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Replace on-the-fly llvm field index calculation with cache

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This commit is contained in:
Hans Kratz 2021-07-19 09:27:18 +02:00
parent 60a523de92
commit e4106581de
2 changed files with 14 additions and 17 deletions
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6
compiler/rustc_codegen_llvm/src/context.rs
View File

@ -79,6 +79,11 @@ pub struct CodegenCx<'ll, 'tcx> {
pub pointee_infos: RefCell<FxHashMap<(Ty<'tcx>, Size), Option<PointeeInfo>>>,
pub isize_ty: &'ll Type,
/// Cache for the mapping from source index to llvm index for struct fields,
/// necessary because the mapping depends on padding and thus depens on
/// TyAndLayout.
pub field_projection_cache: RefCell<FxHashMap<TyAndLayout<'tcx>, Vec<u32>>>,
pub coverage_cx: Option<coverageinfo::CrateCoverageContext<'ll, 'tcx>>,
pub dbg_cx: Option<debuginfo::CrateDebugContext<'ll, 'tcx>>,
@ -308,6 +313,7 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
scalar_lltypes: Default::default(),
pointee_infos: Default::default(),
isize_ty,
field_projection_cache: Default::default(),
coverage_cx,
dbg_cx,
eh_personality: Cell::new(None),

25
compiler/rustc_codegen_llvm/src/type_of.rs
View File

@ -98,6 +98,7 @@ fn struct_llfields<'a, 'tcx>(
let mut offset = Size::ZERO;
let mut prev_effective_align = layout.align.abi;
let mut result: Vec<_> = Vec::with_capacity(1 + field_count * 2);
let mut projection = vec![0; field_count];
for i in layout.fields.index_by_increasing_offset() {
let target_offset = layout.fields.offset(i as usize);
let field = layout.field(cx, i);
@ -122,6 +123,7 @@ fn struct_llfields<'a, 'tcx>(
result.push(cx.type_padding_filler(padding, padding_align));
debug!(" padding before: {:?}", padding);
}
projection[i] = result.len() as u32;
result.push(field.llvm_type(cx));
offset = target_offset + field.size;
prev_effective_align = effective_field_align;
@ -143,6 +145,7 @@ fn struct_llfields<'a, 'tcx>(
} else {
debug!("struct_llfields: offset: {:?} stride: {:?}", offset, layout.size);
}
cx.field_projection_cache.borrow_mut().insert(layout, projection);
(result, packed)
}
@ -356,24 +359,12 @@ impl<'tcx> LayoutLlvmExt<'tcx> for TyAndLayout<'tcx> {
FieldsShape::Array { .. } => index as u64,
FieldsShape::Arbitrary { .. } => {
let mut llvm_index = 0;
let mut offset = Size::ZERO;
for i in self.fields.index_by_increasing_offset() {
let target_offset = self.fields.offset(i as usize);
let field = self.field(cx, i);
let padding = target_offset - offset;
if padding != Size::ZERO {
llvm_index += 1;
}
if i == index {
return llvm_index;
}
offset = target_offset + field.size;
llvm_index += 1;
FieldsShape::Arbitrary { .. } => match cx.field_projection_cache.borrow().get(self) {
Some(projection) => projection[index] as u64,
None => {
bug!("TyAndLayout::llvm_field_index({:?}): field projection not cached", self)
}
bug!("TyAndLayout::llvm_field_index({:?}): index {} out of range", self, index)
}
},
}
}