Branch: refs/heads/main
Home: https://github.com/llvm/llvm-project
Commit: 6c11aebd302dee06d734e6025b4399cd12f204c4
https://github.com/llvm/llvm-project/commit/6c11aebd302dee06d734e6025b4399cd12f204c4
Author: Mark de Wever <koraq at xs4all.nl>
Date: 2022-05-14 (Sat, 14 May 2022)
Changed paths:
M libcxx/include/charconv
Log Message:
-----------
[libc++] Improve std::to_chars for base != 10.
This improves the speed of `to_chars` for bases 2, 8, and 16.
These bases are common and used in `<format>`. This change
uses a lookup table, like done in base 10 and causes an increase
in code size. The change has a small overhead for the other bases.
```
Benchmark Time CPU Time Old Time New CPU Old CPU New
------------------------------------------------------------------------------------------------------------------
BM_to_chars_good/2 -0.9476 -0.9476 252 13 252 13
BM_to_chars_good/3 +0.0018 +0.0018 145 145 145 145
BM_to_chars_good/4 +0.0108 +0.0108 104 105 104 105
BM_to_chars_good/5 +0.0159 +0.0160 89 91 89 91
BM_to_chars_good/6 +0.0162 +0.0162 80 81 80 81
BM_to_chars_good/7 +0.0117 +0.0117 72 73 72 73
BM_to_chars_good/8 -0.8643 -0.8643 64 9 64 9
BM_to_chars_good/9 +0.0095 +0.0095 60 60 60 60
BM_to_chars_good/10 +0.0540 +0.0540 6 6 6 6
BM_to_chars_good/11 +0.0299 +0.0299 55 57 55 57
BM_to_chars_good/12 +0.0060 +0.0060 48 49 49 49
BM_to_chars_good/13 +0.0102 +0.0102 48 48 48 48
BM_to_chars_good/14 +0.0184 +0.0185 47 48 47 48
BM_to_chars_good/15 +0.0269 +0.0269 44 45 44 45
BM_to_chars_good/16 -0.8207 -0.8207 37 7 37 7
BM_to_chars_good/17 +0.0241 +0.0241 37 38 37 38
BM_to_chars_good/18 +0.0221 +0.0221 37 38 37 38
BM_to_chars_good/19 +0.0222 +0.0223 37 38 37 38
BM_to_chars_good/20 +0.0317 +0.0317 38 39 38 39
BM_to_chars_good/21 +0.0342 +0.0341 38 39 38 39
BM_to_chars_good/22 +0.0336 +0.0336 36 38 36 38
BM_to_chars_good/23 +0.0222 +0.0222 34 35 34 35
BM_to_chars_good/24 +0.0185 +0.0185 31 32 31 32
BM_to_chars_good/25 +0.0157 +0.0157 32 32 32 32
BM_to_chars_good/26 +0.0181 +0.0181 32 32 32 32
BM_to_chars_good/27 +0.0153 +0.0153 32 32 32 32
BM_to_chars_good/28 +0.0179 +0.0179 32 32 32 32
BM_to_chars_good/29 +0.0189 +0.0189 32 33 32 33
BM_to_chars_good/30 +0.0212 +0.0212 32 33 32 33
BM_to_chars_good/31 +0.0221 +0.0221 32 33 32 33
BM_to_chars_good/32 +0.0292 +0.0292 32 33 32 33
BM_to_chars_good/33 +0.0319 +0.0319 32 33 32 33
BM_to_chars_good/34 +0.0411 +0.0410 33 34 33 34
BM_to_chars_good/35 +0.0515 +0.0515 33 34 33 34
BM_to_chars_good/36 +0.0502 +0.0502 32 34 32 34
BM_to_chars_bad/2 -0.8752 -0.8752 40 5 40 5
BM_to_chars_bad/3 +0.1952 +0.1952 21 26 21 26
BM_to_chars_bad/4 +0.3626 +0.3626 16 22 16 22
BM_to_chars_bad/5 +0.2267 +0.2268 17 21 17 21
BM_to_chars_bad/6 +0.3560 +0.3559 14 19 14 19
BM_to_chars_bad/7 +0.4599 +0.4600 12 18 12 18
BM_to_chars_bad/8 -0.5074 -0.5074 11 5 11 5
BM_to_chars_bad/9 +0.4814 +0.4814 10 15 10 15
BM_to_chars_bad/10 +0.7761 +0.7761 2 4 2 4
BM_to_chars_bad/11 +0.3948 +0.3948 12 16 12 16
BM_to_chars_bad/12 +0.3203 +0.3203 10 13 10 13
BM_to_chars_bad/13 +0.3067 +0.3067 11 14 11 14
BM_to_chars_bad/14 +0.2235 +0.2235 12 14 12 14
BM_to_chars_bad/15 +0.2675 +0.2675 11 14 11 14
BM_to_chars_bad/16 -0.1801 -0.1801 7 5 7 5
BM_to_chars_bad/17 +0.5651 +0.5651 7 11 7 11
BM_to_chars_bad/18 +0.5407 +0.5406 7 11 7 11
BM_to_chars_bad/19 +0.5593 +0.5593 8 12 8 12
BM_to_chars_bad/20 +0.5823 +0.5823 8 13 8 13
BM_to_chars_bad/21 +0.6032 +0.6032 9 15 9 15
BM_to_chars_bad/22 +0.6407 +0.6408 9 14 9 14
BM_to_chars_bad/23 +0.6292 +0.6292 7 12 7 12
BM_to_chars_bad/24 +0.5784 +0.5784 6 10 6 10
BM_to_chars_bad/25 +0.5784 +0.5784 6 10 6 10
BM_to_chars_bad/26 +0.5713 +0.5713 7 10 7 10
BM_to_chars_bad/27 +0.5969 +0.5969 7 11 7 11
BM_to_chars_bad/28 +0.6131 +0.6131 7 11 7 11
BM_to_chars_bad/29 +0.6937 +0.6937 7 11 7 11
BM_to_chars_bad/30 +0.7655 +0.7656 7 12 7 12
BM_to_chars_bad/31 +0.8939 +0.8939 6 12 6 12
BM_to_chars_bad/32 +1.0157 +1.0157 6 13 6 13
BM_to_chars_bad/33 +1.0279 +1.0279 7 14 7 14
BM_to_chars_bad/34 +1.0388 +1.0388 7 14 7 14
BM_to_chars_bad/35 +1.0990 +1.0990 7 15 7 15
BM_to_chars_bad/36 +1.1503 +1.1503 7 15 7 15
```
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D97705