[llvm] [CodeGen] Fix register pressure computation in MachinePipeliner (PR #87030)

[via llvm-commits]

gulfemsavrun wrote:

`sms-regpress.mir` started failing in our builders.
```
FAIL: LLVM :: CodeGen/AArch64/sms-regpress.mir (4571 of 53741)
******************** TEST 'LLVM :: CodeGen/AArch64/sms-regpress.mir' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 1: /b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins/bin/llc --verify-machineinstrs -mtriple=aarch64 -o - /b/s/w/ir/x/w/llvm-llvm-project/llvm/test/CodeGen/AArch64/sms-regpress.mir -run-pass pipeliner -aarch64-enable-pipeliner -pipeliner-max-mii=40 -pipeliner-register-pressure -pipeliner-ii-search-range=30 -debug-only=pipeliner 2>&1 | /b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins/bin/FileCheck /b/s/w/ir/x/w/llvm-llvm-project/llvm/test/CodeGen/AArch64/sms-regpress.mir
+ /b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins/bin/llc --verify-machineinstrs -mtriple=aarch64 -o - /b/s/w/ir/x/w/llvm-llvm-project/llvm/test/CodeGen/AArch64/sms-regpress.mir -run-pass pipeliner -aarch64-enable-pipeliner -pipeliner-max-mii=40 -pipeliner-register-pressure -pipeliner-ii-search-range=30 -debug-only=pipeliner
+ /b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins/bin/FileCheck /b/s/w/ir/x/w/llvm-llvm-project/llvm/test/CodeGen/AArch64/sms-regpress.mir
/b/s/w/ir/x/w/llvm-llvm-project/llvm/test/CodeGen/AArch64/sms-regpress.mir:6:10: error: CHECK: expected string not found in input
# CHECK: {{^ *}}Try to schedule with {{[0-9]+$}}
         ^
<stdin>:1:1: note: scanning from here
llc: Unknown command line argument '-debug-only=pipeliner'. Try: '/b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins/bin/llc --help'
^
<stdin>:1:3: note: possible intended match here
llc: Unknown command line argument '-debug-only=pipeliner'. Try: '/b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins/bin/llc --help'
  ^

Input file: <stdin>
Check file: /b/s/w/ir/x/w/llvm-llvm-project/llvm/test/CodeGen/AArch64/sms-regpress.mir

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

Input was:
<<<<<<
           1: llc: Unknown command line argument '-debug-only=pipeliner'. Try: '/b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins/bin/llc --help' 
check:6'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
check:6'1       ?                                                                                                                                 possible intended match
           2: llc: Did you mean '--debug-pass=pipeliner'? 
check:6'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>>>
```
https://luci-milo.appspot.com/ui/p/fuchsia/builders/prod/clang-linux-x64/b8751864477467126481/overview

https://github.com/llvm/llvm-project/pull/87030