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645c0fddd2
Previously, it was only put on scalars with range validity invariants like bool, was uninit was obviously invalid for those. Since then, we have normatively declared all uninit primitives to be undefined behavior and can therefore put `noundef` on them. The remaining concern was the `mem::uninitialized` function, which cause quite a lot of UB in the older parts of the ecosystem. This function now doesn't return uninit values anymore, making users of it safe from this change. The only real sources of UB where people could encounter uninit primitives are `MaybeUninit::uninit().assume_init()`, which has always be clear in the docs about being UB and from heap allocations (like reading from the spare capacity of a vec. This is hopefully rare enough to not break anything.
33 lines
841 B
Rust
33 lines
841 B
Rust
// compile-flags: -C no-prepopulate-passes
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// needs-asm-support
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// only-x86_64
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#![crate_type = "lib"]
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#![feature(naked_functions)]
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use std::arch::asm;
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// CHECK: Function Attrs: naked
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// CHECK-NEXT: define{{.*}}void @naked_empty()
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#[no_mangle]
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#[naked]
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pub unsafe extern "C" fn naked_empty() {
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// CHECK-NEXT: {{.+}}:
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// CHECK-NEXT: call void asm
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// CHECK-NEXT: unreachable
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asm!("ret",
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options(noreturn));
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}
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// CHECK: Function Attrs: naked
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// CHECK-NEXT: define{{.*}}i{{[0-9]+}} @naked_with_args_and_return(i64 noundef %a, i64 noundef %b)
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#[no_mangle]
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#[naked]
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pub unsafe extern "C" fn naked_with_args_and_return(a: isize, b: isize) -> isize {
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// CHECK-NEXT: {{.+}}:
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// CHECK-NEXT: call void asm
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// CHECK-NEXT: unreachable
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asm!("lea rax, [rdi + rsi]",
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"ret",
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options(noreturn));
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}
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