVector`. This patch also fixes a bug in
`llvm::FileCollector::addFileImpl`, which was a copy/paste from
`clang::ModuleDependencyCollector::copyToRoot`, both caught by the
no-longer-skipped assertions.
As a drive-by, this also sinks the `const SmallVectorImpl&` versions of
these methods down into `SmallVectorImpl`, since I imagine they'd be
useful elsewhere.
Differential Revision: https://reviews.llvm.org/D95202
This fixes the final (I think?) reference invalidation in `SmallVector`
that we need to fix to align with `std::vector`. (There is still some
left in the range insert / append / assign, but the standard calls that
UB for `std::vector` so I think we don't care?)
For POD-like types, reimplement `emplace_back()` in terms of
`push_back()`, taking a copy even for large `T` rather than lose the
realloc optimization in `grow_pod()`.
For other types, split the grow operation in three and construct the new
element in the middle.
- `mallocForGrow()` calculates the new capacity and returns the result
of `safe_malloc()`. We only need a single definition per
`SmallVectorBase` so this is defined in SmallVector.cpp to avoid code
size bloat. Moving this part of non-POD grow to the source file also
allows the logic to be easily shared with `grow_pod`, and
`report_size_overflow()` and `report_at_maximum_capacity()` can move
there too.
- `moveElementsForGrow()` moves elements from the old to the new
allocation.
- `takeAllocationForGrow()` frees the old allocation and saves the
new allocation and capacity .
`SmallVector:assign(size_type, const T&)` also uses the split-grow
operations for non-POD, but it also has a semantic change when not
growing. Previously, assign would start with `clear()`, and so the old
elements were destructed and all elements of the new vector were
copy-constructed (potentially invalidating references). The new
implementation skips destruction and uses copy-assignment for the prefix
of the new vector that fits. The new semantics match what libc++ does
for `std::vector::assign()`.
Note that the following is another possible implementation:
```
void assign(size_type NumElts, ValueParamT Elt) {
std::fill_n(this->begin(), std::min(NumElts, this->size()), Elt);
this->resize(NumElts, Elt);
}
```
The downside of this simpler implementation is that if the vector has to
grow there will be `size()` redundant copy operations.
(I had planned on splitting this patch up into three for committing
(after getting performance numbers / initial review), but I've realized
that if this does for some reason need to be reverted we'll probably
want to revert the whole package...)
Differential Revision: https://reviews.llvm.org/D94739
This reverts commit 33be50daa9,
effectively reapplying:
- 260a856c2a
- 3043e5a5c3
- 49142991a6
... with a fix to skip a call to `SmallVector::isReferenceToStorage()`
when we know the parameter had been taken by value for small, POD-like
`T`. See https://reviews.llvm.org/D93779 for the discussion on the
revert.
At a high-level, these commits fix reference invalidation in
SmallVector's push_back, append, insert (one or N), and resize
operations. For more details, please see the original commit messages.
This commit fixes a bug that crept into
`SmallVectorTemplateCommon::reserveForAndGetAddress()` during the review
process after performance analysis was done. That function is now called
`reserveForParamAndGetAddress()`, clarifying that it only works for
parameter values. It uses that knowledge to bypass
`SmallVector::isReferenceToStorage()` when `TakesParamByValue`. This is
`constexpr` and avoids adding overhead for "small enough", trivially
copyable `T`.
Performance could potentially be tuned further by increasing the
threshold for `TakesParamByValue`, which is currently defined as:
```
bool TakesParamByValue = sizeof(T) <= 2 * sizeof(void *);
```
in the POD-like version of SmallVectorTemplateBase (else, `false`).
Differential Revision: https://reviews.llvm.org/D94800
This reverts commit 260a856c2a.
This reverts commit 3043e5a5c3.
This reverts commit 49142991a6.
This change had a larger than anticipated compile-time impact,
possibly because the small value optimization is not working as
intended. See D93779.
For small enough, trivially copyable `T`, take the parameter by-value in
`SmallVector::resize`. Otherwise, when growing, update the arugment
appropriately.
Differential Revision: https://reviews.llvm.org/D93781
For small enough, trivially copyable `T`, take the parameter by-value in
`SmallVector::append` and `SmallVector::insert`. Otherwise, when
growing, update the arugment appropriately.
Differential Revision: https://reviews.llvm.org/D93780
This reverts commit 56d1ffb927, reapplying
9abac60309, removing insert_one_maybe_copy
and using a helper called forward_value_param instead. This avoids use
of `std::is_same` (or any SFINAE), so I'm hoping it's more portable and
MSVC will be happier.
Original commit message follows:
For small enough, trivially copyable `T`, take the argument by value in
`SmallVector::push_back` and copy it when forwarding to
`SmallVector::insert_one_impl`. Otherwise, when growing, update the
argument appropriately.
Differential Revision: https://reviews.llvm.org/D93779
For small enough, trivially copyable `T`, take the argument by value in
`SmallVector::push_back` and copy it when forwarding to
`SmallVector::insert_one_impl`. Otherwise, when growing, update the
argument appropriately.
Differential Revision: https://reviews.llvm.org/D93779
Analagous to the std::make_(unqiue|shared)_for_overwrite added in c++20.
If T is POD, and the container gets larger, any new values added wont be initialized.
This is useful when using SmallVector as a buffer where its planned to overwrite any potential new values added.
If T is not POD, `new (Storage) T` functions identically to `new (Storage) T()` so this will function identically to `resize(size_type)`.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D93532
This patch adds a capability to SmallVector to decide a number of
inlined elements automatically. The policy is:
- A minimum of 1 inlined elements, with more as long as
sizeof(SmallVector<T>) <= 64.
