73 lines
2.1 KiB
Rust
73 lines
2.1 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 %ecx
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push %eax
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cmp $$0x1000,%eax
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lea 12(%esp),%ecx
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jb 1f
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2:
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sub $$0x1000,%ecx
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test %ecx,(%ecx)
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sub $$0x1000,%eax
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cmp $$0x1000,%eax
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ja 2b
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1:
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sub %eax,%ecx
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test %ecx,(%ecx)
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pop %eax
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pop %ecx
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ret" ::: "memory" : "volatile");
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intrinsics::unreachable();
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}
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// FIXME: __alloca should be an alias to __chkstk
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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!("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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push %ecx
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cmp $$0x1000,%eax
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lea 8(%esp),%ecx // esp before calling this routine -> ecx
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jb 1f
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2:
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sub $$0x1000,%ecx
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test %ecx,(%ecx)
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sub $$0x1000,%eax
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cmp $$0x1000,%eax
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ja 2b
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1:
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sub %eax,%ecx
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test %ecx,(%ecx)
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lea 4(%esp),%eax // load pointer to the return address into eax
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mov %ecx,%esp // install the new top of stack pointer into esp
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mov -4(%eax),%ecx // restore ecx
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push (%eax) // push return address onto the stack
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sub %esp,%eax // restore the original value in eax
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ret" ::: "memory" : "volatile");
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intrinsics::unreachable();
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}
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