[libc++][format] Implements P3107R5 in <print>. #130500
Open
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
mordante
force-pushed
the
users/mordante/P3107R5-implementation
branch
7 times, most recently
from
3efe358 to
4bd6795
Compare
The followup paper P3235R3 which is voted in as a DR changes the names foo_locking to foo_buffered. These changes have been applied in this patch. Before ------------------------------------------------------- Benchmark Time CPU Iterations ------------------------------------------------------- printf 71.3 ns 71.3 ns 9525175 print_string 226 ns 226 ns 3105850 print_stack 232 ns 232 ns 3026498 print_direct 530 ns 530 ns 1318447 After ------------------------------------------------------- Benchmark Time CPU Iterations ------------------------------------------------------- printf 70.6 ns 70.6 ns 9789585 print_string 222 ns 222 ns 3147678 print_stack 227 ns 227 ns 3084767 print_direct 474 ns 474 ns 1472786 Note: The performance of libc++'s std::print is still extemely slow compared to printf. Based on P3107R5 std::print should outperform printf. The main culprit is the call to isatty, which is resolved after implementing LWG4044 Confusing requirements for std::print on POSIX platforms Implements - P3107R5 - Permit an efficient implementation of ``std::print`` Implements parts of - P3235R3 std::print more types faster with less memory Fixes: #105435
mordante
force-pushed
the
users/mordante/P3107R5-implementation
branch
2 times, most recently
from
071b6c1 to
7ab2024
Compare
mordante
force-pushed
the
users/mordante/P3107R5-implementation
branch
from
7ab2024 to
4fcce8d
Compare
mordante
added a commit
to mordante/llvm-project
that referenced
this pull request
Mar 14, 2025
This was discovered when using this name in llvm#130500.
mordante
added a commit
that referenced
this pull request
Mar 16, 2025
This was discovered when using this name in #130500.
mordante
force-pushed
the
users/mordante/P3107R5-implementation
branch
from
fb15f9b to
4b0bd31
Compare
mordante
force-pushed
the
users/mordante/P3107R5-implementation
branch
from
4b0bd31 to
b190535
Compare
ldionne
reviewed
Apr 1, 2025
| template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563). | ||
| _LIBCPP_HIDE_FROM_ABI inline void | ||
| __vprint_nonunicode(FILE* __stream, string_view __fmt, format_args __args, bool __write_nl) { | ||
| _LIBCPP_HIDE_FROM_ABI inline void __flockfile(FILE* __stream) { |
There was a problem hiding this comment.
I think we should take the opportunity to introduce a proper "platform layer" for these functions. Something similar to what we do in libcxx/include/__thread/support.h or libcxx/include/__locale_dir/locale_base_api.h, or libcxx/include/__atomic/support.h. I think we might be able to grow this into something more generally useful for other parts of the library.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The followup paper P3235R3 which is voted in as a DR changes the names foo_locking to foo_buffered. These changes have been applied in this patch.
Before
Benchmark Time CPU Iterations
printf 71.3 ns 71.3 ns 9525175
print_string 226 ns 226 ns 3105850
print_stack 232 ns 232 ns 3026498
print_direct 530 ns 530 ns 1318447
After
Benchmark Time CPU Iterations
printf 70.6 ns 70.6 ns 9789585
print_string 222 ns 222 ns 3147678
print_stack 227 ns 227 ns 3084767
print_direct 474 ns 474 ns 1472786
Note: The performance of libc++'s std::print is still extemely slow compared to printf. Based on P3107R5 std::print should outperform printf. The main culprit is the call to isatty, which is resolved after implementing
LWG4044 Confusing requirements for std::print on POSIX platforms
Implements
std::printImplements parts of
Fixes: #105435