diff options
| -rw-r--r-- | src/librustc_codegen_llvm/mir/place.rs | 9 | ||||
| -rw-r--r-- | src/librustc_codegen_llvm/type_of.rs | 22 | ||||
| -rw-r--r-- | src/librustc_target/abi/mod.rs | 18 | ||||
| -rw-r--r-- | src/test/run-pass/issue-53728.rs | 26 |
4 files changed, 63 insertions, 12 deletions
diff --git a/src/librustc_codegen_llvm/mir/place.rs b/src/librustc_codegen_llvm/mir/place.rs index 833dca8c75f..05cee034d3f 100644 --- a/src/librustc_codegen_llvm/mir/place.rs +++ b/src/librustc_codegen_llvm/mir/place.rs @@ -174,7 +174,10 @@ impl PlaceRef<'ll, 'tcx> { let cx = bx.cx; let field = self.layout.field(cx, ix); let offset = self.layout.fields.offset(ix); - let align = self.align.min(self.layout.align).min(field.align); + let effective_field_align = self.align + .min(self.layout.align) + .min(field.align) + .restrict_for_offset(offset); let simple = || { // Unions and newtypes only use an offset of 0. @@ -196,7 +199,7 @@ impl PlaceRef<'ll, 'tcx> { None }, layout: field, - align, + align: effective_field_align, } }; @@ -269,7 +272,7 @@ impl PlaceRef<'ll, 'tcx> { llval: bx.pointercast(byte_ptr, ll_fty.ptr_to()), llextra: self.llextra, layout: field, - align, + align: effective_field_align, } } diff --git a/src/librustc_codegen_llvm/type_of.rs b/src/librustc_codegen_llvm/type_of.rs index e6907030ae6..6eec0b0b68c 100644 --- a/src/librustc_codegen_llvm/type_of.rs +++ b/src/librustc_codegen_llvm/type_of.rs @@ -122,25 +122,29 @@ fn struct_llfields<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>, let mut packed = false; let mut offset = Size::ZERO; - let mut prev_align = layout.align; + let mut prev_effective_align = layout.align; let mut result: Vec<_> = Vec::with_capacity(1 + field_count * 2); for i in layout.fields.index_by_increasing_offset() { - let field = layout.field(cx, i); - packed |= layout.align.abi() < field.align.abi(); - let target_offset = layout.fields.offset(i as usize); - debug!("struct_llfields: {}: {:?} offset: {:?} target_offset: {:?}", - i, field, offset, target_offset); + let field = layout.field(cx, i); + let effective_field_align = layout.align + .min(field.align) + .restrict_for_offset(target_offset); + packed |= effective_field_align.abi() < field.align.abi(); + + debug!("struct_llfields: {}: {:?} offset: {:?} target_offset: {:?} \ + effective_field_align: {}", + i, field, offset, target_offset, effective_field_align.abi()); assert!(target_offset >= offset); let padding = target_offset - offset; - let padding_align = layout.align.min(prev_align).min(field.align); + let padding_align = prev_effective_align.min(effective_field_align); assert_eq!(offset.abi_align(padding_align) + padding, target_offset); result.push(Type::padding_filler(cx, padding, padding_align)); debug!(" padding before: {:?}", padding); result.push(field.llvm_type(cx)); offset = target_offset + field.size; - prev_align = field.align; + prev_effective_align = effective_field_align; } if !layout.is_unsized() && field_count > 0 { if offset > layout.size { @@ -148,7 +152,7 @@ fn struct_llfields<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>, layout, layout.size, offset); } let padding = layout.size - offset; - let padding_align = layout.align.min(prev_align); + let padding_align = prev_effective_align; assert_eq!(offset.abi_align(padding_align) + padding, layout.size); debug!("struct_llfields: pad_bytes: {:?} offset: {:?} stride: {:?}", padding, offset, layout.size); diff --git a/src/librustc_target/abi/mod.rs b/src/librustc_target/abi/mod.rs index 16b5241b29a..5c4cd849f89 100644 --- a/src/librustc_target/abi/mod.rs +++ b/src/librustc_target/abi/mod.rs @@ -416,6 +416,24 @@ impl Align { pref_pow2: cmp::max(self.pref_pow2, other.pref_pow2), } } + + /// Compute the best alignment possible for the given offset + /// (the largest power of two that the offset is a multiple of). + /// + /// NB: for an offset of `0`, this happens to return `2^64`. + pub fn max_for_offset(offset: Size) -> Align { + let pow2 = offset.bytes().trailing_zeros() as u8; + Align { + abi_pow2: pow2, + pref_pow2: pow2, + } + } + + /// Lower the alignment, if necessary, such that the given offset + /// is aligned to it (the offset is a multiple of the aligment). + pub fn restrict_for_offset(self, offset: Size) -> Align { + self.min(Align::max_for_offset(offset)) + } } /// Integers, also used for enum discriminants. diff --git a/src/test/run-pass/issue-53728.rs b/src/test/run-pass/issue-53728.rs new file mode 100644 index 00000000000..f9cb5da29a7 --- /dev/null +++ b/src/test/run-pass/issue-53728.rs @@ -0,0 +1,26 @@ +// 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. + +#[repr(u16)] +enum DeviceKind { + Nil = 0, +} + +#[repr(packed)] +struct DeviceInfo { + endianness: u8, + device_kind: DeviceKind, +} + +fn main() { + let _x = None::<(DeviceInfo, u8)>; + let _y = None::<(DeviceInfo, u16)>; + let _z = None::<(DeviceInfo, u64)>; +} |