1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
13 use rustc::ty::layout::Layout;
15 use rustc_data_structures::indexed_vec::Idx;
26 use super::{MirContext, LocalRef};
27 use super::lvalue::Alignment;
29 /// The representation of a Rust value. The enum variant is in fact
30 /// uniquely determined by the value's type, but is kept as a
32 #[derive(Copy, Clone)]
33 pub enum OperandValue {
34 /// A reference to the actual operand. The data is guaranteed
35 /// to be valid for the operand's lifetime.
36 Ref(ValueRef, Alignment),
37 /// A single LLVM value.
39 /// A pair of immediate LLVM values. Used by fat pointers too.
40 Pair(ValueRef, ValueRef)
43 /// An `OperandRef` is an "SSA" reference to a Rust value, along with
46 /// NOTE: unless you know a value's type exactly, you should not
47 /// generate LLVM opcodes acting on it and instead act via methods,
48 /// to avoid nasty edge cases. In particular, using `Builder.store`
49 /// directly is sure to cause problems -- use `MirContext.store_operand`
51 #[derive(Copy, Clone)]
52 pub struct OperandRef<'tcx> {
54 pub val: OperandValue,
56 // The type of value being returned.
60 impl<'tcx> fmt::Debug for OperandRef<'tcx> {
61 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
63 OperandValue::Ref(r, align) => {
64 write!(f, "OperandRef(Ref({:?}, {:?}) @ {:?})",
65 Value(r), align, self.ty)
67 OperandValue::Immediate(i) => {
68 write!(f, "OperandRef(Immediate({:?}) @ {:?})",
71 OperandValue::Pair(a, b) => {
72 write!(f, "OperandRef(Pair({:?}, {:?}) @ {:?})",
73 Value(a), Value(b), self.ty)
79 impl<'a, 'tcx> OperandRef<'tcx> {
80 /// Asserts that this operand refers to a scalar and returns
81 /// a reference to its value.
82 pub fn immediate(self) -> ValueRef {
84 OperandValue::Immediate(s) => s,
85 _ => bug!("not immediate: {:?}", self)
89 /// If this operand is a Pair, we return an
90 /// Immediate aggregate with the two values.
91 pub fn pack_if_pair(mut self, bcx: &Builder<'a, 'tcx>) -> OperandRef<'tcx> {
92 if let OperandValue::Pair(a, b) = self.val {
93 // Reconstruct the immediate aggregate.
94 let llty = type_of::type_of(bcx.ccx, self.ty);
95 let mut llpair = common::C_undef(llty);
98 let mut elem = elems[i];
99 // Extend boolean i1's to i8.
100 if common::val_ty(elem) == Type::i1(bcx.ccx) {
101 elem = bcx.zext(elem, Type::i8(bcx.ccx));
103 llpair = bcx.insert_value(llpair, elem, i);
105 self.val = OperandValue::Immediate(llpair);
110 /// If this operand is a pair in an Immediate,
111 /// we return a Pair with the two halves.
112 pub fn unpack_if_pair(mut self, bcx: &Builder<'a, 'tcx>) -> OperandRef<'tcx> {
113 if let OperandValue::Immediate(llval) = self.val {
114 // Deconstruct the immediate aggregate.
