[NFC][DebugInfo] Switch more call-sites to using iterator-insertion (#124283)

To finalise the "RemoveDIs" work removing debug intrinsics, we're
updating call sites that insert instructions to use i

[NFC][DebugInfo] Switch more call-sites to using iterator-insertion (#124283)

To finalise the "RemoveDIs" work removing debug intrinsics, we're
updating call sites that insert instructions to use iterators instead.
This set of changes are those where it's not immediately obvious that
just calling getIterator to fetch an iterator is correct, and one or two
places where more than one line needs to change.

Overall the same rule holds though: iterators generated for the start of
a block such as getFirstNonPHIIt need to be passed into insert/move
methods without being unwrapped/rewrapped, everything else can use
getIterator.

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[NFC][DebugInfo] Use iterators for instruction insertion in more places (#124291)

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

[NFC][DebugInfo] Use iterators for instruction insertion in more places (#124291)

As part of the "RemoveDIs" work to eliminate debug intrinsics, we're
replacing methods that use Instruction*'s as positions with iterators.
This patch changes some more complex call-sites, those crossing file
boundaries and where I've had to perform some minor rewrites.

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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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[llvm] Remove redundant control flow statements (NFC) (#115831)

Identified with readability-redundant-control-flow.

[NFC] Reapply 3f37c517f, SmallDenseMap speedups

This time with 100% more building unit tests. Original commit message follows.

[NFC] Switch a number of DenseMaps to SmallDenseMaps for speedup (#109

[NFC] Reapply 3f37c517f, SmallDenseMap speedups

This time with 100% more building unit tests. Original commit message follows.

[NFC] Switch a number of DenseMaps to SmallDenseMaps for speedup (#109417)

If we use SmallDenseMaps instead of DenseMaps at these locations,
we get a substantial speedup because there's less spurious malloc
traffic. Discovered by instrumenting DenseMap with some accounting
code, then selecting sites where we'll get the most bang for our buck.

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Revert "[NFC] Switch a number of DenseMaps to SmallDenseMaps for speedup (#109417)"

This reverts commit 3f37c517fbc40531571f8b9f951a8610b4789cd6.

Lo and behold, I missed a unit test

[NFC] Switch a number of DenseMaps to SmallDenseMaps for speedup (#109417)

If we use SmallDenseMaps instead of DenseMaps at these locations,
we get a substantial speedup because there's less spurio

[NFC] Switch a number of DenseMaps to SmallDenseMaps for speedup (#109417)

If we use SmallDenseMaps instead of DenseMaps at these locations,
we get a substantial speedup because there's less spurious malloc
traffic. Discovered by instrumenting DenseMap with some accounting
code, then selecting sites where we'll get the most bang for our buck.

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[Transforms] Refactor CreateControlFlowHub (#103013)

CreateControlFlowHub is a method that redirects control flow edges from a set of
incoming blocks to a set of outgoing blocks through a new set of

[Transforms] Refactor CreateControlFlowHub (#103013)

CreateControlFlowHub is a method that redirects control flow edges from a set of
incoming blocks to a set of outgoing blocks through a new set of "guard" blocks.
This is now refactored into a separate file with one enhancement: The input to
the method is now a set of branches rather than two sets of blocks.

The original implementation reroutes every edge from incoming blocks to outgoing
blocks. But it is possible that for some incoming block InBB, some successor S
might be in the set of outgoing blocks, but that particular edge should not be
rerouted. The new implementation makes this possible by allowing the user to
specify the targets of each branch that need to be rerouted.

This is needed when improving the implementation of FixIrreducible #101386.
Current use in FixIrreducible does not demonstrate this finer control over the
edges being rerouted. But in UnifyLoopExits, when only one successor of an
exiting block is an exit block, this refinement now reroutes only the relevant
control-flow through the edge; the non-exit successor is not rerouted. This
results in fewer branches and PHI nodes in the hub.

