port to iOS

I saw the previous iOS issue. I want to get this working on iOS too so I'm game to do any and all code changes and debugging for you if you point me in the right direction.

I tried linking the object file as well as the static library, same crashes.

This below crash is happening before my main.c is called.

myapp`mi_heap_main_init:
    0x104c18b70 <+0>:   stp    x22, x21, [sp, #-0x30]!
    0x104c18b74 <+4>:   stp    x20, x19, [sp, #0x10]
    0x104c18b78 <+8>:   stp    x29, x30, [sp, #0x20]
    0x104c18b7c <+12>:  add    x29, sp, #0x20            ; =0x20 
    0x104c18b80 <+16>:  adrp   x8, 8778
    0x104c18b84 <+20>:  ldr    x8, [x8, #0x2d0]
    0x104c18b88 <+24>:  cbz    x8, 0x104c18b9c           ; <+44>
    0x104c18b8c <+28>:  ldp    x29, x30, [sp, #0x20]
    0x104c18b90 <+32>:  ldp    x20, x19, [sp, #0x10]
    0x104c18b94 <+36>:  ldp    x22, x21, [sp], #0x30
    0x104c18b98 <+40>:  ret    
    0x104c18b9c <+44>:  mrs    x8, TPIDR_EL0
    0x104c18ba0 <+48>:  ldr    x8, [x8]                                 -> EXC_BAD_ACCESS (code=1, address=0x0)
    0x104c18ba4 <+52>:  adrp   x9, 8778
    0x104c18ba8 <+56>:  str    x8, [x9, #0x2c8]
    0x104c18bac <+60>:  bl     0x1051b5ef8               ; symbol stub for: mach_absolute_time
    0x104c18bb0 <+64>:  adr    x8, #-0xcd28              ; _os_random_weak

If you're familiar with Cocoapods, it's an easy way to compile/link a whole bunch of libraries to your iOS app. And I was getting another crash before as well, on the code snippet below, on the @available line in some GoogleDataTransport pod, before I just commented out the code for now. MI_MALLOC_VERSION was printing correctly though.

printf("MI_MALLOC_VERSION = %d\n", mi_version());
      
#if defined(__IPHONE_13_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 130000
//    if (@available(iOS 13, tvOS 13.0, *)) {
//      [notificationCenter addObserver:self
//                             selector:@selector(iOSApplicationWillEnterForeground:)
//                                 name:UISceneWillEnterForegroundNotification
//                               object:nil];
//      [notificationCenter addObserver:self
//                             selector:@selector(iOSApplicationDidEnterBackground:)
//                                 name:UISceneWillDeactivateNotification
//                               object:nil];
//    }
#endif  // defined(__IPHONE_13_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 130000

and here was that crash..

myapp`malloc:
    0x100929bdc <+0>:  mov    x1, x0
    0x100929be0 <+4>:  mrs    x8, TPIDR_EL0
   0x100929be4 <+8>:  ldr    x8, [x8, #0x2c8]                     ->  EXC_BAD_ACCESS (code=1, address=0x2c8)
    0x100929be8 <+12>: adrp   x9, 8571
    0x100929bec <+16>: add    x9, x9, #0x988            ; =0x988 
    0x100929bf0 <+20>: cmp    x8, #0x0                  ; =0x0 
    0x100929bf4 <+24>: csel   x0, x9, x8, eq
    0x100929bf8 <+28>: cmp    x1, #0x400                ; =0x400 
    0x100929bfc <+32>: b.hi   0x100929c34               ; <+88>
    0x100929c00 <+36>: add    x8, x1, #0x7              ; =0x7 
    0x100929c04 <+40>: and    x8, x8, #0xfffffffffffffff8
    0x100929c08 <+44>: add    x8, x0, x8
    0x100929c0c <+48>: ldr    x9, [x8, #0x8]
    0x100929c10 <+52>: ldr    x8, [x9, #0x8]
    0x100929c14 <+56>: cbz    x8, 0x100929c34           ; <+88>
    0x100929c18 <+60>: ldr    x10, [x8]
    0x100929c1c <+64>: str    x10, [x9, #0x8]
    0x100929c20 <+68>: ldr    w10, [x9, #0x10]
    0x100929c24 <+72>: add    w10, w10, #0x1            ; =0x1 
    0x100929c28 <+76>: str    w10, [x9, #0x10]
    0x100929c2c <+80>: mov    x0, x8
    0x100929c30 <+84>: ret    
    0x100929c34 <+88>: b      0x10092762c               ; _mi_malloc_generic

where do we start?

Start with the reported iOS integration and the entry points mi_heap_main_init and malloc, using the CocoaPods setup described in the issue to reproduce the pre-main crashes. Done means mimalloc links as an object file or static library and an iOS app starts without the reported EXC_BAD_ACCESS failures.