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67 lines
2.8 KiB
Odin
67 lines
2.8 KiB
Odin
package libc
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// 7.13 Nonlocal jumps
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when ODIN_OS == .Windows {
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foreign import libc "system:libucrt.lib"
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} else when ODIN_OS == .Darwin {
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foreign import libc "system:System.framework"
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} else {
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foreign import libc "system:c"
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}
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when ODIN_OS == .Windows {
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@(default_calling_convention="c")
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foreign libc {
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// 7.13.1 Save calling environment
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//
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// NOTE(dweiler): C11 requires setjmp be a macro, which means it won't
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// necessarily export a symbol named setjmp but rather _setjmp in the case
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// of musl, glibc, BSD libc, and msvcrt.
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//
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/// NOTE(dweiler): UCRT has two implementations of longjmp. One that performs
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// stack unwinding and one that doesn't. The choice of which to use depends on a
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// flag which is set inside the jmp_buf structure given to setjmp. The default
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// behavior is to unwind the stack. Within Odin, we cannot use the stack
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// unwinding version as the unwinding information isn't present. To opt-in to
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// the regular non-unwinding version we need a way to set this flag. Since the
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// location of the flag within the struct is not defined or part of the ABI and
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// can change between versions of UCRT, we must rely on setjmp to set it. It
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// turns out that setjmp receives this flag in the RDX register on Win64, this
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// just so happens to coincide with the second argument of a function in the
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// Win64 ABI. By giving our setjmp a second argument with the value of zero,
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// the RDX register will contain zero and correctly set the flag to disable
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// stack unwinding.
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@(link_name="_setjmp")
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setjmp :: proc(env: ^jmp_buf, hack: rawptr = nil) -> int ---
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}
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} else {
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@(default_calling_convention="c")
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foreign libc {
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// 7.13.1 Save calling environment
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//
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// NOTE(dweiler): C11 requires setjmp be a macro, which means it won't
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// necessarily export a symbol named setjmp but rather _setjmp in the case
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// of musl, glibc, BSD libc, and msvcrt.
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@(link_name="_setjmp")
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setjmp :: proc(env: ^jmp_buf) -> int ---
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}
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}
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@(default_calling_convention="c")
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foreign libc {
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// 7.13.2 Restore calling environment
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longjmp :: proc(env: ^jmp_buf, val: int) -> ! ---
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}
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// The C99 Rationale describes jmp_buf as being an array type for backward
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// compatibility. Odin does not need to honor this and couldn't as arrays in
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// Odin don't decay to pointers. It is somewhat easy for us to bind this, we
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// just need to ensure the structure contains enough storage with appropriate
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// alignment. Since there are no types in C with an alignment larger than
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// that of max_align_t, which cannot be larger than sizeof(long double) as any
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// other exposed type wouldn't be valid C, the maximum alignment possible in a
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// strictly conformant C implementation is 16 on the platforms we care about.
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// The choice of 4096 bytes for storage of this type is more than enough on all
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// relevant platforms.
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jmp_buf :: struct #align(16) { _: [4096]char, }
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