We should abstract this logic away to `TargetInfo`. See
https://github.com/llvm/llvm-project/pull/137882 for more information.

---------

Signed-off-by: Sarnie, Nick <nick.sarnie@intel.com>

Move the initialization of ptrauth-* function attributes near the
initialization of branch protection attributes. The semantics of these
groups of attributes partially overlaps, so handle both groups in
getDefaultFunctionAttributes() and setTargetAttributes() functions to
prevent getting them out of sync. This fixes C++ TLS wrappers.

…__builtin_scalbn

Clang generates library calls for __builtin_* functions which can be a
problem for GPUs that cannot handle them. This patch generates call to
device implementation for __builtin_logb and ldexp intrinsic for
__builtin_scalbn.

It isn't used and is redundant with the result pointer type argument.
A more reasonable API would only have LangAS parameters, or IR parameters,
not both. Not all values have a meaningful value for this. I'm also
not sure why we have this at all, it's not overridden by any targets and
further simplification is possible.

This feature is currently not supported in the compiler.
To facilitate this we emit a stub version of each kernel
function body with different name mangling scheme, and
replaces the respective kernel call-sites appropriately.
    
Fixes https://github.com/llvm/llvm-project/issues/60313
    
D120566 was an earlier attempt made to upstream a solution
for this issue.

---------

Co-authored-by: anikelal <anikelal@amd.com>

Processes `HLSLResourceBindingAttr` attributes that represent
`register(c#)` annotations on default constant buffer declarations and
applies its value to the buffer layout. Any default buffer declarations
without an explicit `register(c#)` annotation are placed after the
elements with explicit layout.

This PR also adds a test case for a `cbuffer` that does not have
`packoffset` on all declarations. Same layout rules apply here as well.

Fixes #126791

Translates `cbuffer` declaration blocks to `target("dx.CBuffer")` type. Creates global variables in `hlsl_constant` address space for all `cbuffer` constant and adds metadata describing which global constant belongs to which constant buffer. For explicit constant buffer layout information an explicit layout type `target("dx.Layout")` is used. This might change in the future.

The constant globals are temporary and will be removed in upcoming pass that will translate `load` instructions in the `hlsl_constant` address space to constant buffer load intrinsics calls off a CBV handle (#124630, #112992).

See [Constant buffer design
doc](https://github.com/llvm/wg-hlsl/pull/94) for more details.

Fixes #113514, #106596

If `__attribute__((flatten))` is used on a function, or
`[[clang::always_inline]]` on a statement, don't inline any callees with
incompatible streaming attributes. Without this check, clang may produce
incorrect code when these attributes are used in code with streaming
functions.

Note: The docs for flatten say it can be ignored when inlining is
impossible: "causes calls within the attributed function to be inlined
unless it is impossible to do so".

Similarly, the (clang-only) `[[clang::always_inline]]` statement
attribute is more relaxed than the GNU `__attribute__((always_inline))`
(which says it should error it if it can't inline), saying only "If a
statement is marked [[clang::always_inline]] and contains calls, the
compiler attempts to inline those calls.". The docs also go on to show
an example of where `[[clang::always_inline]]` has no effect.