Re: Big leak fished!

On Thursday, July 31, 2003, at 09:12  AM, Stefano Corsi wrote:

> Hi Dave,
>
> I was not conformatble with moto dying in this kind of loops:
>
> ${
>
>         int i = 10000;
>         while (i-- > 0) {
>                 int j = 10000;
>                 while(j-- > 0) {
>                         int k;
>                 }
>         }
>
> }$
>
> so I noticed that if you take away the declaration and you have only 
> this:
>
> ${
>
>         int i = 10000;
>         while (i-- > 0) {
>                 int j = 10000;
>                 while(j-- > 0) {
>                 }
>         }
>
> }$
>
> moto does not die.
> So the problem is that when moto_freeFrame frees all the frame 
> variables, it
> does not free the strdupped string representing the name and this can 
> lead to
> megabytes of shared memory, in case of such loops (even if probably 
> they are
> not so common nor useful...):
>
> if(env->mode != COMPILER_MODE) {
> 	moto_freeVal(env,var->vs);
> } else {
> 	opool_release(env->valpool,var->vs);
> }
> free(var->n); // <-- this was missing
> free(var);
>

I believe the above variable name free was left out on-purpose for the 
cases when class member variables were pushed onto the frame. I notice 
specifically in motoi_callMDF we have:

		e = vec_elements(mcd->memberVarNames);
		while(enum_hasNext(e)){
			char* varn=(char*)enum_next(e);
			
			/* Fake variable shadowing by simply not loading in a member var
				with the same name as an argument */
				
			if(moto_getFrameVar(env,varn) == NULL) {
				MotoVar* var = moto_createVar(
					env,varn,
					mcd_getMemberType(mcd,varn),
					0,
					'\1',
					mci+mcd_getMemberOffset(mcd,varn)
				);
				stab_put(env->frame->symtab, var->n, var);
			}
		}
		enum_free(e);

which definitely does not duplicate the variable name. Also in 
motoi_callMDF we don't duplicate the argument names when calling moto 
defined functions:

	/* Push arguments onto the frame by declaring them */
	for(i=0;i<argc;i++){
		UnionCell* argdec = uc_operand(argListUC,i);
		UnionCell* atype_uc = uc_operand(argdec,0);
		
		int argdecDim ;
		
		char *aname;
		MotoVar* avar;
		MotoType* atype;
		
		atype = motox_extractType(atype_uc);
		aname = uc_str(argdec,1);
		argdecDim = uc_opcount(uc_operand(argdec, 2));

		/* Declare the argument variable */
		avar = moto_declareVar(env, aname, atype->name, argdecDim, '\0');

		moto_setVarVal(env, avar, args[i]);
	}

So I'm thinking that calling moto_strdup on the variable name in 
motoi_declare is not necessary (since variable names aren't 
specifically freed until the end of a page anyhow). I'm going to try 
removing it from motoi_declare by changing

		/* Get the variable name and dimension */
		varn = moto_strdup(env, uc_str(declarator_uc, 0));
		vdim = uc_opcount(uc_operand(declarator_uc, 1));

to

		/* Get the variable name and dimension */
		varn = uc_str(declarator_uc, 0);
		vdim = uc_opcount(uc_operand(declarator_uc, 1));

and see what breaks :)

-Dave

BTW: after making this change all tests still pass

> Now it works. Slowly, but it works!
>
> Stefano
>
>