The stack ids are hashes that are close to 64 bits in size, so emitting
as a pair of 32-bit fixed-width values is more efficient than a VBR.
This reduced the summary bitcode size for a large target by about 1%.

Bump the index version and ensure we can read the old format.

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>

This restores commit 80d0a137a5aba6998fadb764f1e11cb901aae233, and the
follow on fix in 873c0d0786dcf22f4af39f65df824917f70f2170, with a new
fix for test failures after a 2-stage clang bootstrap, and a more robust
fix for the Chromium build failure that an earlier version partially
fixed. See also discussion on D75201.

Reviewers: evgeny777

Subscribers: mehdi_amini, Prazek, hiraditya, steven_wu, dexonsmith, arphaman, davidxl, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D73242

This reverts commit 80d0a137a5aba6998fadb764f1e11cb901aae233, and the
follow on fix in 873c0d0786dcf22f4af39f65df824917f70f2170. It is
causing test failures after a multi-stage clang bootstrap. See
discussion on D73242 and D75201.

This restores commit 748bb5a0f1964d20dfb3891b0948ab6c66236c70, along
with a fix for a Chromium test suite build issue (and a new test for
that case).

Differential Revision: https://reviews.llvm.org/D73242