[BOLT][NFC] Fix file-description comments

Summary: Fix comments at the start of source files.

(cherry picked from FBD33274597)

[BOLT] Fix profile and tests for nop-removal pass

Summary:
Since nops are now removed in a separate pass, the profile is consumed
on a CFG with nops. If previously a profile was generated without no

[BOLT] Fix profile and tests for nop-removal pass

Summary:
Since nops are now removed in a separate pass, the profile is consumed
on a CFG with nops. If previously a profile was generated without nops,
the offsets in the profile could be different if branches included nops
either as a source or a destination.

This diff adjust offsets to make the profile reading backwards
compatible.

(cherry picked from FBD33231254)

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[BOLT] Move disassemble optimizations to optimization passes

Summary:
The patch moves the shortenInstructions and nop remove to separate binary
passes. As a result when llvm-bolt optimizations stage

[BOLT] Move disassemble optimizations to optimization passes

Summary:
The patch moves the shortenInstructions and nop remove to separate binary
passes. As a result when llvm-bolt optimizations stage will begin the
instructions of the binary functions will be absolutely the same as it
was in the binary. This is needed for the golang support by llvm-bolt.
Some of the tests must be changed, since bb alignment nops might create
unreachable BBs in original functions.

Vladislav Khmelevsky,
Advanced Software Technology Lab, Huawei

(cherry picked from FBD32896517)

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[BOLT][NFC] Reformat with clang-format

Summary: Selectively apply clang-format to BOLT code base.

(cherry picked from FBD33119052)

[BOLT] Split functions: support fragments with multiple parents

Summary:
Gracefully handle binaries with split functions where two fragments are folded
into one, resulting in a fragment with two par

[BOLT] Split functions: support fragments with multiple parents

Summary:
Gracefully handle binaries with split functions where two fragments are folded
into one, resulting in a fragment with two parent functions.

This behavior is expected in GCC8+ with -O2 optimization level, where both
function splitting and ICF are enabled by default.

On the BOLT side, the changes are:
- BinaryFunction: allow multiple parent fragments:
- `ParentFragment` --> `ParentFragments`,
- `setParentFragment` --> `addParentFragment`.
- BinaryContext:
- `populateJumpTables`: mark fragments to be skipped later,
- `registerFragment`: add a name heuristic check, return false if it failed,
- `processInterproceduralReferences`: check if `registerFragment`
succeeded, otherwise issue a warning,
- `skipMarkedFragments`: move out fragment traversal and skipping from
`populateJumpTables` into a separate function.

This change fixes an issue where unrelated functions might be registered
as fragments:

```
BOLT-WARNING: interprocedural reference between unrelated fragments:
bad_gs/1(*2) and amd_decode_mce.cold.27/1(*2)
```

(Linux kernel binary)

(cherry picked from FBD32786688)

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[BOLT] Use more ADT data structures for BinaryFunction

Summary:
Switched members of BinaryFunction to ADT where it was possible and
made sense. As a result, the size of BinaryFunction on x86-64 Linu

[BOLT] Use more ADT data structures for BinaryFunction

Summary:
Switched members of BinaryFunction to ADT where it was possible and
made sense. As a result, the size of BinaryFunction on x86-64 Linux
reduced from 1624 bytes to 1448.

(cherry picked from FBD32981555)

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[BOLT][NFC] Remove misleading debug message

Summary:
The debug message for the last fall-through block was printed under the
reverse condition, i.e. when the block was not a fall-through. Remove
the

[BOLT][NFC] Remove misleading debug message

Summary:
The debug message for the last fall-through block was printed under the
reverse condition, i.e. when the block was not a fall-through. Remove
the debug message. If we'll need such information, we can add a pass
with more analysis, i.e. checking the last instruction, if the block is
reachable, etc.

(cherry picked from FBD32670816)

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[BOLT] Fix Windows build

Summary:
Make BOLT build in VisualStudio compiler and run without
crashing on a simple test. Other tests are not running.

(cherry picked from FBD32378736)

[BOLT][NFC] Remove references to internal tasks

(cherry picked from FBD32272387)

Rebase: [NFC] Refactor sources to be buildable in shared mode

Summary:
Moves source files into separate components, and make explicit
component dependency on each other, so LLVM build system knows h

Rebase: [NFC] Refactor sources to be buildable in shared mode

Summary:
Moves source files into separate components, and make explicit
component dependency on each other, so LLVM build system knows how to
build BOLT in BUILD_SHARED_LIBS=ON.

Please use the -c merge.renamelimit=230 git option when rebasing your
work on top of this change.

To achieve this, we create a new library to hold core IR files (most
classes beginning with Binary in their names), a new library to hold
Utils, some command line options shared across both RewriteInstance
and core IR files, a new library called Rewrite to hold most classes
concerned with running top-level functions coordinating the binary
rewriting process, and a new library called Profile to hold classes
dealing with profile reading and writing.

To remove the dependency from BinaryContext into X86-specific classes,
we do some refactoring on the BinaryContext constructor to receive a
reference to the specific backend directly from RewriteInstance. Then,
the dependency on X86 or AArch64-specific classes is transfered to the
Rewrite library. We can't have the Core library depend on targets
because targets depend on Core (which would create a cycle).

Files implementing the entry point of a tool are transferred to the
tools/ folder. All header files are transferred to the include/
folder. The src/ folder was renamed to lib/.

(cherry picked from FBD32746834)

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