83 lines
2.4 KiB
Rust
83 lines
2.4 KiB
Rust
#![allow(unused_imports)]
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use core::intrinsics;
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// NOTE These functions are implemented using assembly because they using a custom
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// calling convention which can't be implemented using a normal Rust function
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// NOTE These functions are never mangled as they are not tested against compiler-rt
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// and mangling ___chkstk would break the `jmp ___chkstk` instruction in __alloca
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#[cfg(all(windows, target_env = "gnu", not(feature = "mangled-names")))]
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#[naked]
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#[no_mangle]
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pub unsafe fn ___chkstk_ms() {
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llvm_asm!("
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push %rcx
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push %rax
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cmp $$0x1000,%rax
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lea 24(%rsp),%rcx
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jb 1f
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2:
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sub $$0x1000,%rcx
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test %rcx,(%rcx)
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sub $$0x1000,%rax
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cmp $$0x1000,%rax
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ja 2b
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1:
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sub %rax,%rcx
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test %rcx,(%rcx)
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pop %rax
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pop %rcx
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ret" ::: "memory" : "volatile");
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intrinsics::unreachable();
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}
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#[cfg(all(windows, target_env = "gnu", not(feature = "mangled-names")))]
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#[naked]
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#[no_mangle]
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pub unsafe fn __alloca() {
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llvm_asm!("mov %rcx,%rax // x64 _alloca is a normal function with parameter in rcx
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jmp ___chkstk // Jump to ___chkstk since fallthrough may be unreliable"
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::: "memory" : "volatile");
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intrinsics::unreachable();
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}
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#[cfg(all(windows, target_env = "gnu", not(feature = "mangled-names")))]
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#[naked]
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#[no_mangle]
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pub unsafe fn ___chkstk() {
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llvm_asm!(
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"
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push %rcx
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cmp $$0x1000,%rax
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lea 16(%rsp),%rcx // rsp before calling this routine -> rcx
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jb 1f
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2:
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sub $$0x1000,%rcx
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test %rcx,(%rcx)
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sub $$0x1000,%rax
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cmp $$0x1000,%rax
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ja 2b
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1:
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sub %rax,%rcx
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test %rcx,(%rcx)
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lea 8(%rsp),%rax // load pointer to the return address into rax
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mov %rcx,%rsp // install the new top of stack pointer into rsp
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mov -8(%rax),%rcx // restore rcx
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push (%rax) // push return address onto the stack
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sub %rsp,%rax // restore the original value in rax
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ret"
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::: "memory" : "volatile"
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);
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intrinsics::unreachable();
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}
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// HACK(https://github.com/rust-lang/rust/issues/62785): x86_64-unknown-uefi needs special LLVM
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// support unless we emit the _fltused
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#[no_mangle]
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#[used]
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#[cfg(target_os = "uefi")]
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static _fltused: i32 = 0;
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