[MCDwarf] Respect -fdebug-prefix-map= for generated assembly debug info (DWARF v5)

For generated assembly debug info, MCDwarfLineTableHeader::CompilationDir is an
unmapped path set in MCContext::set

[MCDwarf] Respect -fdebug-prefix-map= for generated assembly debug info (DWARF v5)

For generated assembly debug info, MCDwarfLineTableHeader::CompilationDir is an
unmapped path set in MCContext::setGenDwarfRootFile. Remap it.

A relative destination path of -fdebug-prefix-map= exposes a llvm-dwarfdump bug
which joins relative DW_AT_comp_dir and directories[0].

Fix https://github.com/llvm/llvm-project/issues/56609

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D131749

(cherry picked from commit f62e60fb238146113f84e0efb1a2ebc52f05cc0a)

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[MCDwarf] Use emplace to avoid move assignment. NFC

(cherry picked from commit b0c4cd35df89479ec152c1f79e18d0264dd276cc)

Don't use Optional::hasValue (NFC)

[llvm] Use value_or instead of getValueOr (NFC)

[MC][re-land] Omit DWARF unwind info if compact unwind is present where eligible

This reverts commit d941d597837d9e1405086f008c9bd6a71e7263c9.

Differential Revision: https://reviews.llvm.org/D122258

Revert "[MC] Omit DWARF unwind info if compact unwind is present where eligible"

This reverts commit ef501bf85d8c869248e51371f0e74bcec0e7b229.

[MC] Omit DWARF unwind info if compact unwind is present where eligible

Previously, omitting unnecessary DWARF unwinds was only done in two
cases:
* For Darwin + aarch64, if no DWARF unwind info is

[MC] Omit DWARF unwind info if compact unwind is present where eligible

Previously, omitting unnecessary DWARF unwinds was only done in two
cases:
* For Darwin + aarch64, if no DWARF unwind info is needed for all the
functions in a TU, then the `__eh_frame` section would be omitted
entirely. If any one function needed DWARF unwind, then MC would emit
DWARF unwind entries for all the functions in the TU.
* For watchOS, MC would omit DWARF unwind on a per-function basis, as
long as compact unwind was available for that function.

This diff makes it so that we omit DWARF unwind on a per-function basis
for Darwin + aarch64 as well. In addition, we introduce the flag
`--emit-dwarf-unwind=` which can toggle between `always`,
`no-compact-unwind` (only emit DWARF when CU cannot be emitted for a
given function), and the target platform `default`. `no-compact-unwind`
is particularly useful for newer x86_64 platforms: we don't want to omit
DWARF unwind for x86_64 in general due to possible backwards compat
issues, but we should make it possible for people to opt into this
behavior if they are only targeting newer platforms.

**Motivation:** I'm working on adding support for `__eh_frame` to LLD,
but I'm concerned that we would suffer a perf hit. Processing compact
unwind is already expensive, and that's a simpler format than EH frames.
Given that MC currently produces one EH frame entry for every compact
unwind entry, I don't think processing them will be cheap. I tried to do
something clever on LLD's end to drop the unnecessary EH frames at parse
time, but this made the code significantly more complex. So I'm looking
at fixing this at the MC level instead.

**Addendum:** It turns out that there was a latent bug in the X86
backend when `OmitDwarfIfHaveCompactUnwind` is naively enabled, which is
not too surprising given that this combination has not been heretofore
used.

For functions that have unwind info that cannot be encoded with CU, MC
would end up dropping both the compact unwind entry (OK; existing
behavior) as well as the DWARF entries (not OK). This diff fixes things
so that we emit the DWARF entry, as well as a CU entry with encoding
`UNWIND_X86_MODE_DWARF` -- this basically tells the unwinder to look for
the DWARF entry. I'm not 100% sure the `UNWIND_X86_MODE_DWARF` CU entry
is necessary, this was the simplest fix. ld64 seems to be able to handle
both the absence and presence of this CU entry. Ultimately ld64 (and
LLD) will synthesize `UNWIND_X86_MODE_DWARF` if it is absent, so there
is no impact to the final binary size.

Reviewed By: davide, lhames

Differential Revision: https://reviews.llvm.org/D122258

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[MC] De-capitalize SwitchSection. NFC

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

[MC] Add 'G' to augmentation string for MTE instrumented functions

This was agreed on in
https://lists.llvm.org/pipermail/llvm-dev/2020-May/141345.html

The thread proposed two options
* add a chara

[MC] Add 'G' to augmentation string for MTE instrumented functions

This was agreed on in
https://lists.llvm.org/pipermail/llvm-dev/2020-May/141345.html

The thread proposed two options
* add a character to augmentation string and handle in libuwind
* use a separate personality function.

It was determined that this is the simpler and better option.

This is part of ARM's Aarch64 ABI:
https://github.com/ARM-software/abi-aa/blob/main/aadwarf64/aadwarf64.rst#id22

The next step after this is teaching libunwind to untag when this
augmentation character is set.

