bcm5719-llvm/libcxx/include/string, branch meklort-10.0.1

Revert "[libc++] Explicitly enumerate std::string external instantiations."

2020-01-13T13:54:04+00:00

This is causing failures for multiple buildbots and bootstrap builds, details at https://reviews.llvm.org/rG61bd1920. This reverts commit 61bd19206f61ace4b007838a2ff8884a13ec0374.

[libc++] Explicitly enumerate std::string external instantiations.

2020-01-09T20:51:02+00:00

The external instantiation of std::string is a problem for libc++. Additions and removals of inline functions in string can cause ABI breakages, including introducing new symbols. This patch aims to: (1) Make clear which functions are explicitly instatiated. (2) Prevent new functions from being accidentally instantiated. (3) Allow a migration path for adding or removing functions from the explicit instantiation over time. Although this new formulation is uglier, it is preferable from a maintainability and readability standpoint because it explicitly enumerates the functions we've chosen to expose in our ABI. Changing this list is non-trivial and requires thought and planning. (3) is achieved by making it possible to control the extern template declaration separately from it's definition. Meaning we could add a new definition to the dylib, wait for it to roll out, then add the extern template declaration to the header. Similarly, we could remove existing extern template declarations while still keeping the definition to prevent ABI breakages.

[libc++] Add __default_init_tag to basic_string constructors

2019-12-17T00:04:09+00:00

This removes unneeded zero initialization of string data. For example, given the below code: void Init(void *mem) { new (mem) std::string("Hello World"); } Assembly before: Init(void*): xorps xmm0, xmm0 movups xmmword ptr [rdi], xmm0 mov qword ptr [rdi + 16], 0 mov byte ptr [rdi], 22 movabs rax, 8022916924116329800 mov qword ptr [rdi + 1], rax mov dword ptr [rdi + 8], 1684828783 mov byte ptr [rdi + 12], 0 ret Assembly after: Init(): mov byte ptr [rdi], 22 movabs rax, 8022916924116329800 mov qword ptr [rdi + 1], rax mov dword ptr [rdi + 8], 1684828783 mov byte ptr [rdi + 12], 0 ret Patch by Martijn Vels (mvels@google.com) Reviewed as https://reviews.llvm.org/D70621

[libc++] Rework compressed pair constructors.

2019-12-16T23:38:58+00:00

This patch de-duplicates most compressed pair constructors to use the same code in C++11 and C++03. Part of doing that is deleting the "__second_tag()" and replacing it with a "__value_init_tag()" which has the same effect, but allows for the removal of the special "one-arg" first element constructor. This patch is intended to have no semantic change.

Optimize and fix basic_string move assignment operator. Reviewed as https://reviews.llvm.org/D68623. Thanks to mvels for the patch.

2019-11-27T15:13:32+00:00

Rename __is_foo_iterator traits to reflect their Cpp17 nature.

2019-11-18T06:49:32+00:00

With the upcoming introduction of iterator concepts in ranges, the meaning of "__is_contiguous_iterator" changes drastically. Currently we intend it to mean "does it have this iterator category", but it could now also mean "does it meet the requirements of this concept", and these can be different.

[libc++] Rename __to_raw_pointer to __to_address.

2019-11-16T22:16:09+00:00

This function has the same behavior as the now-standand std::to_address. Re-using the name makes the behavior more clear, and in the future it will allow us to correctly get the raw pointer for user provided pointer types.

Optimize operator=(const basic_string&) for tail call.

