4d4c70c91c
This patch is based on the suggestion by @ChuanqiXu on discourse (https://discourse.llvm.org/t/alternatives-to-the-implementation-of-std-modules/71958) Instead of making a module partition per header every header gets an inc file which contains the exports per header. The std module then includes all public headers and these inc files. The one file per header is useful for testing purposes. The CI tests whether the exports of a header's module partition matches the "public" named declarations in the header. With one file per header this can still be done. The patch improves compilation time of files using "import std;" and the size of the std module. A comparision of the compilation speed using a libc++ test build/bin/llvm-lit -a -Dstd=c++23 -Denable_modules=std libcxx/test/std/modules/std.pass.cpp Which boils down to import std; int main(int, char**) { std::println("Hello modular world"); return 0; } and has -ftime-report enabled Before ===-------------------------------------------------------------------------=== Clang front-end time report ===-------------------------------------------------------------------------=== Total Execution Time: 8.6585 seconds (8.6619 wall clock) ---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name --- 4.5041 ( 57.2%) 0.4264 ( 54.4%) 4.9305 ( 56.9%) 4.9331 ( 57.0%) Clang front-end timer 3.2037 ( 40.7%) 0.2408 ( 30.7%) 3.4445 ( 39.8%) 3.4452 ( 39.8%) Reading modules 0.1665 ( 2.1%) 0.1170 ( 14.9%) 0.2835 ( 3.3%) 0.2837 ( 3.3%) Loading .../build/test/__config_module__/CMakeFiles/std.dir/std.pcm 7.8744 (100.0%) 0.7842 (100.0%) 8.6585 (100.0%) 8.6619 (100.0%) Total After ===-------------------------------------------------------------------------=== Clang front-end time report ===-------------------------------------------------------------------------=== Total Execution Time: 1.2420 seconds (1.2423 wall clock) ---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name --- 0.8892 ( 84.6%) 0.1698 ( 88.8%) 1.0590 ( 85.3%) 1.0590 ( 85.2%) Clang front-end timer 0.1533 ( 14.6%) 0.0168 ( 8.8%) 0.1701 ( 13.7%) 0.1704 ( 13.7%) Reading modules 0.0082 ( 0.8%) 0.0047 ( 2.5%) 0.0129 ( 1.0%) 0.0129 ( 1.0%) Loading .../build/test/__config_module__/CMakeFiles/std.dir/std.pcm 1.0507 (100.0%) 0.1913 (100.0%) 1.2420 (100.0%) 1.2423 (100.0%) Total Using "include <print>" instead of "import module;" ===-------------------------------------------------------------------------=== Clang front-end time report ===-------------------------------------------------------------------------=== Total Execution Time: 2.1507 seconds (2.1517 wall clock) ---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name --- 1.9714 (100.0%) 0.1793 (100.0%) 2.1507 (100.0%) 2.1517 (100.0%) Clang front-end timer 1.9714 (100.0%) 0.1793 (100.0%) 2.1507 (100.0%) 2.1517 (100.0%) Total It's possible to use the std module in external projects (https://libcxx.llvm.org/Modules.html#using-in-external-projects) Tested this with a private project to validate the size of the generated files: Before $ du -sch std-* 448M std-build 508K std-src 120K std-subbuild 449M total After $ du -sch std-* 29M std-build 1004K std-src 132K std-subbuild 30M total Reviewed By: ldionne, #libc Differential Revision: https://reviews.llvm.org/D156907
29 lines
1.1 KiB
C++
29 lines
1.1 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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export namespace std {
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// Note the Standard does not mark these symbols optional, but libc++'s header
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// does. So this seems strictly not to be conforming.
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// mbstate_t is conditionally here, but always present in cwchar.cppm. To avoid
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// conflicing declarations omit the using here.
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// size_t is conditionally here, but always present in cstddef.cppm. To avoid
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// conflicing declarations omit the using here.
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#if !defined(_LIBCPP_HAS_NO_C8RTOMB_MBRTOC8)
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using std::mbrtoc8 _LIBCPP_USING_IF_EXISTS;
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using std::c8rtomb _LIBCPP_USING_IF_EXISTS;
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#endif
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using std::mbrtoc16 _LIBCPP_USING_IF_EXISTS;
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using std::c16rtomb _LIBCPP_USING_IF_EXISTS;
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using std::mbrtoc32 _LIBCPP_USING_IF_EXISTS;
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using std::c32rtomb _LIBCPP_USING_IF_EXISTS;
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} // namespace std
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