[Bug rtl-optimization/87871] [9 Regression] testcases fail after r265398 on arm

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87871

--- Comment #39 from Segher Boessenkool <segher at gcc dot gnu.org> ---
On a linux kernel defconfig build it increases code size by 0.567%.
That seems a bit much :-(

The peephole only recognises

  mov rA,rB
  cmp rB,#0

and not

  mov rA,rB
  cmp rA,#0

or

  cmp rB,#0
  mov rA,rB

and we see a lot of the latter, after my patch anyway.