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.
11 use rustc::mir::interpret::{ConstValue, ErrorHandled};
14 use rustc::ty::layout::{self, Align, LayoutOf, TyLayout};
17 use common::{CodegenCx, C_undef, C_usize};
18 use builder::{Builder, MemFlags};
19 use value::{Value, ValueTrait};
20 use type_of::LayoutLlvmExt;
24 use traits::BuilderMethods;
28 use super::{FunctionCx, LocalRef};
29 use super::constant::scalar_to_llvm;
30 use super::place::PlaceRef;
32 /// The representation of a Rust value. The enum variant is in fact
33 /// uniquely determined by the value's type, but is kept as a
35 #[derive(Copy, Clone, Debug)]
36 pub enum OperandValue<V> {
37 /// A reference to the actual operand. The data is guaranteed
38 /// to be valid for the operand's lifetime.
39 /// The second value, if any, is the extra data (vtable or length)
40 /// which indicates that it refers to an unsized rvalue.
41 Ref(V, Option<V>, Align),
42 /// A single LLVM value.
44 /// A pair of immediate LLVM values. Used by fat pointers too.
48 /// An `OperandRef` is an "SSA" reference to a Rust value, along with
51 /// NOTE: unless you know a value's type exactly, you should not
52 /// generate LLVM opcodes acting on it and instead act via methods,
53 /// to avoid nasty edge cases. In particular, using `Builder::store`
54 /// directly is sure to cause problems -- use `OperandRef::store`
56 #[derive(Copy, Clone)]
57 pub struct OperandRef<'tcx, V> {
59 pub val: OperandValue<V>,
61 // The layout of value, based on its Rust type.
62 pub layout: TyLayout<'tcx>,
65 impl<Value: ?Sized> fmt::Debug for OperandRef<'tcx, &'ll Value> where Value: ValueTrait {
66 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
67 write!(f, "OperandRef({:?} @ {:?})", self.val, self.layout)
71 impl OperandRef<'tcx, &'ll Value> {
72 pub fn new_zst(cx: &CodegenCx<'ll, 'tcx>,
73 layout: TyLayout<'tcx>) -> OperandRef<'tcx, &'ll Value> {
74 assert!(layout.is_zst());
76 val: OperandValue::Immediate(C_undef(layout.immediate_llvm_type(cx))),
81 pub fn from_const(bx: &Builder<'a, 'll, 'tcx>,
82 val: &'tcx ty::Const<'tcx>)
83 -> Result<OperandRef<'tcx, &'ll Value>, ErrorHandled> {
84 let layout = bx.cx.layout_of(val.ty);
87 return Ok(OperandRef::new_zst(bx.cx, layout));
90 let val = match val.val {
91 ConstValue::Unevaluated(..) => bug!(),
92 ConstValue::Scalar(x) => {
93 let scalar = match layout.abi {
94 layout::Abi::Scalar(ref x) => x,
95 _ => bug!("from_const: invalid ByVal layout: {:#?}", layout)
97 let llval = scalar_to_llvm(
101 layout.immediate_llvm_type(bx.cx),
103 OperandValue::Immediate(llval)
105 ConstValue::ScalarPair(a, b) => {
106 let (a_scalar, b_scalar) = match layout.abi {
107 layout::Abi::ScalarPair(ref a, ref b) => (a, b),
108 _ => bug!("from_const: invalid ScalarPair layout: {:#?}", layout)
110 let a_llval = scalar_to_llvm(
114 layout.scalar_pair_element_llvm_type(bx.cx, 0, true),
116 let b_layout = layout.scalar_pair_element_llvm_type(bx.cx, 1, true);
117 let b_llval = scalar_to_llvm(
123 OperandValue::Pair(a_llval, b_llval)
125 ConstValue::ByRef(_, alloc, offset) => {
126 return Ok(PlaceRef::from_const_alloc(bx, layout, alloc, offset).load(bx));
136 /// Asserts that this operand refers to a scalar and returns
137 /// a reference to its value.
