[libc] Add osutils for Windows and make libc and its tests build on Windows target (#104676)

This PR first adds osutils for Windows, and changes some libc code to
make libc and its tests build on t

[libc] Add osutils for Windows and make libc and its tests build on Windows target (#104676)

This PR first adds osutils for Windows, and changes some libc code to
make libc and its tests build on the Windows target. It then temporarily
disables some libc tests that are currently problematic on Windows.

Specifically, the changes besides the addition of osutils include:

- Macro `LIBC_TYPES_HAS_FLOAT16` is disabled on Windows. `clang-cl`
generates calls to functions in `compiler-rt` to handle float16
arithmetic and these functions are currently not linked in on Windows.
- Macro `LIBC_TYPES_HAS_INT128` is disabled on Windows.
- The invocation to `::aligned_malloc` is changed to an invocation to
`::_aligned_malloc`.
- The following unit tests are temporarily disabled because they
currently fail on Windows:
- `test.src.__support.big_int_test`
- `test.src.__support.arg_list_test`
- `test.src.fenv.getenv_and_setenv_test`
- Tests involving `__m128i`, `__m256i`, and `__m512i` in
`test.src.string.memory_utils.op_tests.cpp`
- `test_range_errors` in `libc/test/src/math/smoke/AddTest.h` and
`libc/test/src/math/smoke/SubTest.h`

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[libc] Fix warnings emitted by GCC (#98751)

Fixes #98709.

[libc] Migrate to using LIBC_NAMESPACE_DECL for namespace declaration (#98597)

This is a part of #97655.

Revert "[libc] Migrate to using LIBC_NAMESPACE_DECL for namespace declaration" (#98593)

Reverts llvm/llvm-project#98075

bots are broken

[libc] Migrate to using LIBC_NAMESPACE_DECL for namespace declaration (#98075)

This is a part of #97655.

[libc] Fix forward arm32 builtbot (#84794)

Introduced by https://github.com/llvm/llvm-project/pull/83441.

[libc] Provide `LIBC_TYPES_HAS_INT64` (#83441)

Umbrella bug #83182

[libc] Mass replace enclosing namespace (#67032)

This is step 4 of
https://discourse.llvm.org/t/rfc-customizable-namespace-to-allow-testing-the-libc-when-the-system-libc-is-also-llvms-libc/73079

[libc] Improve memcmp latency and codegen

This is based on ideas from @nafi to:
- use a branchless version of 'cmp' for 'uint32_t',
- completely resolve the lexicographic comparison through vector

[libc] Improve memcmp latency and codegen

This is based on ideas from @nafi to:
- use a branchless version of 'cmp' for 'uint32_t',
- completely resolve the lexicographic comparison through vector
operations when wide types are available. We also get rid of byte
reloads and serializing '__builtin_ctzll'.

I did not include the suggestion to replace comparisons of 'uint16_t'
with two 'uint8_t' as it did not seem to help the codegen. This can
be revisited in sub-sequent patches.

The code been rewritten to reduce nested function calls, making the
job of the inliner easier and preventing harmful code duplication.

Reviewed By: nafi3000

Differential Revision: https://reviews.llvm.org/D148717

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Revert D148717 "[libc] Improve memcmp latency and codegen"

Once integrated in our codebase the patch triggered a bunch of failing
tests. We do not yet understand where the bug is but we revert it to

Revert D148717 "[libc] Improve memcmp latency and codegen"

Once integrated in our codebase the patch triggered a bunch of failing
tests. We do not yet understand where the bug is but we revert it to
move forward with integration.
This reverts commit 5e32765c15ab8df3d2635a2bb5078c5b1d5714d5.

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[libc] Improve memcmp latency and codegen

This is based on ideas from @nafi to:
- use a branchless version of 'cmp' for 'uint32_t',
- completely resolve the lexicographic comparison through vector

[libc] Improve memcmp latency and codegen

This is based on ideas from @nafi to:
- use a branchless version of 'cmp' for 'uint32_t',
- completely resolve the lexicographic comparison through vector
operations when wide types are available. We also get rid of byte
reloads and serializing '__builtin_ctzll'.

I did not include the suggestion to replace comparisons of 'uint16_t'
with two 'uint8_t' as it did not seem to help the codegen. This can
be revisited in sub-sequent patches.

The code been rewritten to reduce nested function calls, making the
job of the inliner easier and preventing harmful code duplication.

Reviewed By: nafi3000

Differential Revision: https://reviews.llvm.org/D148717

show more ...

Revert D148717 "[libc] Improve memcmp latency and codegen"

This broke aarch64 debug buildbot https://lab.llvm.org/buildbot/#/builders/223/builds/21703
This reverts commit bd4f978754758d5ef29d1f10370

Revert D148717 "[libc] Improve memcmp latency and codegen"

This broke aarch64 debug buildbot https://lab.llvm.org/buildbot/#/builders/223/builds/21703
This reverts commit bd4f978754758d5ef29d1f10370f45362da3de37.

