[PATCH] D129932: [AArch64] Use SUBXrx64 for dynamic stack to refer to sp

[chenglin.bi via Phabricator via llvm-commits]

bcl5980 created this revision.
bcl5980 added reviewers: dmgreen, efriedma, paulwalker-arm.
Herald added subscribers: hiraditya, kristof.beyls.
Herald added a project: All.
bcl5980 requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

When we lower dynamic stack, we need to substract pattern `number << 4`  from sp.
Subtract instruction with arith shifted register(SUBXrs) can't refer to sp. So for now we need two extra mov like:

  mov x0, sp
  sub x0, x0, x15, lsl #4
  mov sp, x0

If we want to refer to sp in subtract instruction like this:

  sub	sp, sp, x15, lsl #4

We must use arith extended register version(SUBXrx). 
So in this patch we use machine node SUBXrx64 instead of ISD:SUB to make sure the dynamic stack subtract can refer to sp.


https://reviews.llvm.org/D129932

Files:
  llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
  llvm/lib/Target/AArch64/AArch64ISelLowering.h
  llvm/test/CodeGen/AArch64/win-alloca.ll
  llvm/test/CodeGen/AArch64/win64_vararg.ll

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D129932.445227.patch
Type: text/x-patch
Size: 4604 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20220716/22e35213/attachment.bin>