[BOLT] Support files with no symbols

`LastSymbol` handling in `discoverFileObjects` assumes a non-zero number of
symbols in an object file. It's not the case for broken_dynsym.test added in
D130073,

[BOLT] Support files with no symbols

`LastSymbol` handling in `discoverFileObjects` assumes a non-zero number of
symbols in an object file. It's not the case for broken_dynsym.test added in
D130073, and potentially other stripped binaries.

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D130544

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[BOLT] Handle broken .dynsym in stripped binaries

Strip tools cause a few symbols in .dynsym to have bad section index.
This update safely keeps such broken symbols intact.

Test Plan:
```
ninja che

[BOLT] Handle broken .dynsym in stripped binaries

Strip tools cause a few symbols in .dynsym to have bad section index.
This update safely keeps such broken symbols intact.

Test Plan:
```
ninja check-bolt
```

Reviewed By: Amir

Differential Revision: https://reviews.llvm.org/D130073

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[BOLT] Support split landing pad

We previously support split jump table, where some jump table entries
target different fragments of same function. In this fix, we provide
support for another type o

[BOLT] Support split landing pad

We previously support split jump table, where some jump table entries
target different fragments of same function. In this fix, we provide
support for another type of intra-indirect transfer: landing pad.

When C++ exception handling is used, compiler emits .gcc_except_table
that describes the location of catch block (landing pad) for specific
range that potentially invokes a throw(). Normally landing pads reside
in the function, but with -fsplit-machine-functions, landing pads can
be moved to another fragment. The intuition is, landing pads are rarely
executed, so compiler can move them to .cold section.

This update will mark all fragments that have landing pad to another
fragment as non-simple, and later propagate non-simple to all related
fragments.

This update also includes one manual test case: split-landing-pad.s

Reviewed By: Amir

Differential Revision: https://reviews.llvm.org/D128561

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[BOLT] Support multiple parents for split jump table

There are two assumptions regarding jump table:
(a) It is accessed by only one fragment, say, Parent
(b) All entries target instructions in Paren

[BOLT] Support multiple parents for split jump table

There are two assumptions regarding jump table:
(a) It is accessed by only one fragment, say, Parent
(b) All entries target instructions in Parent

For (a), BOLT stores jump table entries as relative offset to Parent.
For (b), BOLT treats jump table entries target somewhere out of Parent
as INVALID_OFFSET, including fragment of same split function.

In this update, we extend (a) and (b) to include fragment of same split
functinon. For (a), we store jump table entries in absolute offset
instead. In addition, jump table will store all fragments that access
it. A fragment uses this information to only create label for jump table
entries that target to that fragment.

For (b), using absolute offset allows jump table entries to target
fragments of same split function, i.e., extend support for split jump
table. This can be done using relocation (fragment start/size) and
fragment detection heuristics (e.g., using symbol name pattern for
non-stripped binaries).

For jump table targets that can only be reached by one fragment, we
mark them as local label; otherwise, they would be the secondary
function entry to the target fragment.

Test Plan
```
ninja check-bolt
```

Reviewed By: Amir

Differential Revision: https://reviews.llvm.org/D128474

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[BOLT][AArch64] Handle gold linker veneers

The gold linker veneers are written between functions without symbols,
so we to handle it specially in BOLT.

Vladislav Khmelevsky,
Advanced Software Techn

[BOLT][AArch64] Handle gold linker veneers

The gold linker veneers are written between functions without symbols,
so we to handle it specially in BOLT.

Vladislav Khmelevsky,
Advanced Software Technology Lab, Huawei