138 pub fn immediate(self) -> &'ll Value {
140 OperandValue::Immediate(s) => s,
141 _ => bug!("not immediate: {:?}", self)
145 pub fn deref(self, cx: &CodegenCx<'ll, 'tcx>) -> PlaceRef<'tcx, &'ll Value> {
146 let projected_ty = self.layout.ty.builtin_deref(true)
147 .unwrap_or_else(|| bug!("deref of non-pointer {:?}", self)).ty;
148 let (llptr, llextra) = match self.val {
149 OperandValue::Immediate(llptr) => (llptr, None),
150 OperandValue::Pair(llptr, llextra) => (llptr, Some(llextra)),
151 OperandValue::Ref(..) => bug!("Deref of by-Ref operand {:?}", self)
153 let layout = cx.layout_of(projected_ty);
162 /// If this operand is a `Pair`, we return an aggregate with the two values.
163 /// For other cases, see `immediate`.
164 pub fn immediate_or_packed_pair(self, bx: &Builder<'a, 'll, 'tcx>) -> &'ll Value {
165 if let OperandValue::Pair(a, b) = self.val {
166 let llty = self.layout.llvm_type(bx.cx);
167 debug!("Operand::immediate_or_packed_pair: packing {:?} into {:?}",
169 // Reconstruct the immediate aggregate.
170 let mut llpair = C_undef(llty);
171 llpair = bx.insert_value(llpair, base::from_immediate(bx, a), 0);
172 llpair = bx.insert_value(llpair, base::from_immediate(bx, b), 1);
179 /// If the type is a pair, we return a `Pair`, otherwise, an `Immediate`.
180 pub fn from_immediate_or_packed_pair(bx: &Builder<'a, 'll, 'tcx>,
182 layout: TyLayout<'tcx>)
183 -> OperandRef<'tcx, &'ll Value> {
184 let val = if let layout::Abi::ScalarPair(ref a, ref b) = layout.abi {
185 debug!("Operand::from_immediate_or_packed_pair: unpacking {:?} @ {:?}",
188 // Deconstruct the immediate aggregate.
189 let a_llval = base::to_immediate_scalar(bx, bx.extract_value(llval, 0), a);
190 let b_llval = base::to_immediate_scalar(bx, bx.extract_value(llval, 1), b);
191 OperandValue::Pair(a_llval, b_llval)
193 OperandValue::Immediate(llval)
195 OperandRef { val, layout }
198 pub fn extract_field(
200 bx: &Builder<'a, 'll, 'tcx>,
202 ) -> OperandRef<'tcx, &'ll Value> {
203 let field = self.layout.field(bx.cx, i);
204 let offset = self.layout.fields.offset(i);
206 let mut val = match (self.val, &self.layout.abi) {
207 // If the field is ZST, it has no data.
208 _ if field.is_zst() => {
209 return OperandRef::new_zst(bx.cx, field);
212 // Newtype of a scalar, scalar pair or vector.
213 (OperandValue::Immediate(_), _) |
214 (OperandValue::Pair(..), _) if field.size == self.layout.size => {
215 assert_eq!(offset.bytes(), 0);
219 // Extract a scalar component from a pair.
220 (OperandValue::Pair(a_llval, b_llval), &layout::Abi::ScalarPair(ref a, ref b)) => {
221 if offset.bytes() == 0 {
222 assert_eq!(field.size, a.value.size(bx.cx));
223 OperandValue::Immediate(a_llval)
225 assert_eq!(offset, a.value.size(bx.cx)
226 .abi_align(b.value.align(bx.cx)));
227 assert_eq!(field.size, b.value.size(bx.cx));
228 OperandValue::Immediate(b_llval)
232 // `#[repr(simd)]` types are also immediate.
233 (OperandValue::Immediate(llval), &layout::Abi::Vector { .. }) => {
234 OperandValue::Immediate(
235 bx.extract_element(llval, C_usize(bx.cx, i as u64)))
238 _ => bug!("OperandRef::extract_field({:?}): not applicable", self)
241 // HACK(eddyb) have to bitcast pointers until LLVM removes pointee types.
