[Support/Hash functions] Change the `final()` and `result()` of the hashing functions to return an array of bytes

Returning `std::array<uint8_t, N>` is better ergonomics for the hashing functions us

[Support/Hash functions] Change the `final()` and `result()` of the hashing functions to return an array of bytes

Returning `std::array<uint8_t, N>` is better ergonomics for the hashing functions usage, instead of a `StringRef`:

* When returning `StringRef`, client code is "jumping through hoops" to do string manipulations instead of dealing with fixed array of bytes directly, which is more natural
* Returning `std::array<uint8_t, N>` avoids the need for the hasher classes to keep a field just for the purpose of wrapping it and returning it as a `StringRef`

As part of this patch also:

* Introduce `TruncatedBLAKE3` which is useful for using BLAKE3 as the hasher type for `HashBuilder` with non-default hash sizes.
* Make `MD5Result` inherit from `std::array<uint8_t, 16>` which improves & simplifies its API.

Differential Revision: https://reviews.llvm.org/D123100

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[CodeView] Fix cycles in debug info when merging Types with global hashes

When type streams with forward references were merged using GHashes, cycles
were introduced in the debug info. This was ca

[CodeView] Fix cycles in debug info when merging Types with global hashes

When type streams with forward references were merged using GHashes, cycles
were introduced in the debug info. This was caused by
GlobalTypeTableBuilder::insertRecordAs() not inserting the record on the second
pass, thus yielding an empty ArrayRef at that record slot. Later on, upon PDB
emission, TpiStreamBuilder::commit() would skip that empty record, thus
offseting all indices that came after in the stream.

This solution comes in two steps:

1. Fix the hash calculation, by doing a multiple-step resolution, iff there are
forward references in the input stream.
2. Fix merge by resolving with multiple passes, therefore moving records with
forward references at the end of the stream.

This patch also adds support for llvm-readoj --codeview-ghash.
Finally, fix dumpCodeViewMergedTypes() which previously could reference deleted
memory.

Fixes PR40221

Differential Revision: https://reviews.llvm.org/D57790

llvm-svn: 353412

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Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the ne

Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636

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Resubmit [pdb] Change /DEBUG:GHASH to emit 8 byte hashes."

This fixes the remaining failing tests, so resubmitting with no
functional change.

llvm-svn: 332676

Revert "[pdb] Change /DEBUG:GHASH to emit 8 byte hashes."

A few tests haven't been properly updated, so reverting while
I have time to investigate proper fixes.

llvm-svn: 332672

[pdb] Change /DEBUG:GHASH to emit 8 byte hashes.

Previously we emitted 20-byte SHA1 hashes. This is overkill
for identifying debug info records, and has the negative side
effect of making object fi

[pdb] Change /DEBUG:GHASH to emit 8 byte hashes.

Previously we emitted 20-byte SHA1 hashes. This is overkill
for identifying debug info records, and has the negative side
effect of making object files bigger and links slower. By
using only the last 8 bytes of a SHA1, we get smaller object
files and ~10% faster links.

This modifies the format of the .debug$H section by adding a new
value for the hash algorithm field, so that the linker will still
work when its object files have an old format.

Differential Revision: https://reviews.llvm.org/D46855

llvm-svn: 332669

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[codeview] Include record prefix in global type hashing

The prefix includes type kind, which is important to preserve. Two
different type leafs can easily have the same interior record contents
as a

[codeview] Include record prefix in global type hashing

The prefix includes type kind, which is important to preserve. Two
different type leafs can easily have the same interior record contents
as another type.

We ran into this issue in PR37492 where a bitfield type record collided
with a const modifier record. Their contents were bitwise identical, but
their kinds were different.

llvm-svn: 332664

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[COFF] Teach LLD to use the COFF .debug$H section.

This adds the /DEBUG:GHASH option to LLD which will look for
the existence of .debug$H sections in linker inputs and use them
to accelerate type me

[COFF] Teach LLD to use the COFF .debug$H section.

This adds the /DEBUG:GHASH option to LLD which will look for
the existence of .debug$H sections in linker inputs and use them
to accelerate type merging. The clang-cl side has already been
added, so this completes the work necessary to begin experimenting
with this feature.

Differential Revision: https://reviews.llvm.org/D40980

llvm-svn: 320719

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Fix -Wmissing-braces error.

llvm-svn: 319855

[CodeView] Add support for content hashing CodeView type records.

Currently nothing uses this, but this at least gets the core
algorithm in, and adds some test to demonstrate correctness.

Different

[CodeView] Add support for content hashing CodeView type records.

Currently nothing uses this, but this at least gets the core
algorithm in, and adds some test to demonstrate correctness.

Differential Revision: https://reviews.llvm.org/D40736

llvm-svn: 319854

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