[IRBuilder] Generate nuw GEPs for struct member accesses (#99538)

Generate nuw GEPs for struct member accesses, as inbounds + non-negative
implies nuw.

Regression tests are updated using update

[IRBuilder] Generate nuw GEPs for struct member accesses (#99538)

Generate nuw GEPs for struct member accesses, as inbounds + non-negative
implies nuw.

Regression tests are updated using update scripts where possible, and by
find + replace where not.

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[OpenMP] Update the default version of OpenMP to 5.1

The default version of OpenMP is updated from 5.0 to 5.1 which means if -fopenmp is specified but -fopenmp-version is not specified with clang, t

[OpenMP] Update the default version of OpenMP to 5.1

The default version of OpenMP is updated from 5.0 to 5.1 which means if -fopenmp is specified but -fopenmp-version is not specified with clang, the default version of OpenMP is taken to be 5.1. After modifying the Frontend for that, various LIT tests were updated. This patch contains all such changes. At a high level, these are the patterns of changes observed in LIT tests -

# RUN lines which mentioned `-fopenmp-version=50` need to kept only if the IR for version 5.0 and 5.1 are different. Otherwise only one RUN line with no version info(i.e. default version) needs to be there.

# Test cases of this sort already had the RUN lines with respect to the older default version 5.0 and the version 5.1. Only swapping the version specification flag `-fopenmp-version` from newer version RUN line to older version RUN line is required.

# Diagnostics: Remove the 5.0 version specific RUN lines if there was no difference in the Diagnostics messages with respect to the default 5.1.

# Diagnostics: In case there was any difference in diagnostics messages between 5.0 and 5.1, mention version specific messages in tests.

# If the test contained version specific ifdef's e.g. "#ifdef OMP5" but there were no RUN lines for any other version than 5.X, then bring the code guarded by ifdef's outside and remove the ifdef's.

# Some tests had RUN lines for both 5.0 and 5.1 versions, but it is found that the IR for 5.0 is not different from the 5.1, therefore such RUN lines are redundant. So, such duplicated lines are removed.

# To generate CHECK lines automatically, use the script llvm/utils/update_cc_test_checks.py

Reviewed By: saiislam, ABataev

Differential Revision: https://reviews.llvm.org/D129635

(cherry picked from commit 9dd2999907dc791136a75238a6000f69bf67cf4e)

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[OpenMP] Convert tests to opaque pointers (NFC)

Conversion performed using the script at:
https://gist.github.com/nikic/98357b71fd67756b0f064c9517b62a34

These are only tests where no manual fixup w

[OpenMP] Convert tests to opaque pointers (NFC)

Conversion performed using the script at:
https://gist.github.com/nikic/98357b71fd67756b0f064c9517b62a34

These are only tests where no manual fixup was required.

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[OpenMPIRBuilder] Remove ContinuationBB argument from Body callback.

The callback is expected to create a branch to the ContinuationBB (sometimes called FiniBB in some lambdas) argument when finishi

[OpenMPIRBuilder] Remove ContinuationBB argument from Body callback.

The callback is expected to create a branch to the ContinuationBB (sometimes called FiniBB in some lambdas) argument when finishing. This creates problems:

1. The InsertPoint used for CodeGenIP does not need to be the end of a block. If it is not, a naive callback will insert a branch instruction into the middle of the block.

2. The BasicBlock the CodeGenIP is pointing to may or may not have a terminator. There is an conflict where to branch to if the block already has a terminator.

3. Some API functions work only with block having a terminator. Some workarounds have been used to insert a temporary terminator that is removed again.

4. Some callbacks are sensitive to whether the BasicBlock has a terminator or not. This creates a callback ordering problem where different callback may have different behaviour depending on whether a previous callback created a terminator or not. The problem also exists for FinalizeCallbackTy where some callbacks do create branch to another "continue" block, but unlike BodyGenCallbackTy does not receive the target as argument. This is not addressed in this patch.

With this patch, the callback receives an CodeGenIP into a BasicBlock where to insert instructions. If it has to insert control flow, it can split the block at that position as needed but otherwise no separate ContinuationBB is needed. In particular, a callback can be empty without breaking the emitted IR. If the caller needs the control flow to branch to a specific target, it can insert the branch instruction itself and pass an InsertPoint before the terminator to the callback.

Certain frontends such as Clang may expect the current IRBuilder position to be at the end of a basic block. In this case its callbacks must split the block at CodeGenIP before setting the IRBuilder position such that the instructions after CodeGenIP are moved to another basic block and before returning create a new branch instruction to the split block.

Some utility functions such as `splitBB` are supporting correct splitting of BasicBlocks, independent of whether they have a terminator or not, returning/setting the InsertPoint of an IRBuilder to the end of split predecessor block, and optionally omitting creating a branch to the split successor block to be added later.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D118409

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[OpaquePtrs][Clang] Add -no-opaque-pointers to tests (NFC)

This adds -no-opaque-pointers to clang tests whose output will
change when opaque pointers are enabled by default. This is
intended to be p

[OpaquePtrs][Clang] Add -no-opaque-pointers to tests (NFC)

This adds -no-opaque-pointers to clang tests whose output will
change when opaque pointers are enabled by default. This is
intended to be part of the migration approach described in
https://discourse.llvm.org/t/enabling-opaque-pointers-by-default/61322/9.

The patch has been produced by replacing %clang_cc1 with
%clang_cc1 -no-opaque-pointers for tests that fail with opaque
pointers enabled. Worth noting that this doesn't cover all tests,
there's a remaining ~40 tests not using %clang_cc1 that will need
a followup change.

Differential Revision: https://reviews.llvm.org/D123115

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[OpenMP] Support OpenMP 5.1 attributes

OpenMP 5.1 added support for writing OpenMP directives using [[]]
syntax in addition to using #pragma and this introduces support for the
new syntax.

In OpenM

[OpenMP] Support OpenMP 5.1 attributes

OpenMP 5.1 added support for writing OpenMP directives using [[]]
syntax in addition to using #pragma and this introduces support for the
new syntax.

In OpenMP, the attributes take one of two forms:
[[omp::directive(...)]] or [[omp::sequence(...)]]. A directive
attribute contains an OpenMP directive clause that is identical to the
analogous #pragma syntax. A sequence attribute can contain either
sequence or directive arguments and is used to ensure that the
attributes are processed sequentially for situations where the order of
the attributes matter (remember:
https://eel.is/c++draft/dcl.attr.grammar#4.sentence-4).

The approach taken here is somewhat novel and deserves mention. We
could refactor much of the OpenMP parsing logic to work for either
pragma annotation tokens or for attribute clauses. It would be a fair
amount of effort to share the logic for both, but it's certainly
doable. However, the semantic attribute system is not designed to
handle the arbitrarily complex arguments that OpenMP directives
contain. Adding support to thread the novel parsed information until we
can produce a semantic attribute would be considerably more effort.
What's more, existing OpenMP constructs are not (often) represented as
semantic attributes. So doing this through Attr.td would be a massive
undertaking that would likely only benefit OpenMP and comes with
additional risks. Rather than walk down that path, I am taking
advantage of the fact that the syntax of the directives within the
directive clause is identical to that of the #pragma form. Once the
parser recognizes that we're processing an OpenMP attribute, it caches
all of the directive argument tokens and then replays them as though
the user wrote a pragma. This reuses the same OpenMP parsing and
semantic logic directly, but does come with a risk if the OpenMP
committee decides to purposefully diverge their pragma and attribute
syntaxes. So, despite this being a novel approach that does token
replay, I think it's actually a better approach than trying to do this
through the declarative syntax in Attr.td.

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