[BOLT][DWARF] Fix for .debug_line with DWARF5

There was a bug in a code that pre-populated line string for a case where parts
of .debug_line are not processed by BOLT, but copied as raw data. We wer

[BOLT][DWARF] Fix for .debug_line with DWARF5

There was a bug in a code that pre-populated line string for a case where parts
of .debug_line are not processed by BOLT, but copied as raw data. We were not
switching sections. This resulted in parts of the binary being over-written with
debug data.

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D154544

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[BOLT] Move from RuntimeDyld to JITLink

RuntimeDyld has been deprecated in favor of JITLink. [1] This patch
replaces all uses of RuntimeDyld in BOLT with JITLink.

Care has been taken to minimize th

[BOLT] Move from RuntimeDyld to JITLink

RuntimeDyld has been deprecated in favor of JITLink. [1] This patch
replaces all uses of RuntimeDyld in BOLT with JITLink.

Care has been taken to minimize the impact on the code structure in
order to ease the inspection of this (rather large) changeset. Since
BOLT relied on the RuntimeDyld API in multiple places, this wasn't
always possible though and I'll explain the changes in code structure
first.

Design note: BOLT uses a JIT linker to perform what essentially is
static linking. No linked code is ever executed; the result of linking
is simply written back to an executable file. For this reason, I
restricted myself to the use of the core JITLink library and avoided ORC
as much as possible.

RuntimeDyld contains methods for loading objects (loadObject) and symbol
lookup (getSymbol). Since JITLink doesn't provide a class with a similar
interface, the BOLTLinker abstract class was added to implement it. It
was added to Core since both the Rewrite and RuntimeLibs libraries make
use of it. Wherever a RuntimeDyld object was used before, it was
replaced with a BOLTLinker object.

There is one major difference between the RuntimeDyld and BOLTLinker
interfaces: in JITLink, section allocation and the application of fixups
(relocation) happens in a single call (jitlink::link). That is, there is
no separate method like finalizeWithMemoryManagerLocking in RuntimeDyld.
BOLT used to remap sections between allocating (loadObject) and linking
them (finalizeWithMemoryManagerLocking). This doesn't work anymore with
JITLink. Instead, BOLTLinker::loadObject accepts a callback that is
called before fixups are applied which is used to remap sections.

The actual implementation of the BOLTLinker interface lives in the
JITLinkLinker class in the Rewrite library. It's the only part of the
BOLT code that should directly interact with the JITLink API.

For loading object, JITLinkLinker first creates a LinkGraph
(jitlink::createLinkGraphFromObject) and then links it (jitlink::link).
For the latter, it uses a custom JITLinkContext with the following
properties:
- Use BOLT's ExecutableFileMemoryManager. This one was updated to
implement the JITLinkMemoryManager interface. Since BOLT never
executes code, its finalization step is a no-op.
- Pass config: don't use the default target passes since they modify
DWARF sections in a way that seems incompatible with BOLT. Also run a
custom pre-prune pass that makes sure sections without symbols are not
pruned by JITLink.
- Implement symbol lookup. This used to be implemented by
BOLTSymbolResolver.
- Call the section mapper callback before the final linking step.
- Copy symbol values when the LinkGraph is resolved. Symbols are stored
inside JITLinkLinker to ensure that later objects (i.e.,
instrumentation libraries) can find them. This functionality used to
be provided by RuntimeDyld but I did not find a way to use JITLink
directly for this.

Some more minor points of interest:
- BinarySection::SectionID: JITLink doesn't have something equivalent to
RuntimeDyld's Section IDs. Instead, sections can only be referred to
by name. Hence, SectionID was updated to a string.
- There seem to be no tests for Mach-O. I've tested a small hello-world
style binary but not more than that.
- On Mach-O, JITLink "normalizes" section names to include the segment
name. I had to parse the section name back from this manually which
feels slightly hacky.

[1] https://reviews.llvm.org/D145686#4222642

Reviewed By: rafauler

Differential Revision: https://reviews.llvm.org/D147544

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[BOLT][DWARF] Fix handling of loclists_base without location accesses

There are CUs that have DW_AT_loclists_base, but no DW_AT_location in children
DIEs. Pre-bolt it points to a valid offset. We we

[BOLT][DWARF] Fix handling of loclists_base without location accesses

There are CUs that have DW_AT_loclists_base, but no DW_AT_location in children
DIEs. Pre-bolt it points to a valid offset. We were not updating it, so it ended
up pointing in the middle of a list and caused LLDB to print out errors. Changed
it to point to first location list. I don't think it should matter since there
are no accesses to it anyway.

