This retries #90692 which was reverted previously due to issues with
lld-available being set, even if the copy of lld is not built from
source.

This does not change any code compared to #90692 to address the
lld-available issue.
The main change w.r.t, lld-available is xfailing tests in PR #99056
(until a longer term fix is available).

If requested, via the -memprof-report-hinted-sizes option, track the
total profiled size of each MIB through the thin link, then report on
the corresponding allocation coldness after all cloning is complete.

To save size, a different bitcode record type is used for the allocation
info when the option is specified, and the sizes are kept separate from
the MIBs in the index.

Reverts llvm/llvm-project#90692

Breaking PPC buildbots. The bots are not meant to test LLD, but are
running a test that is using an old version of LLD without the change
(so is incompatible). Revert until a fix is found.

This reverts commit 2aabfc811670beb843074c765c056fff4a7b443b.

Add fixes to LLD and Gold tests missed in original change.

Co-authored-by: Jan Voung <jvoung@google.com>

Reverts llvm/llvm-project#90497
Broke some LLD tests.

GUID often have content in the higher bits of a 64-bit entry so using
the unabbrev encoding is inefficient (lots of VBR control bits).
Instead, use an abbrev with two 32-bit fixed width chunks.
The abbrev also helps encode the "count" in one place instead of
in every record.

Reduces size of distributed backend summary files by 8.7% in one
example app.

Co-authored-by: Jan Voung <jvoung@google.com>

The motivating use case is to support import the function declaration
across modules to construct call graph edges for indirect calls [1]
when importing the function definition costs too much compile time
(e.g., the function is too large has no `noinline` attribute).
1. Currently, when the compiled IR module doesn't have a function
definition but its postlink combined summary contains the function
summary or a global alias summary with this function as aliasee, the
function definition will be imported from source module by IRMover. The
implementation is in FunctionImporter::importFunctions [2]
2. In order for FunctionImporter to import a declaration of a function,
both function summary and alias summary need to carry the def / decl
state. Specifically, all existing summary fields doesn't differ across
import modules, but the def / decl state of is decided by
`<ImportModule, Function>`.

This change encodes the def/decl state in `GlobalValueSummary::GVFlags`.

In the subsequent changes
1. The indexing step `computeImportForModule` [3]
will compute the set of definitions and the set of declarations for each
module, and passing on the information to bitcode writer.
2. Bitcode writer will look up the def/decl state and sets the state
when it writes out the flag value. This is demonstrated in
https://github.com/llvm/llvm-project/pull/87600
3. Function importer will read the def/decl state when reading the
combined summary to figure out two sets of global values, and IRMover
will be updated to import the declaration (aka linkGlobalValuePrototype [4])
into the destination module.

- The next change is https://github.com/llvm/llvm-project/pull/87600

[1] mentioned in rfc https://discourse.llvm.org/t/rfc-for-better-call-graph-sort-build-a-more-complete-call-graph-by-adding-more-indirect-call-edges/74029#support-cross-module-function-declaration-import-5
[2] https://github.com/llvm/llvm-project/blob/3b337242ee165554f0017b00671381ec5b1ba855/llvm/lib/Transforms/IPO/FunctionImport.cpp#L1608-L1764
[3] https://github.com/llvm/llvm-project/blob/3b337242ee165554f0017b00671381ec5b1ba855/llvm/lib/Transforms/IPO/FunctionImport.cpp#L856
[4] https://github.com/llvm/llvm-project/blob/3b337242ee165554f0017b00671381ec5b1ba855/llvm/lib/Linker/IRMover.cpp#L605

Add annotated vtable GUID as referenced variables in per function
summary, and update bitcode writer to create value-ids for these
referenced vtables.

- This is the part3 of type profiling work, and described in the "Virtual Table Definition Import" [1] section of the
RFC.

[1] https://github.com/llvm/llvm-project/pull/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

A precommit test case to show function summary and global values when a function has instructions annotated with vtable profiles and indirect call profiles.
- This is a precommit test for https://github.com/llvm/llvm-project/pull/79381