[NFC][DebugInfo] Make some block-start-position methods return iterators (#124287)

As part of the "RemoveDIs" work to eliminate debug intrinsics, we're
replacing methods that use Instruction*'s as

[NFC][DebugInfo] Make some block-start-position methods return iterators (#124287)

As part of the "RemoveDIs" work to eliminate debug intrinsics, we're
replacing methods that use Instruction*'s as positions with iterators. A
number of these (such as getFirstNonPHIOrDbg) are sufficiently
infrequently used that we can just replace the pointer-returning version
with an iterator-returning version, hopefully without much/any
disruption.

Thus this patch has getFirstNonPHIOrDbg and
getFirstNonPHIOrDbgOrLifetime return an iterator, and updates all
call-sites. There are no concerns about the iterators returned being
converted to Instruction*'s and losing the debug-info bit: because the
methods skip debug intrinsics, the iterator head bit is always false
anyway.

show more ...

Reland "[LLVM] Add IRNormalizer Pass" (#113780)

`IRNormalizer` will reorder instructions. Thus, we need to invalidate
analyses. Done in cd500d28cba3177c213f2f2faf50f14ea56e230b. This should
resolv

Reland "[LLVM] Add IRNormalizer Pass" (#113780)

`IRNormalizer` will reorder instructions. Thus, we need to invalidate
analyses. Done in cd500d28cba3177c213f2f2faf50f14ea56e230b. This should
resolve the [BuildBot
failure](https://github.com/llvm/llvm-project/pull/68176#issuecomment-2428243474).

---

Original PR: #68176
Original commit: 1295d2e6da2fe90f3b770ab1d35bf5caecd38bed
Reverted with: 8a12e0131f3d84b470fac63af042aa96a1b19f56

---

Add the llvm-canon tool. Description from the [original
PR](https://reviews.llvm.org/D66029#change-wZv3yOpDdxIu):

> Added a new llvm-canon tool which aims to transform LLVM Modules into
a canonical form by reordering and renaming instructions while
preserving the same semantics. This tool makes it easier to spot
semantic differences while diffing two modules which have undergone
different transformation passes.

The current version of this tool can:

- Reorder instructions within a function.
- Rename instructions based on the operands.
- Sort commutative operands.

This code was originally written by @michalpaszkowski and [submitted to
mainline
LLVM](https://github.com/llvm/llvm-project/commit/14d358537f124a732adad1ec6edf3981dc9baece).
However, it was quickly
[reverted](https://github.com/llvm/llvm-project/commit/335de55fa3384946f1e62050f2545c0966163236)
to do BuildBot errors.

Michal presented his version of the tool in [LLVM-Canon: Shooting for
Clear Diffs](https://www.youtube.com/watch?v=c9WMijSOEUg).

@AidanGoldfarb and I ported the code to the new pass manager, added more
tests, and fixed some bugs related to PHI nodes that may have been the
root cause of the BuildBot errors that caused the patch to be reverted.
Additionally, we rewrote the implementation of instruction reordering to
fix cases where the original algorithm would break use-def chains.

Note that this is @AidanGoldfarb and I's first time submitting to LLVM.
Please liberally critique the PR!

CC @plotfi for initial review.

---------

Co-authored-by: Aidan <aidan.goldfarb@mail.mcgill.ca>

show more ...

[LLVM] Add IRNormalizer Pass (#68176)

Add the llvm-canon tool. Description from the [original
PR](https://reviews.llvm.org/D66029#change-wZv3yOpDdxIu):

> Added a new llvm-canon tool which aims t

[LLVM] Add IRNormalizer Pass (#68176)

Add the llvm-canon tool. Description from the [original
PR](https://reviews.llvm.org/D66029#change-wZv3yOpDdxIu):

> Added a new llvm-canon tool which aims to transform LLVM Modules into
a canonical form by reordering and renaming instructions while
preserving the same semantics. This tool makes it easier to spot
semantic differences while diffing two modules which have undergone
different transformation passes.

The current version of this tool can:

- Reorder instructions within a function.
- Rename instructions based on the operands.
- Sort commutative operands.

This code was originally written by @michalpaszkowski and [submitted to
mainline
LLVM](https://github.com/llvm/llvm-project/commit/14d358537f124a732adad1ec6edf3981dc9baece).
However, it was quickly
[reverted](https://github.com/llvm/llvm-project/commit/335de55fa3384946f1e62050f2545c0966163236)
to do BuildBot errors.

Michal presented his version of the tool in [LLVM-Canon: Shooting for
Clear Diffs](https://www.youtube.com/watch?v=c9WMijSOEUg).

@AidanGoldfarb and I ported the code to the new pass manager, added more
tests, and fixed some bugs related to PHI nodes that may have been the
root cause of the BuildBot errors that caused the patch to be reverted.
Additionally, we rewrote the implementation of instruction reordering to
fix cases where the original algorithm would break use-def chains.

Note that this is @AidanGoldfarb and I's first time submitting to LLVM.
Please liberally critique the PR!

CC @plotfi for initial review.

---------

Co-authored-by: Aidan <aidan.goldfarb@mail.mcgill.ca>

show more ...