Re: Equivalency of Code

[blazar]

In addition and not in contraddiction with what has already been said, you may be interested in -MO=Concise, see B::Concise.

[stvn]

This was actually my first instinct too, here was the output I got from testing with B::Concise.

stvn% perl -MO=Concise -e '$x++'
5  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
4     <1> preinc[t2] vK/1 ->5
-        <1> ex-rv2sv sKRM/1 ->4
3           <#> gvsv[*x] s ->4
-e syntax OK
stvn% perl -MO=Concise -e '$x += 1'
6  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
5     <2> add[t2] vKS/2 ->6
-        <1> ex-rv2sv sKRM/1 ->4
3           <#> gvsv[*x] s ->4
4        <$> const[IV 1] s ->5
-e syntax OK
stvn% perl -MO=Concise -e '$x = $x + 1'
8  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
7     <2> sassign vKS/2 ->8
5        <2> add[t3] sK/2 ->6
-           <1> ex-rv2sv sK/1 ->4
3              <#> gvsv[*x] s ->4
4           <$> const[IV 1] s ->5
-        <1> ex-rv2sv sKRM*/1 ->7
6           <#> gvsv[*x] s ->7
-e syntax OK

You can see that the x += 1 and x = x + 1 are similar, but not enough to call equivalent. Besides I am not sure that opcode equivalence would actually work since perl performs optimizations on the opcode tree during compilation which you would not want to include in your comparisons.

[blazar]

This was actually my first instinct too, here was the output I got from testing with B::Concise.

Indeed, it was just a suggestion along the lines of "just look there", you may be interested in it. Actually one of the most interesting points is exactly that it allows you to see the optimizations that the perl compiler makes...