[IR] Convert from nocapture to captures(none) (#123181)

This PR removes the old `nocapture` attribute, replacing it with the new
`captures` attribute introduced in #116990. This change is
intended

[IR] Convert from nocapture to captures(none) (#123181)

This PR removes the old `nocapture` attribute, replacing it with the new
`captures` attribute introduced in #116990. This change is
intended to be essentially NFC, replacing existing uses of `nocapture`
with `captures(none)` without adding any new analysis capabilities.
Making use of non-`none` values is left for a followup.

Some notes:
* `nocapture` will be upgraded to `captures(none)` by the bitcode
reader.
* `nocapture` will also be upgraded by the textual IR reader. This is to
make it easier to use old IR files and somewhat reduce the test churn in
this PR.
* Helper APIs like `doesNotCapture()` will check for `captures(none)`.
* MLIR import will convert `captures(none)` into an `llvm.nocapture`
attribute. The representation in the LLVM IR dialect should be updated
separately.

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[Attributor] Keep track of reached returns in AAPointerInfo (#107479)

Instead of visiting call sites in Attribute::checkForAllUses, we now
keep track of returns in AAPointerInfo and use the call si

[Attributor] Keep track of reached returns in AAPointerInfo (#107479)

Instead of visiting call sites in Attribute::checkForAllUses, we now
keep track of returns in AAPointerInfo and use the call site return
information as required. This way, the user of
AAPointerInfo(CallSite)Argument can determine if the call return should
be visited. We do not collect them as "may accesses" in the
AAPointerInfo(CallSite)Argument itself in case a return user is found.

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[Attributor][NFC] update tests (#91011)

[Attributor] New attribute to identify what byte ranges are alive for an allocation (#66148)

Changes the size of allocations automatically.
For now, implements the case when a single range from sta

[Attributor] New attribute to identify what byte ranges are alive for an allocation (#66148)

Changes the size of allocations automatically.
For now, implements the case when a single range from start of the
allocation is alive and the allocation can be reduced.

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[Attributor] Port AANoCapture to the isImpliedByIR interface

AANoCapture is now the first non-boolean AA that is always queried via
the new APIs and not created manually.

We explicitly do not manif

[Attributor] Port AANoCapture to the isImpliedByIR interface

AANoCapture is now the first non-boolean AA that is always queried via
the new APIs and not created manually.

We explicitly do not manifest nocapture for `null` and `undef` anymore.

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[Attributor] Port AANoAlias to the isImpliedByIR interface

As part of this we do not annotate literal `null` and `undef/poison` as
`noalias` anymore. This was not really needed anyway.

[Attributor] Introduce helpers to judge AAs prior to creation

This is a partial cleanup to centralize the initialization and update
decisions for AAs. Lifting the burdon and boilerplate on users and

[Attributor] Introduce helpers to judge AAs prior to creation

This is a partial cleanup to centralize the initialization and update
decisions for AAs. Lifting the burdon and boilerplate on users and
making it harder to accidentally perform unsound deductions.

The two static helpers show how we can lift the decisions to generate an
AA into the Attributor, avoiding trivial AAs that just cost us compile
time and maintenance code (to check for pre-conditions).

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[Attributor] Remove the iteration count verification

It was never really useful to track #iterations, though it helped during
the initial development. What we should track, in a follow up, are
poten

[Attributor] Remove the iteration count verification

It was never really useful to track #iterations, though it helped during
the initial development. What we should track, in a follow up, are
potentially #updates. That is also what we should restrict instead of
the #iterations.

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[Attributor] Create `AAMustProgress` for the `mustprogress` attribute

Derive the mustprogress attribute based on the willreturn attribute
or the fact that all callers are mustprogress.

Differential

[Attributor] Create `AAMustProgress` for the `mustprogress` attribute

Derive the mustprogress attribute based on the willreturn attribute
or the fact that all callers are mustprogress.

Differential Revision: https://reviews.llvm.org/D94740

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[Attributor] Convert some tests to opaque pointers (NFC)

These were converted without adjustments.

[IR] Switch everything to use memory attribute

This switches everything to use the memory attribute proposed in
https://discourse.llvm.org/t/rfc-unify-memory-effect-attributes/65579.
The old argmemo

[IR] Switch everything to use memory attribute

This switches everything to use the memory attribute proposed in
https://discourse.llvm.org/t/rfc-unify-memory-effect-attributes/65579.
The old argmemonly, inaccessiblememonly and inaccessiblemem_or_argmemonly
attributes are dropped. The readnone, readonly and writeonly attributes
are restricted to parameters only.

The old attributes are auto-upgraded both in bitcode and IR.
The bitcode upgrade is a policy requirement that has to be retained
indefinitely. The IR upgrade is mainly there so it's not necessary
to update all tests using memory attributes in this patch, which
is already large enough. We could drop that part after migrating
tests, or retain it longer term, to make it easier to import IR
from older LLVM versions.

