[PATCH] D138007: [LoongArch] Add emergency spill slot for CFR spill/reload

[wanglei via Phabricator via llvm-commits]

wangleiat created this revision.
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When all registers have been allocated and CFR needs to be saved on the
stack, an emergency spill slot is required. Because CFR's spill and
reload require a general purpose register to transfer.

The attached test case was bugpoint-reduced down from
`MultiSource/Benchmarks/mafft/Lalignmm.c` in the test-suite.
Without this patch, llc will crash and report the following errors:

  LLVM ERROR: Error while trying to spill R4 from class GPR: Cannot scavenge register without an emergency spill slot!


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D138007

Files:
  llvm/lib/Target/LoongArch/LoongArchFrameLowering.cpp
  llvm/test/CodeGen/LoongArch/mafft-Lalignmm.ll

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