| // Copyright 2012-2014 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. |
| |
| use llvm::{self, ValueRef}; |
| use rustc::ty::{self, Ty}; |
| use rustc::ty::layout::{self, Align, TyLayout, LayoutOf}; |
| use rustc::mir; |
| use rustc::mir::tcx::PlaceTy; |
| use rustc_data_structures::indexed_vec::Idx; |
| use base; |
| use builder::Builder; |
| use common::{CodegenCx, C_usize, C_u8, C_u32, C_uint, C_int, C_null, C_uint_big}; |
| use consts; |
| use type_of::LayoutLlvmExt; |
| use type_::Type; |
| use value::Value; |
| use glue; |
| |
| use std::ptr; |
| |
| use super::{FunctionCx, LocalRef}; |
| use super::operand::{OperandRef, OperandValue}; |
| |
| #[derive(Copy, Clone, Debug)] |
| pub struct PlaceRef<'tcx> { |
| /// Pointer to the contents of the place |
| pub llval: ValueRef, |
| |
| /// This place's extra data if it is unsized, or null |
| pub llextra: ValueRef, |
| |
| /// Monomorphized type of this place, including variant information |
| pub layout: TyLayout<'tcx>, |
| |
| /// What alignment we know for this place |
| pub align: Align, |
| } |
| |
| impl<'a, 'tcx> PlaceRef<'tcx> { |
| pub fn new_sized(llval: ValueRef, |
| layout: TyLayout<'tcx>, |
| align: Align) |
| -> PlaceRef<'tcx> { |
| PlaceRef { |
| llval, |
| llextra: ptr::null_mut(), |
| layout, |
| align |
| } |
| } |
| |
| pub fn alloca(bx: &Builder<'a, 'tcx>, layout: TyLayout<'tcx>, name: &str) |
| -> PlaceRef<'tcx> { |
| debug!("alloca({:?}: {:?})", name, layout); |
| let tmp = bx.alloca(layout.llvm_type(bx.cx), name, layout.align); |
| Self::new_sized(tmp, layout, layout.align) |
| } |
| |
| pub fn len(&self, cx: &CodegenCx<'a, 'tcx>) -> ValueRef { |
| if let layout::FieldPlacement::Array { count, .. } = self.layout.fields { |
| if self.layout.is_unsized() { |
| assert!(self.has_extra()); |
| assert_eq!(count, 0); |
| self.llextra |
| } else { |
| C_usize(cx, count) |
| } |
| } else { |
| bug!("unexpected layout `{:#?}` in PlaceRef::len", self.layout) |
| } |
| } |
| |
| pub fn has_extra(&self) -> bool { |
| !self.llextra.is_null() |
| } |
| |
| pub fn load(&self, bx: &Builder<'a, 'tcx>) -> OperandRef<'tcx> { |
| debug!("PlaceRef::load: {:?}", self); |
| |
| assert!(!self.has_extra()); |
| |
| if self.layout.is_zst() { |
| return OperandRef::new_zst(bx.cx, self.layout); |
| } |
| |
| let scalar_load_metadata = |load, scalar: &layout::Scalar| { |
| let (min, max) = (scalar.valid_range.start, scalar.valid_range.end); |
| let max_next = max.wrapping_add(1); |
| let bits = scalar.value.size(bx.cx).bits(); |
| assert!(bits <= 128); |
| let mask = !0u128 >> (128 - bits); |
| // For a (max) value of -1, max will be `-1 as usize`, which overflows. |
| // However, that is fine here (it would still represent the full range), |
| // i.e., if the range is everything. The lo==hi case would be |
| // rejected by the LLVM verifier (it would mean either an |
| // empty set, which is impossible, or the entire range of the |
| // type, which is pointless). |
| match scalar.value { |
| layout::Int(..) if max_next & mask != min & mask => { |
| // llvm::ConstantRange can deal with ranges that wrap around, |
| // so an overflow on (max + 1) is fine. |
| bx.range_metadata(load, min..max_next); |
| } |
| layout::Pointer if 0 < min && min < max => { |
| bx.nonnull_metadata(load); |
| } |
| _ => {} |
| } |
| }; |
| |
| let val = if self.layout.is_llvm_immediate() { |
| let mut const_llval = ptr::null_mut(); |
| unsafe { |
| let global = llvm::LLVMIsAGlobalVariable(self.llval); |
| if !global.is_null() && llvm::LLVMIsGlobalConstant(global) == llvm::True { |
| const_llval = llvm::LLVMGetInitializer(global); |
| } |
| } |
| |
| let llval = if !const_llval.is_null() { |
| const_llval |
| } else { |
| let load = bx.load(self.llval, self.align); |
| if let layout::Abi::Scalar(ref scalar) = self.layout.abi { |
