[llvm] [RISCV] Add a pass to remove ADDI by reassociating to fold into load/store address. (PR #127151)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-expensive-checks-win` running on `as-worker-93` while building `llvm` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/14/builds/2649

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

```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/RISCV/fold-mem-offset.ll' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 2
sed 's/iXLen/i32/g' C:\a\llvm-clang-x86_64-expensive-checks-win\llvm-project\llvm\test\CodeGen\RISCV\fold-mem-offset.ll | c:\a\llvm-clang-x86_64-expensive-checks-win\build\bin\llc.exe -mtriple=riscv32 | c:\a\llvm-clang-x86_64-expensive-checks-win\build\bin\filecheck.exe C:\a\llvm-clang-x86_64-expensive-checks-win\llvm-project\llvm\test\CodeGen\RISCV\fold-mem-offset.ll --check-prefixes=CHECK,RV32I
# executed command: sed s/iXLen/i32/g 'C:\a\llvm-clang-x86_64-expensive-checks-win\llvm-project\llvm\test\CodeGen\RISCV\fold-mem-offset.ll'
# executed command: 'c:\a\llvm-clang-x86_64-expensive-checks-win\build\bin\llc.exe' -mtriple=riscv32
# executed command: 'c:\a\llvm-clang-x86_64-expensive-checks-win\build\bin\filecheck.exe' 'C:\a\llvm-clang-x86_64-expensive-checks-win\llvm-project\llvm\test\CodeGen\RISCV\fold-mem-offset.ll' --check-prefixes=CHECK,RV32I
# .---command stderr------------
# | C:\a\llvm-clang-x86_64-expensive-checks-win\llvm-project\llvm\test\CodeGen\RISCV\fold-mem-offset.ll:16:15: error: RV32I-NEXT: expected string not found in input
# | ; RV32I-NEXT: lw a3, 400(a0)
# |               ^
# | <stdin>:16:16: note: scanning from here
# |  lw a1, 484(a1)
# |                ^
# | <stdin>:17:2: note: possible intended match here
# |  lw a3, 404(a0)
# |  ^
# | C:\a\llvm-clang-x86_64-expensive-checks-win\llvm-project\llvm\test\CodeGen\RISCV\fold-mem-offset.ll:216:15: error: RV32I-NEXT: expected string not found in input
# | ; RV32I-NEXT: lw a2, 400(a1)
# |               ^
# | <stdin>:92:16: note: scanning from here
# |  add a0, a0, a2
# |                ^
# | <stdin>:94:2: note: possible intended match here
# |  lw a3, 400(a1)
# |  ^
# | 
# | Input file: <stdin>
# | Check file: C:\a\llvm-clang-x86_64-expensive-checks-win\llvm-project\llvm\test\CodeGen\RISCV\fold-mem-offset.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |             .
# |             .
# |             .
# |            11:  slli a1, a1, 3 
# |            12:  slli a2, a2, 3 
# |            13:  add a1, a1, a0 
# |            14:  add a0, a0, a2 
# |            15:  lw a2, 480(a1) 
# |            16:  lw a1, 484(a1) 
# | next:16'0                     X error: no match found
# |            17:  lw a3, 404(a0) 
# | next:16'0      ~~~~~~~~~~~~~~~~
# | next:16'1       ?               possible intended match
...

```

</details>

https://github.com/llvm/llvm-project/pull/127151