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D149798

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[BOLT][NFC] Fix UB due to unaligned load in DebugStrOffsetsWriter

The following tests fail when enabling UBSan due to an unaligned memory
load:

> runtime error: load of misaligned address 0x6200000

[BOLT][NFC] Fix UB due to unaligned load in DebugStrOffsetsWriter

The following tests fail when enabling UBSan due to an unaligned memory
load:

> runtime error: load of misaligned address 0x620000000643 for type
> 'const uint32_t' (aka 'const unsigned int'), which requires 4 byte
> alignment

BOLT :: AArch64/asm-func-debug.test
BOLT :: AArch64/update-debug-reloc.test
BOLT :: X86/asm-func-debug.test
BOLT :: X86/dwarf5-df-dualcu.test
BOLT :: X86/dwarf5-df-mono-dualcu.test
BOLT :: X86/dwarf5-ftypes-dwp-input-dwo-output.test
BOLT :: X86/dwarf5-locaddrx.test
BOLT :: X86/dwarf5-split-dwarf4-monolithic.test
BOLT :: X86/inlined-function-mixed.test
BOLT :: non-empty-debug-line.test

This patch fixes this by using read32le for the load.

Reviewed By: ayermolo

Differential Revision: https://reviews.llvm.org/D148217

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[BOLT][NFC] Replace anonymous namespace functions with static

Follow LLVM Coding Standards guideline on using anonymous namespaces
(https://llvm.org/docs/CodingStandards.html#anonymous-namespaces)
a

[BOLT][NFC] Replace anonymous namespace functions with static

Follow LLVM Coding Standards guideline on using anonymous namespaces
(https://llvm.org/docs/CodingStandards.html#anonymous-namespaces)
and use `static` modifier for function definitions.

Reviewed By: #bolt, maksfb

Differential Revision: https://reviews.llvm.org/D143124

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[BOLT][DWARF] Reuse entries in .debug_addr when not modified

In some binaries produced with ThinLTO there are CUs that share entry in
.debug_addr. Before we would generate a new entry for each. Whic

[BOLT][DWARF] Reuse entries in .debug_addr when not modified

In some binaries produced with ThinLTO there are CUs that share entry in
.debug_addr. Before we would generate a new entry for each. Which lead to binary
size increase. This changes the behavior so that we re-use entries in
.debug_addr.

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D142425

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[BOLT][DWARF] Change loclist encoding to use base_addrx

Doing the same thing as for rangelists. Changing loclists to use base_addrx, it
slightly increases .debug_loclists, but reduces .debug_addr se

[BOLT][DWARF] Change loclist encoding to use base_addrx

Doing the same thing as for rangelists. Changing loclists to use base_addrx, it
slightly increases .debug_loclists, but reduces .debug_addr section.

| section | clang-16.bolt.base | clang-16.bolt | raw | % |
| debug_loclists | 198208 | 203398 | 5190 | 102% |
| .debug_addr | 14415808 | 14351448 | -64360 |99.5% |

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D141969

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[llvm][dwwarf] Change CU/TU index to 64-bit

Changed contribution data structure to 64 bit. I added the 32bit and 64bit
accessors to make it explicit where we use 32bit and where we use 64bit. Also t

[llvm][dwwarf] Change CU/TU index to 64-bit

Changed contribution data structure to 64 bit. I added the 32bit and 64bit
accessors to make it explicit where we use 32bit and where we use 64bit. Also to
make sure sure we catch all the cases where this data structure is used.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D139379

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Revert "[llvm][dwwarf] Change CU/TU index to 64-bit"

This reverts commit fa3fa4d0d42326005dfd5887bf047b86904d3be6.