| scalar_load_metadata(load, scalar); |
| } |
| load |
| }; |
| OperandValue::Immediate(base::to_immediate(bx, llval, self.layout)) |
| } else if let layout::Abi::ScalarPair(ref a, ref b) = self.layout.abi { |
| let load = |i, scalar: &layout::Scalar| { |
| let mut llptr = bx.struct_gep(self.llval, i as u64); |
| // Make sure to always load i1 as i8. |
| if scalar.is_bool() { |
| llptr = bx.pointercast(llptr, Type::i8p(bx.cx)); |
| } |
| let load = bx.load(llptr, self.align); |
| scalar_load_metadata(load, scalar); |
| if scalar.is_bool() { |
| bx.trunc(load, Type::i1(bx.cx)) |
| } else { |
| load |
| } |
| }; |
| OperandValue::Pair(load(0, a), load(1, b)) |
| } else { |
| OperandValue::Ref(self.llval, self.align) |
| }; |
| |
| OperandRef { val, layout: self.layout } |
| } |
| |
| /// Access a field, at a point when the value's case is known. |
| pub fn project_field(self, bx: &Builder<'a, 'tcx>, ix: usize) -> PlaceRef<'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 simple = || { |
| // Unions and newtypes only use an offset of 0. |
| let llval = if offset.bytes() == 0 { |
| self.llval |
| } else if let layout::Abi::ScalarPair(ref a, ref b) = self.layout.abi { |
| // Offsets have to match either first or second field. |
| assert_eq!(offset, a.value.size(cx).abi_align(b.value.align(cx))); |
| bx.struct_gep(self.llval, 1) |
| } else { |
| bx.struct_gep(self.llval, self.layout.llvm_field_index(ix)) |
| }; |
| PlaceRef { |
| // HACK(eddyb) have to bitcast pointers until LLVM removes pointee types. |
| llval: bx.pointercast(llval, field.llvm_type(cx).ptr_to()), |
| llextra: if cx.type_has_metadata(field.ty) { |
| self.llextra |
| } else { |
| ptr::null_mut() |
| }, |
| layout: field, |
| align, |
| } |
| }; |
| |
| // Simple cases, which don't need DST adjustment: |
| // * no metadata available - just log the case |
| // * known alignment - sized types, [T], str or a foreign type |
| // * packed struct - there is no alignment padding |
| match field.ty.sty { |
| _ if !self.has_extra() => { |
| debug!("Unsized field `{}`, of `{:?}` has no metadata for adjustment", |
| ix, Value(self.llval)); |
| return simple(); |
| } |
| _ if !field.is_unsized() => return simple(), |
| ty::TySlice(..) | ty::TyStr | ty::TyForeign(..) => return simple(), |
| ty::TyAdt(def, _) => { |
| if def.repr.packed() { |
| // FIXME(eddyb) generalize the adjustment when we |
| // start supporting packing to larger alignments. |
| assert_eq!(self.layout.align.abi(), 1); |
| return simple(); |
| } |
| } |
| _ => {} |
| } |
| |
| // We need to get the pointer manually now. |
| // We do this by casting to a *i8, then offsetting it by the appropriate amount. |
| // We do this instead of, say, simply adjusting the pointer from the result of a GEP |
| // because the field may have an arbitrary alignment in the LLVM representation |
| // anyway. |
| // |
| // To demonstrate: |
| // struct Foo<T: ?Sized> { |
| // x: u16, |
| // y: T |
| // } |
| // |
| // The type Foo<Foo<Trait>> is represented in LLVM as { u16, { u16, u8 }}, meaning that |
| // the `y` field has 16-bit alignment. |
| |
| let meta = self.llextra; |
| |
| let unaligned_offset = C_usize(cx, offset.bytes()); |
| |
| // Get the alignment of the field |
| let (_, unsized_align) = glue::size_and_align_of_dst(bx, field.ty, meta); |
| |
| // Bump the unaligned offset up to the appropriate alignment using the |
| // following expression: |
| // |
| // (unaligned offset + (align - 1)) & -align |
| |
| // Calculate offset |
| let align_sub_1 = bx.sub(unsized_align, C_usize(cx, 1u64)); |
| let offset = bx.and(bx.add(unaligned_offset, align_sub_1), |
| bx.neg(unsized_align)); |
| |
| debug!("struct_field_ptr: DST field offset: {:?}", Value(offset)); |
| |
| // Cast and adjust pointer |