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[UnifyLoopExits] Never generate phis of only `undef` values (#99924)

[IR] Add getDataLayout() helpers to BasicBlock and Instruction (#96902)

This is a helper to avoid writing `getModule()->getDataLayout()`. I
regularly try to use this method only to remember it does

[IR] Add getDataLayout() helpers to BasicBlock and Instruction (#96902)

This is a helper to avoid writing `getModule()->getDataLayout()`. I
regularly try to use this method only to remember it doesn't exist...

`getModule()->getDataLayout()` is also a common (the most common?)
reason why code has to include the Module.h header.

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NFC: Add a comment indicating UpdateAnalysisInformation invalidates DFS Numbering (#91252)

Revert "[BasicBlockUtils] Remove redundant llvm.dbg instructions after blocks to reduce compile time (#89069)"

This reverts commit 2e3e0868748635b779ba89a772eae3664bd822e4. It caused
quadratic slowd

Revert "[BasicBlockUtils] Remove redundant llvm.dbg instructions after blocks to reduce compile time (#89069)"

This reverts commit 2e3e0868748635b779ba89a772eae3664bd822e4. It caused
quadratic slowdown at compilation time in some cases. See the comments
in the original PR: https://github.com/llvm/llvm-project/pull/89069

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[Transforms] Use LLVMContext::MD_loop (NFC)

[BasicBlockUtils] Remove redundant llvm.dbg instructions after blocks to reduce compile time (#89069)

this patch is to fix the compile time for some cases, before this
change, some targets (riscv-6

[BasicBlockUtils] Remove redundant llvm.dbg instructions after blocks to reduce compile time (#89069)

this patch is to fix the compile time for some cases, before this
change, some targets (riscv-64, ve) will spend much more compile time on
this case (https://godbolt.org/z/rrov17cTo). With this change, the
compile time was reduced a lot.

Fixes https://github.com/llvm/llvm-project/issues/89073

PR: https://github.com/llvm/llvm-project/pull/89069

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Fix warnings discovered by #87348 [-Wunused-but-set-variable]

[RemoveDIs][NFC] Rename DPLabel->DbgLabelRecord (#85918)

This patch renames DPLabel to DbgLabelRecord, in accordance with the
ongoing DbgRecord rename. This rename was fairly trivial, since DPLabel

[RemoveDIs][NFC] Rename DPLabel->DbgLabelRecord (#85918)

This patch renames DPLabel to DbgLabelRecord, in accordance with the
ongoing DbgRecord rename. This rename was fairly trivial, since DPLabel
isn't as widely used as DPValue and has no real conflicts in either its
full or abbreviated name. As usual, the entire replacement was done
automatically, with `s/DPLabel/DbgLabelRecord/` and `s/DPL/DLR/`.

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[RemoveDIs][NFC] Rename DPValue -> DbgVariableRecord (#85216)

This is the major rename patch that prior patches have built towards.
The DPValue class is being renamed to DbgVariableRecord, which re

[RemoveDIs][NFC] Rename DPValue -> DbgVariableRecord (#85216)

This is the major rename patch that prior patches have built towards.
The DPValue class is being renamed to DbgVariableRecord, which reflects
the updated terminology for the "final" implementation of the RemoveDI
feature. This is a pure string substitution + clang-format patch. The
only manual component of this patch was determining where to perform
these string substitutions: `DPValue` and `DPV` are almost exclusively
used for DbgRecords, *except* for:

- llvm/lib/target, where 'DP' is used to mean double-precision, and so
appears as part of .td files and in variable names. NB: There is a
single existing use of `DPValue` here that refers to debug info, which
I've manually updated.
- llvm/tools/gold, where 'LDPV' is used as a prefix for symbol
visibility enums.

Outside of these places, I've applied several basic string
substitutions, with the intent that they only affect DbgRecord-related
identifiers; I've checked them as I went through to verify this, with
reasonable confidence that there are no unintended changes that slipped
through the cracks. The substitutions applied are all case-sensitive,
and are applied in the order shown:

```
DPValue -> DbgVariableRecord
DPVal -> DbgVarRec
DPV -> DVR
```

Following the previous rename patches, it should be the case that there
are no instances of any of these strings that are meant to refer to the
general case of DbgRecords, or anything other than the DPValue class.
The idea behind this patch is therefore that pure string substitution is
correct in all cases as long as these assumptions hold.

