[llvm] [IR] Add initial support for the byte type (PR #178666)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-global-isel` running on `linaro-clang-aarch64-global-isel` while building `llvm` at step 7 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/125/builds/13757

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'LLVM :: CodeGen/X86/byte-constants.ll' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 1
/home/tcwg-buildbot/worker/clang-aarch64-global-isel/stage1/bin/llc < /home/tcwg-buildbot/worker/clang-aarch64-global-isel/llvm/llvm/test/CodeGen/X86/byte-constants.ll | /home/tcwg-buildbot/worker/clang-aarch64-global-isel/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-aarch64-global-isel/llvm/llvm/test/CodeGen/X86/byte-constants.ll
# executed command: /home/tcwg-buildbot/worker/clang-aarch64-global-isel/stage1/bin/llc
# executed command: /home/tcwg-buildbot/worker/clang-aarch64-global-isel/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-aarch64-global-isel/llvm/llvm/test/CodeGen/X86/byte-constants.ll
# .---command stderr------------
# | /home/tcwg-buildbot/worker/clang-aarch64-global-isel/llvm/llvm/test/CodeGen/X86/byte-constants.ll:5:10: error: CHECK: expected string not found in input
# | ; CHECK: .quad 10
# |          ^
# | <stdin>:6:3: note: scanning from here
# | x:
# |   ^
# | <stdin>:7:3: note: possible intended match here
# |  .xword 10 // 0xa
# |   ^
# | 
# | Input file: <stdin>
# | Check file: /home/tcwg-buildbot/worker/clang-aarch64-global-isel/llvm/llvm/test/CodeGen/X86/byte-constants.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |            1:  .file "<stdin>" 
# |            2:  .type x, at object // @x 
# |            3:  .data 
# |            4:  .globl x 
# |            5:  .p2align 3, 0x0 
# |            6: x: 
# | check:5'0       X error: no match found
# |            7:  .xword 10 // 0xa 
# | check:5'0     ~~~~~~~~~~~~~~~~~~
# | check:5'1       ?                possible intended match
# |            8:  .size x, 8 
# | check:5'0     ~~~~~~~~~~~~
# |            9:  
# | check:5'0     ~
# |           10:  .type b, at object // @b 
# | check:5'0     ~~~~~~~~~~~~~~~~~~~~~~~
# |           11:  .globl b 
# | check:5'0     ~~~~~~~~~~
# |           12:  .p2align 2, 0x0 
# | check:5'0     ~~~~~~~~~~~~~~~~~
# |            .
# |            .
# |            .
...

```

</details>

https://github.com/llvm/llvm-project/pull/178666