Remove `UnsafeFPMath` in AMDGPU part, it blocks some bugfixes related to
clang and the ultimate goal is to remove `resetTargetOptions` method in
`TargetMachine`, see FIXME in `resetTargetOptions`.
See also
https://discourse.llvm.org/t/rfc-honor-pragmas-with-ffp-contract-fast

https://discourse.llvm.org/t/allowfpopfusion-vs-sdnodeflags-hasallowcontract

---------

Co-authored-by: Matt Arsenault <arsenm2@gmail.com>

Having a finite Depth (or recursion limit) for computeKnownBits is very
limiting, but is currently a load-bearing necessity, as all KnownBits
are recomputed on each call and there is no caching. As a prerequisite
for an effort to remove the recursion limit altogether, either using a
clever caching technique, or writing a easily-invalidable KnownBits
analysis, make the Depth argument in APIs in ValueTracking uniformly the
last argument with a default value. This would aid in removing the
argument when the time comes, as many callers that currently pass 0
explicitly are now updated to omit the argument altogether.

These are identified by misc-include-cleaner.  I've filtered out those
that break builds.  Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.

Previously this would recognize a call to a mangled ldexp(float, float)
as a candidate to replace with the intrinsic. We need to verify the second
parameter is in fact an integer.

Fixes: SWDEV-501389

Identified with misc-include-cleaner.

In a variety of places we change the bitwidth of a parameter but don't
update the attributes.

The issue in this case is from the `range` attribute when inlining
`__memset_chk`. `optimizeMemSetChk` will replace an `i32` with an
`i8`, and if the `i32` had a `range` attr assosiated it will cause an
error.

Fixes #112633

Rename the function to reflect its correct behavior and to be consistent
with `Module::getOrInsertFunction`. This is also in preparation of
adding a new `Intrinsic::getDeclaration` that will have behavior similar
to `Module::getFunction` (i.e, just lookup, no creation).