[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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[RemoveDIs] Fix asan-identified leak in unittest (#106723)

Fixes issue found here
https://github.com/llvm/llvm-project/pull/106691#issuecomment-2320960847

The issue wasn't in the code change its

[RemoveDIs] Fix asan-identified leak in unittest (#106723)

Fixes issue found here
https://github.com/llvm/llvm-project/pull/106691#issuecomment-2320960847

The issue wasn't in the code change itself, just the unittest; the
trailing marker wasn't properly cleaned up.

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[RemoveDIs] Fix spliceDebugInfo splice-to-end edge case (#105671)

Fix #105571 which demonstrates an end() iterator dereference when
performing a non-empty splice to end() from a region that ends at

[RemoveDIs] Fix spliceDebugInfo splice-to-end edge case (#105671)

Fix #105571 which demonstrates an end() iterator dereference when
performing a non-empty splice to end() from a region that ends at
Src::end().

Rather than calling Instruction::adoptDbgRecords from Dest, create a marker
(which takes an iterator) and absorbDebugValues onto that. The "absorb" variant
doesn't clean up the source marker, which in this case we know is a trailing
marker, so we have to do that manually.

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[RemoveDIs] Simplify spliceDebugInfo, fixing splice-to-end edge case (#105670)

Not quite NFC, fixes splitBasicBlockBefore case when we split before an
instruction with debug records (but without th

[RemoveDIs] Simplify spliceDebugInfo, fixing splice-to-end edge case (#105670)

Not quite NFC, fixes splitBasicBlockBefore case when we split before an
instruction with debug records (but without the headBit set, i.e., we are
splitting before the instruction but after the debug records that come before
it). splitBasicBlockBefore splices the instructions before the split point into
a new block. Prior to this patch, the debug records would get shifted up to the
front of the spliced instructions (as seen in the modified unittest - I believe
the unittest was checking erroneous behaviour). We instead want to leave those
debug records at the end of the spliced instructions.

The functionality of the deleted `else if` branch is covered by the remaining
`if` now that `DestMarker` is set to the trailing marker if `Dest` is `end()`.
Previously the "===" markers were sometimes detached, now we always detach
them and always reattach them.

Note: `deleteTrailingDbgRecords` only "unlinks" the tailing marker from the
block, it doesn't delete anything. The trailing marker is still cleaned up
properly inside the final `if` body with `DestMarker->eraseFromParent();`.

Part 1 of 2 needed for #105571

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Reapply#4 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Reapplies commit c5aeca73 (and its followup commit 21396be8), which were
reverted due to missing functionality in

Reapply#4 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Reapplies commit c5aeca73 (and its followup commit 21396be8), which were
reverted due to missing functionality in MLIR and Flang regarding printing
debug records. This has now been added in commit 08aa511, along with support
for printing debug records in flang.

This reverts commit 2dc2290860355dd2bac3b655eea895fe30fde257.

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Revert new debug info format commits:

"[Flang] Update test to not check for tail calls on debug intrinsics" &
"Reapply#3 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Re

Revert new debug info format commits:

"[Flang] Update test to not check for tail calls on debug intrinsics" &
"Reapply#3 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Recent updates to flang have added debug info generation via MLIR, a path
which currently does not support debug records. The patch that enables
debug records by default (and a small followup patch) are thus being
reverted until the MLIR path has been fixed.

This reverts commits:
21396be865b4640abf6afa0b05de6708a1a996e0
c5aeca732d1ff6769b0659efebd1cfb5f60487e4

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Reapply#3 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Reapplies commit 91446e2, which was reverted due to a downstream error,
discussed on the pull request. The error c

Reapply#3 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Reapplies commit 91446e2, which was reverted due to a downstream error,
discussed on the pull request. The error could not be reproduced
upstream, and cannot be reproduced downstream as-of current main, so
until the error can be confirmed to still exist this patch should
return.

This reverts commit 23f8fac745bdde70ed4f9c585d19c4913734f1b8.

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Revert "Repply#2 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)""

This reverts commit 91446e2aa687ec57ad88dc0df793d0c6e694a7c9 and
a unittest followup 1530f319311908b06fe93

Revert "Repply#2 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)""

This reverts commit 91446e2aa687ec57ad88dc0df793d0c6e694a7c9 and
a unittest followup 1530f319311908b06fe935c89fca692d3e53184f (#90476).

