[DebugInfo][NFC] Rename is/setUndef to is/setKilllocation

These names better reflect the semantics and also the implementation, since
it's not just "undef" operands that are sentinels used to signal

[DebugInfo][NFC] Rename is/setUndef to is/setKilllocation

These names better reflect the semantics and also the implementation, since
it's not just "undef" operands that are sentinels used to signal that the debug
intrinsic terminates dominating locations definitions.

Related to https://discourse.llvm.org/t/auto-undef-debug-uses-of-a-deleted-value

Reviewed By: StephenTozer

Differential Revision: https://reviews.llvm.org/D140903

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[NFC] Rename Instruction::insertAt() to Instruction::insertInto(), to be consistent with BasicBlock::insertInto()

Differential Revision: https://reviews.llvm.org/D140085

[NFC] Remove the instruction list from the arguments of llvm::ReplaceInstWithValue().

This is part of a series of cleanup patches towards making BasicBlock::getInstList() private.

Differential Revi

[NFC] Remove the instruction list from the arguments of llvm::ReplaceInstWithValue().

This is part of a series of cleanup patches towards making BasicBlock::getInstList() private.

Differential Revision: https://reviews.llvm.org/D139153

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[NFC] Cleanup: Replaces BB->getInstList().insert() with I->insertAt().

This is part of a series of cleanup patches towards making BasicBlock::getInstList() private.

Differential Revision: https://r

[NFC] Cleanup: Replaces BB->getInstList().insert() with I->insertAt().

This is part of a series of cleanup patches towards making BasicBlock::getInstList() private.

Differential Revision: https://reviews.llvm.org/D138877

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

[SROA] For non-speculatable `load`s of `select`s -- split block, insert then/else blocks, form two-entry PHI node, take 2

Currently, SROA is CFG-preserving.
Not doing so does not affect any pipeline

[SROA] For non-speculatable `load`s of `select`s -- split block, insert then/else blocks, form two-entry PHI node, take 2

Currently, SROA is CFG-preserving.
Not doing so does not affect any pipeline test. (???)
Internally, SROA requires Dominator Tree, and uses it solely for the final `-mem2reg` call.

By design, we can't really SROA alloca if their address escapes somehow,
but we have logic to deal with `load` of `select`/`PHI`,
where at least one of the possible addresses prevents promotion,
by speculating the `load`s and `select`ing between loaded values.

As one would expect, that requires ensuring that the speculation is actually legal.
Even ignoring complexity bailouts, that logic does not deal with everything,
e.g. `isSafeToLoadUnconditionally()` does not recurse into hands of `select`.
There can also be cases where the load is genuinely non-speculate.

So if we can't prove that the load can be speculated,
unfold the select, produce two-entry phi node, and perform predicated load.

Now, that transformation must obviously update Dominator Tree,
since we require it later on. Doing so is trivial.
Additionally, we don't want to do this for the final SROA invocation (D136806).

In the end, this ends up having negative (!) compile-time cost:
https://llvm-compile-time-tracker.com/compare.php?from=c6d7e80ec4c17a415673b1cfd25924f98ac83608&to=ddf9600365093ea50d7e278696cbfa01641c959d&stat=instructions:u

Though indeed, this only deals with `select`s, `PHI`s are still using speculation.

Should we update some more analysis?

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D138238

This reverts commit 739611870d3b06605afe25cc07833f6a62de9545,
and recommits 03e6d9d9d1d48e43f3efc35eb75369b90d4510d5
with a fixed assertion - we should check that DTU is there,
not just assert false...

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Revert "[SROA] For non-speculatable `load`s of `select`s -- split block, insert then/else blocks, form two-entry PHI node"

The assertion about not modifying the CFG seems to not hold,
will recommit

Revert "[SROA] For non-speculatable `load`s of `select`s -- split block, insert then/else blocks, form two-entry PHI node"

The assertion about not modifying the CFG seems to not hold,
will recommit in a bit.

https://lab.llvm.org/buildbot#builders/139/builds/32412

This reverts commit 03e6d9d9d1d48e43f3efc35eb75369b90d4510d5.
This reverts commit 4f90f4ada33718f9025d0870a4fe3fe88276b3da.

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[SROA] For non-speculatable `load`s of `select`s -- split block, insert then/else blocks, form two-entry PHI node

Currently, SROA is CFG-preserving.
Not doing so does not affect any pipeline test. (

[SROA] For non-speculatable `load`s of `select`s -- split block, insert then/else blocks, form two-entry PHI node

Currently, SROA is CFG-preserving.
Not doing so does not affect any pipeline test. (???)
Internally, SROA requires Dominator Tree, and uses it solely for the final `-mem2reg` call.

