266 lines
9.3 KiB
Rust
266 lines
9.3 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::ValueRef;
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use rustc::ty::Ty;
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use rustc::mir;
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use rustc_data_structures::indexed_vec::Idx;
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use base;
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use common::{self, BlockAndBuilder};
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use value::Value;
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use type_of;
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use type_::Type;
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use std::fmt;
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use super::{MirContext, LocalRef};
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/// The representation of a Rust value. The enum variant is in fact
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/// uniquely determined by the value's type, but is kept as a
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/// safety check.
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#[derive(Copy, Clone)]
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pub enum OperandValue {
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/// A reference to the actual operand. The data is guaranteed
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/// to be valid for the operand's lifetime.
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Ref(ValueRef),
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/// A single LLVM value.
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Immediate(ValueRef),
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/// A pair of immediate LLVM values. Used by fat pointers too.
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Pair(ValueRef, ValueRef)
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}
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/// An `OperandRef` is an "SSA" reference to a Rust value, along with
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/// its type.
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///
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/// NOTE: unless you know a value's type exactly, you should not
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/// generate LLVM opcodes acting on it and instead act via methods,
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/// to avoid nasty edge cases. In particular, using `Builder.store`
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/// directly is sure to cause problems -- use `MirContext.store_operand`
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/// instead.
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#[derive(Copy, Clone)]
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pub struct OperandRef<'tcx> {
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// The value.
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pub val: OperandValue,
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// The type of value being returned.
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pub ty: Ty<'tcx>
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}
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impl<'tcx> fmt::Debug for OperandRef<'tcx> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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match self.val {
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OperandValue::Ref(r) => {
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write!(f, "OperandRef(Ref({:?}) @ {:?})",
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Value(r), self.ty)
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}
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OperandValue::Immediate(i) => {
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write!(f, "OperandRef(Immediate({:?}) @ {:?})",
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Value(i), self.ty)
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}
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OperandValue::Pair(a, b) => {
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write!(f, "OperandRef(Pair({:?}, {:?}) @ {:?})",
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Value(a), Value(b), self.ty)
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}
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}
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}
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}
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impl<'a, 'tcx> OperandRef<'tcx> {
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/// Asserts that this operand refers to a scalar and returns
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/// a reference to its value.
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pub fn immediate(self) -> ValueRef {
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match self.val {
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OperandValue::Immediate(s) => s,
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_ => bug!()
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}
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}
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/// If this operand is a Pair, we return an
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/// Immediate aggregate with the two values.
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pub fn pack_if_pair(mut self, bcx: &BlockAndBuilder<'a, 'tcx>)
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-> OperandRef<'tcx> {
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if let OperandValue::Pair(a, b) = self.val {
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// Reconstruct the immediate aggregate.
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let llty = type_of::type_of(bcx.ccx, self.ty);
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let mut llpair = common::C_undef(llty);
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let elems = [a, b];
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for i in 0..2 {
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let mut elem = elems[i];
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// Extend boolean i1's to i8.
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if common::val_ty(elem) == Type::i1(bcx.ccx) {
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elem = bcx.zext(elem, Type::i8(bcx.ccx));
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}
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llpair = bcx.insert_value(llpair, elem, i);
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}
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self.val = OperandValue::Immediate(llpair);
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}
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self
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}
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/// If this operand is a pair in an Immediate,
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/// we return a Pair with the two halves.
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pub fn unpack_if_pair(mut self, bcx: &BlockAndBuilder<'a, 'tcx>)
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-> OperandRef<'tcx> {
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if let OperandValue::Immediate(llval) = self.val {
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// Deconstruct the immediate aggregate.
