Changes

[OpenCL] Enables .rgba vector extension in C++ for OpenCL 2021

`.rgba` vector extension setting in C++ for OpenCL 2021 is now
performed analogously to OpenCL C 3.0. Test case added.

Differential Revision: https://reviews.llvm.org/D109370

[llvm cmake] replace tabs with spaces in config-ix.cmake

[Windows build] Use "DIA SDK" in sysroot

This updates llvm/utils/sysroot.py to include the "DIA SDK" folder in the
sysroot.

It also updates the build to look for the DIA SDK there if a sysroot is set.

This requires moving LLVM_WINSYSROOT to config-ix.cmake.

For the GN build, I chose to pass a qualified path to diaguids in libs instead
of pushing a config with a `/libpath:` flag. The former requires a GN with
https://gn-review.googlesource.com/c/gn/+/12200, the latter requires D109624.
The former is more like the cmake build, arguably a bit simpler, and it's
easier to check for the wrong GN revision and easier to update GN.

Differential Revision: https://reviews.llvm.org/D109708

[Dexter] Improve performance by evaluating expressions only when needed

Currently, Dexter's model for fetching watch values is to build a list of
expressions to watch before running the debugger, then evaluating all of them at
each breakpoint, then finally looking up the values of these expressions at each
line they were expected on. When using dexter on a large project while watching
many different expressions, this is very slow, as Dexter will make a massive
number of calls made to the debugger's API, the vast majority of which are not
being used for anything. This patch fixes this issue by having Dexter only
evaluate expressions at a breakpoint when it will be used by a Dexter command.

Reviewed By: jmorse

Differential Revision: https://reviews.llvm.org/D107070

Cleanup identifier parsing; NFC

Rename methods to clearly signal when they only deal with ASCII,
simplify the parsing of identifier, and use start/continue instead of
head/body for consistency with Unicode terminology.

[lldb/test] Start pexpect tests with a custom HOME

This addresses the flakyness of (at least) TestMultilineNavigation,
which was failing when the editline history of a concurrently executing
test made leaked in. Using a test-specific home directory ensures the
tests are independent.

AMDGPU: Avoid relying on an undef value in test

This was really becoming a direct call during the DAG, so it wasn't as
true to the test purpose.

Remove incorrect comment in getSingleUndroppableUse. NFC

We traverse the entire use list to find the undroppable use.

[PowerPC] Exploit Prefixed Load/Stores using the refactored Load/Store Implementation

This patch exploits the prefixed load and store instructions utilizing the
refactored load/store implementation introduced in D93370.

Prefixed load and store instructions are emitted whenever we are loading or
storing a value with an offset that fits into a 34-bit signed immediate.
Patterns for the prefixed load and stores are added in this patch, as well as
the implementation that detects when we are loading and storing a value with an
offset that fits in 34-bits.

Differential Revision: https://reviews.llvm.org/D96075

[WebAssembly] Allow import and export of TLS symbols between DSOs

We previously had a limitation that TLS variables could not
be exported (and therefore could also not be imported).  This
change removed that limitation.

Differential Revision: https://reviews.llvm.org/D108877

[clangd] Ignore ObjC `id` and `instancetype` in FindTarget

Even though they're implemented via typedefs, we typically
want to treat them like keywords.

We could add hover information / xrefs, but it's very unlikely
to provide any value.

Differential Revision: https://reviews.llvm.org/D108556

Fix a unittest file after D108695 when Z3 is enabled

Fix test failure created by ef8c9135efcb

Followup to https://reviews.llvm.org/D108877 to fix test
failure.

[IR] Reduce max supported integer from 2^24-1 to 2^23.

SelectionDAG will promote illegal types up to a power of 2 before
splitting down to a legal type. This will create an IntegerType
with a bit width that must be <= MAX_INT_BITS. This places an
effective upper limit on any type of 2^23 so that we don't try
create a 2^24 type.

I considered putting a fatal error somewhere in the path from
TargetLowering::getTypeConversion down to IntegerType::get, but
limiting the type in IR seemed better.

This breaks backwards compatibility with IR that is using a really
large type. I suspect such IR is going to be very rare due to the
the compile time costs such a type likely incurs.

Prevents the ICE in PR51829.

Reviewed By: efriedma, aaron.ballman

Differential Revision: https://reviews.llvm.org/D109721

clang-tidy: introduce readability-containter-data-pointer check

This introduces a new check, readability-containter-data-pointer.  This
check is meant to catch the cases where the user may be trying to
materialize the data pointer by taking the address of the 0-th member of
a container.  With C++11 or newer, the `data` member should be used for
this.  This provides the following benefits:

- `.data()` is easier to read than `&[0]`
- it avoids an unnecessary re-materialization of the pointer
  * this doesn't matter in the case of optimized code, but in the case
    of unoptimized code, this will be visible
- it avoids a potential invalid memory de-reference caused by the
  indexing when the container is empty (in debug mode, clang will
  normally optimize away the re-materialization in optimized builds).

The small potential behavioural change raises the question of where the
check should belong.  A reasoning of defense in depth applies here, and
this does an unchecked conversion, with the assumption that users can
use the static analyzer to catch cases where we can statically identify
an invalid memory de-reference.  For the cases where the static analysis
is unable to prove the size of the container, UBSan can be used to track
the invalid access.

Special thanks to Aaron Ballmann for the discussion on whether this
check would be useful and where to place it.

This also partially resolves PR26817!

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D108893