[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.

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[NFC][DebugInfo] Use iterator moveBefore at many call-sites (#123583)

As part of the "RemoveDIs" project, BasicBlock::iterator now carries a
debug-info bit that's needed when getFirstNonPHI and sim

[NFC][DebugInfo] Use iterator moveBefore at many call-sites (#123583)

As part of the "RemoveDIs" project, BasicBlock::iterator now carries a
debug-info bit that's needed when getFirstNonPHI and similar feed into
instruction insertion positions. Call-sites where that's necessary were
updated a year ago; but to ensure some type safety however, we'd like to
have all calls to moveBefore use iterators.

This patch adds a (guaranteed dereferenceable) iterator-taking
moveBefore, and changes a bunch of call-sites where it's obviously safe
to change to use it by just calling getIterator() on an instruction
pointer. A follow-up patch will contain less-obviously-safe changes.

We'll eventually deprecate and remove the instruction-pointer
insertBefore, but not before adding concise documentation of what
considerations are needed (very few).

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[CodeMoverUtils] Enhance CodeMoverUtils to sink an entire BB (#87857)

When moving an entire basic block after `InsertPoint`, currently we
check each instruction whether their users are dominated by

[CodeMoverUtils] Enhance CodeMoverUtils to sink an entire BB (#87857)

When moving an entire basic block after `InsertPoint`, currently we
check each instruction whether their users are dominated by
`InsertPoint`, however, this can be improved such that even a user is
not dominated by `InsertPoint`, as long as it appears as a subsequent
instruction in the same BB, it is safe to move.

This patch is similar to commit 751be2a064f119af74c7b9b1e52bc904d8aa114d
that enhanced hoisting an entire BB, and this patch enhances sinking an
entire BB. Please refer to the added functionality in test case
`llvm/unittests/Transforms/Utils/CodeMoverUtilsTest.cpp` that was not
supported without this patch.

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[NFC][RemoveDIs] Create a new spelling of the moveBefore method

As outlined in my proposal of how to get rid of debug intrinsics, this
patch adds a moveBefore method that signals the caller /intends

[NFC][RemoveDIs] Create a new spelling of the moveBefore method

As outlined in my proposal of how to get rid of debug intrinsics, this
patch adds a moveBefore method that signals the caller /intends/ the order
of moved instructions is to stay the same. This semantic difference has an
effect on debug-info, as it signals whether debug-info needs to move with
instructions or not.

The patch just replaces a few calls to moveBefore with calls to
moveBeforePreserving -- and the latter just calls the former, so it's all
NFC right now. A future patch will add an implementation of
moveBeforePreserving that takes action to correctly preserve debug-info,
but that's tightly coupled with our non-instruction debug-info
representation that's still being reviewed.

[0] https://discourse.llvm.org/t/rfc-instruction-api-changes-needed-to-eliminate-debug-intrinsics-from-ir/68939

Differential Revision: https://reviews.llvm.org/D156369

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Don't include Optional.h

These files no longer use llvm::Optional.

Transforms/Utils: llvm::Optional => std::optional

[llvm] Use std::nullopt instead of None in comments (NFC)

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalu

[llvm] Use std::nullopt instead of None in comments (NFC)

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

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[Transforms] Use std::nullopt instead of None (NFC)

This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount

[Transforms] Use std::nullopt instead of None (NFC)

This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

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[llvm] Qualify auto in range-based for loops (NFC)

Identified with readability-qualified-auto.

[Transforms] Use make_early_inc_range (NFC)

[CodeMoverUtils] Enhance isSafeToMoveBefore() when control flow equivalence is satisfied

With improved analysis in determining CFG equivalence that does
not require strict dominance and post-dominan

[CodeMoverUtils] Enhance isSafeToMoveBefore() when control flow equivalence is satisfied

With improved analysis in determining CFG equivalence that does
not require strict dominance and post-dominance conditions, we
now relax isSafeToMoveBefore() such that an instruction I can
be moved before InsertPoint even if they do not strictly dominate
each other, as long as they follow the same control flow path.

