[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] 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][NFC] Rename files

This patch mostly renames files so it better reflects the function they declare.

Reviewed By: michaelrj

Differential Revision: https://reviews.llvm.org/D155607

[reland][libc] Switch to new implementation of mem* functions

The new framework makes it explicit which processor feature is being
used and allows for easier per platform customization:
- ARM cpu n

[reland][libc] Switch to new implementation of mem* functions

The new framework makes it explicit which processor feature is being
used and allows for easier per platform customization:
- ARM cpu now uses trivial implementations to reduce code size.
- Memcmp, Bcmp and Memmove have been optimized for x86
- Bcmp has been optimized for aarch64.

This is a reland of https://reviews.llvm.org/D135134 (b3f1d58, 028414881381)

Reviewed By: courbet

Differential Revision: https://reviews.llvm.org/D136595

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Revert D136595 "[libc] Switch to new implementation of mem* functions"

This patch seems to introduce bugs on aarch64.
Reverting while we investigate the root cause.

This reverts commit 028414881381

Revert D136595 "[libc] Switch to new implementation of mem* functions"

This patch seems to introduce bugs on aarch64.
Reverting while we investigate the root cause.

This reverts commit 02841488138160f9064f334a833d4bf3e80385c6.

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[libc] Switch to new implementation of mem* functions

The new framework makes it explicit which processor feature is being
used and allows for easier per platform customization:
- ARM cpu now uses

[libc] Switch to new implementation of mem* functions

The new framework makes it explicit which processor feature is being
used and allows for easier per platform customization:
- ARM cpu now uses trivial implementations to reduce code size.
- Memcmp, Bcmp and Memmove have been optimized for x86
- Bcmp has been optimized for aarch64.

This is a reland of https://reviews.llvm.org/D135134 (b3f1d58)

Differential Revision: https://reviews.llvm.org/D136595

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[libc][NFC] Allow memcpy to be inlined

This allows shipping individual functions without also having to provide
`memcpy` at the expense of bigger functions.
Next is to use this `inlined_memcpy` in:

[libc][NFC] Allow memcpy to be inlined

This allows shipping individual functions without also having to provide
`memcpy` at the expense of bigger functions.
Next is to use this `inlined_memcpy` in:
- loader/linux/x86_64/start.cpp
- src/string/memmove.cpp
- src/string/mempcpy.cpp
- src/string/strcpy.cpp
- src/string/strdup.cpp
- src/string/strndup.cpp

Differential Revision: https://reviews.llvm.org/D113097

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[libc] Add a set of elementary operations

Resubmission of D100646 now making sure that we handle cases were `__builtin_memcpy_inline` is not available.

Original commit message:
Each of these elemen

[libc] Add a set of elementary operations

Resubmission of D100646 now making sure that we handle cases were `__builtin_memcpy_inline` is not available.

Original commit message:
Each of these elementary operations can be assembled to support higher order constructs (Overlapping access, Loop, Aligned Loop).
The patch does not compile yet as it depends on other ones (D100571, D100631) but it allows to get the conversation started.

A self-contained version of this code is available at https://godbolt.org/z/e1x6xdaxM

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Revert "[libc] Add a set of elementary operations"

This reverts commit 4694321fbe54628513b75a4395124cd7508581a6.

[libc] Add a set of elementary operations

Resubmission of D100646 now making sure that we handle cases were `__builtin_memcpy_inline` is not available.

Original commit message:
Each of these elemen

[libc] Add a set of elementary operations

Resubmission of D100646 now making sure that we handle cases were `__builtin_memcpy_inline` is not available.

Original commit message:
Each of these elementary operations can be assembled to support higher order constructs (Overlapping access, Loop, Aligned Loop).
The patch does not compile yet as it depends on other ones (D100571, D100631) but it allows to get the conversation started.

A self-contained version of this code is available at https://godbolt.org/z/e1x6xdaxM

show more ...

Revert "[libc] Add a set of elementary operations"

This reverts commit 8387187c2ffe0bef0696edfffab00cd7d0ee3e6e.

[libc] Add a set of elementary operations

Resubmission of D100646 now making sure that we handle cases were `__builtin_memcpy_inline` is not available.

Original commit message:
Each of these elemen

[libc] Add a set of elementary operations

Resubmission of D100646 now making sure that we handle cases were `__builtin_memcpy_inline` is not available.

Original commit message:
Each of these elementary operations can be assembled to support higher order constructs (Overlapping access, Loop, Aligned Loop).
The patch does not compile yet as it depends on other ones (D100571, D100631) but it allows to get the conversation started.

A self-contained version of this code is available at https://godbolt.org/z/e1x6xdaxM

show more ...

Revert "[libc] Add a set of elementary operations"

This reverts commit 454d92ac3b3b13f5c8b3f57e03b2d93f0cf60738.