High-level Function/CallBase APIs like doesNotAccessMemory() or
setDoesNotAccessMemory() are mapped transparently to the memory
attribute. Code that directly manipulates attributes (e.g. via
AttributeList) on the other hand needs to switch to working with
the memory attribute instead.

Differential Revision: https://reviews.llvm.org/D135780

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[Attribute] Clean up test prefixes (NFC)

Now that the legacy PM is no longer tested, the huge matrix of
test prefixes used by attributor tests is no longer needed and very
confusing for the casual r

[Attribute] Clean up test prefixes (NFC)

Now that the legacy PM is no longer tested, the huge matrix of
test prefixes used by attributor tests is no longer needed and very
confusing for the casual reader. Reduce the prefixes down to just
CHECK, TUNIT and CGSCC.

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[NFC][1/n] Remove -enable-new-pm=0 flags from lit tests

This is the first patch in a series intended for removing flag
-enable-new-pm=0 from lit tests. This is part of a bigger
effort of completely

[NFC][1/n] Remove -enable-new-pm=0 flags from lit tests

This is the first patch in a series intended for removing flag
-enable-new-pm=0 from lit tests. This is part of a bigger
effort of completely removing legacy code related to legacy
pass manager in favor of currently default new pass manager.

In this patch flag has been removed only from tests where no significant
change has been required because checks has been duplicated for
both PMs.

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D134150

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[Attributor] CGSCC pass should not recompute results outside the SCC (reapply)

When we run the CGSCC pass we should only invest time on the SCC. We can
initialize AAs with information from the modul

[Attributor] CGSCC pass should not recompute results outside the SCC (reapply)

When we run the CGSCC pass we should only invest time on the SCC. We can
initialize AAs with information from the module slice but we should not
update those AAs. We make an exception for are call site of the SCC as
they are helpful providing information for the SCC.

Minor modifications to pointer privatization allow us to perform it even
in the CGSCC pass, similar to ArgumentPromotion.

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Revert "[Attributor] CGSCC pass should not recompute results outside the SCC"

This reverts commit 0d7f81e31315f8cda56ce6fde5ff5145e0325c51, it caused
the AMDGPU tests that use the Attributor to fail.

[Attributor] CGSCC pass should not recompute results outside the SCC

When we run the CGSCC pass we should only invest time on the SCC. We can
initialize AAs with information from the module slice bu

[Attributor] CGSCC pass should not recompute results outside the SCC

When we run the CGSCC pass we should only invest time on the SCC. We can
initialize AAs with information from the module slice but we should not
update those AAs.

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[Attributor] Cleanup manifest and liveness for CGSCC passes

There was some ad-hoc handling of liveness and manifest to avoid
breaking CGSCC guarantees. Things always slipped through though.
This cle

[Attributor] Cleanup manifest and liveness for CGSCC passes

There was some ad-hoc handling of liveness and manifest to avoid
breaking CGSCC guarantees. Things always slipped through though.
This cleanup will:

1) Prevent us from manifesting any "information" outside the CGSCC.
This might be too conservative but we need to opt-in to annotation
not try to avoid some problematic ones.
2) Avoid running any liveness analysis outside the CGSCC. We did have
some AAIsDeadFunction handling to this end but we need this for all
AAIsDead classes. The reason is that AAIsDead information is only
correct if we actually manifest it, since we don't (see point 1) we
cannot actually derive/use it at all. We are currently trying to
avoid running any AA updates outside the CGSCC but that seems to
impact things quite a bit.
3) Assert, don't check, that our modifications (during cleanup) modifies
only CGSCC functions.

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[Attributor] Introduce the concept of query AAs

D106720 introduced features that did not work properly as we could add
new queries after a fixpoint was reached and which could not be answered
by the

[Attributor] Introduce the concept of query AAs

D106720 introduced features that did not work properly as we could add
new queries after a fixpoint was reached and which could not be answered
by the information gathered up to the fixpoint alone.

As an alternative to D110078, which forced eager computation where we
want to continue to be lazy, this patch fixes the problem.

QueryAAs are AAs that allow lazy queries during their lifetime. They are
never fixed if they have no outstanding dependences and always run as
part of the updates in an iteration. To determine if we are done, all
query AAs are asked if they received new queries, if not, we only need
to consider updated AAs, as before. If new queries are present we go for
another iteration.

Differential Revision: https://reviews.llvm.org/D118669

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[Attributor] Use AAFunctionReachability to determine AANoRecurse

We missed out on AANoRecurse in the module pass because we had no call
graph. With AAFunctionReachability we can simply ask if the fu

[Attributor] Use AAFunctionReachability to determine AANoRecurse

We missed out on AANoRecurse in the module pass because we had no call
graph. With AAFunctionReachability we can simply ask if the function may
reach itself.

