bjoernager/rust
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Reduce the maximum alignment to repr(align(1 << 29))

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This brings it into line with LLVM's maximum permitted alignment.
This commit is contained in:
varkor 2018-05-01 21:26:23 +01:00
parent c1607f80b3
commit cd2f5f7d97
3 changed files with 11 additions and 8 deletions
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8
src/librustc_target/abi/mod.rs
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@ -326,9 +326,9 @@ impl AddAssign for Size {
} }
/// Alignment of a type in bytes, both ABI-mandated and preferred. /// Alignment of a type in bytes, both ABI-mandated and preferred.
/// Each field is a power of two, giving the alignment a maximum value of /// Each field is a power of two, giving the alignment a maximum value
/// 2<sup>(2<sup>8</sup> - 1)</sup>, which is limited by LLVM to a i32, /// of 2<sup>(2<sup>8</sup> - 1)</sup>, which is limited by LLVM to a
/// with a maximum capacity of 2<sup>31</sup> - 1 or 2147483647. /// maximum capacity of 2<sup>29</sup> or 536870912.
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)] #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
pub struct Align { pub struct Align {
abi_pow2: u8, abi_pow2: u8,
@ -356,7 +356,7 @@ impl Align {
} }
if bytes != 1 { if bytes != 1 {
Err(format!("`{}` is not a power of 2", align)) Err(format!("`{}` is not a power of 2", align))
} else if pow > 30 { } else if pow > 29 {
Err(format!("`{}` is too large", align)) Err(format!("`{}` is too large", align))
} else { } else {
Ok(pow) Ok(pow)

6
src/libsyntax/attr.rs
View file

@ -1012,11 +1012,11 @@ pub fn find_repr_attrs(diagnostic: &Handler, attr: &Attribute) -> Vec<ReprAttr>
let parse_alignment = |node: &ast::LitKind| -> Result<u32, &'static str> { let parse_alignment = |node: &ast::LitKind| -> Result<u32, &'static str> {
if let ast::LitKind::Int(literal, ast::LitIntType::Unsuffixed) = node { if let ast::LitKind::Int(literal, ast::LitIntType::Unsuffixed) = node {
if literal.is_power_of_two() { if literal.is_power_of_two() {
// rustc::ty::layout::Align restricts align to <= 2147483647 // rustc::ty::layout::Align restricts align to <= 2^29
if *literal <= 2147483647 { if *literal <= 1 << 29 {
Ok(*literal as u32) Ok(*literal as u32)
} else { } else {
Err("larger than 2147483647") Err("larger than 2^29")
} }
} else { } else {
Err("not a power of two") Err("not a power of two")

5
src/test/compile-fail/repr-align.rs
View file

@ -15,7 +15,10 @@ struct A(i32);
#[repr(align(15))] //~ ERROR: invalid `repr(align)` attribute: not a power of two #[repr(align(15))] //~ ERROR: invalid `repr(align)` attribute: not a power of two
struct B(i32); struct B(i32);
#[repr(align(4294967296))] //~ ERROR: invalid `repr(align)` attribute: larger than 2147483647 #[repr(align(4294967296))] //~ ERROR: invalid `repr(align)` attribute: larger than 2^29
struct C(i32); struct C(i32);
#[repr(align(536870912))] // ok: this is the largest accepted alignment
struct D(i32);
fn main() {} fn main() {}