[all-commits] [llvm/llvm-project] 6f1474: [RegAlloc] Constrain rematted regclass to use (#16...

[Luke Lau via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6f147445f7cfa8b5f09f154b63ef8073ed6243a1
      https://github.com/llvm/llvm-project/commit/6f147445f7cfa8b5f09f154b63ef8073ed6243a1
  Author: Luke Lau <luke at igalia.com>
  Date:   2025-10-23 (Thu, 23 Oct 2025)

  Changed paths:
    M llvm/lib/CodeGen/InlineSpiller.cpp
    A llvm/test/CodeGen/AArch64/pr164181.ll

  Log Message:
  -----------
  [RegAlloc] Constrain rematted regclass to use (#164386)

When rematting we create a new virtual register with the original def's
register class. However the use may have a different register class if
the interval is split, which means we end up with an invalid register
class.

This fixes #164181 by constraining the newly created register to the
use's register class.

The test case is reduced as far as it goes. Because this test requires
us to reach a certain amount of register pressure in certain conditions
I'm not sure if there's an easy way to handwrite this scenario.



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