[llvm][dwwarf] Change CU/TU index to 64-bit

Changed contribution data structure to 64 bit. I added the 32bit and 64bit
accessors to make it explicit where we use 32bit and where we use 64bit. Also t

[llvm][dwwarf] Change CU/TU index to 64-bit

Changed contribution data structure to 64 bit. I added the 32bit and 64bit
accessors to make it explicit where we use 32bit and where we use 64bit. Also to
make sure sure we catch all the cases where this data structure is used.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D139379

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[BOLT][DWARF] Change rangelists to use DW_RLE_offset_pair

Before we always used DW_RLE_startx_length. This is not very efficient and leads
to bigger .debug_addr section. Changed it to use
DW_RLE_bas

[BOLT][DWARF] Change rangelists to use DW_RLE_offset_pair

Before we always used DW_RLE_startx_length. This is not very efficient and leads
to bigger .debug_addr section. Changed it to use
DW_RLE_base_addressx/DW_RLE_offset_pair.

clang-16 build in debug mode
llvm-bolt ran on it with --update-debug-sections
| section | before | after | diff | % decrease |
| .debug_rnglists | 32732292 | 31986051 | -746241 | 2.3% |
| .debug_addr | 14415808 | 14184128 | -231680 | 1.6% |

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D140439

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[BOLT][NFC] Use llvm::reverse

Use llvm::reverse instead of `for (auto I = rbegin(), E = rend(); I != E; ++I)`

Reviewed By: #bolt, rafauler

Differential Revision: https://reviews.llvm.org/D140516

Revert "[llvm][dwwarf] Change CU/TU index to 64-bit"

This reverts commit 5ebd28f3e56c00a739fda46c72c9e0f6528add87.

[BOLT][DWARF] Don't create extra .debug_str_offsets contributions

With ThinLTO mutliple CUs can share the same .debug_str_offsets contribution. We
were creating a new one for each CU. This lead to a

[BOLT][DWARF] Don't create extra .debug_str_offsets contributions

With ThinLTO mutliple CUs can share the same .debug_str_offsets contribution. We
were creating a new one for each CU. This lead to a binary size increase.

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D139214

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[llvm][dwwarf] Change CU/TU index to 64-bit

Summary:

Changed contribution data structure to 64 bit. I added the 32bit and 64bit
accessors to make it explicit where we use 32bit and where we use 64b

[llvm][dwwarf] Change CU/TU index to 64-bit

Summary:

Changed contribution data structure to 64 bit. I added the 32bit and 64bit
accessors to make it explicit where we use 32bit and where we use 64bit. Also to
make sure sure we catch all the cases where this data structure is used.

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[BOLT][NFC] Use std::optional for findAttributeInfo

LLVM started switching from `llvm::Optional` to `std::optional`:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getval

[BOLT][NFC] Use std::optional for findAttributeInfo

LLVM started switching from `llvm::Optional` to `std::optional`:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716/11

Reviewed By: #bolt, maksfb

Differential Revision: https://reviews.llvm.org/D139259

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[DebugInfo] llvm::Optional => std::optional

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

[MC] llvm::Optional => std::optional

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

[BOLT] Use std::nullopt instead of None (NFC)

This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of ma

[BOLT] Use std::nullopt instead of None (NFC)

This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

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[BOLT] Use range-based for loops (NFC)

LLVM Coding Standards discourage for_each unless callable objects
already exist.

[BOLT] Use Optional::emplace to avoid move assignment. NFC

[BOLT][NFC] Use llvm::less_first

Follow the case of https://reviews.llvm.org/D126068 and simplify call sites
with `llvm::less_first`.

Reviewed By: rafauler

Differential Revision: https://reviews.l

[BOLT][NFC] Use llvm::less_first

Follow the case of https://reviews.llvm.org/D126068 and simplify call sites
with `llvm::less_first`.

Reviewed By: rafauler

Differential Revision: https://reviews.llvm.org/D128242

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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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[MC] De-capitalize SwitchSection. NFC

Add SwitchSection to return switchSection. The API will be removed soon.

[BOLT]DWARF] Eagerly write out loclists

Taking advantage of us being able to re-write .debug_info to reduce memory
footprint loclists. Writing out loc-list as they are added, similar to how
we handl

[BOLT]DWARF] Eagerly write out loclists

Taking advantage of us being able to re-write .debug_info to reduce memory
footprint loclists. Writing out loc-list as they are added, similar to how
we handle ranges.

Collected on clang-14
trunk
4:41.20 real, 389.50 user, 59.50 sys, 0 amem, 38412532 mmem
4:30.08 real, 376.10 user, 63.75 sys, 0 amem, 38477844 mmem
4:25.58 real, 373.76 user, 54.71 sys, 0 amem, 38439660 mmem
diff
4:34.66 real, 392.83 user, 57.73 sys, 0 amem, 38382560 mmem
4:35.96 real, 377.70 user, 58.62 sys, 0 amem, 38255840 mmem
4:27.61 real, 390.18 user, 57.02 sys, 0 amem, 38223224 mmem

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D126999

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