For example, we can move Instruction 0 before Instruction 1,
and vice versa.

```
if (cond1)
// Instruction 0: %add = add i32 1, 2
if (cond1)
// Instruction 1: %add2 = add i32 2, 1
```

Reviewed By: Whitney

Differential Revision: https://reviews.llvm.org/D110456

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[CodeMoverUtils] Enhance isSafeToMoveBefore() when moving BBs

When moving an entire basic block BB before InsertPoint, currently
we check for all instructions whether the operands dominates
InsertPo

[CodeMoverUtils] Enhance isSafeToMoveBefore() when moving BBs

When moving an entire basic block BB before InsertPoint, currently
we check for all instructions whether the operands dominates
InsertPoint, however, this can be improved such that even an
operand does not dominate InsertPoint, as long as it appears as
a previous instruction in the same BB, it is safe to move.

Reviewed By: Whitney

Differential Revision: https://reviews.llvm.org/D110378

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[CodeGen, Transforms] Use llvm::any_of (NFC)

[CodeMoverUtils] Move OrderedInstructions to CodeMoverUtils
Summary: This patch moves OrderedInstructions to CodeMoverUtils as It was
the only place where OrderedInstructions is required.
Authored By

[CodeMoverUtils] Move OrderedInstructions to CodeMoverUtils
Summary: This patch moves OrderedInstructions to CodeMoverUtils as It was
the only place where OrderedInstructions is required.
Authored By: RithikSharma
Reviewer: Whitney, bmahjour, etiotto, fhahn, nikic
Reviewed By: Whitney, nikic
Subscribers: mgorny, hiraditya, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D80643

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[CodeMoverUtils] Make specific analysis dependent checks optional

Summary: This patch makes code motion checks optional which are dependent on
specific analysis example, dominator tree, post dominat

[CodeMoverUtils] Make specific analysis dependent checks optional

Summary: This patch makes code motion checks optional which are dependent on
specific analysis example, dominator tree, post dominator tree and dependence
info. The aim is to make the adoption of CodeMoverUtils easier for clients that
don't use analysis which were strictly required by CodeMoverUtils. This will
also help in diversifying code motion checks using other analysis example MSSA.
Authored By: RithikSharma
Reviewer: Whitney, bmahjour, etiotto
Reviewed By: Whitney
Subscribers: Prazek, hiraditya, george.burgess.iv, asbirlea, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D82566

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[CodeMoverUtils] Use dominator tree level to decide the direction of
code motion

Summary: Currently isSafeToMoveBefore uses DFS numbering for determining
the relative position of instruction and ins

[CodeMoverUtils] Use dominator tree level to decide the direction of
code motion

Summary: Currently isSafeToMoveBefore uses DFS numbering for determining
the relative position of instruction and insert point which is not
always correct. This PR proposes the use of Dominator Tree depth for the
same. If a node is at a higher level than the insert point then it is
safe to say that we want to move in the forward direction.
Authored By: RithikSharma
Reviewer: Whitney, nikic, bmahjour, etiotto, fhahn
Reviewed By: Whitney
Subscribers: fhahn, hiraditya, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D80084

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Fix MSVC lamdba default capture mode warning. NFCI.

[LoopFusion] Move instructions from FC1.Preheader to FC0.Preheader when
proven safe.

Summary:
Currently LoopFusion give up when the second loop nest preheader is
not empty. For example:

for (int i

[LoopFusion] Move instructions from FC1.Preheader to FC0.Preheader when
proven safe.

Summary:
Currently LoopFusion give up when the second loop nest preheader is
not empty. For example:

for (int i = 0; i < 100; ++i) {}
x+=1;
for (int i = 0; i < 100; ++i) {}
The above example should be safe to fuse.
This PR moves instructions in FC1 preheader (e.g. x+=1; ) to
FC0 preheader, which then LoopFusion is able to fuse them.
Reviewer: kbarton, Meinersbur, jdoerfert, dmgreen, fhahn, hfinkel,
bmahjour, etiotto
Reviewed By: jdoerfert
Subscribers: hiraditya, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D71821

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Fix warning of `-Wcast-qual`. NFC.

