499 lines
20 KiB
Rust
499 lines
20 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use llvm::{self, ValueRef};
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use rustc::ty::{self, Ty};
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use rustc::ty::layout::{self, Align, TyLayout, LayoutOf};
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use rustc::mir;
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use rustc::mir::tcx::PlaceTy;
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use rustc_data_structures::indexed_vec::Idx;
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use base;
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use builder::Builder;
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use common::{CodegenCx, C_undef, C_usize, C_u8, C_u32, C_uint, C_null, C_uint_big};
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use consts;
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use type_of::LayoutLlvmExt;
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use type_::Type;
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use value::Value;
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use glue;
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use std::ptr;
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use super::{FunctionCx, LocalRef};
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use super::operand::{OperandRef, OperandValue};
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#[derive(Copy, Clone, Debug)]
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pub struct PlaceRef<'tcx> {
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/// Pointer to the contents of the place
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pub llval: ValueRef,
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/// This place's extra data if it is unsized, or null
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pub llextra: ValueRef,
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/// Monomorphized type of this place, including variant information
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pub layout: TyLayout<'tcx>,
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/// What alignment we know for this place
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pub align: Align,
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}
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impl<'a, 'tcx> PlaceRef<'tcx> {
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pub fn new_sized(llval: ValueRef,
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layout: TyLayout<'tcx>,
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align: Align)
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-> PlaceRef<'tcx> {
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PlaceRef {
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llval,
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llextra: ptr::null_mut(),
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layout,
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align
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}
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}
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pub fn alloca(bx: &Builder<'a, 'tcx>, layout: TyLayout<'tcx>, name: &str)
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-> PlaceRef<'tcx> {
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debug!("alloca({:?}: {:?})", name, layout);
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let tmp = bx.alloca(layout.llvm_type(bx.cx), name, layout.align);
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Self::new_sized(tmp, layout, layout.align)
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}
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pub fn len(&self, cx: &CodegenCx<'a, 'tcx>) -> ValueRef {
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if let layout::FieldPlacement::Array { count, .. } = self.layout.fields {
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if self.layout.is_unsized() {
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assert!(self.has_extra());
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assert_eq!(count, 0);
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self.llextra
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} else {
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C_usize(cx, count)
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}
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} else {
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bug!("unexpected layout `{:#?}` in PlaceRef::len", self.layout)
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}
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}
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pub fn has_extra(&self) -> bool {
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!self.llextra.is_null()
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}
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pub fn load(&self, bx: &Builder<'a, 'tcx>) -> OperandRef<'tcx> {
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debug!("PlaceRef::load: {:?}", self);
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assert!(!self.has_extra());
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if self.layout.is_zst() {
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return OperandRef::new_zst(bx.cx, self.layout);
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}
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let scalar_load_metadata = |load, scalar: &layout::Scalar| {
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let vr = scalar.valid_range.clone();
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match scalar.value {
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layout::Int(..) => {
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let range = scalar.valid_range_exclusive(bx.cx);
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if range.start != range.end {
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bx.range_metadata(load, range);
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}
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}
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layout::Pointer if vr.start() < vr.end() && !vr.contains(&0) => {
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bx.nonnull_metadata(load);
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}
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_ => {}
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}
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};
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let val = if self.layout.is_llvm_immediate() {
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let mut const_llval = ptr::null_mut();
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unsafe {
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let global = llvm::LLVMIsAGlobalVariable(self.llval);
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if !global.is_null() && llvm::LLVMIsGlobalConstant(global) == llvm::True {
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const_llval = llvm::LLVMGetInitializer(global);
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}
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}
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let llval = if !const_llval.is_null() {
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const_llval
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} else {
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let load = bx.load(self.llval, self.align);
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if let layout::Abi::Scalar(ref scalar) = self.layout.abi {
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scalar_load_metadata(load, scalar);
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}
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load
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};
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OperandValue::Immediate(base::to_immediate(bx, llval, self.layout))
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} else if let layout::Abi::ScalarPair(ref a, ref b) = self.layout.abi {
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let load = |i, scalar: &layout::Scalar| {
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let mut llptr = bx.struct_gep(self.llval, i as u64);
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// Make sure to always load i1 as i8.
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if scalar.is_bool() {
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llptr = bx.pointercast(llptr, Type::i8p(bx.cx));
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}
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let load = bx.load(llptr, self.align);
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scalar_load_metadata(load, scalar);
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if scalar.is_bool() {
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bx.trunc(load, Type::i1(bx.cx))
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} else {
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load
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}
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};
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OperandValue::Pair(load(0, a), load(1, b))
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} else {
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OperandValue::Ref(self.llval, self.align)
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};
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OperandRef { val, layout: self.layout }
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}
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/// Access a field, at a point when the value's case is known.
