Changes

[clang] Add a new nullability annotation for swift async: _Nullable_result

_Nullable_result generally like _Nullable, except when being imported into a
swift async method. rdar://70106409

Differential revision: https://reviews.llvm.org/D92495

[clang] Add support for attribute 'swift_async'

This attributes specifies how (or if) a given function or method will be
imported into a swift async method. rdar://70111252

Differential revision: https://reviews.llvm.org/D92742

Revert "[test] Fix asan/TestCases/Linux/globals-gc-sections-lld.cpp with -fsanitize-address-globals-dead-stripping"

This reverts commit 140808768d3e5c0f4e52dd42094650f5d282e34a.

Reason: Broke the upstream bots - discussed offline.

    [clang] Fix noderef for array member of deref expr

    Committing on behalf of thejh (Jann Horn).

    Given an attribute((noderef)) pointer "p" to the struct

    struct s { int a[2]; };
    ensure that the following expressions are treated the same way by the
    noderef logic:

    p->a
    (*p).a
    Until now, the first expression would be treated correctly (nothing is
    added to PossibleDerefs because CheckMemberAccessOfNoDeref() bails out
    on array members), but the second expression would incorrectly warn
    because "*p" creates a PossibleDerefs entry.

    Handle this case the same way as for the AddrOf operator.

    Differential Revision: https://reviews.llvm.org/D92140

[flang] Improve initializer semantics, esp. for component default values

This patch plugs many holes in static initializer semantics, improves error
messages for default initial values and other component properties in
parameterized derived type instantiations, and cleans up several small
issues noticed during development.  We now do proper scalar expansion,
folding, and type, rank, and shape conformance checking for component
default initializers in derived types and PDT instantiations.
The initial values of named constants are now guaranteed to have been folded
when installed in the symbol table, and are no longer folded or
scalar-expanded at each use in expression folding.  Semantics documentation
was extended with information about the various kinds of initializations
in Fortran and when each of them are processed in the compiler.

Some necessary concomitant changes have bulked this patch out a bit:
* contextual messages attachments, which are now produced for parameterized
  derived type instantiations so that the user can figure out which
  instance caused a problem with a component, have been added as part
  of ContextualMessages, and their implementation was debugged
* several APIs in evaluate::characteristics was changed so that a FoldingContext
  is passed as an argument rather than just its intrinsic procedure table;
  this affected client call sites in many files
* new tools in Evaluate/check-expression.cpp to determine when an Expr
  actually is a single constant value and to validate a non-pointer
  variable initializer or object component default value
* shape conformance checking has additional arguments that control
  whether scalar expansion is allowed
* several now-unused functions and data members noticed and removed
* several crashes and bogus errors exposed by testing this new code
  were fixed
* a -fdebug-stack-trace option to enable LLVM's stack tracing on
  a crash, which might be useful in the future

TL;DR: Initialization processing does more and takes place at the right
times for all of the various kinds of things that can be initialized.

Differential Review: https://reviews.llvm.org/D92783

[clang] Fix noderef for AddrOf on MemberExpr

Committing on behalf of thejh (Jann Horn).

As part of this change, one existing test case has to be adjusted
because it accidentally stripped the NoDeref attribute without
getting caught.

Depends on D92140

Differential Review: https://reviews.llvm.org/D92141

Teach isKnownNonEqual how to recurse through invertible multiplies

Build on the work started in 8f07629, and add the multiply case. In the process, more clearly describe the requirement for the operation we're looking through.

Differential Revision: https://reviews.llvm.org/D92726

[AArch64][GlobalISel] Narrow 128-bit regs to 64-bit regs in emitTestBit

When we have a 128-bit register, emitTestBit would incorrectly narrow to 32
bits always. If the bit number was > 32, then we would need a TB(N)ZX. This
would cause a crash, as we'd have the wrong register class. (PR48379)

This generalizes `narrowExtReg` into `moveScalarRegClass`.

This also allows us to remove `widenGPRBankRegIfNeeded` entirely, since
`selectCopy` correctly handles SUBREG_TO_REG etc.

This does create some codegen changes (since `selectCopy` uses the `all`
regclass variants). However, I think that these will likely be optimized away,
and we can always improve the `selectCopy` code. It looks like we should
revisit `selectCopy` at this point, and possibly refactor it into at least one
`emit` function.

Differential Revision: https://reviews.llvm.org/D92707

[clang][AMDGPU] rename sram-ecc as sramecc

As backend renamed sram-ecc to sramecc, this patch makes
corresponding change in clang.

Differential Revision: https://reviews.llvm.org/D86217

Customize exception thrown from mlir.Operation.create() python bindings

The default exception handling isn't very user friendly and does not
point accurately to the issue. Instead we can indicate which of the
operands isn't valid and provide contextual information in the error
message.

Differential Revision: https://reviews.llvm.org/D92710

Add Python binding for MLIR Type Attribute

Differential Revision: https://reviews.llvm.org/D92711