Reapply "[BOLT][AArch64] Handle OpNegateRAState to enable optimizing
binaries with pac-ret hardening (#120064)" (#162353)

This reverts commit c7d776b06897567e2d698e447d80279664b67d47.

#120064 was reverted for breaking builders.

Fix: changed the mismatched type in MarkRAStates.cpp to `auto`.

---

Original message:

OpNegateRAState is an AArch64-specific DWARF CFI used to change the value
of the RA_SIGN_STATE pseudoregister. The RA_SIGN_STATE register records
whether the current return address has been signed with PAC.

OpNegateRAState requires special handling in BOLT because its placement
depends on the function layout. Since BOLT reorders basic blocks during
optimization, these CFIs must be regenerated after layout is finalized.

This patch introduces two new passes:

- MarkRAStates (runs before optimizations): assigns a signedness annotation to each
  instruction based on OpNegateRAState CFIs in the input binary.

- InsertNegateRAStates (runs after optimizations): reads the annotations and emits
  new OpNegateRAState CFIs where RA state changes between instructions.

Design details are described in: `bolt/docs/PacRetDesign.md`.

Reverts llvm/llvm-project#120064.

@gulfemsavrun reported that the patch broke toolchain builders.

OpNegateRAState is an AArch64-specific DWARF CFI used to change the value
of the RA_SIGN_STATE pseudoregister. The RA_SIGN_STATE register records
if the current return address has been signed with PAC.

OpNegateRAState requires special handling in BOLT because its placement
depends on the function layout. Since BOLT reorders basic blocks during
optimization, these CFIs must be regenerated after layout is finalized.

This patch introduces two new passes:

- MarkRAStates (runs before optimizations): assigns a signedness annotation to each
  instruction based on OpNegateRAState CFIs in the input binary.

- InsertNegateRAStates (runs after optimizations): reads the annotations and emits
  new OpNegateRAState CFIs where RA state changes between instructions.

Design details are described in: `bolt/docs/PacRetDesign.md`.

"Large" functions are functions that are too big to fit into their
original slots after code modifications. CheckLargeFunctions pass is
designed to prevent such functions from emission. Extend this pass to
work with functions with constant islands.

Now that CheckLargeFunctions covers all functions, it guarantees that we
will never see such functions after code emission on all platforms
(previously it was guaranteed on x86 only). Hence, we can get rid of
RewriteInstance extensions that were meant to support "large" functions.

Use AsmInfo instead of DWARFObj interface for extracting address size
and format.

Three-way splitting can create references between split fragments (warm
to cold or vice versa) that are not handled by
`isChildOf/isParentOf/isChildOrParentOf`. Generalize fragment
relationships to allow checking if two functions belong to one group,
potentially in presence of ICF which can join multiple groups.

Test Plan: NFC for existing tests

Reviewers: maksfb, ayermolo, rafaelauler, dcci

Reviewed By: rafaelauler

Pull Request: https://github.com/llvm/llvm-project/pull/99979

To avoid accidentally setting the label twice for the same instruction,
which can lead to a "lost" label, introduce getOrSetInstLabel()
function. Rename existing functions to getInstLabel()/setInstLabel() to
make it explicit that they operate on instruction labels. Add an
assertion in setInstLabel() that the instruction did not have a prior
label set.

Make core BOLT functionality more friendly to being used as a
library instead of in our standalone driver llvm-bolt. To
accomplish this, we augment BinaryContext with journaling streams
that are to be used by most BOLT code whenever something needs to
be logged to the screen. Users of the library can decide if logs
should be printed to a file, no file or to the screen, as
before. To illustrate this, this patch adds a new option
`--log-file` that allows the user to redirect BOLT logging to a
file on disk or completely hide it by using
`--log-file=/dev/null`. Future BOLT code should now use
`BinaryContext::outs()` for printing important messages instead of
`llvm::outs()`. A new test log.test enforces this by verifying that
no strings are print to screen once the `--log-file` option is
used.

In previous patches we also added a new BOLTError class to report
common and fatal errors, so code shouldn't call exit(1) now. To
easily handle problems as before (by quitting with exit(1)),
callers can now use
`BinaryContext::logBOLTErrorsAndQuitOnFatal(Error)` whenever code
needs to deal with BOLT errors. To test this, we have fatal.s
that checks we are correctly quitting and printing a fatal error
to the screen.

Because this is a significant change by itself, not all code was
yet ported. Code from Profiler libs (DataAggregator and friends)
still print errors directly to screen.

Co-authored-by: Rafael Auler <rafaelauler@fb.com>

Test Plan: NFC

As part of the effort to refactor old error handling code that
would directly call exit(1), in this patch continue the migration
on libCore, libRewrite and libPasses to use the new BOLTError
class whenever a failure occurs.

Test Plan: NFC

Co-authored-by: Rafael Auler <rafaelauler@fb.com>