kit

kit
git clone https://git.ryansepassi.com/git/kit.git
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chkstk_x86_64_win.c (847B)

      1 /*
      2  * Win64 stack probes.
      3  *
      4  * x64 callers pass the pending frame allocation size in rax, call the probe,
      5  * then subtract rax from rsp. The probe touches each intervening page and
      6  * returns with rax preserved.
      7  */
      8 
      9 __asm__(
     10     ".text\n"
     11     ".globl __chkstk\n"
     12     "__chkstk:\n"
     13     ".globl ___chkstk_ms\n"
     14     "___chkstk_ms:\n"
     15     "    movq %rsp, %r10\n"
     16     "    addq $8, %r10\n"
     17     "    movq %rax, %r11\n"
     18     "    cmpq $4096, %r11\n"
     19     "    jb __kit_chkstk_last\n"
     20     "__kit_chkstk_loop:\n"
     21     "    subq $4096, %r10\n"
     22     "    movq (%r10), %rcx\n"
     23     "    subq $4096, %r11\n"
     24     "    cmpq $4096, %r11\n"
     25     "    jae __kit_chkstk_loop\n"
     26     "    testq %r11, %r11\n"
     27     "    je __kit_chkstk_done\n"
     28     "__kit_chkstk_last:\n"
     29     "    subq %r11, %r10\n"
     30     "    movq (%r10), %rcx\n"
     31     "__kit_chkstk_done:\n"
     32     "    ret\n");