bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Emit the enum discriminant separately for the Encodable macro

Browse source
This commit is contained in:
John Kåre Alsaker 2023-02-24 23:58:32 +01:00
parent 07c993eba8
commit 7de205ea3a
2 changed files with 30 additions and 29 deletions
Download patch file Download diff file Expand all files Collapse all files

12
compiler/rustc_serialize/src/serialize.rs
View file

@ -43,7 +43,6 @@ pub trait Encoder {
fn emit_str(&mut self, v: &str);
fn emit_raw_bytes(&mut self, s: &[u8]);
// Convenience for the derive macro:
fn emit_enum_variant<F>(&mut self, v_id: usize, f: F)
where
F: FnOnce(&mut Self),
@ -51,17 +50,6 @@ pub trait Encoder {
self.emit_usize(v_id);
f(self);
}
// We put the field index in a const generic to allow the emit_usize to be
// compiled into a more efficient form. In practice, the variant index is
// known at compile-time, and that knowledge allows much more efficient
// codegen than we'd otherwise get. LLVM isn't always able to make the
// optimization that would otherwise be necessary here, likely due to the
// multiple levels of inlining and const-prop that are needed.
#[inline]
fn emit_fieldless_enum_variant<const ID: usize>(&mut self) {
self.emit_usize(ID)
}
}
// Note: all the methods in this trait are infallible, which may be surprising.