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pub fn project_field(self, bx: &Builder<'a, 'tcx>, ix: usize) -> PlaceRef<'tcx> {
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let cx = bx.cx;
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let field = self.layout.field(cx, ix);
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let offset = self.layout.fields.offset(ix);
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let align = self.align.min(self.layout.align).min(field.align);
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let simple = || {
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// Unions and newtypes only use an offset of 0.
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let llval = if offset.bytes() == 0 {
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self.llval
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} else if let layout::Abi::ScalarPair(ref a, ref b) = self.layout.abi {
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// Offsets have to match either first or second field.
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assert_eq!(offset, a.value.size(cx).abi_align(b.value.align(cx)));
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bx.struct_gep(self.llval, 1)
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} else {
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bx.struct_gep(self.llval, self.layout.llvm_field_index(ix))
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};
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PlaceRef {
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// HACK(eddyb) have to bitcast pointers until LLVM removes pointee types.
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llval: bx.pointercast(llval, field.llvm_type(cx).ptr_to()),
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llextra: if cx.type_has_metadata(field.ty) {
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self.llextra
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} else {
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ptr::null_mut()
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},
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layout: field,
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align,
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}
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};
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// Simple cases, which don't need DST adjustment:
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// * no metadata available - just log the case
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// * known alignment - sized types, [T], str or a foreign type
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// * packed struct - there is no alignment padding
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match field.ty.sty {
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_ if !self.has_extra() => {
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debug!("Unsized field `{}`, of `{:?}` has no metadata for adjustment",
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ix, Value(self.llval));
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return simple();
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}
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_ if !field.is_unsized() => return simple(),
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ty::TySlice(..) | ty::TyStr | ty::TyForeign(..) => return simple(),
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ty::TyAdt(def, _) => {
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if def.repr.packed() {
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// FIXME(eddyb) generalize the adjustment when we
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// start supporting packing to larger alignments.
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assert_eq!(self.layout.align.abi(), 1);
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return simple();
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}
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}
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_ => {}
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}
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// We need to get the pointer manually now.
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// We do this by casting to a *i8, then offsetting it by the appropriate amount.
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// We do this instead of, say, simply adjusting the pointer from the result of a GEP
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// because the field may have an arbitrary alignment in the LLVM representation
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// anyway.
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//
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// To demonstrate:
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// struct Foo<T: ?Sized> {
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// x: u16,
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// y: T
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// }
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//
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// The type Foo<Foo<Trait>> is represented in LLVM as { u16, { u16, u8 }}, meaning that
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// the `y` field has 16-bit alignment.
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let meta = self.llextra;
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let unaligned_offset = C_usize(cx, offset.bytes());
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// Get the alignment of the field
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let (_, unsized_align) = glue::size_and_align_of_dst(bx, field.ty, meta);
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// Bump the unaligned offset up to the appropriate alignment using the
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// following expression:
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//
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// (unaligned offset + (align - 1)) & -align
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// Calculate offset
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let align_sub_1 = bx.sub(unsized_align, C_usize(cx, 1u64));
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let offset = bx.and(bx.add(unaligned_offset, align_sub_1),
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bx.neg(unsized_align));
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debug!("struct_field_ptr: DST field offset: {:?}", Value(offset));
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// Cast and adjust pointer
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let byte_ptr = bx.pointercast(self.llval, Type::i8p(cx));
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let byte_ptr = bx.gep(byte_ptr, &[offset]);
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// Finally, cast back to the type expected
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let ll_fty = field.llvm_type(cx);
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debug!("struct_field_ptr: Field type is {:?}", ll_fty);
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PlaceRef {
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llval: bx.pointercast(byte_ptr, ll_fty.ptr_to()),
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llextra: self.llextra,
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layout: field,
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align,
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}
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}
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/// Obtain the actual discriminant of a value.
