Re: Problem with peephole to peephole2 conversion

[Paolo Bonzini <paolo dot bonzini at lu dot unisi dot ch>]

Ashwin wrote:
> The problem in front of me is something like this..
>
> op0 = 1
> op1 = op0 leftshift op2
>
> This will be optimized to
> op1 = 1 leftshift op2 (by the peephole2 pass to the rtl pattern 
> corresponding to this and hence the requirement that op0 should be dead 
> after insn2)
>
> However if the pattern happens to be something like this :
>
> op0 = 1
> op0 = op0 leftshift op2
> ...
> use of op0 here
> ...
>
> The pattern matches in any case.

You'll have something like this in your test

operands[0] == operands[1] || peep2_regno_dead_p (2, operands[0])

i.e. you only need to test for op0's death if it is different from op1.

Paolo