[libc] Add a set of elementary operations

Resubmission of D100646 now making sure that we handle cases were `__builtin_memcpy_inline` is not available.

Original commit message:
Each of these elemen

[libc] Add a set of elementary operations

Resubmission of D100646 now making sure that we handle cases were `__builtin_memcpy_inline` is not available.

Original commit message:
Each of these elementary operations can be assembled to support higher order constructs (Overlapping access, Loop, Aligned Loop).
The patch does not compile yet as it depends on other ones (D100571, D100631) but it allows to get the conversation started.

A self-contained version of this code is available at https://godbolt.org/z/e1x6xdaxM

show more ...

Revert "[libc] Add a set of elementary operations"

This reverts commit e63f27a3cf8129cb66b8350ad50bf19633554a6b.

[libc] Add a set of elementary operations

Each of these elementary operations can be assembled to support higher order constructs (Overlapping access, Loop, Aligned Loop).
The patch does not compile

[libc] Add a set of elementary operations

Each of these elementary operations can be assembled to support higher order constructs (Overlapping access, Loop, Aligned Loop).
The patch does not compile yet as it depends on other ones (D100571, D100631) but it allows to get the conversation started.

Differential Revision: https://reviews.llvm.org/D100646

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[libc] Use different alignment for memcpy between ARM and x86.

Aligned copy used to be 'destination aligned' for x86 but this decision was reverted in D93457 where we noticed that it was better for

[libc] Use different alignment for memcpy between ARM and x86.

Aligned copy used to be 'destination aligned' for x86 but this decision was reverted in D93457 where we noticed that it was better for ARM to be 'source aligned'.
More benchmarking confirmed that it can be up to 30% faster to align copy to destination for x86. This Patch offers both implementations and switches x86 back to destination aligned.
It also fixes alignment to 32 byte on x86.

Differential Revision: https://reviews.llvm.org/D101296

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[libc] Switch to use a macro which does not insert a section for every libc function.

Summary:
The new macro also inserts the C alias for the C++ implementations
without needing an objcopy based pos

[libc] Switch to use a macro which does not insert a section for every libc function.

Summary:
The new macro also inserts the C alias for the C++ implementations
without needing an objcopy based post processing step. The CMake
rules have been updated to reflect this. More CMake cleanup can be
taken up in future rounds and appropriate TODOs have been added for them.

Reviewers: mcgrathr, sivachandra

Subscribers:

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[libc] Remove special case for 8 and 16 bytes

They don't seem to gain much in real apps and its better to favor less branches and smaller code.

[libc] Extract an architecture independent copy of memcpy implementation.

Along that way, platform specific options to memcpy, memset and bzero
builds have been enclosed in conditionals. Also, the o

[libc] Extract an architecture independent copy of memcpy implementation.

Along that way, platform specific options to memcpy, memset and bzero
builds have been enclosed in conditionals. Also, the optimization level
has been set to -O2 for the memory function builds to actually see the
static functions inlined.

Reviewers: gchatelet

Differential Revision: https://reviews.llvm.org/D81621

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[libc][NFC] Make all top of file comments consistent.

Summary:
Made all header files consistent based of this documentation: https://llvm.org/docs/CodingStandards.html#file-headers.
And did the same

[libc][NFC] Make all top of file comments consistent.

Summary:
Made all header files consistent based of this documentation: https://llvm.org/docs/CodingStandards.html#file-headers.
And did the same for all source files top of file comments.

Reviewers: sivachandra, abrachet

Reviewed By: sivachandra, abrachet

Subscribers: MaskRay, tschuett, libc-commits

Tags: #libc-project

Differential Revision: https://reviews.llvm.org/D77533

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[libc] Adding memcpy implementation for x86_64

Summary:
The patch is not ready yet and is here to discuss a few options:
- How do we customize the implementation? (i.e. how to define `kRepMovsBSize

[libc] Adding memcpy implementation for x86_64

Summary:
The patch is not ready yet and is here to discuss a few options:
- How do we customize the implementation? (i.e. how to define `kRepMovsBSize`),
- How do we specify custom compilation flags? (We'd need `-fno-builtin-memcpy` to be passed in),
- How do we build? We may want to test in debug but build the libc with `-march=native` for instance,
- Clang has a brand new builtin `__builtin_memcpy_inline` which makes the implementation easy and efficient, but:
- If we compile with `gcc` or `msvc` we can't use it, resorting on less efficient code generation,
- With gcc we can use `__builtin_memcpy` but then we'd need a postprocess step to check that the final assembly do not contain call to `memcpy` (unlikely but allowed),
- For msvc we'd need to resort on the compiler optimization passes.

Reviewers: sivachandra, abrachet

Subscribers: mgorny, MaskRay, tschuett, libc-commits, courbet

Tags: #libc-project

Differential Revision: https://reviews.llvm.org/D74397

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