[CodeMoverUtils] Improve IsControlFlowEquivalent.

Summary:
Currently IsControlFlowEquivalent determine if two blocks are control
flow equivalent by checking if A dominates B and B post dominates A.

[CodeMoverUtils] Improve IsControlFlowEquivalent.

Summary:
Currently IsControlFlowEquivalent determine if two blocks are control
flow equivalent by checking if A dominates B and B post dominates A.
There exists blocks that are control flow equivalent even if they don't
satisfy the A dominates B and B post dominates A condition.
For example,

if (cond)
A
if (cond)
B
In the PR, we determine if two blocks are control flow equivalent by
also checking if the two sets of conditions A and B depends on are
equivalent.
Reviewer: jdoerfert, Meinersbur, dmgreen, etiotto, bmahjour, fhahn,
hfinkel, kbarton
Reviewed By: fhahn
Subscribers: hiraditya, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D71578

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[LoopFusion] Move instructions from FC0.Latch to FC1.Latch.

Summary:This PR move instructions from FC0.Latch bottom up to the
beginning of FC1.Latch as long as they are proven safe.

To illustrate w

[LoopFusion] Move instructions from FC0.Latch to FC1.Latch.

Summary:This PR move instructions from FC0.Latch bottom up to the
beginning of FC1.Latch as long as they are proven safe.

To illustrate why this is beneficial, let's consider the following
example:
Before Fusion:
header1:
br header2
header2:
br header2, latch1
latch1:
br header1, preheader3
preheader3:
br header3
header3:
br header4
header4:
br header4, latch3
latch3:
br header3, exit3

After Fusion (before this PR):
header1:
br header2
header2:
br header2, latch1
latch1:
br header3
header3:
br header4
header4:
br header4, latch3
latch3:
br header1, exit3

Note that preheader3 is removed during fusion before this PR.
Notice that we cannot fuse loop2 with loop4 as there exists block latch1
in between.
This PR move instructions from latch1 to beginning of latch3, and remove
block latch1. LoopFusion is now able to fuse loop nest recursively.

After Fusion (after this PR):
header1:
br header2
header2:
br header3
header3:
br header4
header4:
br header2, latch3
latch3:
br header1, exit3

Reviewer: kbarton, jdoerfert, Meinersbur, dmgreen, fhahn, hfinkel,
bmahjour, etiotto
Reviewed By: kbarton, Meinersbur
Subscribers: hiraditya, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D71165

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[NFC][LoopFusion] Use isControlFlowEquivalent() from CodeMoverUtils.
Reviewer: kbarton, jdoerfert, Meinersbur, bmahjour, etiotto
Reviewed By: Meinersbur
Subscribers: hiraditya, llvm-commits
Tag: LLVM

[NFC][LoopFusion] Use isControlFlowEquivalent() from CodeMoverUtils.
Reviewer: kbarton, jdoerfert, Meinersbur, bmahjour, etiotto
Reviewed By: Meinersbur
Subscribers: hiraditya, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D70619

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[CodeMoverUtils] Added an API to check if an instruction can be safely
moved before another instruction.
Summary:Added an API to check if an instruction can be safely moved
before another instruction

[CodeMoverUtils] Added an API to check if an instruction can be safely
moved before another instruction.
Summary:Added an API to check if an instruction can be safely moved
before another instruction. In future PRs, we will like to add support
of moving instructions between blocks that are not control flow
equivalent, and add other APIs to enhance usability, e.g. moving basic
blocks, moving list of instructions...
Loop Fusion will be its first user. When there is intervening code in
between two loops, fusion is currently unable to fuse them. Loop Fusion
can use this utility to check if the intervening code can be safely
moved before or after the two loops, and move them, then it can
successfully fuse them.
Reviewer:kbarton,jdoerfert,Meinersbur,bmahjour,etiotto
Reviewed By:bmahjour
Subscribers:mgorny,hiraditya,llvm-commits
Tag:LLVM
Differential Revision:https://reviews.llvm.org/D70049

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