[PATCH] D126948: [ARM] Make narrow push/pop in SEH prologues/epilogues where applicable

[Martin Storsjö via Phabricator via llvm-commits]

mstorsjo created this revision.
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We intentionally disable Thumb2SizeReduction for SEH
prologues/epilogues, to avoid needing to guess what will happen with
the instructions in a potential future pass in frame lowering.

But for this specific case, where we know we can express the
intent with a narrow instruction, change to that instruction form
directly in frame lowering.

I'm unsure if there's some other set of MachineInstr properties I should
copy over here - I didn't try to follow all the generic bits of
Thumb2SizeReduction - this at least seems to work for my testcases;
it only needs to work for these three specific instructions.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D126948

Files:
  llvm/lib/Target/ARM/ARMFrameLowering.cpp
  llvm/test/CodeGen/ARM/Windows/wineh-opcodes.ll
  llvm/test/DebugInfo/COFF/ARMNT/arm-register-variables.ll

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