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Add missing inline asm register operand types #2402

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Add missing inline asm register operand types #2402

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17 changes: 16 additions & 1 deletion src/inline-assembly.md
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Original file line number Diff line number Diff line change
Expand Up @@ -549,7 +549,10 @@ Only the following types are allowed as operands for inline assembly:
- Floating-point numbers
- Pointers (thin only)
- Function pointers
- SIMD vectors (structs defined with `#[repr(simd)]` and which implement `Copy`). This includes architecture-specific vector types defined in `std::arch` such as `__m128` (x86) or `int8x16_t` (ARM).
- `NonNull<T>` (only as [inputs](#operand-type))
- Shared and mutable references (only as [inputs](#operand-type))
- SIMD vectors (structs defined with `#[repr(simd)]` and which implement `Copy`). This includes architecture-specific vector types defined in `std::arch` such as `__m128` (x86) or `int8x16_t` (ARM)
- `MaybeUninit<T>` for any type `T` listed above.

```rust
# #[cfg(target_arch = "x86_64")] {
Expand All @@ -563,6 +566,9 @@ unsafe { core::arch::asm!("/* {} */", in(reg) y); }
let py = &raw const y;
unsafe { core::arch::asm!("/* {} */", in(reg) py); }

let py = core::ptr::NonNull::from_ref(&y);
unsafe { core::arch::asm!("/* {} */", in(reg) py); }

// floats as well...
let f = 1.0f32;
unsafe { core::arch::asm!("/* {} */", in(xmm_reg) f); }
Expand All @@ -573,6 +579,10 @@ unsafe { core::arch::asm!("/* {} */", in(reg) func); }

let z = unsafe { core::arch::x86_64::_mm_set_epi64x(1, 0) };
unsafe { core::arch::asm!("/* {} */", in(xmm_reg) z); }

// Also `MaybeUninit`s wrapping any of those types.
let m: core::mem::MaybeUninit<i64>;
unsafe { core::arch::asm!("/* {} */", out(reg) m); }
# }
```

Expand All @@ -583,6 +593,11 @@ let x: Foo = Foo;
// Complex types like structs are not allowed
unsafe { core::arch::asm!("/* {} */", in(reg) x); }
// ERROR: cannot use value of type `Foo` for inline assembly

// `NonNull` pointers can only be inputs.
let y: NonNull<u8>;
unsafe { core::arch::asm!("/* {} */", out(reg) y); }
// ERROR: cannot use value of type `NonNull<u8>` for inline assembly
# }
# #[cfg(not(target_arch = "x86_64"))] core::compile_error!("Test not supported on this arch");
```
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