In a stage-2 -flto=thin -gsplit-dwarf -g -fdebug-info-for-profiling
-fprofile-sample-use= build of clang, a ThinLTO backend compile has
assertion failures:

Global is external, but doesn't have external or weak linkage!
ptr @_ZN5clang12ast_matchers8internal18makeAllOfCompositeINS_8QualTypeEEENS1_15BindableMatcherIT_EEN4llvm8ArrayRefIPKNS1_7MatcherIS5_EEEE
function declaration may only have a unique !dbg attachment
ptr @_ZN5clang12ast_matchers8internal18makeAllOfCompositeINS_8QualTypeEEENS1_15BindableMatcherIT_EEN4llvm8ArrayRefIPKNS1_7MatcherIS5_EEEE

The failures somehow go away if -fprofile-sample-use= is removed.

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Repply#2 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Reapplies the original commit:
2f01fd99eb8c8ab3db9aba72c4f00e31e9e60a05

The previous application of this patch f

Repply#2 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Reapplies the original commit:
2f01fd99eb8c8ab3db9aba72c4f00e31e9e60a05

The previous application of this patch failed due to some missing
DbgVariableRecord support in clang, which has been added now by commit
8805465e.

This will probably break some downstream tools that don't already handle
debug records. If your downstream code breaks as a result of this
change, the simplest fix is to convert the module in question to the old
debug format before you process it, using
`Module::convertFromNewDbgValues()`. For more information about how to
handle debug records or about what has changed, see the migration
document:
https://llvm.org/docs/RemoveDIsDebugInfo.html

This reverts commit 4fd319ae273ed6c252f2067909c1abd9f6d97efa.

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Revert#2 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Reverted following probably-causing failures on some clang buildbots:
https://lab.llvm.org/buildbot/#/builders/24

Revert#2 "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Reverted following probably-causing failures on some clang buildbots:
https://lab.llvm.org/buildbot/#/builders/245/builds/24037

This reverts commit a12622543de15df45fb9ad64e8ab723289d55169.

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Reapply "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Fixes the broken tests in the original commit:
2f01fd99eb8c8ab3db9aba72c4f00e31e9e60a05

This will probably break

Reapply "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

Fixes the broken tests in the original commit:
2f01fd99eb8c8ab3db9aba72c4f00e31e9e60a05

This will probably break some downstream tools that don't already handle
debug records. If your downstream code breaks as a result of this
change, the simplest fix is to convert the module in question to the old
debug format before you process it, using
`Module::convertFromNewDbgValues()`. For more information about how to
handle debug records or about what has changed, see the migration
document:
https://llvm.org/docs/RemoveDIsDebugInfo.html

This reverts commit 00821fed09969305b0003d3313c44d1e761a7131.

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Revert "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

A unit test was broken by the above commit:
https://lab.llvm.org/buildbot/#/builders/139/builds/64627

This reverts

Revert "[RemoveDIs] Load into new debug info format by default in LLVM (#89799)"

A unit test was broken by the above commit:
https://lab.llvm.org/buildbot/#/builders/139/builds/64627

This reverts commit 2f01fd99eb8c8ab3db9aba72c4f00e31e9e60a05.

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[RemoveDIs] Load into new debug info format by default in LLVM (#89799)

This patch enables parsing and creating modules directly into the new
debug info format. Prior to this patch, all modules wer

[RemoveDIs] Load into new debug info format by default in LLVM (#89799)

This patch enables parsing and creating modules directly into the new
debug info format. Prior to this patch, all modules were constructed
with the old debug info format by default, and would be converted into
the new format just before running LLVM passes. This is an important
milestone, in that this means that every tool will now be exposed to
debug records, rather than those that run LLVM passes. As far as I've
tested, all LLVM tools/projects now either handle debug records, or
convert them to the old intrinsic format.