Reviewed By: MaskRay, eugenis

Differential Revision: https://reviews.llvm.org/D127007

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[DWARF] Add API to get data from MCDwarfLineStr

This API will be used in D121876, to get finalized string data for
.debug_line_str.

Reviewed By: dblaikie, rafauler

Differential Revision: https://r

[DWARF] Add API to get data from MCDwarfLineStr

This API will be used in D121876, to get finalized string data for
.debug_line_str.

Reviewed By: dblaikie, rafauler

Differential Revision: https://reviews.llvm.org/D124052

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[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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Revert "Rename llvm::array_lengthof into llvm::size to match std::size from C++17"

This reverts commit ef8206320769ad31422a803a0d6de6077fd231d2.

- It conflicts with the existing llvm::size in STLEx

Revert "Rename llvm::array_lengthof into llvm::size to match std::size from C++17"

This reverts commit ef8206320769ad31422a803a0d6de6077fd231d2.

- It conflicts with the existing llvm::size in STLExtras, which will now
never be called.
- Calling it without llvm:: breaks C++17 compat

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Rename llvm::array_lengthof into llvm::size to match std::size from C++17

As a conquence move llvm::array_lengthof from STLExtras.h to
STLForwardCompat.h (which is included by STLExtras.h so no buil

Rename llvm::array_lengthof into llvm::size to match std::size from C++17

As a conquence move llvm::array_lengthof from STLExtras.h to
STLForwardCompat.h (which is included by STLExtras.h so no build
breakage expected).

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[DebugInfo][NFC] Do not call 'isRootFile' for DWARF Version < 5

A quicker comparison should be done first.

Differential Revision: https://reviews.llvm.org/D117786

[DebugInfo] Fix handling '# line "file"' for DWARFv5

`CppHashInfo.Filename` is a `StringRef` that references a part of the
source file and it is not null-terminated at the end of the file name.
`Asm

[DebugInfo] Fix handling '# line "file"' for DWARFv5

`CppHashInfo.Filename` is a `StringRef` that references a part of the
source file and it is not null-terminated at the end of the file name.
`AsmParser::parseAndMatchAndEmitTargetInstruction()` passes it to
`getStreamer().emitDwarfFileDirective()`, and it eventually comes to
`isRootFile()`. The comparison fails because `FileName.data()` is not
properly terminated.

In addition, the old code might cause a significant speed degradation
for long source files. The `operator!=()` for `std::string` and
`const char *` can be implemented in a way that it finds the length of
the second argument first, which slows the comparison for long data.
`parseAndMatchAndEmitTargetInstruction()` calls
`emitDwarfFileDirective()` every time if `CppHashInfo.Filename` is not
empty. As a result, the longer the source file is, the slower the
compilation wend, and for a very long file, it might take hours instead
of a couple of seconds normally.

Differential Revision: https://reviews.llvm.org/D117785

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[DebugInfo] Fix end_sequence of debug_line in LTO Object

In a LTO build, the `end_sequence` in debug_line table for each compile unit (CU) points the end of text section which merged all CUs. The `e

[DebugInfo] Fix end_sequence of debug_line in LTO Object

In a LTO build, the `end_sequence` in debug_line table for each compile unit (CU) points the end of text section which merged all CUs. The `end_sequence` needs to point to the end of each CU's range. This bug often causes invalid `debug_line` table in the final `.dSYM` binary for MachO after running `dsymutil` which tries to compensate an out-of-range address of `end_sequence`.
The fix is to sync the line table termination with the range operations that are already maintained in DwarfDebug. When CU or section changes, or nodebug functions appear or module is finished, the prior pending line table is terminated using the last range label. In the MC path where no range is tracked, the old logic is conservatively used to end the line table using the section end symbol.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D108261

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[MC] Make MCDwarfLineStr class public

Add MCDwarfLineStr class to the public API.

Note that MCDwarfLineTableHeader::Emit(), takes MCDwarfLineStr as
an Optional<> parameter making it impossible to u

[MC] Make MCDwarfLineStr class public

Add MCDwarfLineStr class to the public API.

Note that MCDwarfLineTableHeader::Emit(), takes MCDwarfLineStr as
an Optional<> parameter making it impossible to use the API if the class
is not publicly defined.

Reviewed By: alexander-shaposhnikov

Differential Revision: https://reviews.llvm.org/D109412

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RISCV: adjust handling of relocation emission for RISCV

This re-architects the RISCV relocation handling to bring the
implementation closer in line with the implementation in binutils. We
would pre

RISCV: adjust handling of relocation emission for RISCV

This re-architects the RISCV relocation handling to bring the
implementation closer in line with the implementation in binutils. We
would previously aggressively resolve the relocation. With this
restructuring, we always will emit a paired relocation for any symbolic
difference of the type of S±T[±C] where S and T are labels and C is a
constant.

GAS has a special target hook controlled by `RELOC_EXPANSION_POSSIBLE`
which indicates that a fixup may be expanded into multiple relocations.
This is used by the RISCV backend to always emit a paired relocation -
either ADD[WIDTH] + SUB[WIDTH] for text relocations or SET[WIDTH] +
SUB[WIDTH] for a debug info relocation. Irrespective of whether linker
relaxation support is enabled, symbolic difference is always emitted as
a paired relocation.