115 if common::type_is_imm_pair(bcx.ccx, self.ty) {
116 debug!("Operand::unpack_if_pair: unpacking {:?}", self);
118 let mut a = bcx.extract_value(llval, 0);
119 let mut b = bcx.extract_value(llval, 1);
121 let pair_fields = common::type_pair_fields(bcx.ccx, self.ty);
122 if let Some([a_ty, b_ty]) = pair_fields {
124 a = bcx.trunc(a, Type::i1(bcx.ccx));
127 b = bcx.trunc(b, Type::i1(bcx.ccx));
131 self.val = OperandValue::Pair(a, b);
138 impl<'a, 'tcx> MirContext<'a, 'tcx> {
139 pub fn trans_load(&mut self,
140 bcx: &Builder<'a, 'tcx>,
146 debug!("trans_load: {:?} @ {:?}", Value(llval), ty);
148 let val = if common::type_is_fat_ptr(bcx.ccx, ty) {
149 let (lldata, llextra) = base::load_fat_ptr(bcx, llval, align, ty);
150 OperandValue::Pair(lldata, llextra)
151 } else if common::type_is_imm_pair(bcx.ccx, ty) {
152 let f_align = match *bcx.ccx.layout_of(ty) {
153 Layout::Univariant { ref variant, .. } =>
154 Alignment::from_packed(variant.packed) | align,
157 let [a_ty, b_ty] = common::type_pair_fields(bcx.ccx, ty).unwrap();
158 let a_ptr = bcx.struct_gep(llval, 0);
159 let b_ptr = bcx.struct_gep(llval, 1);
162 base::load_ty(bcx, a_ptr, f_align, a_ty),
163 base::load_ty(bcx, b_ptr, f_align, b_ty)
165 } else if common::type_is_immediate(bcx.ccx, ty) {
166 OperandValue::Immediate(base::load_ty(bcx, llval, align, ty))
168 OperandValue::Ref(llval, align)
171 OperandRef { val: val, ty: ty }
174 pub fn trans_consume(&mut self,
175 bcx: &Builder<'a, 'tcx>,
176 lvalue: &mir::Lvalue<'tcx>)
179 debug!("trans_consume(lvalue={:?})", lvalue);
181 // watch out for locals that do not have an
182 // alloca; they are handled somewhat differently
183 if let mir::Lvalue::Local(index) = *lvalue {
184 match self.locals[index] {
185 LocalRef::Operand(Some(o)) => {
188 LocalRef::Operand(None) => {
189 bug!("use of {:?} before def", lvalue);
191 LocalRef::Lvalue(..) => {
197 // Moves out of pair fields are trivial.
198 if let &mir::Lvalue::Projection(ref proj) = lvalue {
199 if let mir::Lvalue::Local(index) = proj.base {
200 if let LocalRef::Operand(Some(o)) = self.locals[index] {
201 match (o.val, &proj.elem) {
202 (OperandValue::Pair(a, b),
203 &mir::ProjectionElem::Field(ref f, ty)) => {
204 let llval = [a, b][f.index()];
205 let op = OperandRef {
206 val: OperandValue::Immediate(llval),
207 ty: self.monomorphize(&ty)
210 // Handle nested pairs.
211 return op.unpack_if_pair(bcx);
219 // for most lvalues, to consume them we just load them
220 // out from their home
221 let tr_lvalue = self.trans_lvalue(bcx, lvalue);
222 let ty = tr_lvalue.ty.to_ty(bcx.tcx());
223 self.trans_load(bcx, tr_lvalue.llval, tr_lvalue.alignment, ty)
226 pub fn trans_operand(&mut self,
227 bcx: &Builder<'a, 'tcx>,
228 operand: &mir::Operand<'tcx>)
231 debug!("trans_operand(operand={:?})", operand);
234 mir::Operand::Consume(ref lvalue) => {
235 self.trans_consume(bcx, lvalue)
238 mir::Operand::Constant(ref constant) => {
239 let val = self.trans_constant(bcx, constant);
240 let operand = val.to_operand(bcx.ccx);
241 if let OperandValue::Ref(ptr, align) = operand.val {
242 // If this is a OperandValue::Ref to an immediate constant, load it.
243 self.trans_load(bcx, ptr, align, operand.ty)
251 pub fn store_operand(&mut self,
252 bcx: &Builder<'a, 'tcx>,
255 operand: OperandRef<'tcx>) {
256 debug!("store_operand: operand={:?}, align={:?}", operand, align);
257 // Avoid generating stores of zero-sized values, because the only way to have a zero-sized
258 // value is through `undef`, and store itself is useless.
259 if common::type_is_zero_size(bcx.ccx, operand.ty) {
263 OperandValue::Ref(r, Alignment::Packed) =>
264 base::memcpy_ty(bcx, lldest, r, operand.ty, Some(1)),
265 OperandValue::Ref(r, Alignment::AbiAligned) =>
266 base::memcpy_ty(bcx, lldest, r, operand.ty, align),
267 OperandValue::Immediate(s) => {
268 bcx.store(base::from_immediate(bcx, s), lldest, align);
270 OperandValue::Pair(a, b) => {
271 let a = base::from_immediate(bcx, a);
272 let b = base::from_immediate(bcx, b);
273 bcx.store(a, bcx.struct_gep(lldest, 0), align);
274 bcx.store(b, bcx.struct_gep(lldest, 1), align);