This option complements -funique-source-file-names and allows the user
to use a different unique identifier than the source file path.

Reviewers: teresajohnson

Reviewed By: teresajohnson

Pull Request: https://github.com/llvm/llvm-project/pull/142901

The purpose of this flag is to allow the compiler to assume that each
object file passed to the linker has been compiled using a unique
source file name. This is useful for reducing link times when doing
ThinLTO in combination with whole-program devirtualization or CFI,
as it allows modules without exported symbols to be built with ThinLTO.

Reviewers: vitalybuka, teresajohnson

Reviewed By: teresajohnson

Pull Request: https://github.com/llvm/llvm-project/pull/135728

Failed to notice them when landing that patch - apologies!

In accordance with https://github.com/llvm/llvm-project/issues/123569

In order to keep the patch at reasonable size, this PR only covers for
the llvm subproject, unittests excluded.

With -fsanitize-cfi-icall-experimental-normalize-integers, Clang
appends ".normalized" to KCFI types in CodeGenModule::CreateKCFITypeId,
which changes type hashes also for functions that don't have integer
types in their signatures. However, llvm::setKCFIType does not take
integer normalization into account, which means LLVM generated
functions with KCFI types, e.g. sanitizer constructors, will fail KCFI
checks when integer normalization is enabled in Clang.

Add a cfi-normalize-integers module flag to indicate integer
normalization is used, and append ".normalized" to KCFI types also in
llvm::setKCFIType to fix the type mismatch.

For #101772

Avoid including MD5.h in a core IR header.

This fixes #71892 allowing us to check magled names in the IR verifier.

Minor simplification applied to VFShape::getScalarShape,
VFShape::get, and VFABI::tryDemangleForVFABI methods.

Also, remove unnecessary `static_cast` in `SLPVectorizer.cpp`

We can determine the VF from a combination of the mangled name (which
indicates the arguments that take vectors) and the element sizes of
the arguments for the scalar function the mapping has been established
for.

The assert when demangling fails has been removed in favour of just
not adding the mapping, which prevents the crash seen in
https://github.com/llvm/llvm-project/issues/71892

This patch also stops using _LLVM_ as an ISA for scalable vector tests,
since there aren't defined rules for the way vector arguments should be
handled (e.g. packed vs. unpacked representation).