[clang] [llvm] [X86] Add ACE v1 (AI Compute Extensions) support (PR #208408)

[via cfe-commits]

mahesh-attarde wrote:

@ganeshgit last week i found  machine code error in code. For all ACE (in fact helpful for all machine code changes)  can you also include `-DLLVM_ENABLE_EXPENSIVE_CHECKS=ON` in your configuration.
```
# | # After Instruction Selection
# | # Machine code for function test_bsrmovh_set: IsSSA, TracksLiveness
# | Function Live Ins: $zmm0 in %0
# | 
# | bb.0 (%ir-block.0):
# |   liveins: $zmm0
# |   %0:vr512 = COPY $zmm0
# |   BSRMOVHrr_set %0:vr512, implicit-def dead $bsr0, implicit $bsr0
# |   RET 0
# | 
# | # End machine code for function test_bsrmovh_set.
# | 
# | *** Bad machine code: Using an undefined physical register ***
# | - function:    test_bsrmovh_set
# | - basic block: %bb.0  (0x613d39cc0168)
# | - instruction: BSRMOVHrr_set %0:vr512, implicit-def dead $bsr0, implicit $bsr0
# | - operand 2:   implicit $bsr0
# | LLVM ERROR: Found 1 machine code errors
```



https://github.com/llvm/llvm-project/pull/208408