1*7c3d14c8STreehugger Robot// This file is dual licensed under the MIT and the University of Illinois Open 2*7c3d14c8STreehugger Robot// Source Licenses. See LICENSE.TXT for details. 3*7c3d14c8STreehugger Robot 4*7c3d14c8STreehugger Robot#include "../assembly.h" 5*7c3d14c8STreehugger Robot 6*7c3d14c8STreehugger Robot#ifdef __i386__ 7*7c3d14c8STreehugger Robot 8*7c3d14c8STreehugger Robot// _chkstk (_alloca) routine - probe stack between %esp and (%esp-%eax) in 4k increments, 9*7c3d14c8STreehugger Robot// then decrement %esp by %eax. Preserves all registers except %esp and flags. 10*7c3d14c8STreehugger Robot// This routine is windows specific 11*7c3d14c8STreehugger Robot// http://msdn.microsoft.com/en-us/library/ms648426.aspx 12*7c3d14c8STreehugger Robot 13*7c3d14c8STreehugger Robot.text 14*7c3d14c8STreehugger Robot.balign 4 15*7c3d14c8STreehugger RobotDEFINE_COMPILERRT_FUNCTION(_alloca) // _chkstk and _alloca are the same function 16*7c3d14c8STreehugger RobotDEFINE_COMPILERRT_FUNCTION(__chkstk) 17*7c3d14c8STreehugger Robot push %ecx 18*7c3d14c8STreehugger Robot cmp $0x1000,%eax 19*7c3d14c8STreehugger Robot lea 8(%esp),%ecx // esp before calling this routine -> ecx 20*7c3d14c8STreehugger Robot jb 1f 21*7c3d14c8STreehugger Robot2: 22*7c3d14c8STreehugger Robot sub $0x1000,%ecx 23*7c3d14c8STreehugger Robot test %ecx,(%ecx) 24*7c3d14c8STreehugger Robot sub $0x1000,%eax 25*7c3d14c8STreehugger Robot cmp $0x1000,%eax 26*7c3d14c8STreehugger Robot ja 2b 27*7c3d14c8STreehugger Robot1: 28*7c3d14c8STreehugger Robot sub %eax,%ecx 29*7c3d14c8STreehugger Robot test %ecx,(%ecx) 30*7c3d14c8STreehugger Robot 31*7c3d14c8STreehugger Robot lea 4(%esp),%eax // load pointer to the return address into eax 32*7c3d14c8STreehugger Robot mov %ecx,%esp // install the new top of stack pointer into esp 33*7c3d14c8STreehugger Robot mov -4(%eax),%ecx // restore ecx 34*7c3d14c8STreehugger Robot push (%eax) // push return address onto the stack 35*7c3d14c8STreehugger Robot sub %esp,%eax // restore the original value in eax 36*7c3d14c8STreehugger Robot ret 37*7c3d14c8STreehugger RobotEND_COMPILERRT_FUNCTION(__chkstk) 38*7c3d14c8STreehugger RobotEND_COMPILERRT_FUNCTION(_alloca) 39*7c3d14c8STreehugger Robot 40*7c3d14c8STreehugger Robot#endif // __i386__ 41