This PR is part of #123870.
The pseudo probe desc emission code can be reused by other target.

Unlike other formats, the GOFF object file format uses a 2 dimensional structure
to define the location of data. For example, the equivalent of the ELF .text
section is made up of a Section Definition (SD) and a class (Element Definition;
ED). The name of the SD symbol depends on the application, while the class has
the predefined name C_CODE/C_CODE64 in AMODE31 and AMODE64 respectively.

Data can be placed into this structure in 2 ways. First, the data (in a text
record) can be associated with an ED symbol. To refer to data, a Label
Definition (LD) is used to give an offset into the data a name. When binding,
the whole data is pulled into the resulting executable, and the addresses
given by the LD symbols are resolved.

The alternative is to use a Part Definition (PR). In this case, the data (in
a text record) is associated with the part. When binding, only the data of
referenced PRs is pulled into the resulting binary.

Both approaches are used. SD, ED, and PR elements are modeled by nested
MCSectionGOFF instances, while LD elements are associated with MCSymbolGOFF
instances.

At the binary level, a record called "External Symbol Definition" (ESD) is used. The
ESD has a type (SD, ED, PR, LD), and depending on the type a different subset of
the fields is used. 

This annotates the `Twine` passed to the constructors of the various
DiagnosticInfo subclasses with `[[clang::lifetimebound]]`, which causes
us to warn when we would try to print the twine after it had already
been destructed.

We also update `DiagnosticInfoUnsupported` to hold a `const Twine &`
like all of the other DiagnosticInfo classes, since this warning allows
us to clean up all of the places where it was being used incorrectly.

Cygwin-gcc emits COMDAT in the same format as MinGW-gcc.

https://reviews.llvm.org/D17938 introduced lowerRelativeReference to
give ConstantExpr sub (A-B) special semantics in ELF: when `A` is an
`unnamed_addr` function, create a PLT-generating relocation. This was
intended for C++ relative vtables, but C++ relative vtable ended up
using DSOLocalEquivalent (lowerDSOLocalEquivalent).

This special treatment of `unnamed_addr` seems unusual.
Let's remove it. Only COFF needs an overload to generate a @IMGREL32
relocation specifier (llvm/test/MC/COFF/cross-section-relative.ll).

Pull Request: https://github.com/llvm/llvm-project/pull/134781

Reverts llvm/llvm-project#132684

https://reviews.llvm.org/D17938 introduced lowerRelativeReference to
give ConstantExpr sub (A-B) special semantics in ELF: when `A` is an
`unnamed_addr` function, create a PLT-generating relocation. This was
intended for C++ relative vtables, but C++ relative vtable ended up
using DSOLocalEquivalent (lowerDSOLocalEquivalent).

This special treatment of `unnamed_addr` seems unusual.
Let's remove it. Only COFF needs an overload to generate a @IMGREL32
relocation specifier (llvm/test/MC/COFF/cross-section-relative.ll).

Pull Request: https://github.com/llvm/llvm-project/pull/132684

This is a follow-up patch of
https://github.com/llvm/llvm-project/pull/125756

In this PR, static-data-splitter pass produces the aggregated profile
counts of constants for constant pools in a global state
(`StateDataProfileInfo`), and asm printer consumes the profile counts to
produce `.hot` or `.unlikely` prefixes.

This implementation covers both x86 and aarch64 asm printer.

clang -fexperimental-relative-c++-abi-vtables might generate `@plt` and
`@gotpcrel` specifiers in data directives. The syntax is not used in
humand-written assembly code, and is not supported by GNU assembler.
Note: the `@plt` in `.word foo@plt` is different from
the legacy `call func@plt` (where `@plt` is simply ignored).

The `@plt` syntax was selected was simply due to a quirk of AsmParser:
the syntax was supported by all targets until I updated it
to be an opt-in feature in a0671758eb6e52a758bd1b096a9b421eec60204c

RISC-V favors the `%specifier(expr)` syntax following MIPS and Sparc,
and we should follow this convention.

This PR adds support for `.word %pltpcrel(foo+offset)` and
`.word %gotpcrel(foo)`, and drops `@plt` and `@gotpcrel`.

* MCValue::SymA can no longer have a SymbolVariant. Add an assert
  similar to that of AArch64ELFObjectWriter.cpp before
  https://reviews.llvm.org/D81446 (see my analysis at
  https://maskray.me/blog/2025-03-16-relocation-generation-in-assemblers
  if intrigued)
* `jump foo@plt, x31` now has a different diagnostic.

Pull Request: https://github.com/llvm/llvm-project/pull/132569