"J.A. Magallón" <jamagallon@ono.com> writes:

quoted text
> That's what __attribute__ ((pure)) is for, but if none of the
> functions is pure, the compiler can not be sure about side effects
> and can not reorder things. Don't forget that functions can do
> anything apart from mangling with their arguments.

Though it seems it could legally transform:

void kfree(const int *x);

{
int v, *ptr = malloc(sizeof(int));
*ptr = 51;
v = *ptr;
kfree(ptr);
printf("%d", v);

into:

{
int v, *ptr = malloc(sizeof(int));
*ptr = 51;
kfree(ptr);
v = *ptr;
printf("%d", v);
}

if it knows that malloc generates unaliased pointers, which seems
reasonable in general.
-- 
Krzysztof Halasa
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