[PATCH] D24747: [AArch64] Improve isel of negate of zext.

[Geoff Berry via llvm-commits]

gberry created this revision.
gberry added reviewers: t.p.northover, jmolloy.
gberry added subscribers: llvm-commits, mcrosier.
Herald added subscribers: rengolin, aemerson.

Given the below IR:
  %m = and i32 %x, 3
  %ext = zext i32 %m to i64
  %ret = sub i64 0, %ext

generate:
  and w8, w0, #3
  sub x0, xzr, x8

instead of:
  mov x8, xzr
  and w9, w0, #3
  sub x0, x8, w9, uxtw

https://reviews.llvm.org/D24747

Files:
  lib/Target/AArch64/AArch64InstrInfo.td
  test/CodeGen/AArch64/addsub_ext.ll
  test/CodeGen/AArch64/neg-zext.ll

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