| commit | b019c5c0372eb08800327efb5e7955ce918b75d1 | [log] [tgz] |
|---|---|---|
| author | Martijn Vels <[email protected]> | Wed Mar 04 22:52:46 2020 |
| committer | Martijn Vels <[email protected]> | Wed Mar 04 22:52:46 2020 |
| tree | dc64b7b93170b69f42d2dafcff061bc09a8ed73d | |
| parent | 45499f3801d8a00919deaf38c801885d8e75b942 [diff] |
Partially inline basic_string copy constructor in UNSTABLE
Summary:
This is a recommit of https://reviews.llvm.org/D73223 where the added function accidentally ended up inside an idef block.
This change splits the copy constructor up inlining short initialization, and explicitly outlining long initialization into __init_copy_ctor_external() which is the externally instantiated slow path.
For unstable ABI, this has the following changes:
remove basic_string(const basic_string&)
remove basic_string(const basic_string&, const Allocator&)
add __init_copy_ctor_external(const value_type*, size_type)
Quick local benchmark for Copy:
Master
```
---------------------------------------------------------------
Benchmark Time CPU Iterations
---------------------------------------------------------------
BM_StringCopy_Empty 3.50 ns 3.51 ns 199326720
BM_StringCopy_Small 3.50 ns 3.51 ns 199510016
BM_StringCopy_Large 15.7 ns 15.7 ns 45230080
BM_StringCopy_Huge 1503 ns 1503 ns 464896
```
With this change
```
---------------------------------------------------------------
Benchmark Time CPU Iterations
---------------------------------------------------------------
BM_StringCopy_Empty 1.99 ns 2.00 ns 356471808
BM_StringCopy_Small 3.29 ns 3.30 ns 203425792
BM_StringCopy_Large 13.3 ns 13.3 ns 52948992
BM_StringCopy_Huge 1472 ns 1472 ns 475136
```
Subscribers: libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D75639
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