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[libc] Improve memcmp latency and codegen

This is based on ideas from @nafi to:
- use a branchless version of 'cmp' for 'uint32_t',
- completely resolve the lexicographic comparison through vector

[libc] Improve memcmp latency and codegen

This is based on ideas from @nafi to:
- use a branchless version of 'cmp' for 'uint32_t',
- completely resolve the lexicographic comparison through vector
operations when wide types are available. We also get rid of byte
reloads and serializing '__builtin_ctzll'.

I did not include the suggestion to replace comparisons of 'uint16_t'
with two 'uint8_t' as it did not seem to help the codegen. This can
be revisited in sub-sequent patches.

The code been rewritten to reduce nested function calls, making the
job of the inliner easier and preventing harmful code duplication.

Reviewed By: nafi3000

Differential Revision: https://reviews.llvm.org/D148717

show more ...

Revert D148717 "[libc] Improve memcmp latency and codegen"

This reverts commit 9ec6ebd3ceabb29482aa18a64b943788b65223dc.

The patch broke RISCV and aarch64 builtbots.

[libc] Improve memcmp latency and codegen

This is based on ideas from @nafi to:
- use a branchless version of 'cmp' for 'uint32_t',
- completely resolve the lexicographic comparison through vector

[libc] Improve memcmp latency and codegen

This is based on ideas from @nafi to:
- use a branchless version of 'cmp' for 'uint32_t',
- completely resolve the lexicographic comparison through vector
operations when wide types are available. We also get rid of byte
reloads and serializing '__builtin_ctzll'.

I did not include the suggestion to replace comparisons of 'uint16_t'
with two 'uint8_t' as it did not seem to help the codegen. This can
be revisited in sub-sequent patches.

The code been rewritten to reduce nested function calls, making the
job of the inliner easier and preventing harmful code duplication.

Reviewed By: nafi3000

Differential Revision: https://reviews.llvm.org/D148717

show more ...

[libc] Remove use of 'assert' from the string tests

Currently we use `assert` as a stand-in for the typical test assertions.
This is because these functions exist outside of the base test class so
w

[libc] Remove use of 'assert' from the string tests

Currently we use `assert` as a stand-in for the typical test assertions.
This is because these functions exist outside of the base test class so
we can't use the typical assertion methods. The presence of these
asserts makes it difficult to compile these tests in a standalone
format. This patch removes all occurrences.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D149656

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[reland][libc] handle memset sequence as a separate struct

These sequence of calls don't really make sense for head_tail and loop_and_tail.

Revert "[libc] handle memset sequence as a separate struct"

This patch broke the build bots.
This reverts commit 6fdc244e9f13d2ce20a26d05513f22a1e099f90a.

[libc] handle memset sequence as a separate struct

These sequence of calls don't really make sense for head_tail and loop_and_tail.

[libc][NFC] Use new approach based on types to code memset

[libc][NFC] Rename macros

[libc][NFC] Move UnitTest and IntegrationTest to the 'test' directory.

This part of the effort to make all test related pieces into the `test`
directory. This helps is excluding test related pieces

[libc][NFC] Move UnitTest and IntegrationTest to the 'test' directory.

This part of the effort to make all test related pieces into the `test`
directory. This helps is excluding test related pieces in a straight
forward manner if LLVM_INCLUDE_TESTS is OFF. Future patches will also move
the MPFR wrapper and testutils into the 'test' directory.

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[libc][NFC] Rename architecture macros and move to macros folder

[libc] Improve testing of mem functions

This patch extracts the testing logic from `op_tests.cpp` into
`memory_check_utils.h` so we can reuse it for mem* function integration
tests.

This makes test

[libc] Improve testing of mem functions

This patch extracts the testing logic from `op_tests.cpp` into
`memory_check_utils.h` so we can reuse it for mem* function integration
tests.

This makes testing consistent and thorough.
For instance this catches a bug that got unnoticed during submission of
D136595 and D135134. Integration test for memcmp was only testing a
single size.

This also leverages ASAN to make sure that data is not read / written
outside permitted boundaries

Differential Revision: https://reviews.llvm.org/D136865

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[libc] Use cpp::byte instead of char in mem* functions

`cpp::byte` is better than `char` which -depending on platform- can be `signed char` or `unsigned char`. This has introduced subtle arithmetic

[libc] Use cpp::byte instead of char in mem* functions

`cpp::byte` is better than `char` which -depending on platform- can be `signed char` or `unsigned char`. This has introduced subtle arithmetic errors.

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