src/compiler-rt/lib/builtins/x86_64/chkstk.S

   1 // This file is dual licensed under the MIT and the University of Illinois Open
   2 // Source Licenses. See LICENSE.TXT for details.
   3
   4 #include "../assembly.h"
   5
   6 // _chkstk routine
   7 // This routine is windows specific
   8 // http://msdn.microsoft.com/en-us/library/ms648426.aspx
   9
  10 // Notes from r227519
  11 // MSVC x64s __chkstk and cygmings ___chkstk_ms do not adjust %rsp
  12 // themselves. It also does not clobber %rax so we can reuse it when
  13 // adjusting %rsp.
  14
  15 #ifdef __x86_64__
  16
  17 .text
  18 .balign 4
  19 DEFINE_COMPILERRT_FUNCTION(___chkstk_ms)
  20         push   %rcx
  21         push   %rax
  22         cmp    $0x1000,%rax
  23         lea    24(%rsp),%rcx
  24         jb     1f
  25 2:
  26         sub    $0x1000,%rcx
  27         test   %rcx,(%rcx)
  28         sub    $0x1000,%rax
  29         cmp    $0x1000,%rax
  30         ja     2b
  31 1:
  32         sub    %rax,%rcx
  33         test   %rcx,(%rcx)
  34         pop    %rax
  35         pop    %rcx
  36         ret
  37 END_COMPILERRT_FUNCTION(___chkstk_ms)
  38
  39 #endif // __x86_64__