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[RemoveDIs][NFC] Move DPValue::filter -> filterDbgVars (#85208)

This patch changes DPValue::filter to be a non-member method
filterDbgVars. There are two reasons for this: firstly, the name of
DPV

[RemoveDIs][NFC] Move DPValue::filter -> filterDbgVars (#85208)

This patch changes DPValue::filter to be a non-member method
filterDbgVars. There are two reasons for this: firstly, the name of
DPValue is about to change to DbgVariableRecord, which will result in
every `for` loop that uses DPValue::filter to require a line break. This
is a small thing, but it makes the rename patch more difficult to
review, and is just generally more awkward for what is a fairly common
loop. Secondly, the intent is to later break up the DPValue class into
subclasses, at which point it would be better to have a non-member
function that allows template arguments for the cases we want to filter
with greater specificity.

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[RemoveDIs][NFC] Rename common interface functions for DPValues->DbgRecords (#84793)

As part of the effort to rename the DbgRecord classes, this patch
renames the widely-used functions that operate

[RemoveDIs][NFC] Rename common interface functions for DPValues->DbgRecords (#84793)

As part of the effort to rename the DbgRecord classes, this patch
renames the widely-used functions that operate on DbgRecords but refer
to DbgValues or DPValues in their names to refer to DbgRecords instead;
all such functions are defined in one of `BasicBlock.h`,
`Instruction.h`, and `DebugProgramInstruction.h`.

This patch explicitly does not change the names of any comments or
variables, except for where they use the exact name of one of the
renamed functions. The reason for this is reviewability; this patch can
be trivially examined to determine that the only changes are direct
string substitutions and any results from clang-format responding to the
changed line lengths. Future patches will cover renaming variables and
comments, and then renaming the classes themselves.

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[RemoveDIs] Reapply 3fda50d3915, insert instructions using iterators

I'd reverted this in 6c7805d5d1 after a bad stage. Original commit
messsage follows:

[NFC][RemoveDIs] Bulk update utilities to i

[RemoveDIs] Reapply 3fda50d3915, insert instructions using iterators

I'd reverted this in 6c7805d5d1 after a bad stage. Original commit
messsage follows:

[NFC][RemoveDIs] Bulk update utilities to insert with iterators

As part of the RemoveDIs project we need LLVM to insert instructions using
iterators wherever possible, so that the iterators can carry a bit of
debug-info. This commit implements some of that by updating the contents of
llvm/lib/Transforms/Utils to always use iterator-versions of instruction
constructors.

There are two general flavours of update:
* Almost all call-sites just call getIterator on an instruction
* Several make use of an existing iterator (scenarios where the code is
actually significant for debug-info)
The underlying logic is that any call to getFirstInsertionPt or similar
APIs that identify the start of a block need to have that iterator passed
directly to the insertion function, without being converted to a bare
Instruction pointer along the way.

I've also switched DemotePHIToStack to take an optional iterator: it needs
to take an iterator, and having a no-insert-location behaviour appears to
be important. The constructors for ICmpInst and FCmpInst have been updated
too. They're the only instructions that take block _references_ rather than
pointers for certain calls, and a future patch is going to make use of
default-null block insertion locations.

All of this should be NFC.

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Revert "[NFC][RemoveDIs] Bulk update utilities to insert with iterators"

This reverts commit 3fda50d3915b2163a54a37b602be7783a89dd808.

Apparently I've missed a hunk while staging this; will back ou

Revert "[NFC][RemoveDIs] Bulk update utilities to insert with iterators"

This reverts commit 3fda50d3915b2163a54a37b602be7783a89dd808.

Apparently I've missed a hunk while staging this; will back out for now.

