Catfish-Man

As of iOS 11/macOS High Sierra, and only including ones in Foundation and CoreFoundation

Strings:

_NSCFString - a CFStringRef or CFMutableStringRef. This is the most common type of string object currently.
    - May have 8 bit (ASCII) or 16 bit (UTF-16) backing store
_NSCFConstantString - a compile time constant CFStringRef, like you'd get with @"foo"
    - May also be generated by dynamic string creation if matches a string in a pre-baked table of common strings called the StringROM
NSBigMutableString - an NSString backed by a CFStorage (https://github.com/opensource-apple/CF/blob/master/CFStorage.h) for faster handling of very large strings
NSCheapMutableString - a very limited NSMutableString that allows for zero-copy initialization. Used in NSFileManager for temporarily wrapping stack buffers.

Catfish-Man

#import <Foundation/Foundation.h>
#import <time.h>

#define USE_CF_NONOBJC 1

#if USE_CF_NONOBJC
extern CFTypeRef _CFNonObjCRetain(CFTypeRef cf);
extern void _CFNonObjCRelease(CFTypeRef cf);
#endif

Catfish-Man

Let's Reinvent Modern CPU Caches!

In The Beginning, programs were hard-coded, entered directly with switches. Values would be input, and then results would output,
but couldn't really be stored. We'll draw this like so:

Input -> Fixed Calculations -> Output

An early improvement in generality was the addition of storage (ENIAC eventually gained 100 words of magnetic core memory),
leaving us with something along these lines:

Catfish-Man

// Compile with clang -framework Foundation sethack.m

#import <Foundation/Foundation.h>
#import <objc/runtime.h>

/*
 CFHashBytes from http://www.opensource.apple.com/source/CF/CF-1153.18/CFUtilities.c
 */
#define ELF_STEP(B) T1 = (H << 4) + B; T2 = T1 & 0xF0000000; if (T2) T1 ^= (T2 >> 24); T1 &= (~T2); H = T1;

Catfish-Man

#import <Foundation/Foundation.h>
#import <assert.h>

//Compile with `clang -Os -framework Foundation -fno-objc-arc inlinestorage.m -o inline, run with `inline clever` or `inline naive`

/*
 NaiveArray implements a simple immutable NSArray-like interface in probably the most obvious way: store a pointer to a C array of objects
 */
@interface NaiveArray : NSObject {
    NSUInteger count;

Catfish-Man

#import <stdlib.h>
#import <malloc/malloc.h>

#define SLOW 1

int main(int argc, const char * argv[]) {
#if SLOW
  int sizes[] = { 256032, 512032, 1024032, 1792032 };
  
  for (int ii = 0; ii < 10000; ii++) {

Catfish-Man

/*
Shell version:

paste -d , oldoutput.txt output.txt | awk -F "," '{printf "%s %s %s %f\n", $2, $8, $16, $8 / $16}' | sort -k4 | egrep -v "(1\.0|0\.9[1-9])"
*/

import Foundation

// "paste -d , oldfile.txt newfile.txt"
let paths = CommandLine.arguments[1...2].map(URL.init(fileURLWithPath:))

Catfish-Man

func g(_ x: inout Int) {
    x = x * x
}

func f() { 
     var computed:Int { 
         get { return 5 } 
         set { print(newValue) } 
     } 
     g(&computed) 

Catfish-Man

//compile with "clang -framework Foundation -arch i386 failbuzz.m -o FizzBuzz"
//Yes, it only works in 32 bit
//No, I can't fix it to work correctly past 12 without coming up with a new implementation strategy, 
//or compiling a new CoreFoundation that caches more CFNumbers (…I did do that to be sure it worked though)

#import <Foundation/Foundation.h>
#import <libgen.h>

static void setup(const char * argv[]) {
    for (int i = 1; i <= 100; i++) {

Catfish-Man

//Given this:
NSArray *objects = @[@1, @2, @3]

//These are equivalent in behavior
NSNumber *first = [objects objectAtIndex:0]
NSNumber *second = (NSNumber *)CFArrayGetValueAtIndex(objects, 0)

//But is the code that runs the same? Not so much… in the first one we do…
objc_msgSend(objects, <selector reference>, 0)
-> http://sealiesoftware.com/msg/x86-mavericks.html