The SPIR-V backend does not have access to the original name of a
resource in the source, so it tries to create a name. This leads to some
problems with reflection.
    
That is why start to pass the name of the resource from Clang to the
SPIR-V backend.
    
Fixes #138533

Current implementation outputs opcode is an immediate but spirv-tools
requires that the name of the operation without "Op" is needed for the
instruction OpSpecConstantOp
that is if the opcode is OpBitcast the instruction must be
`%1 = OpSpecConstantOp %6 Bitcast %17` 
instead of 
`%1 = OpBitcast %6 124 %17`

[refer this commit for more
info](https://github.com/KhronosGroup/SPIRV-Tools/commit/0f166be68d4b6624a10d6bf312679505d391ec22)

---------

Co-authored-by: Dmitry Sidorov <dmitry.sidorov@intel.com>
Co-authored-by: Ebin-McW <ebin.jose@multicorewareinc.com>

1. There are failed LIT tests at the moment due to type inference
errors.
```
Failed Tests (3):
  LLVM :: CodeGen/SPIRV/pointers/ptr-eq-types.ll
  LLVM :: CodeGen/SPIRV/validate/sycl-hier-par-basic.ll
  LLVM :: CodeGen/SPIRV/validate/sycl-tangle-group-algorithms.ll
```
This PR improves type inference to fix the errors.

2. The following tests start passing:
```
Unexpectedly Passed Tests (2):
  LLVM :: CodeGen/SPIRV/pointers/resource-addrspacecast-2.ll
  LLVM :: CodeGen/SPIRV/pointers/resource-addrspacecast.ll
```
This PR removes XFAILS in those two test cases.

This commit enables a pass in the backend which propagates the addrspace
of the pointers down to the last use, making sure the addrspace remains
consistent, and thus stripping any addrspacecast. This is required to
lower LLVM-IR to logical SPIR-V, which does not support generic
pointers.

This is now required as HLSL emits several address spaces, and thus
addrspacecasts in some cases:

Example 1: resource access

```llvm
%handle = tail call target("spirv.VulkanBuffer", ...)
%rptr = @llvm.spv.resource.getpointer(%handle, ...);
%cptr = addrspacecast ptr addrspace(11) %rptr to ptr
%fptr = load i32, ptr %cptr
```

Example 2: object methods

```llvm
define void @objectMethod(ptr %this) {
}

define void @foo(ptr addrspace(11) %object) {
  call void @objectMethod(ptr addrspacecast(addrspace(11) %object to ptr));
}
```

The patch adds an intrinsic to encode OpGenericCastToPtrExplicit and the
associated lowering logic.

This commits adds handling for spv.ptrcast result being used in a store
instruction, modifying the store to operate on the source type.

The generated OpVectorShuffle was wrong, as the indices we pass are not
to select the vector to sample from, but the position in the vector.

Adds support the the spv.gep intrinsic to the spv ptrcast legalization
step. Those intrinsics are generated by the backend thus not directly
visible in the tests.
This is a pre-requisite to implement addrspacecast legalization for
logical SPIR-V.

This PR is to thoroughly rework duplicate tracker implementation and
tracking of IR entities and types. These are legacy parts of the project
resulting in an extremely bloated intermediate representation and
computational delays due to inefficient data flow and structure choices.

Main results of the rework:

1) Improved compile-time performance. The reference binary LLVM IR used
to measure speed gains in
https://github.com/llvm/llvm-project/pull/120415 shows ~x5 speed up also
after this PR. The timing before this PR is ~42s and after this PR it's
~7.5s. In total this PR and the previous overhaul of the module analysis
in https://github.com/llvm/llvm-project/pull/120415 results in ~x25
speed improvement.
```
$ time llc -O0 -mtriple=spirv64v1.6-unknown-unknown _group_barrier_phi.bc -o 1 --filetype=obj

real    0m7.545s
user    0m6.685s
sys     0m0.859s
```

2) Less bloated intermediate representation of internal translation
steps. Elimination of `spv_track_constant` intrinsic usage for scalar
constants, rework of `spv_assign_name`, removal of the gMIR `GET_XXX`
pseudo code and a smaller number of generated `ASSIGN_TYPE` pseudo codes
substantially decrease volume of data generated during translation.

3) Simpler code and easier maintenance. The duplicate tracker
implementation is simplified, as well as other features.

4) Numerous fixes of issues and logical flaws in different passes. The
main achievement is rework of the duplicate tracker itself that had
never guaranteed a correct caching of LLVM IR entities, rarely and
randomly returning stale/incorrect records (like, remove an instruction
from gMIR but still refer to it). Other fixes comprise consistent
generation of OpConstantNull, assigning types to newly created
registers, creation of integer/bool types, and other minor fixes.

5) Numerous fixes of LIT tests: mainly CHECK-DAG to properly reflect
SPIR-V spec guarantees, `{{$}}` at the end of constants to avoid
matching of substrings, and XFAILS for `SPV_INTEL_long_composites` test
cases, because the feature is not completed in full yet and doesn't
generate a requested by the extension sequence of instructions.

6) New test cases are added.

Adds support for loading the first element of an aggregate from a GEP
instruction & load to the member type.