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pub fn codegen_get_discr(self, bx: &Builder<'a, 'tcx>, cast_to: Ty<'tcx>) -> ValueRef {
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let cast_to = bx.cx.layout_of(cast_to).immediate_llvm_type(bx.cx);
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if self.layout.abi == layout::Abi::Uninhabited {
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return C_undef(cast_to);
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}
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match self.layout.variants {
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layout::Variants::Single { index } => {
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let discr_val = self.layout.ty.ty_adt_def().map_or(
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index as u128,
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|def| def.discriminant_for_variant(bx.cx.tcx, index).val);
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return C_uint_big(cast_to, discr_val);
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}
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layout::Variants::Tagged { .. } |
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layout::Variants::NicheFilling { .. } => {},
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}
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let discr = self.project_field(bx, 0);
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let lldiscr = discr.load(bx).immediate();
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match self.layout.variants {
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layout::Variants::Single { .. } => bug!(),
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layout::Variants::Tagged { ref tag, .. } => {
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let signed = match tag.value {
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layout::Int(_, signed) => signed,
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_ => false
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};
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bx.intcast(lldiscr, cast_to, signed)
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}
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layout::Variants::NicheFilling {
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dataful_variant,
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ref niche_variants,
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niche_start,
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..
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} => {
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let niche_llty = discr.layout.immediate_llvm_type(bx.cx);
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if niche_variants.start() == niche_variants.end() {
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// FIXME(eddyb) Check the actual primitive type here.
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let niche_llval = if niche_start == 0 {
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// HACK(eddyb) Using `C_null` as it works on all types.
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C_null(niche_llty)
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} else {
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C_uint_big(niche_llty, niche_start)
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};
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bx.select(bx.icmp(llvm::IntEQ, lldiscr, niche_llval),
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C_uint(cast_to, *niche_variants.start() as u64),
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C_uint(cast_to, dataful_variant as u64))
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} else {
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// Rebase from niche values to discriminant values.
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let delta = niche_start.wrapping_sub(*niche_variants.start() as u128);
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let lldiscr = bx.sub(lldiscr, C_uint_big(niche_llty, delta));
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let lldiscr_max = C_uint(niche_llty, *niche_variants.end() as u64);
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bx.select(bx.icmp(llvm::IntULE, lldiscr, lldiscr_max),
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bx.intcast(lldiscr, cast_to, false),
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C_uint(cast_to, dataful_variant as u64))
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}
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}
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}
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}
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/// Set the discriminant for a new value of the given case of the given
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/// representation.
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pub fn codegen_set_discr(&self, bx: &Builder<'a, 'tcx>, variant_index: usize) {
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if self.layout.for_variant(bx.cx, variant_index).abi == layout::Abi::Uninhabited {
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return;
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}
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match self.layout.variants {
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layout::Variants::Single { index } => {
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assert_eq!(index, variant_index);
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}
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layout::Variants::Tagged { .. } => {
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let ptr = self.project_field(bx, 0);
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let to = self.layout.ty.ty_adt_def().unwrap()
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.discriminant_for_variant(bx.tcx(), variant_index)
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.val;
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bx.store(
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C_uint_big(ptr.layout.llvm_type(bx.cx), to),
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ptr.llval,
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ptr.align);
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}
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layout::Variants::NicheFilling {
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dataful_variant,
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ref niche_variants,
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niche_start,
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..
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} => {
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if variant_index != dataful_variant {
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if bx.sess().target.target.arch == "arm" ||
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bx.sess().target.target.arch == "aarch64" {
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// Issue #34427: As workaround for LLVM bug on ARM,
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// use memset of 0 before assigning niche value.
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let llptr = bx.pointercast(self.llval, Type::i8(bx.cx).ptr_to());
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let fill_byte = C_u8(bx.cx, 0);
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let (size, align) = self.layout.size_and_align();
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let size = C_usize(bx.cx, size.bytes());
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let align = C_u32(bx.cx, align.abi() as u32);
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base::call_memset(bx, llptr, fill_byte, size, align, false);
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}
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let niche = self.project_field(bx, 0);
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let niche_llty = niche.layout.immediate_llvm_type(bx.cx);
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let niche_value = ((variant_index - *niche_variants.start()) as u128)
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.wrapping_add(niche_start);
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// FIXME(eddyb) Check the actual primitive type here.
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let niche_llval = if niche_value == 0 {
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// HACK(eddyb) Using `C_null` as it works on all types.
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C_null(niche_llty)
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} else {
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C_uint_big(niche_llty, niche_value)
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};
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OperandValue::Immediate(niche_llval).store(bx, niche);
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}
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}
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}
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}
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pub fn project_index(&self, bx: &Builder<'a, 'tcx>, llindex: ValueRef)
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-> PlaceRef<'tcx> {
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PlaceRef {
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llval: bx.inbounds_gep(self.llval, &[C_usize(bx.cx, 0), llindex]),
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llextra: ptr::null_mut(),
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layout: self.layout.field(bx.cx, 0),
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align: self.align
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}
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}
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pub fn project_downcast(&self, bx: &Builder<'a, 'tcx>, variant_index: usize)
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-> PlaceRef<'tcx> {
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let mut downcast = *self;
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downcast.layout = self.layout.for_variant(bx.cx, variant_index);
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// Cast to the appropriate variant struct type.
