Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Sync x86 chkstk intrinsics with LLVM #575

Merged
merged 1 commit into from
Mar 30, 2024
Merged

Sync x86 chkstk intrinsics with LLVM #575

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 0 additions & 2 deletions README.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -163,7 +163,6 @@ features = ["c"]
- [ ] i386/ashldi3.S
- [ ] i386/ashrdi3.S
- [x] i386/chkstk.S
- [x] i386/chkstk2.S
- [ ] i386/divdi3.S
- [ ] i386/lshrdi3.S
- [ ] i386/moddi3.S
Expand Down Expand Up @@ -192,7 +191,6 @@ features = ["c"]
- [x] umoddi3.c
- [x] umodsi3.c
- [x] x86_64/chkstk.S
- [x] x86_64/chkstk2.S

These builtins are needed to support 128-bit integers, which are in the process of being added to Rust.

Expand Down
47 changes: 2 additions & 45 deletions src/x86.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@ use core::intrinsics;
// 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

intrinsics! {
#[naked]
Expand All @@ -15,50 +14,8 @@ intrinsics! {
target_env = "gnu",
not(feature = "no-asm")
))]
pub unsafe extern "C" fn ___chkstk_ms() {
core::arch::asm!(
"push %ecx",
"push %eax",
"cmp $0x1000,%eax",
"lea 12(%esp),%ecx",
"jb 1f",
"2:",
"sub $0x1000,%ecx",
"test %ecx,(%ecx)",
"sub $0x1000,%eax",
"cmp $0x1000,%eax",
"ja 2b",
"1:",
"sub %eax,%ecx",
"test %ecx,(%ecx)",
"pop %eax",
"pop %ecx",
"ret",
options(noreturn, att_syntax)
);
}

// FIXME: __alloca should be an alias to __chkstk
#[naked]
#[cfg(all(
windows,
target_env = "gnu",
not(feature = "no-asm")
))]
pub unsafe extern "C" fn __alloca() {
core::arch::asm!(
"jmp ___chkstk", // Jump to ___chkstk since fallthrough may be unreliable"
options(noreturn, att_syntax)
);
}

#[naked]
#[cfg(all(
windows,
target_env = "gnu",
not(feature = "no-asm")
))]
pub unsafe extern "C" fn ___chkstk() {
pub unsafe extern "C" fn _alloca() {
// _chkstk and _alloca are the same function
core::arch::asm!(
"push %ecx",
"cmp $0x1000,%eax",
Expand Down
44 changes: 0 additions & 44 deletions src/x86_64.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@ use core::intrinsics;
// 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

intrinsics! {
#[naked]
Expand Down Expand Up @@ -36,49 +35,6 @@ intrinsics! {
options(noreturn, att_syntax)
);
}

#[naked]
#[cfg(all(
any(all(windows, target_env = "gnu"), target_os = "uefi"),
not(feature = "no-asm")
))]
pub unsafe extern "C" fn __alloca() {
core::arch::asm!(
"mov %rcx,%rax", // x64 _alloca is a normal function with parameter in rcx
"jmp ___chkstk", // Jump to ___chkstk since fallthrough may be unreliable"
options(noreturn, att_syntax)
);
}

#[naked]
#[cfg(all(
any(all(windows, target_env = "gnu"), target_os = "uefi"),
not(feature = "no-asm")
))]
pub unsafe extern "C" fn ___chkstk() {
core::arch::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",
options(noreturn, att_syntax)
);
}
}

// HACK(https://github.com/rust-lang/rust/issues/62785): x86_64-unknown-uefi needs special LLVM
Expand Down