This change also sinks the target specific behaviour down into the
target specific area rather than exposing it to the shared relocation
handling. In the process, we also sink the "special" handling for debug
information down into the RISCV target. Although this improves the path
for the other targets, this is not necessarily entirely ideal either.
The changes in the debug info emission could be done through another
type of hook as this functionality would be required by any other target
which wishes to do linker relaxation. However, as there are no other
targets in LLVM which currently do this, this is a reasonable thing to
do until such time as the code needs to be shared.

Improve the handling of the relocation (and add a reduced test case from
the Linux kernel) to ensure that we handle complex expressions for
symbolic difference. This ensures that we correct relocate symbols with
the adddends normalized and associated with the addition portion of the
paired relocation.

This change also addresses some review comments from Alex Bradbury about
the relocations meant for use in the DWARF CFA being named incorrectly
(using ADD6 instead of SET6) in the original change which introduced the
relocation type.

This resolves the issues with the symbolic difference emission
sufficiently to enable building the Linux kernel with clang+IAS+lld
(without linker relaxation).

Resolves PR50153, PR50156!
Fixes: ClangBuiltLinux/linux#1023, ClangBuiltLinux/linux#1143

Reviewed By: nickdesaulniers, maskray

Differential Revision: https://reviews.llvm.org/D103539

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Implement DW_CFA_LLVM_* for Heterogeneous Debugging

Add support in MC/MIR for writing/parsing, and DebugInfo.

This is part of the Extensions for Heterogeneous Debugging defined at
https://llvm.org/

Implement DW_CFA_LLVM_* for Heterogeneous Debugging

Add support in MC/MIR for writing/parsing, and DebugInfo.

This is part of the Extensions for Heterogeneous Debugging defined at
https://llvm.org/docs/AMDGPUDwarfExtensionsForHeterogeneousDebugging.html

Specifically the CFI instructions implemented here are defined at
https://llvm.org/docs/AMDGPUDwarfExtensionsForHeterogeneousDebugging.html#cfa-definition-instructions

Reviewed By: clayborg

Differential Revision: https://reviews.llvm.org/D76877

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[Debug-Info] Add names for the debug line prologue.

Summary: This is a minor patch to add names for the debug line prologue, as a follow-up of D95998.

Reviewed By: dblaikie, ikudrin, shchenz

Diffe

[Debug-Info] Add names for the debug line prologue.

Summary: This is a minor patch to add names for the debug line prologue, as a follow-up of D95998.

Reviewed By: dblaikie, ikudrin, shchenz

Differential Revision: https://reviews.llvm.org/D98383

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[XCOFF][DebugInfo] support DWARF for XCOFF for assembly output.

Reviewed By: jasonliu

Differential Revision: https://reviews.llvm.org/D95518

[Debug-Info][NFC] use emitDwarfUnitLength for debug line section

Use emitDwarfUnitLength for debug line, so we can benefit from
overriding of emitDwarfUnitLength inside different streamers.

Reviewe

[Debug-Info][NFC] use emitDwarfUnitLength for debug line section

Use emitDwarfUnitLength for debug line, so we can benefit from
overriding of emitDwarfUnitLength inside different streamers.

Reviewed By: ikudrin, dblaikie

Differential Revision: https://reviews.llvm.org/D95998

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[MC] Use std::make_tuple to make some toolchains happy again

My toolchain (LLVM 8.0, libstdc++ 5.4.0) complained with:

12:27:43 ../lib/MC/MCDwarf.cpp:814:10: error: chosen constructor is explicit i

[MC] Use std::make_tuple to make some toolchains happy again

My toolchain (LLVM 8.0, libstdc++ 5.4.0) complained with:

12:27:43 ../lib/MC/MCDwarf.cpp:814:10: error: chosen constructor is explicit in copy-initialization
12:27:43 return {Offset, Size, SetDelta};
12:27:43 ^~~~~~~~~~~~~~~~~~~~~~~~
12:27:43 /proj/flexasic/app/llvm/8.0/bin/../lib/gcc/x86_64-unknown-linux-gnu/5.4.0/../../../../include/c++/5.4.0/tuple:479:19: note: explicit constructor declared here
12:27:43 constexpr tuple(_UElements&&... __elements)
12:27:43 ^
12:27:43 1 error generated.

This commit adds explicit calls to std::make_tuple to work around
the problem.

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MCDwarf: Delete uneeded parameter

And change signature

[MC] Split MCContext::createTempSymbol, default AlwaysAddSuffix to true, and add comments

CanBeUnnamed is rarely false. Splitting to a createNamedTempSymbol makes the
intention clearer and matches t

[MC] Split MCContext::createTempSymbol, default AlwaysAddSuffix to true, and add comments

CanBeUnnamed is rarely false. Splitting to a createNamedTempSymbol makes the
intention clearer and matches the direction of reverted r240130 (to drop the
unneeded parameters).

No behavior change.

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