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

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

Note that for some types (like `&Struct` and `&mut Struct`),
we already apply `dereferenceable`, which implies `noundef`,
so the IR does not change.
This commit is contained in:
Erik Desjardins 2022-02-05 01:00:37 -05:00
parent 71226d717a
commit 8cb0b6ca5b
10 changed files with 56 additions and 22 deletions
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7
compiler/rustc_target/src/abi/call/mod.rs
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@ -73,6 +73,7 @@ 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;
}
}
}
@ -494,7 +495,11 @@ 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.