2019-10-09T03:07:02+00:00

Patch by Martijn Vels (mvels@google.com) Reviewed as https://reviews.llvm.org/D68276 This is a non trivial win for externally templated assignment operator. x86 without tail call (current libc++) 0000000000000000 : 0: 55 push %rbp 1: 48 89 e5 mov %rsp,%rbp 4: 53 push %rbx 5: 50 push %rax 6: 48 89 fb mov %rdi,%rbx 9: 48 39 f7 cmp %rsi,%rdi c: 74 17 je 25 e: 0f b6 56 17 movzbl 0x17(%rsi),%edx 12: 84 d2 test %dl,%dl 14: 79 07 jns 1d 16: 48 8b 56 08 mov 0x8(%rsi),%rdx 1a: 48 8b 36 mov (%rsi),%rsi 1d: 48 89 df mov %rbx,%rdi 20: e8 00 00 00 00 callq 25 25: 48 89 d8 mov %rbx,%rax 28: 48 83 c4 08 add $0x8,%rsp 2c: 5b pop %rbx 2d: 5d pop %rbp 2e: c3 retq After: 0000000000000000 : 0: 48 39 f7 cmp %rsi,%rdi 3: 74 14 je 19 5: 0f b6 56 17 movzbl 0x17(%rsi),%edx 9: 84 d2 test %dl,%dl b: 79 07 jns 14 d: 48 8b 56 08 mov 0x8(%rsi),%rdx 11: 48 8b 36 mov (%rsi),%rsi 14: e9 00 00 00 00 jmpq 19 19: 48 89 f8 mov %rdi,%rax 1c: c3 retq Benchmark (pending per https://reviews.llvm.org/D67667) ``` BM_StringAssignStr_Empty_Opaque 6.23ns ± 0% 5.19ns ± 0% -16.70% (p=0.016 n=5+4) BM_StringAssignStr_Empty_Transparent 5.86ns ± 0% 5.14ns ± 0% -12.24% (p=0.008 n=5+5) BM_StringAssignStr_Small_Opaque 8.79ns ± 1% 7.69ns ± 0% -12.53% (p=0.008 n=5+5) BM_StringAssignStr_Small_Transparent 9.44ns ± 0% 8.00ns ± 0% -15.26% (p=0.008 n=5+5) BM_StringAssignStr_Large_Opaque 25.2ns ± 0% 24.3ns ± 0% -3.50% (p=0.008 n=5+5) BM_StringAssignStr_Large_Transparent 23.6ns ± 0% 22.5ns ± 0% -4.76% (p=0.008 n=5+5) BM_StringAssignStr_Huge_Opaque 319ns ± 5% 317ns ± 5% ~ (p=0.690 n=5+5) BM_StringAssignStr_Huge_Transparent 319ns ± 5% 317ns ± 5% ~ (p=0.421 n=5+5) BM_StringAssignAsciiz_Empty_Opaque 7.41ns ± 0% 7.77ns ± 0% +4.89% (p=0.008 n=5+5) BM_StringAssignAsciiz_Empty_Transparent 7.54ns ± 3% 7.30ns ± 0% -3.24% (p=0.008 n=5+5) BM_StringAssignAsciiz_Small_Opaque 9.87ns ± 0% 10.24ns ± 1% +3.76% (p=0.008 n=5+5) BM_StringAssignAsciiz_Small_Transparent 10.4ns ± 1% 9.8ns ± 2% -5.78% (p=0.008 n=5+5) BM_StringAssignAsciiz_Large_Opaque 30.1ns ± 0% 30.1ns ± 0% ~ (p=0.167 n=5+5) BM_StringAssignAsciiz_Large_Transparent 27.1ns ± 0% 27.4ns ± 0% +0.92% (p=0.016 n=4+5) BM_StringAssignAsciiz_Huge_Opaque 383ns ± 4% 382ns ± 4% ~ (p=0.548 n=5+5) BM_StringAssignAsciiz_Huge_Transparent 375ns ± 0% 380ns ± 0% +1.37% (p=0.029 n=4+4) BM_StringAssignAsciizMix_Opaque 14.0ns ± 0% 14.0ns ± 0% ~ (p=0.881 n=5+5) BM_StringAssignAsciizMix_Transparent 13.7ns ± 1% 13.8ns ± 0% ~ (p=0.056 n=5+5) ``` llvm-svn: 374137

[libc++] Fix link error with _LIBCPP_HIDE_FROM_ABI_PER_TU and std::string

2019-07-19T11:52:55+00:00

Summary: This is effectively a revert of r344616, which was a partial fix for PR38964 (compilation of with GCC in C++03 mode). However, that configuration is explicitly not supported anymore and that partial fix breaks compilation with Clang when per-TU insulation is provided. PR42676 rdar://52899715 Reviewers: mclow.lists, EricWF Subscribers: christof, jkorous, dexonsmith, libcxx-commits Tags: #libc Differential Revision: https://reviews.llvm.org/D64941 llvm-svn: 366567

[NFC][libcxx] Remove trailing whitespace

2019-05-29T16:01:36+00:00

It's incredibly annoying when trying to create diffs llvm-svn: 361981