Expand peephole pass has matched two pattern but diff instruction list

[wangnianwu]

pseudo code

I have two pattern rules like this.

• First case
  I need to remove the instruction 'iget-wide '

iput-wide v1, v0, Lcom/example/myapplication/ui/home/Peephole;->put_wide_value:J
iget-wide v1, v0, Lcom/example/myapplication/ui/home/Peephole;->put_wide_value:J 
return-void

Pattern A:

iput_field(Register::A, Register::B, reference)
iget_field(Register::A, Register::B, reference)

• Second case
  I need to replace the second instruction 'iget-wide ' to 'move v2, v1'

iput-wide v1, v0, Lcom/example/myapplication/ui/home/Peephole;->put_wide_value:J
iget-wide v2, v0, Lcom/example/myapplication/ui/home/Peephole;->put_wide_value:J 
return-void

Pattern B:

iput_field(Register::A, Register::B, reference)
iget_field(Register::C, Register::B, reference)

Problem

The instruction list at this:

iput-wide v1, v0, Lcom/example/myapplication/ui/home/Peephole;->put_wide_value:J
iget-wide v2, v0, Lcom/example/myapplication/ui/home/Peephole;->put_wide_value:J 
return-void

has been matched by the pattern A and B.

Analyze

From redex source code at try_match method in peephole pass

    auto match_reg = [&](Register pattern_reg, reg_t insn_reg) {
      // This register has been observed already. Check whether they are same.
      if (matched_regs.find(pattern_reg) != end(matched_regs)) {
        return matched_regs.at(pattern_reg) == insn_reg;
      }

      // Newly observed. Remember it.
      matched_regs.emplace(pattern_reg, insn_reg);
      return true;
    };

The pattern_reg and insn_reg is not one to one. The insn_reg can set to multi Register value.

[NTillmann]

I am confused. Are you suggesting there's a bug? For your "Problem", pattern A cannot match.

[wangnianwu]

I am confused. Are you suggesting there's a bug? For your "Problem", pattern A cannot match.

@NTillmann Yes. I think that the source code（“Problem”） can match pattern B not A. But I get all matched.
In the patterns, I think that I have set 3 different registers(A\B\C) in pattern B but set 2 different registers(A\B) in pattern A.
So, it should match pattern B.