- If sizeof(T) is "too big", then trigger a static_assert: this dodges
the more pathological cases
This is expected to systematically improve SmallVector use in the
LLVM codebase, which has historically been plagued by semi-arbitrary /
cargo culted N parameters, often leading to bad outcomes due to
excessive sizeof(SmallVector<T, N>). This default also makes
programming more convenient by avoiding edit/rebuild cycles due to
forgetting to type the N parameter.
Differential Revision: https://reviews.llvm.org/D92522
There's no need to check for reference invalidation when
`SmallVector::resize` is shrinking; the parameter isn't accessed.
Differential Revision: https://reviews.llvm.org/D91832
2c196bbc6b asserted that
`SmallVector::push_back` doesn't invalidate the parameter when it needs
to grow. Do the same for `resize`, `append`, `assign`, `insert`, and
`emplace_back`.
Differential Revision: https://reviews.llvm.org/D91744
Adds a method called pop_back_n to SmallVector.
This is more readable and less error prone than the alternatives of using
```lang=c++
Vector.resize(Vector.size() - N);
Vector.erase(Vector.end() - N, Vector.end());
for (unsigned I = 0;I<N;++I) Vector.pop_back();
```
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D90576
rL356312 changed the return type of emplace_back from void to reference.
Update the tests to check the behavior.
Reviewers: dblaikie
Reviewed By: dblaikie
Subscribers: dexonsmith, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59809
llvm-svn: 356980
to reflect the new license.
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: 351636
They're unused with recent versions of libstdc++ but older ones
(e.g. libstdc++ 4.9 still requires them). Maybe we should bump
the requirements on the minimum version to make GCC 7 happy, but
in the meanwhile we need to live with the warning.
llvm-svn: 305158
Summary:
This prevents the iterator overrides from being selected in
the case where non-iterator types are used as arguments, which
is of particular importance in cases where other overrides with
identical types exist.
Reviewers: dblaikie, bkramer, rafael
Subscribers: llvm-commits, efriedma
Differential Revision: https://reviews.llvm.org/D33919
llvm-svn: 305105
clang-format (https://reviews.llvm.org/D33932) to keep primary headers
at the top and handle new utility headers like 'gmock' consistently with
other utility headers.
No other change was made. I did no manual edits, all of this is
clang-format.
This should allow other changes to have more clear and focused diffs,
and is especially motivated by moving some headers into more focused
libraries.
llvm-svn: 304786
This might give a few better opportunities to optimize these to memcpy
rather than loops - also a few minor cleanups (StringRef-izing,
templating (to avoid std::function indirection), etc).
The SmallVector::assign(iter, iter) could be improved with the use of
SFINAE, but the (iter, iter) ctor and append(iter, iter) need it to and
don't have it - so, workaround it for now rather than bothering with the
added complexity.
(also, as noted in the added FIXME, these assign ops could potentially
be optimized better at least for non-trivially-copyable types)
llvm-svn: 304566
Some Include What You Use suggestions were used too.
Use anonymous namespaces in source files.
Differential revision: http://reviews.llvm.org/D18778
llvm-svn: 265454
The patch is generated using clang-tidy misc-use-override check.
This command was used:
tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py \
-checks='-*,misc-use-override' -header-filter='llvm|clang' \
-j=32 -fix -format
http://reviews.llvm.org/D8925
llvm-svn: 234679
Unfortunately there's no way to elegantly do this with pre-canned
algorithms. Using a generating iterator doesn't work because you default
construct for each element, then move construct into the actual slot
(bad for copy but non-movable types, and a little unneeded overhead even
in the move-only case), so just write it out manually.
This solution isn't exception safe (if one of the element's ctors calls
we don't fall back, destroy the constructed elements, and throw on -
which std::uninitialized_fill does do) but SmallVector (and LLVM) isn't
exception safe anyway.
llvm-svn: 210495
To test cases that involve actual repetition (> 1 elements), at least
one element before the insertion point, and some elements of the
original range that still fit in that range space after insertion.
Actually we need coverage for the inverse case too (where no elements
after the insertion point fit into the previously allocated space), but
this'll do for now, and I might end up rewriting bits of SmallVector to
avoid that special case anyway.
llvm-svn: 210436
Specifically this caused inserting an element from a SmallVector into
itself when such an insertion would cause a reallocation. We have code
to handle this for non-reallocating cases, but it's not robust against
reallocation.
llvm-svn: 210430
(& because it makes it easier to test, this also improves
correctness/performance slightly by moving the last element in an insert
operation, rather than copying it)
llvm-svn: 210429
This would cause the last element in a range to be in a moved-from state
after an insert at a non-end position, losing that value entirely in the
process.
Side note: move_backward is subtle. It copies [A, B) to C-1 and down.
(the fact that it decrements both the second and third iterators before
the first movement is the subtle part... kind of surprising, anyway)
llvm-svn: 210426
When we were moving from a larger vector to a smaller one but didn't
need to re-allocate, we would move-assign over uninitialized memory in
the target, then move-construct that same data again.
llvm-svn: 207663
This reverts commit r203374.
Ambiguities in assign... oh well. I'm just going to revert this and
probably not try to recommit it as it's not terribly important.
llvm-svn: 203375
Move a common utility (assign(iter, iter)) into SmallVector (some of the
others could be moved there too, but this one seemed particularly
generic) and replace repetitions overrides with using directives.
And simplify SmallVector::assign(num, element) while I'm here rather
than thrashing these files (that cause everyone to rebuild) again.
llvm-svn: 203374
Duncan P. N. Exon Smith