[llvm] [AArch64] Avoid overflow when using shl lower mul (PR #97148)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-armv8-quick` running on `linaro-clang-armv8-quick` while building `llvm` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/154/builds/712

Here is the relevant piece of the build log for the reference:
```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'LLVM :: Analysis/StructuralHash/structural-hash-printer.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 1: /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/opt -passes='print<structural-hash>' -disable-output /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/Analysis/StructuralHash/structural-hash-printer.ll 2>&1 | /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/Analysis/StructuralHash/structural-hash-printer.ll
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/opt '-passes=print<structural-hash>' -disable-output /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/Analysis/StructuralHash/structural-hash-printer.ll
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/Analysis/StructuralHash/structural-hash-printer.ll
RUN: at line 2: /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/opt -passes='print<structural-hash><detailed>' -disable-output /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/Analysis/StructuralHash/structural-hash-printer.ll 2>&1 | /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/Analysis/StructuralHash/structural-hash-printer.ll -check-prefix=DETAILED-HASH
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/opt '-passes=print<structural-hash><detailed>' -disable-output /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/Analysis/StructuralHash/structural-hash-printer.ll
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/Analysis/StructuralHash/structural-hash-printer.ll -check-prefix=DETAILED-HASH
/home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/Analysis/StructuralHash/structural-hash-printer.ll:21:18: error: DETAILED-HASH: expected string not found in input
; DETAILED-HASH: Module Hash: {{([a-z0-9]{14,})}}
                 ^
<stdin>:1:1: note: scanning from here
Module Hash: b88d71c254a5c
^

Input file: <stdin>
Check file: /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/llvm/test/Analysis/StructuralHash/structural-hash-printer.ll

-dump-input=help explains the following input dump.

Input was:
<<<<<<
          1: Module Hash: b88d71c254a5c 
check:21     X~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
          2: Function f1 Hash: 8933af6f80a7d453 
check:21     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          3: Function f2 Hash: cf63b3f551222a7c 
check:21     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>>>

--

********************


```

https://github.com/llvm/llvm-project/pull/97148