The code in ysth's post is completely definitive, of course, and can be further verified by using the Perl bytecode compiler (B::Bytecode). If you execute the following:

perl -MO=Bytecode,-H,-ofor_loop    -e 'for (;;) {}'
perl -MO=Bytecode,-H,-owhile_loop  -e 'while () {}'
perl -MO=Bytecode,-H,-owhile1_loop -e 'while (1) {}'
[download]

and then diff the resulting files (for_loop, while_loop and while1_loop), you will find that they are all completely identical. This means that all three are exactly equivalent as far as code execution goes.