Differential Revision: https://reviews.llvm.org/D129260

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Revert "Rebase: [Facebook] Revert "[BOLT] Update dynamic relocations from section relocations""

This reverts commit 76029cc53e838e6d86b13b0c39152f474fb09263.

Rebase: [Facebook] Revert "[BOLT] Update dynamic relocations from section relocations"

Summary:
This reverts commit 729d29e167a553ee1190c310b6a510db8d8731ac.

Needed as a workaround for T112872562.

Rebase: [Facebook] Revert "[BOLT] Update dynamic relocations from section relocations"

Summary:
This reverts commit 729d29e167a553ee1190c310b6a510db8d8731ac.

Needed as a workaround for T112872562.

Manual rebase conflict history:
https://phabricator.intern.facebook.com/D35230076
https://phabricator.intern.facebook.com/D35681740

Test Plan: sandcastle

Reviewers: #llvm-bolt

Subscribers: spupyrev

Differential Revision: https://phabricator.intern.facebook.com/D37098481

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Revert "[BOLT][AArch64] Handle gold linker veneers"

This reverts commit 425dda76e9fac93117289fd68a2abdfb1e4a0ba5.

This commit is currently causing BOLT to crash in one of our
binaries and needs a b

Revert "[BOLT][AArch64] Handle gold linker veneers"

This reverts commit 425dda76e9fac93117289fd68a2abdfb1e4a0ba5.

This commit is currently causing BOLT to crash in one of our
binaries and needs a bit more checking to make sure it is safe
to land.

show more ...

[BOLT][AArch64] Handle gold linker veneers

The gold linker veneers are written between functions without symbols,
so we to handle it specially in BOLT.

Vladislav Khmelevsky,
Advanced Software Techn

[BOLT][AArch64] Handle gold linker veneers

The gold linker veneers are written between functions without symbols,
so we to handle it specially in BOLT.

Vladislav Khmelevsky,
Advanced Software Technology Lab, Huawei

Differential Revision: https://reviews.llvm.org/D128082

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[BOLT][NFC] Use range-based STL wrappers

Replace `std::` algorithms taking begin/end iterators with `llvm::` counterparts
accepting ranges.

Reviewed By: rafauler

Differential Revision: https://rev

[BOLT][NFC] Use range-based STL wrappers

Replace `std::` algorithms taking begin/end iterators with `llvm::` counterparts
accepting ranges.

Reviewed By: rafauler

Differential Revision: https://reviews.llvm.org/D128154

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[BOLT] Split functions with exceptions in shared objects and PIEs

Add functionality to allow splitting code with C++ exceptions in shared
libraries and PIEs. To overcome a limitation in exception ra

[BOLT] Split functions with exceptions in shared objects and PIEs

Add functionality to allow splitting code with C++ exceptions in shared
libraries and PIEs. To overcome a limitation in exception ranges format,
for functions with fragments spanning multiple sections, add trampoline
landing pads in the same section as the corresponding throwing range.

Reviewed By: Amir

Differential Revision: https://reviews.llvm.org/D127936

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[BOLT] Allow function entry to be a cold fragment

Allow cold fragment to get new address.

Our previous assumption is that a fragment (.cold) is only reached
through the main fragment of same functi

[BOLT] Allow function entry to be a cold fragment

Allow cold fragment to get new address.

Our previous assumption is that a fragment (.cold) is only reached
through the main fragment of same function. In addition, .cold fragment
must be reached through either (a) direct transfer, or (b) split jump
table. For (a), we perform a simple fix-up. For (b), we currently mark
all relevant fragments as non-simple. Therefore, there is no need to
get new address for .cold fragment.

This is not always the case, as function entry can be rarely executed,
and is placed in .text.cold segment. Essentially we cannot tell which
the source-level function entry is based on hot and cold segments,
so we must treat each fragment a function on its own. Therfore, we
remove the assertion that a function entry cannot be cold fragment.

Test Plan:
```
ninja check-bolt
```

Reviewed By: Amir

Differential Revision: https://reviews.llvm.org/D128111

