[PATCH] D143711: [ARM] Fix Crash in 't'/'w' handling without fp16/fp16

[Sam Elliott via Phabricator via llvm-commits]

lenary created this revision.
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After https://reviews.llvm.org/rGff4027d152d0 and
https://reviews.llvm.org/rG7d15212b8c0c we saw crashes in SelectionDAG
when trying to use these constraints when you don't have the fp16 or
bf16 extensions.

However, it is still possible to move 16-bit floating point values into
the right place in S registers with a normal `vmov`, even if we don't
have fp16 instructions we can use within the inline assembly string.
This patch therefore fixes the crash.

I think the reason we weren't getting this crash before is because I
think the __fp16 and __bf16 types got an error diagnostic in the Clang
frontend when you didn't have the right architectural extensions to use
them. This restriction was recently relaxed.

Test Changes:

- Added more testing for testing inline asm (the core part)
- fp16-promote.ll and pr47454.ll show improvements where unnecessary fp16-fp32 up/down-casts are no longer emitted. This results in fewer libcalls where those casts would be done with a libcall.
- aes-erratum-fix.ll is fairly noisy, and I need to revisit this test so that the IR is more minimal than it is right now, because most of the changes in this commit do not relate to what AES is actually trying to verify.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D143711

Files:
  llvm/lib/Target/ARM/ARMISelLowering.cpp
  llvm/test/CodeGen/ARM/aes-erratum-fix.ll
  llvm/test/CodeGen/ARM/fp16-promote.ll
  llvm/test/CodeGen/ARM/inlineasm-fp-half.ll
  llvm/test/CodeGen/ARM/pr47454.ll

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