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Auto merge of #93670 - erikdesjardins:noundef, r=nikic

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Apply noundef attribute to &T, &mut T, Box<T>, bool

This doesn't handle `char` because it's a bit awkward to distinguish it from `u32` at this point in codegen.

Note that this _does not_ change whether or not it is UB for `&`, `&mut`, or `Box` to point to undef. It only applies to the pointer itself, not the pointed-to memory.

Fixes (partially) #74378.

r? `@nikic` cc `@RalfJung`
This commit is contained in:
bors 2022-02-13 00:14:52 +00:00
commit 5c30d65683
13 changed files with 94 additions and 91 deletions
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7
compiler/rustc_target/src/abi/call/mod.rs
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@ -74,6 +74,7 @@ mod attr_impl {
// or not to actually emit the attribute. It can also be controlled
// with the `-Zmutable-noalias` debugging option.
const NoAliasMutRef = 1 << 6;
const NoUndef = 1 << 7;
}
}
}
@ -495,7 +496,11 @@ impl<'a, Ty> ArgAbi<'a, Ty> {
// For non-immediate arguments the callee gets its own copy of
// the value on the stack, so there are no aliases. It's also
// program-invisible so can't possibly capture
attrs.set(ArgAttribute::NoAlias).set(ArgAttribute::NoCapture).set(ArgAttribute::NonNull);
attrs
.set(ArgAttribute::NoAlias)
.set(ArgAttribute::NoCapture)
.set(ArgAttribute::NonNull)
.set(ArgAttribute::NoUndef);
attrs.pointee_size = layout.size;
// FIXME(eddyb) We should be doing this, but at least on
// i686-pc-windows-msvc, it results in wrong stack offsets.