By design, we can't really SROA alloca if their address escapes somehow,
but we have logic to deal with `load` of `select`/`PHI`,
where at least one of the possible addresses prevents promotion,
by speculating the `load`s and `select`ing between loaded values.

As one would expect, that requires ensuring that the speculation is actually legal.
Even ignoring complexity bailouts, that logic does not deal with everything,
e.g. `isSafeToLoadUnconditionally()` does not recurse into hands of `select`.
There can also be cases where the load is genuinely non-speculate.

So if we can't prove that the load can be speculated,
unfold the select, produce two-entry phi node, and perform predicated load.

Now, that transformation must obviously update Dominator Tree,
since we require it later on. Doing so is trivial.
Additionally, we don't want to do this for the final SROA invocation (D136806).

In the end, this ends up having negative (!) compile-time cost:
https://llvm-compile-time-tracker.com/compare.php?from=c6d7e80ec4c17a415673b1cfd25924f98ac83608&to=ddf9600365093ea50d7e278696cbfa01641c959d&stat=instructions:u

Though indeed, this only deals with `select`s, `PHI`s are still using speculation.

Should we update some more analysis?

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D138238

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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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[NFC] Cleanup: Replaces BB->getInstList().splice() with BB->splice().

This is part of a series of cleanup patches towards making BasicBlock::getInstList() private.

Differential Revision: https://re

[NFC] Cleanup: Replaces BB->getInstList().splice() with BB->splice().

This is part of a series of cleanup patches towards making BasicBlock::getInstList() private.

Differential Revision: https://reviews.llvm.org/D138979

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[NFC] Replaced BB->getInstList().{erase(),pop_front(),pop_back()} with eraseFromParent().

Differential Revision: https://reviews.llvm.org/D138617

[NFC] Use BB->size() instead of BB->getInstList().size().

Differential Revision: https://reviews.llvm.org/D138616

Use None consistently (NFC)

This patch replaces NoneType() and NoneType::None with None in
preparation for migration from llvm::Optional to std::optional.

In the std::optional world, we are not gur

Use None consistently (NFC)

This patch replaces NoneType() and NoneType::None with None in
preparation for migration from llvm::Optional to std::optional.

In the std::optional world, we are not guranteed to be able to
default-construct std::nullopt_t or peek what's inside it, so neither
NoneType() nor NoneType::None has a corresponding expression in the
std::optional world.

Once we consistently use None, we should even be able to replace the
contents of llvm/include/llvm/ADT/None.h with something like:

using NoneType = std::nullopt_t;
inline constexpr std::nullopt_t None = std::nullopt;

to ease the migration from llvm::Optional to std::optional.

Differential Revision: https://reviews.llvm.org/D138376

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[Assignment Tracking][11/*] Update RemoveRedundantDbgInstrs

The Assignment Tracking debug-info feature is outlined in this RFC:

https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of

[Assignment Tracking][11/*] Update RemoveRedundantDbgInstrs

The Assignment Tracking debug-info feature is outlined in this RFC:

https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir

Update the RemoveRedundantDbgInstrs utility to avoid sometimes losing
information when deleting dbg.assign intrinsics.

removeRedundantDbgInstrsUsingBackwardScan - treat dbg.assign intrinsics that
are not linked to any instruction just like dbg.values. That is, in a block of
contiguous debug intrinsics, delete all other than the last definition for a
fragment. Leave linked dbg.assign intrinsics in place.

removeRedundantDbgInstrsUsingForwardScan - Don't delete linked dbg.assign
intrinsics and don't delete the next intrinsic found even if it would otherwise
be eligible for deletion.

remomveUndefDbgAssignsFromEntryBlock - Delete undef and unlinked dbg.assign
intrinsics encountered in the entry block that come before non-undef
non-unlinked intrinsics for the same variable.

Reviewed By: jmorse

Differential Revision: https://reviews.llvm.org/D133294

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[BasicBlockUtils] Add a new way for CreateControlFlowHub()

The existing way of creating the predicate in the guard blocks uses
a boolean value per outgoing block. This increases the number of live
b

[BasicBlockUtils] Add a new way for CreateControlFlowHub()

The existing way of creating the predicate in the guard blocks uses
a boolean value per outgoing block. This increases the number of live
booleans as the number of outgoing blocks increases. The new way added
in this change is to store one integer to represent the outgoing block
we want to branch to, then at each guard block, an integer equality
check is performed to decide which a specific outgoing block is taken.

