1// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
2// See https://llvm.org/LICENSE.txt for license information.
3// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
4
5#include "../assembly.h"
6
7// __chkstk routine
8// This routine is windows specific.
9// http://msdn.microsoft.com/en-us/library/ms648426.aspx
10
11// This clobbers the register r12, and the condition codes, and uses r5 and r6
12// as temporaries by backing them up and restoring them afterwards.
13// Does not modify any memory or the stack pointer.
14
15//      movw    r4,  #256 // Number of bytes of stack, in units of 4 byte
16//      bl      __chkstk
17//      sub.w   sp, sp, r4
18
19#define PAGE_SIZE 4096
20
21        .p2align 2
22DEFINE_COMPILERRT_FUNCTION(__chkstk)
23        lsl    r4,  r4,  #2
24        mov    r12, sp
25        push   {r5, r6}
26        mov    r5,  r4
271:
28        sub    r12, r12, #PAGE_SIZE
29        subs   r5,  r5,  #PAGE_SIZE
30        ldr    r6,  [r12]
31        bgt    1b
32
33        pop    {r5, r6}
34        bx     lr
35END_COMPILERRT_FUNCTION(__chkstk)
36