[llvm] [CFIFixup] Factor logic into helpers and use range-based loops (NFC) (PR #125137)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `lld-x86_64-ubuntu-fast` running on `as-builder-4` while building `llvm` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/33/builds/10648

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

```
Step 5 (build-unified-tree) failure: build (failure)
...
13.579 [866/43/3012] Linking CXX static library lib/libLLVMSystemZInfo.a
13.612 [865/43/3013] Linking CXX static library lib/libLLVMSystemZDesc.a
13.631 [864/43/3014] Linking CXX static library lib/libLLVMSystemZDisassembler.a
13.878 [864/42/3015] Building CXX object lib/Object/CMakeFiles/LLVMObject.dir/IRSymtab.cpp.o
13.886 [864/41/3016] Building X86GenCallingConv.inc...
13.970 [864/40/3017] Building X86GenExegesis.inc...
14.130 [864/39/3018] Building X86GenRegisterBank.inc...
14.144 [864/38/3019] Building X86GenAsmWriter.inc...
14.315 [864/37/3020] Building X86GenRegisterInfo.inc...
14.326 [864/36/3021] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/CFIFixup.cpp.o
FAILED: lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/CFIFixup.cpp.o 
CCACHE_CPP2=yes CCACHE_HASHDIR=yes /usr/bin/ccache /usr/bin/c++ -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbot/worker/as-builder-4/ramdisk/lld-x86_64/build/lib/CodeGen -I/home/buildbot/worker/as-builder-4/ramdisk/lld-x86_64/llvm-project/llvm/lib/CodeGen -I/home/buildbot/worker/as-builder-4/ramdisk/lld-x86_64/build/include -I/home/buildbot/worker/as-builder-4/ramdisk/lld-x86_64/llvm-project/llvm/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -fno-lifetime-dse -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -std=c++17 -MD -MT lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/CFIFixup.cpp.o -MF lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/CFIFixup.cpp.o.d -o lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/CFIFixup.cpp.o -c /home/buildbot/worker/as-builder-4/ramdisk/lld-x86_64/llvm-project/llvm/lib/CodeGen/CFIFixup.cpp
/home/buildbot/worker/as-builder-4/ramdisk/lld-x86_64/llvm-project/llvm/lib/CodeGen/CFIFixup.cpp: In function ‘llvm::SmallVector<BlockFlags> computeBlockInfo(const llvm::MachineFunction&, const llvm::MachineBasicBlock*)’:
/home/buildbot/worker/as-builder-4/ramdisk/lld-x86_64/llvm-project/llvm/lib/CodeGen/CFIFixup.cpp:174:10: error: could not convert ‘BlockInfo’ from ‘SmallVector<[...],32>’ to ‘SmallVector<[...],40>’
  174 |   return BlockInfo;
      |          ^~~~~~~~~
      |          |
      |          SmallVector<[...],32>
14.636 [864/35/3022] Building X86GenAsmMatcher.inc...
14.761 [864/34/3023] Building X86GenInstrMapping.inc...
14.803 [864/33/3024] Building X86GenAsmWriter1.inc...
14.953 [864/32/3025] Building X86GenMnemonicTables.inc...
15.090 [864/31/3026] Building X86GenFoldTables.inc...
15.619 [864/30/3027] Building X86GenDisassemblerTables.inc...
16.783 [864/29/3028] Building X86GenFastISel.inc...
16.941 [864/28/3029] Building X86GenGlobalISel.inc...
18.822 [864/27/3030] Building X86GenDAGISel.inc...
19.035 [864/26/3031] Building AArch64GenSubtargetInfo.inc...
19.482 [864/25/3032] Building X86GenSubtargetInfo.inc...
20.047 [864/24/3033] Building CXX object lib/MC/MCParser/CMakeFiles/LLVMMCParser.dir/AsmParser.cpp.o
20.207 [864/23/3034] Building AArch64GenInstrInfo.inc...
21.700 [864/22/3035] Building X86GenInstrInfo.inc...
21.988 [864/21/3036] Building RISCVGenInstrInfo.inc...
22.484 [864/20/3037] Building AMDGPUGenMCPseudoLowering.inc...
22.948 [864/19/3038] Building AMDGPUGenCallingConv.inc...
23.087 [864/18/3039] Building RISCVGenGlobalISel.inc...
23.234 [864/17/3040] Building AMDGPUGenPostLegalizeGICombiner.inc...
23.620 [864/16/3041] Building AMDGPUGenRegBankGICombiner.inc...
23.812 [864/15/3042] Building AMDGPUGenSubtargetInfo.inc...
23.936 [864/14/3043] Building AMDGPUGenPreLegalizeGICombiner.inc...
24.007 [864/13/3044] Building AMDGPUGenDisassemblerTables.inc...
24.447 [864/12/3045] Building AMDGPUGenMCCodeEmitter.inc...
25.352 [864/11/3046] Building AMDGPUGenSearchableTables.inc...
26.036 [864/10/3047] Building CXX object lib/CodeGen/AsmPrinter/CMakeFiles/LLVMAsmPrinter.dir/AsmPrinter.cpp.o
26.985 [864/9/3048] Building RISCVGenDAGISel.inc...
27.537 [864/8/3049] Building CXX object lib/LTO/CMakeFiles/LLVMLTO.dir/LTO.cpp.o
31.170 [864/7/3050] Building AMDGPUGenAsmWriter.inc...
32.583 [864/6/3051] Building AMDGPUGenGlobalISel.inc...
33.415 [864/5/3052] Building AMDGPUGenAsmMatcher.inc...

```

</details>

https://github.com/llvm/llvm-project/pull/125137