390 lines
15 KiB
Rust
390 lines
15 KiB
Rust
use crate::abi::{FnAbi};
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use crate::common::*;
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use crate::type_::Type;
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use rustc::ty::{self, Ty, TypeFoldable};
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use rustc::ty::layout::{self, Align, LayoutOf, FnAbiExt, PointeeInfo, Size, TyLayout};
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use rustc_target::abi::TyLayoutMethods;
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use rustc::ty::print::obsolete::DefPathBasedNames;
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use rustc_codegen_ssa::traits::*;
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use log::debug;
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use rustc::bug;
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use std::fmt::Write;
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fn uncached_llvm_type<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
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layout: TyLayout<'tcx>,
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defer: &mut Option<(&'a Type, TyLayout<'tcx>)>)
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-> &'a Type {
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match layout.abi {
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layout::Abi::Scalar(_) => bug!("handled elsewhere"),
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layout::Abi::Vector { ref element, count } => {
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// LLVM has a separate type for 64-bit SIMD vectors on X86 called
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// `x86_mmx` which is needed for some SIMD operations. As a bit of a
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// hack (all SIMD definitions are super unstable anyway) we
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// recognize any one-element SIMD vector as "this should be an
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// x86_mmx" type. In general there shouldn't be a need for other
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// one-element SIMD vectors, so it's assumed this won't clash with
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// much else.
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let use_x86_mmx = count == 1 && layout.size.bits() == 64 &&
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(cx.sess().target.target.arch == "x86" ||
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cx.sess().target.target.arch == "x86_64");
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if use_x86_mmx {
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return cx.type_x86_mmx()
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} else {
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let element = layout.scalar_llvm_type_at(cx, element, Size::ZERO);
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return cx.type_vector(element, count);
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}
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}
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layout::Abi::ScalarPair(..) => {
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return cx.type_struct( &[
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layout.scalar_pair_element_llvm_type(cx, 0, false),
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layout.scalar_pair_element_llvm_type(cx, 1, false),
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], false);
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}
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layout::Abi::Uninhabited |
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layout::Abi::Aggregate { .. } => {}
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}
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let name = match layout.ty.kind {
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ty::Closure(..) |
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ty::Generator(..) |
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ty::Adt(..) |
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// FIXME(eddyb) producing readable type names for trait objects can result
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// in problematically distinct types due to HRTB and subtyping (see #47638).
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// ty::Dynamic(..) |
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ty::Foreign(..) |
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ty::Str => {
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let mut name = String::with_capacity(32);
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let printer = DefPathBasedNames::new(cx.tcx, true, true);
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printer.push_type_name(layout.ty, &mut name, false);
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if let (&ty::Adt(def, _), &layout::Variants::Single { index })
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= (&layout.ty.kind, &layout.variants)
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{
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if def.is_enum() && !def.variants.is_empty() {
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write!(&mut name, "::{}", def.variants[index].ident).unwrap();
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}
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}
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if let (&ty::Generator(_, substs, _), &layout::Variants::Single { index })
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= (&layout.ty.kind, &layout.variants)
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{
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write!(&mut name, "::{}", substs.as_generator().variant_name(index)).unwrap();
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}
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Some(name)
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}
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_ => None
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};
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match layout.fields {
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layout::FieldPlacement::Union(_) => {
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let fill = cx.type_padding_filler(layout.size, layout.align.abi);
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let packed = false;
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match name {
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None => {
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cx.type_struct(&[fill], packed)
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}
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Some(ref name) => {
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let llty = cx.type_named_struct(name);
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cx.set_struct_body(llty, &[fill], packed);
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llty
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}
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}
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}
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layout::FieldPlacement::Array { count, .. } => {
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cx.type_array(layout.field(cx, 0).llvm_type(cx), count)
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}
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layout::FieldPlacement::Arbitrary { .. } => {
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match name {
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None => {
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let (llfields, packed) = struct_llfields(cx, layout);
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cx.type_struct( &llfields, packed)
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}
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Some(ref name) => {
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let llty = cx.type_named_struct( name);
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*defer = Some((llty, layout));
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llty
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}
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}
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}
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}
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}
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fn struct_llfields<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
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layout: TyLayout<'tcx>)
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-> (Vec<&'a Type>, bool) {
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debug!("struct_llfields: {:#?}", layout);
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let field_count = layout.fields.count();
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let mut packed = false;
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let mut offset = Size::ZERO;
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let mut prev_effective_align = layout.align.abi;
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let mut result: Vec<_> = Vec::with_capacity(1 + field_count * 2);
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for i in layout.fields.index_by_increasing_offset() {
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let target_offset = layout.fields.offset(i as usize);
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let field = layout.field(cx, i);
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let effective_field_align = layout.align.abi
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.min(field.align.abi)
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.restrict_for_offset(target_offset);
