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| author | Martijn Vels <mvels@google.com> | 2020-02-26 15:55:49 -0500 |
|---|---|---|
| committer | Martijn Vels <mvels@google.com> | 2020-03-02 09:58:11 -0500 |
| commit | f87d30cba2b54a9083a0b276ad97d645c4b8b16c (patch) | |
| tree | a7c89ffbd78643223e0d74ddfd66994e59e5cb79 /llvm/lib/Support/BinaryStreamWriter.cpp | |
| parent | ad497658d25a3616e4c57cf7d12e3497a1c66f35 (diff) | |
| download | llvm-f87d30cba2b54a9083a0b276ad97d645c4b8b16c.zip llvm-f87d30cba2b54a9083a0b276ad97d645c4b8b16c.tar.gz llvm-f87d30cba2b54a9083a0b276ad97d645c4b8b16c.tar.bz2 | |
Partially inline basic_string::operator=(const basic_string&)
Summary:
This change partially inlines operator=(const basic_string&) where both the input and current instance are short strings, making the assignment a fixed length inlined memcpy.
Assignments where either of the strings are long are delegate to __assign_no_alias<__is_short>(), which is templated for the long / short branch already observed in the caller.
Stable:
```
--------------------------------------------------------------------------------
Benchmark Time CPU Iterations
--------------------------------------------------------------------------------
BM_StringAssignStr_Empty_Opaque 2.65 ns 2.66 ns 263745536
BM_StringAssignStr_Empty_Transparent 2.95 ns 2.96 ns 236494848
BM_StringAssignStr_Small_Opaque 2.93 ns 2.94 ns 237301760
BM_StringAssignStr_Small_Transparent 2.69 ns 2.69 ns 265809920
BM_StringAssignStr_Large_Opaque 19.6 ns 19.6 ns 35573760
BM_StringAssignStr_Large_Transparent 19.1 ns 19.1 ns 36716544
BM_StringAssignStr_Huge_Opaque 1901 ns 1901 ns 364544
BM_StringAssignStr_Huge_Transparent 1889 ns 1889 ns 360448
```
Unstable
```
--------------------------------------------------------------------------------
Benchmark Time CPU Iterations
--------------------------------------------------------------------------------
BM_StringAssignStr_Empty_Opaque 1.29 ns 1.29 ns 540454912
BM_StringAssignStr_Empty_Transparent 1.11 ns 1.12 ns 628482048
BM_StringAssignStr_Small_Opaque 1.29 ns 1.29 ns 541216768
BM_StringAssignStr_Small_Transparent 1.11 ns 1.11 ns 629469184
BM_StringAssignStr_Large_Opaque 15.6 ns 15.6 ns 44945408
BM_StringAssignStr_Large_Transparent 14.9 ns 14.9 ns 46764032
BM_StringAssignStr_Huge_Opaque 1713 ns 1713 ns 401408
BM_StringAssignStr_Huge_Transparent 1704 ns 1704 ns 397312
```
Subscribers: libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D75211
Diffstat (limited to 'llvm/lib/Support/BinaryStreamWriter.cpp')
0 files changed, 0 insertions, 0 deletions