| let byte_ptr = bx.pointercast(self.llval, Type::i8p(cx)); |
| let byte_ptr = bx.gep(byte_ptr, &[offset]); |
| |
| // Finally, cast back to the type expected |
| let ll_fty = field.llvm_type(cx); |
| debug!("struct_field_ptr: Field type is {:?}", ll_fty); |
| |
| PlaceRef { |
| llval: bx.pointercast(byte_ptr, ll_fty.ptr_to()), |
| llextra: self.llextra, |
| layout: field, |
| align, |
| } |
| } |
| |
| /// Obtain the actual discriminant of a value. |
| pub fn trans_get_discr(self, bx: &Builder<'a, 'tcx>, cast_to: Ty<'tcx>) -> ValueRef { |
| let cast_to = bx.cx.layout_of(cast_to).immediate_llvm_type(bx.cx); |
| match self.layout.variants { |
| layout::Variants::Single { index } => { |
| return C_uint(cast_to, index as u64); |
| } |
| layout::Variants::Tagged { .. } | |
| layout::Variants::NicheFilling { .. } => {}, |
| } |
| |
| let discr = self.project_field(bx, 0); |
| let lldiscr = discr.load(bx).immediate(); |
| match self.layout.variants { |
| layout::Variants::Single { .. } => bug!(), |
| layout::Variants::Tagged { ref discr, .. } => { |
| let signed = match discr.value { |
| layout::Int(_, signed) => signed, |
| _ => false |
| }; |
| bx.intcast(lldiscr, cast_to, signed) |
| } |
| layout::Variants::NicheFilling { |
| dataful_variant, |
| ref niche_variants, |
| niche_start, |
| .. |
| } => { |
| let niche_llty = discr.layout.immediate_llvm_type(bx.cx); |
| if niche_variants.start == niche_variants.end { |
| // FIXME(eddyb) Check the actual primitive type here. |
| let niche_llval = if niche_start == 0 { |
| // HACK(eddyb) Using `C_null` as it works on all types. |
| C_null(niche_llty) |
| } else { |
| C_uint_big(niche_llty, niche_start) |
| }; |
| bx.select(bx.icmp(llvm::IntEQ, lldiscr, niche_llval), |
| C_uint(cast_to, niche_variants.start as u64), |
| C_uint(cast_to, dataful_variant as u64)) |
| } else { |
| // Rebase from niche values to discriminant values. |
| let delta = niche_start.wrapping_sub(niche_variants.start as u128); |
| let lldiscr = bx.sub(lldiscr, C_uint_big(niche_llty, delta)); |
| let lldiscr_max = C_uint(niche_llty, niche_variants.end as u64); |
| bx.select(bx.icmp(llvm::IntULE, lldiscr, lldiscr_max), |
| bx.intcast(lldiscr, cast_to, false), |
| C_uint(cast_to, dataful_variant as u64)) |
| } |
| } |
| } |
| } |
| |
| /// Set the discriminant for a new value of the given case of the given |
| /// representation. |
| pub fn trans_set_discr(&self, bx: &Builder<'a, 'tcx>, variant_index: usize) { |
| if self.layout.for_variant(bx.cx, variant_index).abi == layout::Abi::Uninhabited { |
| return; |
| } |
| match self.layout.variants { |
| layout::Variants::Single { index } => { |
| assert_eq!(index, variant_index); |
| } |
| layout::Variants::Tagged { .. } => { |
| let ptr = self.project_field(bx, 0); |
| let to = self.layout.ty.ty_adt_def().unwrap() |
| .discriminant_for_variant(bx.tcx(), variant_index) |
| .to_u128_unchecked() as u64; |
| bx.store(C_int(ptr.layout.llvm_type(bx.cx), to as i64), |
| ptr.llval, ptr.align); |
| } |
| layout::Variants::NicheFilling { |
| dataful_variant, |
| ref niche_variants, |
| niche_start, |
| .. |
| } => { |
| if variant_index != dataful_variant { |
| if bx.sess().target.target.arch == "arm" || |
| bx.sess().target.target.arch == "aarch64" { |
| // Issue #34427: As workaround for LLVM bug on ARM, |
| // use memset of 0 before assigning niche value. |
| let llptr = bx.pointercast(self.llval, Type::i8(bx.cx).ptr_to()); |
| let fill_byte = C_u8(bx.cx, 0); |
| let (size, align) = self.layout.size_and_align(); |
| let size = C_usize(bx.cx, size.bytes()); |
| let align = C_u32(bx.cx, align.abi() as u32); |
| base::call_memset(bx, llptr, fill_byte, size, align, false); |
| } |
| |
| let niche = self.project_field(bx, 0); |
| let niche_llty = niche.layout.immediate_llvm_type(bx.cx); |
| let niche_value = ((variant_index - niche_variants.start) as u128) |