243 OperandValue::Immediate(ref mut llval) => {
244 *llval = bx.bitcast(*llval, field.immediate_llvm_type(bx.cx));
246 OperandValue::Pair(ref mut a, ref mut b) => {
247 *a = bx.bitcast(*a, field.scalar_pair_element_llvm_type(bx.cx, 0, true));
248 *b = bx.bitcast(*b, field.scalar_pair_element_llvm_type(bx.cx, 1, true));
250 OperandValue::Ref(..) => bug!()
260 impl OperandValue<&'ll Value> {
261 pub fn store(self, bx: &Builder<'a, 'll, 'tcx>, dest: PlaceRef<'tcx, &'ll Value>) {
262 self.store_with_flags(bx, dest, MemFlags::empty());
265 pub fn volatile_store(
267 bx: &Builder<'a, 'll, 'tcx, &'ll Value>,
268 dest: PlaceRef<'tcx, &'ll Value>
270 self.store_with_flags(bx, dest, MemFlags::VOLATILE);
273 pub fn unaligned_volatile_store(
275 bx: &Builder<'a, 'll, 'tcx>,
276 dest: PlaceRef<'tcx, &'ll Value>,
278 self.store_with_flags(bx, dest, MemFlags::VOLATILE | MemFlags::UNALIGNED);
282 impl<'a, 'll: 'a, 'tcx: 'll, Value : ?Sized> OperandValue<&'ll Value> where
284 Builder<'a, 'll, 'tcx, &'ll Value>: BuilderMethods<'a, 'll, 'tcx, Value>
286 pub fn nontemporal_store(
288 bx: &Builder<'a, 'll, 'tcx, &'ll Value>,
289 dest: PlaceRef<'tcx, &'ll Value>
291 self.store_with_flags(bx, dest, MemFlags::NONTEMPORAL);
294 fn store_with_flags<Builder: BuilderMethods<'a, 'll, 'tcx, Value>>(
297 dest: PlaceRef<'tcx, &'ll Value>,
300 debug!("OperandRef::store: operand={:?}, dest={:?}", self, dest);
301 // Avoid generating stores of zero-sized values, because the only way to have a zero-sized
302 // value is through `undef`, and store itself is useless.
303 if dest.layout.is_zst() {
307 OperandValue::Ref(r, None, source_align) => {
308 base::memcpy_ty(bx, dest.llval, dest.align, r, source_align,
311 OperandValue::Ref(_, Some(_), _) => {
312 bug!("cannot directly store unsized values");
314 OperandValue::Immediate(s) => {
315 let val = base::from_immediate(bx, s);
316 bx.store_with_flags(val, dest.llval, dest.align, flags);
318 OperandValue::Pair(a, b) => {
319 for (i, &x) in [a, b].iter().enumerate() {
320 let llptr = bx.struct_gep(dest.llval, i as u64);
321 let val = base::from_immediate(bx, x);
322 bx.store_with_flags(val, llptr, dest.align, flags);
329 impl OperandValue<&'ll Value> {
330 pub fn store_unsized(
332 bx: &Builder<'a, 'll, 'tcx, &'ll Value>,
333 indirect_dest: PlaceRef<'tcx, &'ll Value>
335 debug!("OperandRef::store_unsized: operand={:?}, indirect_dest={:?}", self, indirect_dest);
336 let flags = MemFlags::empty();
338 // `indirect_dest` must have `*mut T` type. We extract `T` out of it.
339 let unsized_ty = indirect_dest.layout.ty.builtin_deref(true)
340 .unwrap_or_else(|| bug!("indirect_dest has non-pointer type: {:?}", indirect_dest)).ty;
342 let (llptr, llextra) =
343 if let OperandValue::Ref(llptr, Some(llextra), _) = self {
346 bug!("store_unsized called with a sized value")
349 // FIXME: choose an appropriate alignment, or use dynamic align somehow
350 let max_align = Align::from_bits(128, 128).unwrap();
351 let min_align = Align::from_bits(8, 8).unwrap();
353 // Allocate an appropriate region on the stack, and copy the value into it
354 let (llsize, _) = glue::size_and_align_of_dst(bx, unsized_ty, Some(llextra));
355 let lldst = bx.array_alloca(Type::i8(bx.cx), llsize, "unsized_tmp", max_align);
356 base::call_memcpy(bx, lldst, max_align, llptr, min_align, llsize, flags);
358 // Store the allocated region and the extra to the indirect place.
