Re: [Tinycc-devel] if (0 == 1) { some_code(); }

[Michael Matz]

Hi,

On Sun, 24 Apr 2016, Sergey Korshunoff wrote:

> What to do with 78_vla_label test? May be a tcc switch to skip unused code?

No.

> void f1(int argc) {
>  char test[argc];
>  if(0)
>  label:
>    printf("boom!\n");
>  if(argc-- == 0)
>    return;
>  goto label;
> }

This is valid code, while your kernel example (and the implicit 
expectation in your printf example, that there's no reference to printf) 
is simply buggy code (buggy in that it doesn't provide the necessary 
definition of a symbol despite it being referenced).

TCC should foremost be able to compile correct code.  "Optimizations" that 
make it sometimes also accept invalid code don't have a place in TCC IMHO, 
even less so if not trivial to implement.  A switch that would do the 
wrong thing with valid code, while working around invalid code simply is a 
no-go to start with.


Ciao,
Michael.