Yonghong Song e91802f336 bpf: New post-RA peephole optimization pass to eliminate bad RA codegen ...

This new pass eliminate identical move:

  MOV rA, rA

This is particularly possible to happen when sub-register support
enabled. The special type cast insn MOV_32_64 involves different
register class on src (i32) and dst (i64), RA could generate useless
instruction due to this.

This pass also could serve as the bast for further post-RA optimization.

Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
llvm-svn: 327370

2018-03-13 06:47:06 +00:00

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