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packed |= effective_field_align < field.align.abi;
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debug!("struct_llfields: {}: {:?} offset: {:?} target_offset: {:?} \
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effective_field_align: {}",
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i, field, offset, target_offset, effective_field_align.bytes());
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assert!(target_offset >= offset);
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let padding = target_offset - offset;
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let padding_align = prev_effective_align.min(effective_field_align);
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assert_eq!(offset.align_to(padding_align) + padding, target_offset);
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result.push(cx.type_padding_filler( padding, padding_align));
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debug!(" padding before: {:?}", padding);
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result.push(field.llvm_type(cx));
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offset = target_offset + field.size;
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prev_effective_align = effective_field_align;
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}
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if !layout.is_unsized() && field_count > 0 {
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if offset > layout.size {
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bug!("layout: {:#?} stride: {:?} offset: {:?}",
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layout, layout.size, offset);
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}
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let padding = layout.size - offset;
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let padding_align = prev_effective_align;
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assert_eq!(offset.align_to(padding_align) + padding, layout.size);
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debug!("struct_llfields: pad_bytes: {:?} offset: {:?} stride: {:?}",
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padding, offset, layout.size);
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result.push(cx.type_padding_filler(padding, padding_align));
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assert_eq!(result.len(), 1 + field_count * 2);
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} else {
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debug!("struct_llfields: offset: {:?} stride: {:?}",
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offset, layout.size);
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}
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(result, packed)
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}
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impl<'a, 'tcx> CodegenCx<'a, 'tcx> {
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pub fn align_of(&self, ty: Ty<'tcx>) -> Align {
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self.layout_of(ty).align.abi
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}
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pub fn size_of(&self, ty: Ty<'tcx>) -> Size {
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self.layout_of(ty).size
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}
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pub fn size_and_align_of(&self, ty: Ty<'tcx>) -> (Size, Align) {
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let layout = self.layout_of(ty);
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(layout.size, layout.align.abi)
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}
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}
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pub trait LayoutLlvmExt<'tcx> {
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fn is_llvm_immediate(&self) -> bool;
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fn is_llvm_scalar_pair(&self) -> bool;
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fn llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type;
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fn immediate_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type;
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fn scalar_llvm_type_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>,
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scalar: &layout::Scalar, offset: Size) -> &'a Type;
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fn scalar_pair_element_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>,
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index: usize, immediate: bool) -> &'a Type;
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fn llvm_field_index(&self, index: usize) -> u64;
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fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size)
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-> Option<PointeeInfo>;
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}
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impl<'tcx> LayoutLlvmExt<'tcx> for TyLayout<'tcx> {
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fn is_llvm_immediate(&self) -> bool {
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match self.abi {
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layout::Abi::Scalar(_) |
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layout::Abi::Vector { .. } => true,
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layout::Abi::ScalarPair(..) => false,
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layout::Abi::Uninhabited |
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layout::Abi::Aggregate { .. } => self.is_zst()
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}
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}
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fn is_llvm_scalar_pair(&self) -> bool {
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match self.abi {
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layout::Abi::ScalarPair(..) => true,
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layout::Abi::Uninhabited |
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layout::Abi::Scalar(_) |
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layout::Abi::Vector { .. } |
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layout::Abi::Aggregate { .. } => false
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}
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}
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/// Gets the LLVM type corresponding to a Rust type, i.e., `rustc::ty::Ty`.
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/// The pointee type of the pointer in `PlaceRef` is always this type.
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/// For sized types, it is also the right LLVM type for an `alloca`
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/// containing a value of that type, and most immediates (except `bool`).
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/// Unsized types, however, are represented by a "minimal unit", e.g.
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/// `[T]` becomes `T`, while `str` and `Trait` turn into `i8` - this
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/// is useful for indexing slices, as `&[T]`'s data pointer is `T*`.
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/// If the type is an unsized struct, the regular layout is generated,
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/// with the inner-most trailing unsized field using the "minimal unit"
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/// of that field's type - this is useful for taking the address of
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/// that field and ensuring the struct has the right alignment.
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fn llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type {
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if let layout::Abi::Scalar(ref scalar) = self.abi {
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// Use a different cache for scalars because pointers to DSTs
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// can be either fat or thin (data pointers of fat pointers).
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if let Some(&llty) = cx.scalar_lltypes.borrow().get(&self.ty) {
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return llty;
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}
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let llty = match self.ty.kind {
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ty::Ref(_, ty, _) |
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ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
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cx.type_ptr_to(cx.layout_of(ty).llvm_type(cx))
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}
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ty::Adt(def, _) if def.is_box() => {
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cx.type_ptr_to(cx.layout_of(self.ty.boxed_ty()).llvm_type(cx))
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}
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ty::FnPtr(sig) => {
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cx.fn_ptr_backend_type(&FnAbi::of_fn_ptr(cx, sig, &[]))
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}
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_ => self.scalar_llvm_type_at(cx, scalar, Size::ZERO)
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};
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cx.scalar_lltypes.borrow_mut().insert(self.ty, llty);
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return llty;
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}
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// Check the cache.