Differential Revision: https://reviews.llvm.org/D110099

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Reland [IR] Increase max alignment to 4GB

Currently the max alignment representable is 1GB, see D108661.
Setting the align of an object to 4GB is desirable in some cases to make sure the lower 32 bi

Reland [IR] Increase max alignment to 4GB

Currently the max alignment representable is 1GB, see D108661.
Setting the align of an object to 4GB is desirable in some cases to make sure the lower 32 bits are clear which can be used for some optimizations, e.g. https://crbug.com/1016945.

This uses an extra bit in instructions that carry an alignment. We can store 15 bits of "free" information, and with this change some instructions (e.g. AtomicCmpXchgInst) use 14 bits.
We can increase the max alignment representable above 4GB (up to 2^62) since we're only using 33 of the 64 values, but I've just limited it to 4GB for now.

The one place we have to update the bitcode format is for the alloca instruction. It stores its alignment into 5 bits of a 32 bit bitfield. I've added another field which is 8 bits and should be future proof for a while. For backward compatibility, we check if the old field has a value and use that, otherwise use the new field.

Updating clang's max allowed alignment will come in a future patch.

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D110451

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Revert "Reland [IR] Increase max alignment to 4GB"

This reverts commit 8d64314ffea55f2ad94c1b489586daa8ce30f451.

Reland [IR] Increase max alignment to 4GB

Currently the max alignment representable is 1GB, see D108661.
Setting the align of an object to 4GB is desirable in some cases to make sure the lower 32 bi

Reland [IR] Increase max alignment to 4GB

Currently the max alignment representable is 1GB, see D108661.
Setting the align of an object to 4GB is desirable in some cases to make sure the lower 32 bits are clear which can be used for some optimizations, e.g. https://crbug.com/1016945.

This uses an extra bit in instructions that carry an alignment. We can store 15 bits of "free" information, and with this change some instructions (e.g. AtomicCmpXchgInst) use 14 bits.
We can increase the max alignment representable above 4GB (up to 2^62) since we're only using 33 of the 64 values, but I've just limited it to 4GB for now.

The one place we have to update the bitcode format is for the alloca instruction. It stores its alignment into 5 bits of a 32 bit bitfield. I've added another field which is 8 bits and should be future proof for a while. For backward compatibility, we check if the old field has a value and use that, otherwise use the new field.

Updating clang's max allowed alignment will come in a future patch.

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D110451

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Revert "[IR] Increase max alignment to 4GB"

This reverts commit df84c1fe78130a86445d57563dea742e1b85156a.

Breaks some bots

[IR] Increase max alignment to 4GB

Currently the max alignment representable is 1GB, see D108661.
Setting the align of an object to 4GB is desirable in some cases to make sure the lower 32 bits are

[IR] Increase max alignment to 4GB

Currently the max alignment representable is 1GB, see D108661.
Setting the align of an object to 4GB is desirable in some cases to make sure the lower 32 bits are clear which can be used for some optimizations, e.g. https://crbug.com/1016945.

This uses an extra bit in instructions that carry an alignment. We can store 15 bits of "free" information, and with this change some instructions (e.g. AtomicCmpXchgInst) use 14 bits.
We can increase the max alignment representable above 4GB (up to 2^62) since we're only using 33 of the 64 values, but I've just limited it to 4GB for now.

The one place we have to update the bitcode format is for the alloca instruction. It stores its alignment into 5 bits of a 32 bit bitfield. I've added another field which is 8 bits and should be future proof for a while. For backward compatibility, we check if the old field has a value and use that, otherwise use the new field.

Updating clang's max allowed alignment will come in a future patch.

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D110451

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The maximal representable alignment in LLVM IR is 1GiB, not 512MiB

In LLVM IR, `AlignmentBitfieldElementT` is 5-bit wide
But that means that the maximal alignment exponent is `(1<<5)-2`,
which is `3

The maximal representable alignment in LLVM IR is 1GiB, not 512MiB

In LLVM IR, `AlignmentBitfieldElementT` is 5-bit wide
But that means that the maximal alignment exponent is `(1<<5)-2`,
which is `30`, not `29`. And indeed, alignment of `1073741824`
roundtrips IR serialization-deserialization.

While this doesn't seem all that important, this doubles
the maximal supported alignment from 512MiB to 1GiB,
and there's actually one noticeable use-case for that;
On X86, the huge pages can have sizes of 2MiB and 1GiB (!).

So while this doesn't add support for truly huge alignments,
which i think we can easily-ish do if wanted, i think this adds
zero-cost support for a not-trivially-dismissable case.

I don't believe we need any upgrade infrastructure,
and since we don't explicitly record the IR version,
we don't need to bump one either.

As @craig.topper speculates in D108661#2963519,
this might be an artificial limit imposed by the original implementation
of the `getAlignment()` functions.

Differential Revision: https://reviews.llvm.org/D108661

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