Picked up here: https://lab.llvm.org/buildbot/#/builders/139/builds/60429/steps/6/logs/stdio

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[NFC][RemoveDIs] Bulk update utilities to insert with iterators

As part of the RemoveDIs project we need LLVM to insert instructions using
iterators wherever possible, so that the iterators can carr

[NFC][RemoveDIs] Bulk update utilities to insert with iterators

As part of the RemoveDIs project we need LLVM to insert instructions using
iterators wherever possible, so that the iterators can carry a bit of
debug-info. This commit implements some of that by updating the contents of
llvm/lib/Transforms/Utils to always use iterator-versions of instruction
constructors.

There are two general flavours of update:
* Almost all call-sites just call getIterator on an instruction
* Several make use of an existing iterator (scenarios where the code is
actually significant for debug-info)
The underlying logic is that any call to getFirstInsertionPt or similar
APIs that identify the start of a block need to have that iterator passed
directly to the insertion function, without being converted to a bare
Instruction pointer along the way.

I've also switched DemotePHIToStack to take an optional iterator: it needs
to take an iterator, and having a no-insert-location behaviour appears to
be important. The constructors for ICmpInst and FCmpInst have been updated
too. They're the only instructions that take block _references_ rather than
pointers for certain calls, and a future patch is going to make use of
default-null block insertion locations.

All of this should be NFC.

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[RemoveDIs] Add DPLabels support [3a/3] (#82633)

Patch 2 of 3 to add llvm.dbg.label support to the RemoveDIs project. The
patch stack adds the DPLabel class, which is the RemoveDIs llvm.dbg.label

[RemoveDIs] Add DPLabels support [3a/3] (#82633)

Patch 2 of 3 to add llvm.dbg.label support to the RemoveDIs project. The
patch stack adds the DPLabel class, which is the RemoveDIs llvm.dbg.label
equivalent.

1. Add DbgRecord base class for DPValue and the not-yet-added
DPLabel class.
2. Add the DPLabel class.
-> 3. Add support to passes.

The next patch, #82639, will enable conversion between dbg.labels and DPLabels.

AssignemntTrackingAnalysis support could have gone two ways:

1. Have the analysis store a DPLabel representation in its results -
SelectionDAGBuilder reads the analysis results and ignores all DbgRecord
kinds.
2. Ignore DPLabels in the analysis - SelectionDAGBuilder reads the analysis
results but still needs to iterate over DPLabels from the IR.

I went with option 2 because it's less work and is no less correct than 1. It's
worth noting that causes labels to sink to the bottom of packs of debug records.
e.g., [value, label, value] becomes [value, value, label]. This shouldn't be a
problem because labels and variable locations don't have an ordering requirement.
The ordering between variable locations is maintained and the label movement is
deterministic

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[RemoveDIs][NFC] Introduce DbgRecord base class [1/3] (#78252)

Patch 1 of 3 to add llvm.dbg.label support to the RemoveDIs project. The
patch stack adds a new base class

-> 1. Add DbgRecord

[RemoveDIs][NFC] Introduce DbgRecord base class [1/3] (#78252)

Patch 1 of 3 to add llvm.dbg.label support to the RemoveDIs project. The
patch stack adds a new base class

-> 1. Add DbgRecord base class for DPValue and the not-yet-added
DPLabel class.
2. Add the DPLabel class.
3. Enable dbg.label conversion and add support to passes.

Patches 1 and 2 are NFC.

In the near future we also will rename DPValue to DbgVariableRecord and
DPLabel to DbgLabelRecord, at which point we'll overhaul the function
names too. The name DPLabel keeps things consistent for now.

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[RemoveDIs][DebugInfo] Remove redundant DPVAssigns (#78574)

DPValues are already supported by most of the utilities that remove
redundant debug info after certain passes; the exception to this is

[RemoveDIs][DebugInfo] Remove redundant DPVAssigns (#78574)

DPValues are already supported by most of the utilities that remove
redundant debug info after certain passes; the exception to this is
`removeUndefDbgAssignsFromEntryBlock`, which applies only to
llvm.dbg.assigns which were previously unimplemented for DPValues. Now
that DPVAssigns exist, we have to support removing redundant instances
in the same way, which this patch implements.

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