This explicit listing of the bitcodes is out of date, and had fallen out of date in the past as well.

Delete the explicit listing and point users to where they can find it.

It is now translated to `<1 x i64>`, which allows the removal of a bunch
of special casing.

This _incompatibly_ changes the ABI of any LLVM IR function with
`x86_mmx` arguments or returns: instead of passing in mmx registers,
they will now be passed via integer registers. However, the real-world
incompatibility caused by this is expected to be minimal, because Clang
never uses the x86_mmx type -- it lowers `__m64` to either `<1 x i64>`
or `double`, depending on ABI.

This change does _not_ eliminate the SelectionDAG `MVT::x86mmx` type.
That type simply no longer corresponds to an IR type, and is used only
by MMX intrinsics and inline-asm operands.

Because SelectionDAGBuilder only knows how to generate the
operands/results of intrinsics based on the IR type, it thus now
generates the intrinsics with the type MVT::v1i64, instead of
MVT::x86mmx. We need to fix this before the DAG LegalizeTypes, and thus
have the X86 backend fix them up in DAGCombine. (This may be a
short-lived hack, if all the MMX intrinsics can be removed in upcoming
changes.)

Works towards issue #98272.

The WebKit Calling Convention was created specifically for the WebKit
FTL. FTL
doesn't use LLVM anymore and therefore this calling convention is
obsolete.

This commit removes the WebKit CC, its associated tests, and
documentation.

This patch adds a new fn attribute, `optdebug`, that specifies that
optimizations should make decisions that prioritize debug info quality,
potentially at the cost of runtime performance.

This patch does not add any functional changes triggered by this
attribute, only the attribute itself. A subsequent patch will use this
flag to disable the post-RA scheduler.

This patch adds some missing documentation for some attributes in
BitCodeFormat, where the integer code mappings for attributes after code
79 were not listed, and in LangRef where the incompatibility between
minsize/optsize and optnone was not mentioned.

This changes the definition if isSectionBitcode to only be valid for the
.llvm.lto section, since this API is only called from LTO, and the
.llvmbc section was not intended to be used for LTO. This allows the
gold plugin to keep its existing behavior without introducing any
significant changes.

Reviewed By: MaskRay, nikic

Differential Revision: https://reviews.llvm.org/D152973

Target-extension types represent types that need to be preserved through
optimization, but otherwise are not introspectable by target-independent
optimizations. This patch doesn't add any uses of these types by an existing
backend, it only provides basic infrastructure such that these types would work
correctly.

Reviewed By: nikic, barannikov88

Differential Revision: https://reviews.llvm.org/D135202

-fembed-bitcode will put bitcode into special sections within object
files, but this is not meant to be used by LTO, so the gold plugin
should ignore it.

https://github.com/llvm/llvm-project/issues/47216

Reviewed By: tejohnson, MaskRay

Differential Revision: https://reviews.llvm.org/D116995

Currently adding attribute no_sanitize("bounds") isn't disabling
-fsanitize=local-bounds (also enabled in -fsanitize=bounds). The Clang
frontend handles fsanitize=array-bounds which can already be disabled by
no_sanitize("bounds"). However, instrumentation added by the
BoundsChecking pass in the middle-end cannot be disabled by the
attribute.

The fix is very similar to D102772 that added the ability to selectively
disable sanitizer pass on certain functions.

In this patch, if no_sanitize("bounds") is provided, an additional
function attribute (NoSanitizeBounds) is attached to IR to let the
BoundsChecking pass know we want to disable local-bounds checking. In
order to support this feature, the IR is extended (similar to D102772)
to make Clang able to preserve the information and let BoundsChecking
pass know bounds checking is disabled for certain function.

Reviewed By: melver

Differential Revision: https://reviews.llvm.org/D119816