[PATCH] D42006: AArch64: Omit callframe setup/destroy when not necessary

[Matthias Braun via Phabricator via llvm-commits]

MatzeB created this revision.
MatzeB added reviewers: t.p.northover, aemerson, eli.friedman, qcolombet, gberry.
Herald added subscribers: kristof.beyls, javed.absar, mcrosier, rengolin.

Do not create CALLSEQ_START/CALLSEQ_END when there is no callframe to
setup and the callframe size is 0.

- Fixes an invalid callframe nesting for byval arguments. This would fail the machine verifier as it looked like this before this patch (as in `big-byval.ll`):

  ...
  ADJCALLSTACKDOWN 32768, 0, ...   # Setup for extfunc
  ...
  ADJCALLSTACKDOWN 0, 0, ...  # setup for memcpy
  ...
  BL &memcpy ...
  ADJCALLSTACKUP 0, 0, ...    # destroy for memcpy
  ...
  BL &extfunc
  ADJCALLSTACKUP 32768, 0, ...   # destroy for extfunc

- Saves us two instructions in the common case of zero-sized stackframes.
- Remove an unnecessary scheduling barrier (hence the small unittest changes).


Repository:
  rL LLVM

https://reviews.llvm.org/D42006

Files:
  lib/Target/AArch64/AArch64ISelLowering.cpp
  test/CodeGen/AArch64/arm64-hello.ll
  test/CodeGen/AArch64/arm64-shrink-wrapping.ll
  test/CodeGen/AArch64/big-byval.ll
  test/CodeGen/AArch64/func-calls.ll
  test/CodeGen/AArch64/nontemporal.ll
  test/CodeGen/AArch64/swifterror.ll
  test/CodeGen/AArch64/tailcall-explicit-sret.ll

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D42006.129679.patch
Type: text/x-patch
Size: 15070 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180112/98310e00/attachment.bin>