[PATCH] D35075: [AArch64] Redundant copy elimination - remove more zero copies.

[Chad Rosier via Phabricator via llvm-commits]

mcrosier created this revision.
Herald added subscribers: kristof.beyls, javed.absar, rengolin, aemerson.

This pass removes unnecessary zero copies in BBs that are targets of b.eq/b.ne and we know the result of the compare instruction is zero.  For example,

  BB#0:
    subs w0, w1, w2
    str w0, [x1]
    b.ne .LBB0_2
  BB#1:
    mov w0, wzr  ; <-- redundant
    str w0, [x2]
  .LBB0_2

See test cases for additional examples.

Chad


https://reviews.llvm.org/D35075

Files:
  lib/Target/AArch64/AArch64RedundantCopyElimination.cpp
  test/CodeGen/AArch64/machine-zero-copy-remove.mir

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