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if common::type_is_imm_pair(bcx.ccx, self.ty) {
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debug!("Operand::unpack_if_pair: unpacking {:?}", self);
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let mut a = bcx.extract_value(llval, 0);
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let mut b = bcx.extract_value(llval, 1);
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let pair_fields = common::type_pair_fields(bcx.ccx, self.ty);
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if let Some([a_ty, b_ty]) = pair_fields {
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if a_ty.is_bool() {
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a = bcx.trunc(a, Type::i1(bcx.ccx));
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}
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if b_ty.is_bool() {
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b = bcx.trunc(b, Type::i1(bcx.ccx));
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}
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}
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self.val = OperandValue::Pair(a, b);
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}
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}
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self
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}
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}
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impl<'a, 'tcx> MirContext<'a, 'tcx> {
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pub fn trans_load(&mut self,
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bcx: &BlockAndBuilder<'a, 'tcx>,
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llval: ValueRef,
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ty: Ty<'tcx>)
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-> OperandRef<'tcx>
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{
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debug!("trans_load: {:?} @ {:?}", Value(llval), ty);
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let val = if common::type_is_fat_ptr(bcx.ccx, ty) {
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let (lldata, llextra) = base::load_fat_ptr(bcx, llval, ty);
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OperandValue::Pair(lldata, llextra)
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} else if common::type_is_imm_pair(bcx.ccx, ty) {
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let [a_ty, b_ty] = common::type_pair_fields(bcx.ccx, ty).unwrap();
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let a_ptr = bcx.struct_gep(llval, 0);
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let b_ptr = bcx.struct_gep(llval, 1);
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OperandValue::Pair(
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base::load_ty(bcx, a_ptr, a_ty),
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base::load_ty(bcx, b_ptr, b_ty)
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)
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} else if common::type_is_immediate(bcx.ccx, ty) {
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OperandValue::Immediate(base::load_ty(bcx, llval, ty))
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} else {
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OperandValue::Ref(llval)
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};
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OperandRef { val: val, ty: ty }
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}
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pub fn trans_consume(&mut self,
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bcx: &BlockAndBuilder<'a, 'tcx>,
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lvalue: &mir::Lvalue<'tcx>)
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-> OperandRef<'tcx>
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{
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debug!("trans_consume(lvalue={:?})", lvalue);
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// watch out for locals that do not have an
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// alloca; they are handled somewhat differently
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if let mir::Lvalue::Local(index) = *lvalue {
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match self.locals[index] {
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LocalRef::Operand(Some(o)) => {
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return o;
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}
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LocalRef::Operand(None) => {
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bug!("use of {:?} before def", lvalue);
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}
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LocalRef::Lvalue(..) => {
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// use path below
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}
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}
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}
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// Moves out of pair fields are trivial.
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if let &mir::Lvalue::Projection(ref proj) = lvalue {
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if let mir::Lvalue::Local(index) = proj.base {
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if let LocalRef::Operand(Some(o)) = self.locals[index] {
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match (o.val, &proj.elem) {
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(OperandValue::Pair(a, b),
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&mir::ProjectionElem::Field(ref f, ty)) => {
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let llval = [a, b][f.index()];
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let op = OperandRef {
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val: OperandValue::Immediate(llval),
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ty: self.monomorphize(&ty)
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};
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// Handle nested pairs.
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return op.unpack_if_pair(bcx);
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}
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_ => {}
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}
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}
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}
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}
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// for most lvalues, to consume them we just load them
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// out from their home
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let tr_lvalue = self.trans_lvalue(bcx, lvalue);
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let ty = tr_lvalue.ty.to_ty(bcx.tcx());
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self.trans_load(bcx, tr_lvalue.llval, ty)
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}
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pub fn trans_operand(&mut self,
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bcx: &BlockAndBuilder<'a, 'tcx>,
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operand: &mir::Operand<'tcx>)
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-> OperandRef<'tcx>
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{
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debug!("trans_operand(operand={:?})", operand);
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match *operand {
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mir::Operand::Consume(ref lvalue) => {
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self.trans_consume(bcx, lvalue)
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}
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mir::Operand::Constant(ref constant) => {
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let val = self.trans_constant(bcx, constant);
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let operand = val.to_operand(bcx.ccx);
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if let OperandValue::Ref(ptr) = operand.val {
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// If this is a OperandValue::Ref to an immediate constant, load it.
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self.trans_load(bcx, ptr, operand.ty)
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} else {
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operand
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}
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}
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}
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}
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pub fn store_operand(&mut self,
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bcx: &BlockAndBuilder<'a, 'tcx>,
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lldest: ValueRef,
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operand: OperandRef<'tcx>) {
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debug!("store_operand: operand={:?}", operand);
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// Avoid generating stores of zero-sized values, because the only way to have a zero-sized
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// value is through `undef`, and store itself is useless.
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if common::type_is_zero_size(bcx.ccx, operand.ty) {
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return;
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}
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match operand.val {
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OperandValue::Ref(r) => base::memcpy_ty(bcx, lldest, r, operand.ty),
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OperandValue::Immediate(s) => base::store_ty(bcx, s, lldest, operand.ty),
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OperandValue::Pair(a, b) => {
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let a = base::from_immediate(bcx, a);
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let b = base::from_immediate(bcx, b);
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bcx.store(a, bcx.struct_gep(lldest, 0));
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bcx.store(b, bcx.struct_gep(lldest, 1));
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}
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}
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}
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}
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