There are a few unit tests that need updating for this patch; these are
either cases of tests that previously needed to set the debug info
format to function, or tests that depend on the old debug info format in
some way. There should be no visible change in the output of any LLVM
tool as a result of this patch, although the likelihood of this patch
breaking downstream code means an NFC tag might be a little misleading,
if not technically incorrect:

This will probably break some downstream tools that don't already handle
debug records. If your downstream code breaks as a result of this
change, the simplest fix is to convert the module in question to the old
debug format before you process it, using
`Module::convertFromNewDbgValues()`. For more information about how to
handle debug records or about what has changed, see the migration
document:
https://llvm.org/docs/RemoveDIsDebugInfo.html

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[RemoveDIs] Fix SIGSEGV caused by splitBasicBlock (#90312)

See `llvm/unittests/IR/BasicBlockDbgInfoTest.cpp` for a test case.

[RemoveDIs][NFC] Rename DPMarker->DbgMarker (#85931)

Another trivial rename patch, the last big one for now, which renamed
DPMarkers to DbgMarkers. This required the field `DbgMarker` in
`Instruct

[RemoveDIs][NFC] Rename DPMarker->DbgMarker (#85931)

Another trivial rename patch, the last big one for now, which renamed
DPMarkers to DbgMarkers. This required the field `DbgMarker` in
`Instruction` to be renamed to `DebugMarker` to avoid a clash, but
otherwise was a simple string substitution of `s/DPMarker/DbgMarker` and
a manual renaming of `DPM` to `DM` in the few places where that acronym
was used for debug markers.

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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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[RemoveDI][NFC] Rename DPValue->DbgRecord in comments and varnames (#84939)

This patch continues the ongoing rename work, replacing DPValue with
DbgRecord in comments and the names of variables, bo

[RemoveDI][NFC] Rename DPValue->DbgRecord in comments and varnames (#84939)

This patch continues the ongoing rename work, replacing DPValue with
DbgRecord in comments and the names of variables, both members and
fn-local. This is the most labour-intensive part of the rename, as it is
where the most decisions have to be made about whether a given comment
or variable is referring to DPValues (equivalent to debug variable
intrinsics) or DbgRecords (a catch-all for all debug intrinsics); these
decisions are not individually difficult, but comprise a fairly large
amount of text to review.

This patch still largely performs basic string substitutions followed by
clang-format; there are almost* no places where, for example, a comment
has been expanded or modified to reflect the semantic difference between
DPValues and DbgRecords. I don't believe such a change is generally
necessary in LLVM, but it may be useful in the docs, and so I'll be
submitting docs changes as a separate patch.

*In a few places, `dbg.values` was replaced with `debug intrinsics`.

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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][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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[NFC][RemoveDIs] Remove conditional compilation for RemoveDIs (#81149)

A colleague observes that switching the default value of
LLVM_EXPERIMENTAL_DEBUGINFO_ITERATORS to "On" hasn't flipped the valu

[NFC][RemoveDIs] Remove conditional compilation for RemoveDIs (#81149)

A colleague observes that switching the default value of
LLVM_EXPERIMENTAL_DEBUGINFO_ITERATORS to "On" hasn't flipped the value
in their CMakeCache.txt. This probably means that everyone with an
existing build tree is going to not have support built in, meaning
everyone in LLVM would need to clean+rebuild their worktree when we flip
the switch on... which doesn't sound good.

So instead, just delete the flag and everything it does, making everyone
build and run ~400 lit tests in RemoveDIs mode. None of the buildbots
have had trouble with this, so it Should Be Fine (TM).

(Sending for review as this is changing various comments, and touches
several different areas -- I don't want to get too punchy).

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[DebugInfo][RemoveDIs] Final omnibus test fixing for RemoveDIs (#81125)

With this, I get a clean test suite running under RemoveDIs, the
non-intrinsic representation of debug-info, including under

[DebugInfo][RemoveDIs] Final omnibus test fixing for RemoveDIs (#81125)

With this, I get a clean test suite running under RemoveDIs, the
non-intrinsic representation of debug-info, including under asan. We've
previously established that we generate identical binaries for some
large projects, so this i just edge-case cleanup. The changes:
* CodeGenPrepare fixups need to apply to dbg.assigns as well as
dbg.values (a dbg.assign is a dbg.value).
* Pin a test for constant-deletion to intrinsic debug-info: this very
rare scenario uses a different kill-location sigil in dbg.value mode to
RemoveDIs mode, which generates spurious test differences.
* Suppress a memory leak in a unit test: the code for dealing with
trailing debug-info in a block is necessarily fiddly, leading to this
leak when testing it. Developer-facing interfaces for moving
instructions around always deal with this behind the scenes.
* SROA, when replacing some vector-loads, needs to insert the
replacement loads ahead of any debug-info records so that their values
remain dominated by a definition. Set the head-bit indicating our
insertion should come before debug-info.

