Add x86_64 builtins

This commit is contained in:
Matt Ickstadt 2016-08-16 17:46:46 -05:00
parent 89594e16ae
commit b6091ababa
2 changed files with 70 additions and 0 deletions

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@ -23,6 +23,9 @@ extern crate rlibc;
#[cfg(target_arch = "arm")] #[cfg(target_arch = "arm")]
pub mod arm; pub mod arm;
#[cfg(target_arch = "x86_64")]
pub mod x86_64;
pub mod udiv; pub mod udiv;
pub mod mul; pub mod mul;
pub mod shift; pub mod shift;

67
src/x86_64.rs Normal file
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@ -0,0 +1,67 @@
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
#[cfg(windows)]
#[naked]
#[cfg_attr(not(test), no_mangle)]
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]
#[cfg_attr(not(test), no_mangle)]
pub unsafe fn __alloca() {
asm!("mov %rcx,%rax // x64 _alloca is a normal function with parameter in rcx");
// The original behavior had __alloca fall through to ___chkstk here, but
// I don't believe that this behavior is guaranteed, and a program that uses
// only __alloca could have ___chkstk removed by --gc-sections. Call
// ___chkstk here to guarantee that neither of those happen.
___chkstk();
}
#[cfg(windows)]
#[naked]
#[cfg_attr(not(test), no_mangle)]
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();
}