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let variant_index = match self.variants {
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layout::Variants::Single { index } => Some(index),
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_ => None
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};
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if let Some(&llty) = cx.lltypes.borrow().get(&(self.ty, variant_index)) {
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return llty;
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}
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debug!("llvm_type({:#?})", self);
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assert!(!self.ty.has_escaping_bound_vars(), "{:?} has escaping bound vars", self.ty);
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// Make sure lifetimes are erased, to avoid generating distinct LLVM
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// types for Rust types that only differ in the choice of lifetimes.
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let normal_ty = cx.tcx.erase_regions(&self.ty);
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let mut defer = None;
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let llty = if self.ty != normal_ty {
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let mut layout = cx.layout_of(normal_ty);
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if let Some(v) = variant_index {
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layout = layout.for_variant(cx, v);
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}
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layout.llvm_type(cx)
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} else {
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uncached_llvm_type(cx, *self, &mut defer)
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};
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debug!("--> mapped {:#?} to llty={:?}", self, llty);
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cx.lltypes.borrow_mut().insert((self.ty, variant_index), llty);
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if let Some((llty, layout)) = defer {
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let (llfields, packed) = struct_llfields(cx, layout);
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cx.set_struct_body(llty, &llfields, packed)
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}
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llty
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}
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fn immediate_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> &'a Type {
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if let layout::Abi::Scalar(ref scalar) = self.abi {
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if scalar.is_bool() {
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return cx.type_i1();
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}
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}
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self.llvm_type(cx)
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}
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fn scalar_llvm_type_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>,
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scalar: &layout::Scalar, offset: Size) -> &'a Type {
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match scalar.value {
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layout::Int(i, _) => cx.type_from_integer( i),
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layout::F32 => cx.type_f32(),
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layout::F64 => cx.type_f64(),
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layout::Pointer => {
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// If we know the alignment, pick something better than i8.
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let pointee = if let Some(pointee) = self.pointee_info_at(cx, offset) {
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cx.type_pointee_for_align(pointee.align)
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} else {
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cx.type_i8()
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};
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cx.type_ptr_to(pointee)
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}
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}
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}
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fn scalar_pair_element_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>,
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index: usize, immediate: bool) -> &'a Type {
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// HACK(eddyb) special-case fat pointers until LLVM removes
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// pointee types, to avoid bitcasting every `OperandRef::deref`.
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match self.ty.kind {
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ty::Ref(..) |
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ty::RawPtr(_) => {
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return self.field(cx, index).llvm_type(cx);
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}
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ty::Adt(def, _) if def.is_box() => {
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let ptr_ty = cx.tcx.mk_mut_ptr(self.ty.boxed_ty());
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return cx.layout_of(ptr_ty).scalar_pair_element_llvm_type(cx, index, immediate);
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}
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_ => {}
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}
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let (a, b) = match self.abi {
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layout::Abi::ScalarPair(ref a, ref b) => (a, b),
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_ => bug!("TyLayout::scalar_pair_element_llty({:?}): not applicable", self)
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};
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let scalar = [a, b][index];
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// Make sure to return the same type `immediate_llvm_type` would when
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// dealing with an immediate pair. This means that `(bool, bool)` is
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// effectively represented as `{i8, i8}` in memory and two `i1`s as an
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// immediate, just like `bool` is typically `i8` in memory and only `i1`
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// when immediate. We need to load/store `bool` as `i8` to avoid
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// crippling LLVM optimizations or triggering other LLVM bugs with `i1`.
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if immediate && scalar.is_bool() {
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return cx.type_i1();
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}
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let offset = if index == 0 {
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Size::ZERO
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} else {
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a.value.size(cx).align_to(b.value.align(cx).abi)
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};
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self.scalar_llvm_type_at(cx, scalar, offset)
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}
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fn llvm_field_index(&self, index: usize) -> u64 {
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match self.abi {
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layout::Abi::Scalar(_) |
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layout::Abi::ScalarPair(..) => {
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bug!("TyLayout::llvm_field_index({:?}): not applicable", self)
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}
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_ => {}
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}
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match self.fields {
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layout::FieldPlacement::Union(_) => {
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bug!("TyLayout::llvm_field_index({:?}): not applicable", self)
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}
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layout::FieldPlacement::Array { .. } => {
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index as u64
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}
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layout::FieldPlacement::Arbitrary { .. } => {
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1 + (self.fields.memory_index(index) as u64) * 2
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}
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}
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}
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fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size)
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-> Option<PointeeInfo> {
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if let Some(&pointee) = cx.pointee_infos.borrow().get(&(self.ty, offset)) {
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return pointee;
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}
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let result = Ty::pointee_info_at(*self, cx, offset);
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cx.pointee_infos.borrow_mut().insert((self.ty, offset), result);
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result
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}
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}
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