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[DebugInfo][RemoveDIs] Don't allocate one DPMarker per instruction (#79345)

This is an optimisation patch that shouldn't have any functional effect.
There's no need for all instructions to have a DP

[DebugInfo][RemoveDIs] Don't allocate one DPMarker per instruction (#79345)

This is an optimisation patch that shouldn't have any functional effect.
There's no need for all instructions to have a DPMarker attached to them,
because not all instructions have adjacent DPValues (aka dbg.values).

This patch inserts the appropriate conditionals into functions like
BasicBlock::spliceDebugInfo to ensure we don't step on a null pointer when
there isn't a DPMarker allocated. Mostly, this is a case of calling
createMarker occasionally, which will create a marker on an instruction
if there isn't one there already.

Also folded into this is the use of adoptDbgValues, which is a natural
extension: if we have a sequence of instructions and debug records:

%foo = add i32 %0,...
# dbg_value { %foo, ...
# dbg_value { %bar, ...
%baz = add i32 %...
%qux = add i32 %...

and delete, for example, the %baz instruction, then the dbg_value records
would naturally be transferred onto the %qux instruction (they "fall down"
onto it). There's no point in creating and splicing DPMarkers in the case
shown when %qux doesn't have a DPMarker already, we can instead just change
the owner of %baz's DPMarker from %baz to %qux. This also avoids calling
setParent on every DPValue.

Update LoopRotationUtils: it was relying on each instruction having it's
own distinct end(), so that we could express ranges and lack-of-ranges.
That's no longer true though: so switch to storing the range of DPValues on
the next instruction when we want to consider it's range next time around
the loop (see the nearby comment).

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[DebugInfo][RemoveDIs] Final cleanup for enabling non-instr-debuginfo (#74497)

Some final errors have turned up when doing stage2clang builds:
* We can insert before end(), which won't have an atta

[DebugInfo][RemoveDIs] Final cleanup for enabling non-instr-debuginfo (#74497)

Some final errors have turned up when doing stage2clang builds:
* We can insert before end(), which won't have an attached DPMarker,
thus we can have a nullptr DPMarker in Instruction::insertBefore. Add a
null check there.
* We need to use the iterator-returning form of getFirstNonPHI to ensure
we don't insert any PHIs behind debug-info at the start of a block.

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[DebugInfo][RemoveDIs] Cope with instructions moving after themselves (#74113)

We occasionally move instructions to their own positions, which is not
an error, and has no effect on the program. How

[DebugInfo][RemoveDIs] Cope with instructions moving after themselves (#74113)

We occasionally move instructions to their own positions, which is not
an error, and has no effect on the program. However, if dbg.value
intrinsics are present then they can effectively be moved without any
other effect on the program.

This is a problem if we're using non-instruction debug-info: a moveAfter
that appears to be a no-op in RemoveDIs mode can jump in front of
intrinsics in dbg.value mode. Thus: if an instruction is moved to itself
and the head bit is set, force attached debug-info to shift down one
instruction, which replicates the dbg.value behaviour.

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[DebugInfo][RemoveDIs] Handle a debug-info splicing corner case (#73810)

A large amount of complexity when it comes to shuffling DPValue objects
around is pushed into BasicBlock::spliceDebugInfo, an

[DebugInfo][RemoveDIs] Handle a debug-info splicing corner case (#73810)

A large amount of complexity when it comes to shuffling DPValue objects
around is pushed into BasicBlock::spliceDebugInfo, and it gets
comprehensive testing there via the unit tests. It turns out that there's a
corner case though: splicing instructions and debug-info to the end()
iterator requires blocks of DPValues to be concatenated, but the DPValues
don't behave normally as they're dangling at the end of a block. While this
splicing-to-an-empty-block case is rare, and it's even rarer for it to
contain debug-info, it does happen occasionally.

Fix this by wrapping spliceDebugInfo with an outer layer that removes any
dangling DPValues in the destination block -- that way the main splicing
function (renamed to spliceDebugInfoImpl) doesn't need to worry about that
scenario. See the diagram in the added function for more info.

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