objective c - @autorelease Pool and Loops (for, while, do) Syntax -

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clang allows following loop syntax:

for (...) @autorelease { ... }  while (...) @autorelease { ... }  @autorelease { ... } while (...);

i haven't found documentation on syntax far (apple doesn't use syntax in guides, @ least no in guides introducing @autorelease construct), reasonable assume 3 statement above equivalent 3 statements below:

for (...) { @autorelease { ... } }  while (...) { @autorelease { ... } }  { @autorelease { ... } } while (...);

since expect them (going standard c syntax rules), yet i'm not entirely sure if that's case. "special syntax", autorelease pool not renewed every loop iteration.

both syntax same

-(void)afunc {     int i=0;     for(;i<5;)         @autoreleasepool {             ++i;         } } -(void)bfunc {     int i=0;     for(;i<5;)     {         @autoreleasepool {             ++i;         }     } }

assembly code

 "-[appdelegate afunc]":                 ## @"\01-[appdelegate afunc]"     .cfi_startproc lfunc_begin0:     .loc    1 12 0                  ## /users/parag/desktop/test/test/appdelegate.m:12:0 ## bb#0:     pushq   %rbp ltmp2:     .cfi_def_cfa_offset 16 ltmp3:     .cfi_offset %rbp, -16     movq    %rsp, %rbp ltmp4:     .cfi_def_cfa_register %rbp     subq    $32, %rsp     movq    %rdi, -8(%rbp)     movq    %rsi, -16(%rbp)     .loc    1 14 12 prologue_end    ## /users/parag/desktop/test/test/appdelegate.m:14:12 ltmp5:     movl    $0, -20(%rbp) lbb0_1:                                 ## =>this inner loop header: depth=1     .loc    1 15 5                  ## /users/parag/desktop/test/test/appdelegate.m:15:5 ltmp6:     cmpl    $5, -20(%rbp)     jge lbb0_3 ## bb#2:                                ##   in loop: header=bb0_1 depth=1     .loc    1 16 26                 ## /users/parag/desktop/test/test/appdelegate.m:16:26 ltmp7:     callq   _objc_autoreleasepoolpush     .loc    1 17 13                 ## /users/parag/desktop/test/test/appdelegate.m:17:13     movl    -20(%rbp), %ecx     addl    $1, %ecx     movl    %ecx, -20(%rbp)     .loc    1 18 9                  ## /users/parag/desktop/test/test/appdelegate.m:18:9     movq    %rax, %rdi     callq   _objc_autoreleasepoolpop     jmp lbb0_1 ltmp8: lbb0_3:     .loc    1 19 1                  ## /users/parag/desktop/test/test/appdelegate.m:19:1     addq    $32, %rsp     popq    %rbp     ret ltmp9: lfunc_end0:     .file   2 "/applications/xcode.app/contents/developer/platforms/macosx.platform/developer/sdks/macosx10.8.sdk/system/library/frameworks/foundation.framework/headers/nsobject.h"     .file   3 "/users/parag/desktop/test/test/appdelegate.h"     .cfi_endproc      .align  4, 0x90 "-[appdelegate bfunc]":                 ## @"\01-[appdelegate bfunc]"     .cfi_startproc lfunc_begin1:     .loc    1 20 0                  ## /users/parag/desktop/test/test/appdelegate.m:20:0 ## bb#0:     pushq   %rbp ltmp12:     .cfi_def_cfa_offset 16 ltmp13:     .cfi_offset %rbp, -16     movq    %rsp, %rbp ltmp14:     .cfi_def_cfa_register %rbp     subq    $32, %rsp     movq    %rdi, -8(%rbp)     movq    %rsi, -16(%rbp)     .loc    1 22 12 prologue_end    ## /users/parag/desktop/test/test/appdelegate.m:22:12 ltmp15:     movl    $0, -20(%rbp) lbb1_1:                                 ## =>this inner loop header: depth=1     .loc    1 23 5                  ## /users/parag/desktop/test/test/appdelegate.m:23:5 ltmp16:     cmpl    $5, -20(%rbp)     jge lbb1_3 ## bb#2:                                ##   in loop: header=bb1_1 depth=1     .loc    1 25 26                 ## /users/parag/desktop/test/test/appdelegate.m:25:26 ltmp17:     callq   _objc_autoreleasepoolpush     .loc    1 26 14                 ## /users/parag/desktop/test/test/appdelegate.m:26:14     movl    -20(%rbp), %ecx     addl    $1, %ecx     movl    %ecx, -20(%rbp)     .loc    1 27 9                  ## /users/parag/desktop/test/test/appdelegate.m:27:9     movq    %rax, %rdi     callq   _objc_autoreleasepoolpop ltmp18:     .loc    1 28 5                  ## /users/parag/desktop/test/test/appdelegate.m:28:5     jmp lbb1_1 ltmp19: lbb1_3:     .loc    1 29 1                  ## /users/parag/desktop/test/test/appdelegate.m:29:1     addq    $32, %rsp     popq    %rbp     ret ltmp20: lfunc_end1:

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