This patch adds fix-it hints for unknown attribute names when Clang
suggests a correction

Add a missing valid triple "aarch64-apple-macosx" for usability.

#140595 used vp.load in the cases where we need to widen masked.load.
However, we didn't account for the passthru operand so it might
miscompile when the passthru is not undef. While we can simply avoid
using vp.load to widen when passthru is not undef, doing so will ran
into the exact same crash described in #140198 , so for scalable vector,
this patch manually merges the vp.load result with passthru when the
latter is not undef.

This reverts commit 0604dc199c019b23746f4a54885ba0c75569cdae.

The recommitted version addresses post-commit comments and adjusts the
place the branch weights are added. It now runs before VPlans are optimized
for VF and UF, which may remove the vector loop region, causing a crash
trying to get the middle block after that. Test case added in
72f99b75afc12bb.

Original message:
Manage branch weights for the BranchOnCond in the middle block in VPlan.
This requires updating VPInstruction to inherit from VPIRMetadata, which
in general makes sense as there are a number of opcodes that could take
metadata.

There are other branches (part of the skeleton) that also need branch
weights adding.

PR: https://github.com/llvm/llvm-project/pull/143035

Add test case with branch weights where the vector loop can
be removed. Exposed a crash with db8d34db26e9
(https://github.com/llvm/llvm-project/pull/143035).

This reverts commit 10bc17fc3676b82c7240046a948d2925dd2045d3.

Multiple buildbot failures have been reported:
https://github.com/llvm/llvm-project/pull/143914

fixes https://github.com/llvm/llvm-project/issues/116116

Fix a crash that happened during parsing of a "declare mapper" construct
for a struct that contains an element for which we also declared a
custom default mapper.

Extend `FindFFI.cmake` to include the paths obtained from pkg-config
when searching for libffi. This is going to help systems where libffi is
installed in nonstandard directory such as Gentoo, saving us from having
to copy the paths from pkg-config to `FFI_*` variables explicitly. The
logic is inspired by `FindLibEdit.cmake`.