Test on the LLVM compiler optimisation

gistfile1.txt

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        
        // insert code here...
        NSURL *url = [NSURL fileURLWithPath:@"file://localhost/usr/bin/"];
        NSMutableArray *a = [NSMutableArray array];
        NSMutableArray *b = [NSMutableArray array];
        NSDate *date = [NSDate date];
        for (int i = 0; i < 99999 ; i++) {
            [a addObject:[url path]];
            [b addObject:[url path]];
        }
        NSLog(@"no resolve: %lfs", -1*([date timeIntervalSinceNow]));

        // insert code here...
        NSURL *url2 = [NSURL fileURLWithPath:@"file://localhost/usr/bin/"];
        NSMutableArray *c = [NSMutableArray array];
        NSMutableArray *d = [NSMutableArray array];
        NSDate *d2 = [NSDate date];
        for (int i = 0; i < 99999 ; i++) {
            NSString *p = [url2 path];
            [c addObject:p];
            [d addObject:p];
        }
        NSLog(@"resolve: %lfs", -1*([d2 timeIntervalSinceNow]));
        
    }
    return 0;
}

Results: It takes twice as long for loop 1 to run than loop 2. You'd have thought LLVM would figure out that [url path] is called twice. Oh well

Notes: the only difference between the two loops is line 25 which resolves the URL path first