359 let indirect_operand = OperandValue::Pair(lldst, llextra);
360 indirect_operand.store(bx, indirect_dest);
364 impl FunctionCx<'a, 'll, 'tcx, &'ll Value> {
365 fn maybe_codegen_consume_direct(&mut self,
366 bx: &Builder<'a, 'll, 'tcx>,
367 place: &mir::Place<'tcx>)
368 -> Option<OperandRef<'tcx, &'ll Value>>
370 debug!("maybe_codegen_consume_direct(place={:?})", place);
372 // watch out for locals that do not have an
373 // alloca; they are handled somewhat differently
374 if let mir::Place::Local(index) = *place {
375 match self.locals[index] {
376 LocalRef::Operand(Some(o)) => {
379 LocalRef::Operand(None) => {
380 bug!("use of {:?} before def", place);
382 LocalRef::Place(..) | LocalRef::UnsizedPlace(..) => {
388 // Moves out of scalar and scalar pair fields are trivial.
389 if let &mir::Place::Projection(ref proj) = place {
390 if let Some(o) = self.maybe_codegen_consume_direct(bx, &proj.base) {
392 mir::ProjectionElem::Field(ref f, _) => {
393 return Some(o.extract_field(bx, f.index()));
395 mir::ProjectionElem::Index(_) |
396 mir::ProjectionElem::ConstantIndex { .. } => {
397 // ZSTs don't require any actual memory access.
398 // FIXME(eddyb) deduplicate this with the identical
399 // checks in `codegen_consume` and `extract_field`.
400 let elem = o.layout.field(bx.cx, 0);
402 return Some(OperandRef::new_zst(bx.cx, elem));
413 pub fn codegen_consume(&mut self,
414 bx: &Builder<'a, 'll, 'tcx>,
415 place: &mir::Place<'tcx>)
416 -> OperandRef<'tcx, &'ll Value>
418 debug!("codegen_consume(place={:?})", place);
420 let ty = self.monomorphized_place_ty(place);
421 let layout = bx.cx.layout_of(ty);
423 // ZSTs don't require any actual memory access.
425 return OperandRef::new_zst(bx.cx, layout);
428 if let Some(o) = self.maybe_codegen_consume_direct(bx, place) {
432 // for most places, to consume them we just load them
433 // out from their home
434 self.codegen_place(bx, place).load(bx)
437 pub fn codegen_operand(&mut self,
438 bx: &Builder<'a, 'll, 'tcx>,
439 operand: &mir::Operand<'tcx>)
440 -> OperandRef<'tcx, &'ll Value>
442 debug!("codegen_operand(operand={:?})", operand);
445 mir::Operand::Copy(ref place) |
446 mir::Operand::Move(ref place) => {
447 self.codegen_consume(bx, place)
450 mir::Operand::Constant(ref constant) => {
451 let ty = self.monomorphize(&constant.ty);
452 self.eval_mir_constant(bx, constant)
453 .and_then(|c| OperandRef::from_const(bx, c))
454 .unwrap_or_else(|err| {
456 // errored or at least linted
457 ErrorHandled::Reported => {},
458 ErrorHandled::TooGeneric => {
459 bug!("codgen encountered polymorphic constant")
462 // Allow RalfJ to sleep soundly knowing that even refactorings that remove
463 // the above error (or silence it under some conditions) will not cause UB
464 let fnname = bx.cx.get_intrinsic(&("llvm.trap"));
465 bx.call(fnname, &[], None);
466 // We've errored, so we don't have to produce working code.
467 let layout = bx.cx.layout_of(ty);
469 C_undef(layout.llvm_type(bx.cx).ptr_to()),