Pirama Arumuga Nainar | 799172d | 2016-03-03 15:50:30 -0800 | [diff] [blame^] | 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 | #ifdef __i386__ |
| 7 | |
| 8 | // _chkstk (_alloca) routine - probe stack between %esp and (%esp-%eax) in 4k increments, |
| 9 | // then decrement %esp by %eax. Preserves all registers except %esp and flags. |
| 10 | // This routine is windows specific |
| 11 | // http://msdn.microsoft.com/en-us/library/ms648426.aspx |
| 12 | |
| 13 | .text |
| 14 | .balign 4 |
| 15 | DEFINE_COMPILERRT_FUNCTION(_alloca) // _chkstk and _alloca are the same function |
| 16 | DEFINE_COMPILERRT_FUNCTION(__chkstk) |
| 17 | push %ecx |
| 18 | cmp $0x1000,%eax |
| 19 | lea 8(%esp),%ecx // esp before calling this routine -> ecx |
| 20 | jb 1f |
| 21 | 2: |
| 22 | sub $0x1000,%ecx |
| 23 | test %ecx,(%ecx) |
| 24 | sub $0x1000,%eax |
| 25 | cmp $0x1000,%eax |
| 26 | ja 2b |
| 27 | 1: |
| 28 | sub %eax,%ecx |
| 29 | test %ecx,(%ecx) |
| 30 | |
| 31 | lea 4(%esp),%eax // load pointer to the return address into eax |
| 32 | mov %ecx,%esp // install the new top of stack pointer into esp |
| 33 | mov -4(%eax),%ecx // restore ecx |
| 34 | push (%eax) // push return address onto the stack |
| 35 | sub %esp,%eax // restore the original value in eax |
| 36 | ret |
| 37 | END_COMPILERRT_FUNCTION(__chkstk) |
| 38 | END_COMPILERRT_FUNCTION(_alloca) |
| 39 | |
| 40 | #endif // __i386__ |