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let variant_ty = downcast.layout.llvm_type(bx.cx);
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downcast.llval = bx.pointercast(downcast.llval, variant_ty.ptr_to());
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downcast
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}
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pub fn storage_live(&self, bx: &Builder<'a, 'tcx>) {
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bx.lifetime_start(self.llval, self.layout.size);
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}
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pub fn storage_dead(&self, bx: &Builder<'a, 'tcx>) {
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bx.lifetime_end(self.llval, self.layout.size);
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}
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}
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impl<'a, 'tcx> FunctionCx<'a, 'tcx> {
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pub fn codegen_place(&mut self,
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bx: &Builder<'a, 'tcx>,
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place: &mir::Place<'tcx>)
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-> PlaceRef<'tcx> {
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debug!("codegen_place(place={:?})", place);
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let cx = bx.cx;
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let tcx = cx.tcx;
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if let mir::Place::Local(index) = *place {
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match self.locals[index] {
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LocalRef::Place(place) => {
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return place;
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}
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LocalRef::Operand(..) => {
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bug!("using operand local {:?} as place", place);
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}
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}
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}
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let result = match *place {
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mir::Place::Local(_) => bug!(), // handled above
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mir::Place::Static(box mir::Static { def_id, ty }) => {
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let layout = cx.layout_of(self.monomorphize(&ty));
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PlaceRef::new_sized(consts::get_static(cx, def_id), layout, layout.align)
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},
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mir::Place::Projection(box mir::Projection {
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ref base,
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elem: mir::ProjectionElem::Deref
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}) => {
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// Load the pointer from its location.
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self.codegen_consume(bx, base).deref(bx.cx)
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}
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mir::Place::Projection(ref projection) => {
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let cg_base = self.codegen_place(bx, &projection.base);
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match projection.elem {
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mir::ProjectionElem::Deref => bug!(),
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mir::ProjectionElem::Field(ref field, _) => {
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cg_base.project_field(bx, field.index())
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}
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mir::ProjectionElem::Index(index) => {
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let index = &mir::Operand::Copy(mir::Place::Local(index));
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let index = self.codegen_operand(bx, index);
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let llindex = index.immediate();
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cg_base.project_index(bx, llindex)
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}
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mir::ProjectionElem::ConstantIndex { offset,
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from_end: false,
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min_length: _ } => {
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let lloffset = C_usize(bx.cx, offset as u64);
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cg_base.project_index(bx, lloffset)
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}
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mir::ProjectionElem::ConstantIndex { offset,
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from_end: true,
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min_length: _ } => {
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let lloffset = C_usize(bx.cx, offset as u64);
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let lllen = cg_base.len(bx.cx);
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let llindex = bx.sub(lllen, lloffset);
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cg_base.project_index(bx, llindex)
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}
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mir::ProjectionElem::Subslice { from, to } => {
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let mut subslice = cg_base.project_index(bx,
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C_usize(bx.cx, from as u64));
|
|
let projected_ty = PlaceTy::Ty { ty: cg_base.layout.ty }
|
|
.projection_ty(tcx, &projection.elem).to_ty(bx.tcx());
|
|
subslice.layout = bx.cx.layout_of(self.monomorphize(&projected_ty));
|
|
|
|
if subslice.layout.is_unsized() {
|
|
assert!(cg_base.has_extra());
|
|
subslice.llextra = bx.sub(cg_base.llextra,
|
|
C_usize(bx.cx, (from as u64) + (to as u64)));
|
|
}
|
|
|
|
// Cast the place pointer type to the new
|
|
// array or slice type (*[%_; new_len]).
|
|
subslice.llval = bx.pointercast(subslice.llval,
|
|
subslice.layout.llvm_type(bx.cx).ptr_to());
|
|
|
|
subslice
|
|
}
|
|
mir::ProjectionElem::Downcast(_, v) => {
|
|
cg_base.project_downcast(bx, v)
|
|
}
|
|
}
|
|
}
|
|
};
|
|
debug!("codegen_place(place={:?}) => {:?}", place, result);
|
|
result
|
|
}
|
|
|
|
pub fn monomorphized_place_ty(&self, place: &mir::Place<'tcx>) -> Ty<'tcx> {
|
|
let tcx = self.cx.tcx;
|
|
let place_ty = place.ty(self.mir, tcx);
|
|
self.monomorphize(&place_ty.to_ty(tcx))
|
|
}
|
|
}
|