Re: Bootstraping compilers ?

On 2008-04-18, Damian Thomas <damian.thomas@[EMAIL PROTECTED]
> wrote:
> Do not stop at simply compiling, but also using the resulting compiler
to
> compile itself again and again and again.
> I suggest at least 3 generations of compiles.  Some say you should need
5
> generations.
> 1st - finds compile-time errors
> 2nd - finds run-time errors
> 3rd - finds errors where the compiler ran improperly
> 4th - finds errors where the program ran correctly, but produced
incorrect
> results
> 5th - ?

Binary comparing the nth and the n+1th can give information about
uninitialised data written to constants, alignment spaces etc, padding
bytes
to make the binary a multiple of some blocksize and other non
deterministic
behaviour

Moreover, only the 2nd time the compiler is compiled in full, e.g. since
the
first step might suffer from ifdefs due to the reference compiler having
certain bugs or missing language features. So the 2nd time might find
compile bugs there too.