| .wrapping_add(niche_start); |
| // FIXME(eddyb) Check the actual primitive type here. |
| let niche_llval = if niche_value == 0 { |
| // HACK(eddyb) Using `C_null` as it works on all types. |
| C_null(niche_llty) |
| } else { |
| C_uint_big(niche_llty, niche_value) |
| }; |
| OperandValue::Immediate(niche_llval).store(bx, niche); |
| } |
| } |
| } |
| } |
| |
| pub fn project_index(&self, bx: &Builder<'a, 'tcx>, llindex: ValueRef) |
| -> PlaceRef<'tcx> { |
| PlaceRef { |
| llval: bx.inbounds_gep(self.llval, &[C_usize(bx.cx, 0), llindex]), |
| llextra: ptr::null_mut(), |
| layout: self.layout.field(bx.cx, 0), |
| align: self.align |
| } |
| } |
| |
| pub fn project_downcast(&self, bx: &Builder<'a, 'tcx>, variant_index: usize) |
| -> PlaceRef<'tcx> { |
| let mut downcast = *self; |
| downcast.layout = self.layout.for_variant(bx.cx, variant_index); |
| |
| // Cast to the appropriate variant struct type. |
| let variant_ty = downcast.layout.llvm_type(bx.cx); |
| downcast.llval = bx.pointercast(downcast.llval, variant_ty.ptr_to()); |
| |
| downcast |
| } |
| |
| pub fn storage_live(&self, bx: &Builder<'a, 'tcx>) { |
| bx.lifetime_start(self.llval, self.layout.size); |
| } |
| |
| pub fn storage_dead(&self, bx: &Builder<'a, 'tcx>) { |
| bx.lifetime_end(self.llval, self.layout.size); |
| } |
| } |
| |
| impl<'a, 'tcx> FunctionCx<'a, 'tcx> { |
| pub fn trans_place(&mut self, |
| bx: &Builder<'a, 'tcx>, |
| place: &mir::Place<'tcx>) |
| -> PlaceRef<'tcx> { |
| debug!("trans_place(place={:?})", place); |
| |
| let cx = bx.cx; |
| let tcx = cx.tcx; |
| |
| if let mir::Place::Local(index) = *place { |
| match self.locals[index] { |
| LocalRef::Place(place) => { |
| return place; |
| } |
| LocalRef::Operand(..) => { |
| bug!("using operand local {:?} as place", place); |
| } |
| } |
| } |
| |
| let result = match *place { |
| mir::Place::Local(_) => bug!(), // handled above |
| mir::Place::Static(box mir::Static { def_id, ty }) => { |
| let layout = cx.layout_of(self.monomorphize(&ty)); |
| PlaceRef::new_sized(consts::get_static(cx, def_id), layout, layout.align) |
| }, |
| mir::Place::Projection(box mir::Projection { |
| ref base, |
| elem: mir::ProjectionElem::Deref |
| }) => { |
| // Load the pointer from its location. |
| self.trans_consume(bx, base).deref(bx.cx) |
| } |
| mir::Place::Projection(ref projection) => { |
| let tr_base = self.trans_place(bx, &projection.base); |
| |
| match projection.elem { |
| mir::ProjectionElem::Deref => bug!(), |
| mir::ProjectionElem::Field(ref field, _) => { |
| tr_base.project_field(bx, field.index()) |
| } |
| mir::ProjectionElem::Index(index) => { |
| let index = &mir::Operand::Copy(mir::Place::Local(index)); |
| let index = self.trans_operand(bx, index); |
| let llindex = index.immediate(); |
| tr_base.project_index(bx, llindex) |
| } |
| mir::ProjectionElem::ConstantIndex { offset, |
| from_end: false, |
| min_length: _ } => { |
| let lloffset = C_usize(bx.cx, offset as u64); |
| tr_base.project_index(bx, lloffset) |
| } |
| mir::ProjectionElem::ConstantIndex { offset, |
| from_end: true, |
| min_length: _ } => { |
| let lloffset = C_usize(bx.cx, offset as u64); |
| let lllen = tr_base.len(bx.cx); |
| let llindex = bx.sub(lllen, lloffset); |
| tr_base.project_index(bx, llindex) |
| } |
| mir::ProjectionElem::Subslice { from, to } => { |
| let mut subslice = tr_base.project_index(bx, |
| C_usize(bx.cx, from as u64)); |
| let projected_ty = PlaceTy::Ty { ty: tr_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!(tr_base.has_extra()); |
| subslice.llextra = bx.sub(tr_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) => { |
| tr_base.project_downcast(bx, v) |
| } |
| } |
| } |
| }; |
| debug!("trans_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)) |
| } |
| } |
| |
