[llvm] [RegAllocFast] Lower tied operands, absorbing TwoAddressInstructionPass (PR #225316)

[Fangrui Song via llvm-commits]

MaskRay wrote:

Tracker run for `setEnableTiedFastRegAlloc(true);` within `llvm/lib/Target/X86/X86TargetMachine.cpp`

% ct_table.rb 'https://llvm-compile-time-tracker.com/compare.php?from=8f564591b6fd0677350c27861271b56cf1686327&to=fe440981b0ba9b0e6700a1da4f5dbdabeda4b239&stat=instructions:u'
CTMark geomean `instructions:u`: 🟢 2 improved (best -0.84%) · 6 within noise.

| Config                | instructions:u |   σ | max-rss |
| :-------------------- | -------------: | --: | ------: |
| stage1-O3             |         +0.02% | 1.5 |  +0.03% |
| stage1-ReleaseThinLTO |         +0.00% | 0.1 |  +0.14% |
| stage1-ReleaseLTO-g   |         -0.01% | 0.4 |  +0.15% |
| stage1-O0-g           |  🟢 **-0.84%** |  51 |  -0.20% |
| stage1-aarch64-O3     |         -0.01% | 0.8 |  -0.01% |
| stage1-aarch64-O0-g   |         +0.02% | 1.1 |  +0.01% |
| stage2-O3             |         +0.00% | 0.1 |  +0.18% |
| stage2-O0-g           |  🟢 **-0.84%** |  38 |  -0.24% |

https://github.com/llvm/llvm-project/pull/225316