Using an integer reduces the number of live values and decreases
register pressure especially in cases where there are a large number
of outgoing blocks. The integer based approach is used when the
number of outgoing blocks crosses a threshold, which is currently set
to 32.

Patch by Ruiling Song.

Differential review: https://reviews.llvm.org/D127831

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NFC: restructure code for CreateControlFlowHub()

Differential review: https://reviews.llvm.org/D127830

Use PoisonValue instead of UndefValue when RAUWing unreachable code [NFC]

Replacing the following instances of UndefValue with PoisonValue, where the UndefValue is used as an arbitrary value:

- llv

Use PoisonValue instead of UndefValue when RAUWing unreachable code [NFC]

Replacing the following instances of UndefValue with PoisonValue, where the UndefValue is used as an arbitrary value:

- llvm/lib/CodeGen/WinEHPrepare.cpp
`demotePHIsOnFunclets`: RAUW arbitrary value for lingering uses of removed PHI nodes

- llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
`FoldSingleEntryPHINodes`: Removes a self-referential single entry phi node.

- llvm/lib/Transforms/Utils/CallGraphUpdater.cpp
`finalize`: Remove all references to removed functions.

- llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
`cleanup`: the result is not used then the inserted instructions are removed.

- llvm/tools/bugpoint/CrashDebugger.cpp
`TestInts`: the program is cloned and instructions are removed to narrow down source of crash.

Differential Revision: https://reviews.llvm.org/D133640

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[llvm] Use range-based for loops (NFC)

Identified with modernize-loop-convert.

[llvm] Qualify auto (NFC)

Identified with readability-qualified-auto.

[NFC] Switch a few uses of undef to poison as placeholders for unreachable code

[BasicBlockUtils] Don't drop callbr with unique successor

As callbr is now allowed to have duplicate destinations, we can
have a callbr with a unique successor. Make sure it doesn't get
dropped, as

[BasicBlockUtils] Don't drop callbr with unique successor

As callbr is now allowed to have duplicate destinations, we can
have a callbr with a unique successor. Make sure it doesn't get
dropped, as we still need to preserve the side-effect.

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[BasicBlockUtils] Allow critical edge splitting with callbr terminators

After D129205, we support SplitBlockPredecessors() for predecessors
with callbr terminators. This means that it is now also sa

[BasicBlockUtils] Allow critical edge splitting with callbr terminators

After D129205, we support SplitBlockPredecessors() for predecessors
with callbr terminators. This means that it is now also safe to
invoke critical edge splitting for an edge coming from a callbr
terminator. Remove checks in various passes that were protecting
against that.

Differential Revision: https://reviews.llvm.org/D129256

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[BasicBlockUtils] Allow splitting predecessors with callbr terminators

SplitBlockPredecessors currently asserts if one of the predecessor
terminators is a callbr. This limitation was originally nece

[BasicBlockUtils] Allow splitting predecessors with callbr terminators

SplitBlockPredecessors currently asserts if one of the predecessor
terminators is a callbr. This limitation was originally necessary,
because just like with indirectbr, it was not possible to replace
successors of a callbr. However, this is no longer the case since
D67252. As the requirement nowadays is that callbr must reference
all blockaddrs directly in the call arguments, and these get
automatically updated when setSuccessor() is called, we no longer
need this limitation.

The only thing we need to do here is use replaceSuccessorWith()
instead of replaceUsesOfWith(), because only the former does the
necessary blockaddr updating magic.

I believe there's other similar limitations that can be removed,
e.g. related to critical edge splitting.

Differential Revision: https://reviews.llvm.org/D129205

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[BasicBlockUtils] Do not move loop metadata if outer loop header.

Fixes a bug preventing moving the loop's metadata to an outer loop's header,
which happens if the loop's exit is also the header of

[BasicBlockUtils] Do not move loop metadata if outer loop header.

Fixes a bug preventing moving the loop's metadata to an outer loop's header,
which happens if the loop's exit is also the header of an outer loop.

Adjusts test for above.

Fixes #55416.

Differential Revision: https://reviews.llvm.org/D125574

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Cleanup includes: TransformsUtils

Estimation on the impact on preprocessor output:
before: 1065307662
after: 1064800684

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-

Cleanup includes: TransformsUtils

Estimation on the impact on preprocessor output:
before: 1065307662
after: 1064800684

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D120741

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