[PATCH] D18374: [X86] Use "and $0" and "orl $-1" to store 0 and -1 when optimizing for minsize

[Hans Wennborg via llvm-commits]

hans created this revision.
hans added reviewers: DavidKreitzer, zansari.
hans added subscribers: llvm-commits, joerg.

64-bit, 32-bit and 16-bit move-immediate instructions are 7, 6, and 5 bytes, respectively, whereas 8-bit and/or is only three bytes.

Since these instructions imply an additional memory read (which the CPU could elide, but we don't think it does), restrict these patterns to minsize functions.

http://reviews.llvm.org/D18374

Files:
  lib/Target/X86/X86ISelDAGToDAG.cpp
  lib/Target/X86/X86InstrCompiler.td
  lib/Target/X86/X86InstrInfo.td
  test/CodeGen/X86/store-zero.ll
  test/CodeGen/X86/tail-opts.ll

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