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[BOLT] Allow function fragments to point to one jump table

Resolve a crash related to split functions

Due to split function optimization, a function can be divided to two

fragments, and both fragm

[BOLT] Allow function fragments to point to one jump table

Resolve a crash related to split functions

Due to split function optimization, a function can be divided to two

fragments, and both fragments can access same jump table. This
violates 
the assumption that a jump table can only have one parent
function, 
which causes a crash during instrumentation.

We want to support the case: different functions cannot access same
jump tables, but different fragments of same function can!

As all fragments are from same function, we point JT::Parent to one
specific fragment. Right now it is the first disassembled fragment, but
we can point it to the function's main fragment later.

Functions are disassembled sequentially. Previously, at the end of
processing a function, JT::OffsetEntries is cleared, so other fragment
can no longer reuse JT::OffsetEntries. To extend the support for split
function, we only clear JT::OffsetEntries after all functions are
disassembled.

Let say A.hot and A.cold access JT of three targets {X, Y, Z}, where
X and Y are in A.hot, and Z is in A.cold. Suppose that A.hot is
disassembled first, JT::OffsetEntries = {X',Y',INVALID_OFFSET}. When
A.cold is disassembled, it cannot reuse JT::OffsetEntries above due to
different fragment start. A simple solution:
A.hot = {X',Y',INVALID_OFFSET}
A.cold = {INVALID_OFFSET, INVALID_OFFSET, INVALID_OFFSET}

We update the assertion to allow different fragments of same function
to get the same JumpTable object.

Potential improvements:
A.hot = {X',Y',INVALID_OFFSET}
A.cold = {INVALID_OFFSET, INVALID_OFFSET, Z'}
The main issue is A.hot and A.cold have separate CFGs, thus jump table
targets are still constrained within fragment bounds.

Future improvements:
A.hot = {X, Y, Z}
A.cold = {X, Y, Z}

Reviewed By: Amir

Differential Revision: https://reviews.llvm.org/D127924

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[BOLT][AARCH64] Skip R_AARCH64_LD_PREL_LO19 relocation

Supress failed to analyze relocations warning for R_AARCH64_LD_PREL_LO19
relocation. This relocation is mostly used to get value stored in CI a

[BOLT][AARCH64] Skip R_AARCH64_LD_PREL_LO19 relocation

Supress failed to analyze relocations warning for R_AARCH64_LD_PREL_LO19
relocation. This relocation is mostly used to get value stored in CI and
we don't process it since we are caluclating target address using the
instruction value in evaluateMemOperandTarget().

Differential Revision: https://reviews.llvm.org/D127413

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[BOLT] Mark fragments related to split jump table as non-simple

Mark fragments related to split jump table as non-simple.

A function could be splitted into hot and cold fragments. A split jump tabl

[BOLT] Mark fragments related to split jump table as non-simple

Mark fragments related to split jump table as non-simple.

A function could be splitted into hot and cold fragments. A split jump table is
challenging for correctly reconstructing control flow graphs, so it was marked
as ignored. This update marks those fragments as non-simple, allowing them
to be printed and partial control flow graph construction.

Test Plan:
```
llvm-lit -a tools/bolt/test/X86/split-func-icf.s
```
This test has two functions (main, main2), each has a jump table target to the
same cold portion main2.cold.1(*2). We try to print out only this cold portion.
If it is ignored, it cannot be printed. If it is non-simple, it can be printed. We
verify that it can be printed.

Reviewed By: Amir

Differential Revision: https://reviews.llvm.org/D127464

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[MC] De-capitalize MCStreamer functions

Follow-up to c031378ce01b8485ba0ef486654bc9393c4ac024 .
The class is mostly consistent now.

[bolt] Remove unneeded cl::ZeroOrMore for cl::opt options

Remove unneeded cl::ZeroOrMore for cl::opt options

Similar to 557efc9a8b68628c2c944678c6471dac30ed9e8e.
This commit handles options where cl::ZeroOrMore is more than one line below
cl::opt.

[BOLT][NFC] Use colors in CFG dumps

