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Auto merge of #51594 - eddyb:issue-51582, r=nagisa

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rustc_codegen_llvm: don't treat i1 as signed, even for #[repr(i8)] enums.

Fixes #51582. r? @nagisa cc @nox @oli-obk
This commit is contained in:
bors 2018-06-16 21:48:31 +00:00
commit ae46aefd5b
3 changed files with 37 additions and 2 deletions
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6
src/librustc_codegen_llvm/mir/place.rs
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@ -275,7 +275,11 @@ impl<'a, 'tcx> PlaceRef<'tcx> {
layout::Variants::Single { .. } => bug!(),
layout::Variants::Tagged { ref tag, .. } => {
let signed = match tag.value {
layout::Int(_, signed) => signed,
// We use `i1` for bytes that are always `0` or `1`,
// e.g. `#[repr(i8)] enum E { A, B }`, but we can't
// let LLVM interpret the `i1` as signed, because
// then `i1 1` (i.e. E::B) is effectively `i8 -1`.
layout::Int(_, signed) => !tag.is_bool() && signed,
_ => false
};
bx.intcast(lldiscr, cast_to, signed)

6
src/librustc_codegen_llvm/mir/rvalue.rs
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@ -298,7 +298,11 @@ impl<'a, 'tcx> FunctionCx<'a, 'tcx> {
let mut signed = false;
if let layout::Abi::Scalar(ref scalar) = operand.layout.abi {
if let layout::Int(_, s) = scalar.value {
signed = s;
// We use `i1` for bytes that are always `0` or `1`,
// e.g. `#[repr(i8)] enum E { A, B }`, but we can't
// let LLVM interpret the `i1` as signed, because
// then `i1 1` (i.e. E::B) is effectively `i8 -1`.
signed = !scalar.is_bool() && s;
if scalar.valid_range.end() > scalar.valid_range.start() {
// We want `table[e as usize]` to not

27
src/test/run-pass/issue-51582.rs Normal file
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@ -0,0 +1,27 @@
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#![feature(core_intrinsics)]
#[repr(i8)]
pub enum Enum {
VariantA,
VariantB,
}
fn make_b() -> Enum { Enum::VariantB }
fn main() {
assert_eq!(1, make_b() as i8);
assert_eq!(1, make_b() as u8);
assert_eq!(1, make_b() as i32);
assert_eq!(1, make_b() as u32);
assert_eq!(1, unsafe { std::intrinsics::discriminant_value(&make_b()) });
}