compiler-builtins-zynq/src/x86_64.rs

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#![allow(unused_imports)]
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use core::intrinsics;
// NOTE These functions are implemented using assembly because they using a custom
// calling convention which can't be implemented using a normal Rust function
// NOTE These functions are never mangled as they are not tested against compiler-rt
// and mangling ___chkstk would break the `jmp ___chkstk` instruction in __alloca
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#[cfg(windows)]
#[naked]
#[no_mangle]
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pub unsafe fn ___chkstk_ms() {
asm!("push %rcx
push %rax
cmp $$0x1000,%rax
lea 24(%rsp),%rcx
jb 1f
2:
sub $$0x1000,%rcx
test %rcx,(%rcx)
sub $$0x1000,%rax
cmp $$0x1000,%rax
ja 2b
1:
sub %rax,%rcx
test %rcx,(%rcx)
pop %rax
pop %rcx
ret");
intrinsics::unreachable();
}
#[cfg(windows)]
#[naked]
#[no_mangle]
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pub unsafe fn __alloca() {
asm!("mov %rcx,%rax // x64 _alloca is a normal function with parameter in rcx
jmp ___chkstk // Jump to ___chkstk since fallthrough may be unreliable");
intrinsics::unreachable();
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}
#[cfg(windows)]
#[naked]
#[no_mangle]
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pub unsafe fn ___chkstk() {
asm!("push %rcx
cmp $$0x1000,%rax
lea 16(%rsp),%rcx // rsp before calling this routine -> rcx
jb 1f
2:
sub $$0x1000,%rcx
test %rcx,(%rcx)
sub $$0x1000,%rax
cmp $$0x1000,%rax
ja 2b
1:
sub %rax,%rcx
test %rcx,(%rcx)
lea 8(%rsp),%rax // load pointer to the return address into rax
mov %rcx,%rsp // install the new top of stack pointer into rsp
mov -8(%rax),%rcx // restore rcx
push (%rax) // push return address onto the stack
sub %rsp,%rax // restore the original value in rax
ret");
intrinsics::unreachable();
}