Version 2 was added more than two years ago
(https://github.com/llvm/llvm-project/commit/6015a045d768feab3bae9ad9c0c81e118df8b04a).
So it should be safe to deprecate older versions.

This reapplies commit 1911a50fae8a441b445eb835b98950710d28fc88 with a
minor fix in lld/ELF/LTO.cpp which sets Options.BBAddrMap when
`--lto-basic-block-sections=labels` is passed.

This reverts commit 1911a50fae8a441b445eb835b98950710d28fc88.

Several bots are failing:

https://lab.llvm.org/buildbot/#/builders/190/builds/6519
https://lab.llvm.org/buildbot/#/builders/3/builds/5248
https://lab.llvm.org/buildbot/#/builders/18/builds/4463

This feature is supported via the newer option
`-fbasic-block-address-map`. Using the old option still works by
delegating to the newer option, while a warning is printed to show
deprecation.

This patch will make LLVM emit a new section .llvm_jump_table_sizes 
containing tuples of (jump table address, entry count) in object files.
This section is useful for tools that need to statically reconstruct the
control flow of executables.

At the moment this is only enabled by default for the PS5 target.

Uses machine analyses to emit PGOAnalysisMap into the bb-addr-map ELF
section. Implements filecheck tests to verify emitting new fields.

This patch emits optional PGO related analyses into the bb-addr-map ELF
section during AsmPrinter. This currently supports Function Entry Count,
Machine Block Frequencies. and Machine Branch Probabilities. Each is
independently enabled via the `feature` byte of `bb-addr-map` for the given
function.

A part of [RFC - PGO Accuracy Metrics: Emitting and Evaluating Branch and Block Analysis](https://discourse.llvm.org/t/rfc-pgo-accuracy-metrics-emitting-and-evaluating-branch-and-block-analysis/73902).

clang -ffat-lto-objects can use this new ELF section type for the .llvm.lto
section for fat LTO support (D146776).

Original RFC: https://discourse.llvm.org/t/rfc-ffat-lto-objects-support/63977

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D153215

.addrsig_sym forces registering the symbol regardless whether it is otherwise
registered. This creates an undefined symbol which is inconvenient/undesired:

* `extern int x; void f() { (void)x; }` has inconsistent behavior whether `x` is emitted as an undefined symbol.
  `-O0 -faddrsig` makes `x` undefined while other -O levels and -fno-addrsig eliminate the symbol.
* In ThinLTO, after a non-prevailing linkonce_odr definition is converted to available_externally, and then a declaration,
  the addrsig code emits a symbol while the symbol is otherwise unseen.

D135427 fixed a bug that a non-prevailing `__cxx_global_var_init` was
incorrectly retained. However, the IR declaration causes an undesired
`.addrsig_sym __cxx_global_var_init`. This can be addressed in a way similar
to D101512 (`isTransitiveUsedByMetadataOnly`) but the increased
`OutStreamer->emitAddrsigSym(getSymbol(&GV));` complexity makes me nervous.
Just ignoring unregistered symbols circumvents the problem.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D135642

Currently we use the `.llvm.offloading` section to store device-side
objects inside the host, creating a fat binary. The contents of these
sections is currently determined by the name of the section while it
should ideally be determined by its type. This patch adds the new
`SHT_LLVM_OFFLOADING` section type to the ELF section types. Which
should make it easier to identify this specific data format.

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D129052

This is a resurrection of D106421 with the change that it keeps backward-compatibility. This means decoding the previous version of `LLVM_BB_ADDR_MAP` will work. This is required as the profile mapping tool is not released with LLVM (AutoFDO). As suggested by @jhenderson we rename the original  section type value to `SHT_LLVM_BB_ADDR_MAP_V0` and assign a new value to the `SHT_LLVM_BB_ADDR_MAP` section type. The new encoding adds a version byte to each function entry to specify the encoding version for that function.  This patch also adds a feature byte to be used with more flexibility in the future. An use-case example for the feature field is encoding multi-section functions more concisely using a different format.

Conceptually, the new encoding emits basic block offsets and sizes as label differences between each two consecutive basic block begin and end label. When decoding, offsets must be aggregated along with basic block sizes to calculate the final offsets of basic blocks relative to the function address.

This encoding uses smaller values compared to the existing one (offsets relative to function symbol).
Smaller values tend to occupy fewer bytes in ULEB128 encoding. As a result, we get about 17% total reduction in the size of the bb-address-map section (from about 11MB to 9MB for the clang PGO binary).
The extra two bytes (version and feature fields) incur a small 3% size overhead to the `LLVM_BB_ADDR_MAP` section size.

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D121346