Use color coding to distinguish nodes:
- Entry nodes have bold border
- Scalar (non-loopy) code is milk white
- Outer loops are light yellow
- Innermost loops are

[BOLT][NFC] Use colors in CFG dumps

Use color coding to distinguish nodes:
- Entry nodes have bold border
- Scalar (non-loopy) code is milk white
- Outer loops are light yellow
- Innermost loops are light blue

`-print-loops` needs to be enabled to provide BinaryLoopInfo.
Examples:
{F23170673}
{F23170680}

Reviewed By: rafauler

Differential Revision: https://reviews.llvm.org/D126248

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[BOLT] [AArch64] Handle constant islands spanning multiple functions

Fix BOLT's constant island mapping when a constant island marked by $d
spans multiple functions. Currently, because BOLT only mar

[BOLT] [AArch64] Handle constant islands spanning multiple functions

Fix BOLT's constant island mapping when a constant island marked by $d
spans multiple functions. Currently, because BOLT only marks the
constant island in the first function where $d is located, if the next
function contains data at its start, BOLT will miss the data and try
to disassemble it. This patch adds code to explicitly go through all
symbols between $d and $x markers and mark their respective offsets as
data, which stops BOLT from trying to disassemble data. It also adds
MarkerType enum and refactors related functions.

Reviewed By: yota9, rafauler

Differential Revision: https://reviews.llvm.org/D126177

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[BOLT][NFC] Suppress unused variable warnings

Addresses the warnings emitted by Apple Clang 13.1.6 (Xcode 13.3.1).
Tip @tschuett issue #55404.

Reviewed By: rafauler

Differential Revision: https://

[BOLT][NFC] Suppress unused variable warnings

Addresses the warnings emitted by Apple Clang 13.1.6 (Xcode 13.3.1).
Tip @tschuett issue #55404.

Reviewed By: rafauler

Differential Revision: https://reviews.llvm.org/D125733

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[BOLT][DWARF] Implement monolithic DWARF5

Added implementation to support DWARF5 in monolithic mode.
Next step DWARF5 split dwarf support.

Reviewed By: maksfb

Differential Revision: https://review

[BOLT][DWARF] Implement monolithic DWARF5

Added implementation to support DWARF5 in monolithic mode.
Next step DWARF5 split dwarf support.

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D121876

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[BOLT] Fix build with GCC 7.3.0

The gcc 7.3.0 version raises "could not covert" error without std::move
used explicitly.

Differential Revision: https://reviews.llvm.org/D124009

[BOLT] Ignore PC-relative relocations from data to data

BOLT expects PC-relative relocations in data sections to reference code
and the relocated data to form a jump table. However, there are cases

[BOLT] Ignore PC-relative relocations from data to data

BOLT expects PC-relative relocations in data sections to reference code
and the relocated data to form a jump table. However, there are cases
where PC-relative addressing is used for data-to-data references
(e.g. clang-15 can generate such code). BOLT should recognize and ignore
such relocations. Otherwise, they will be considered relocations not
claimed by any jump table and cause a failure in the strict mode.

Reviewed By: yota9, Amir

Differential Revision: https://reviews.llvm.org/D123650

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[BOLT] Check MCContext errors

Abort on emission errors to prevent a malformed binary being written.
Example:
```
<unknown>:0: error: Undefined temporary symbol .Ltmp26310
<unknown>:0: error: Undefin

[BOLT] Check MCContext errors

Abort on emission errors to prevent a malformed binary being written.
Example:
```
<unknown>:0: error: Undefined temporary symbol .Ltmp26310
<unknown>:0: error: Undefined temporary symbol .Ltmp26311
<unknown>:0: error: Undefined temporary symbol .Ltmp26312
<unknown>:0: error: Undefined temporary symbol .Ltmp26313
<unknown>:0: error: Undefined temporary symbol .Ltmp26314
<unknown>:0: error: Undefined temporary symbol .Ltmp26315
BOLT-ERROR: Emission failed.
```

Reviewed By: yota9

Differential Revision: https://reviews.llvm.org/D123263

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