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Re: [tree-ssa] Removing useless/redundant "const" calls
Fergus Henderson <fjh@cs.mu.oz.au> writes:
> On 12-Jun-2003, Zack Weinberg <zack@codesourcery.com> wrote:
>> This seems like an opportune moment to point out that calls to
>> noreturn functions shouldn't count as side effects when determining
>> whether functions are pure or const.
>
> That is not correct in general.
I disagree.
> Doing that would violate the C standard, and would potentially create
> security holes. Consider, for example:
>
> #define ARRAY_SIZE 10
> int array[ARRAY_SIZE];
>
> void checkbounds(int arg) {
> if (arg < 0) abort();
> if (arg > ARRAY_SIZE) abort();
> }
>
> int set_array(int posn, int val) {
> checkbounds(posn);
> array[posn] = val;
> }
checkbounds() returns no value, so it must be used for its side
effects, so it isn't pure.
zw