src/librustc_trans/mir/statement.rs

   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.
   4 //
   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.
  10
  11 use rustc::mir::repr as mir;
  12
  13 use base;
  14 use common::{self, BlockAndBuilder};
  15
  16 use super::MirContext;
  17 use super::LocalRef;
  18 use super::super::adt;
  19 use super::super::disr::Disr;
  20
  21 impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
  22     pub fn trans_statement(&mut self,
  23                            bcx: BlockAndBuilder<'bcx, 'tcx>,
  24                            statement: &mir::Statement<'tcx>)
  25                            -> BlockAndBuilder<'bcx, 'tcx> {
  26         debug!("trans_statement(statement={:?})", statement);
  27
  28         let debug_loc = self.debug_loc(statement.source_info);
  29         debug_loc.apply_to_bcx(&bcx);
  30         debug_loc.apply(bcx.fcx());
  31         match statement.kind {
  32             mir::StatementKind::Assign(ref lvalue, ref rvalue) => {
  33                 if let Some(index) = self.mir.local_index(lvalue) {
  34                     match self.locals[index] {
  35                         LocalRef::Lvalue(tr_dest) => {
  36                             self.trans_rvalue(bcx, tr_dest, rvalue, debug_loc)
  37                         }
  38                         LocalRef::Operand(None) => {
  39                             let (bcx, operand) = self.trans_rvalue_operand(bcx, rvalue,
  40                                                                            debug_loc);
  41                             self.locals[index] = LocalRef::Operand(Some(operand));
  42                             bcx
  43                         }
  44                         LocalRef::Operand(Some(_)) => {
  45                             let ty = self.monomorphized_lvalue_ty(lvalue);
  46
  47                             if !common::type_is_zero_size(bcx.ccx(), ty) {
  48                                 span_bug!(statement.source_info.span,
  49                                           "operand {:?} already assigned",
  50                                           rvalue);
  51                             } else {
  52                                 // If the type is zero-sized, it's already been set here,
  53                                 // but we still need to make sure we translate the operand
  54                                 self.trans_rvalue_operand(bcx, rvalue, debug_loc).0
  55                             }
  56                         }
  57                     }
  58                 } else {
  59                     let tr_dest = self.trans_lvalue(&bcx, lvalue);
  60                     self.trans_rvalue(bcx, tr_dest, rvalue, debug_loc)
  61                 }
  62             }
  63             mir::StatementKind::SetDiscriminant{ref lvalue, variant_index} => {
  64                 let ty = self.monomorphized_lvalue_ty(lvalue);
  65                 let repr = adt::represent_type(bcx.ccx(), ty);
  66                 let lvalue_transed = self.trans_lvalue(&bcx, lvalue);
  67                 bcx.with_block(|bcx|
  68                     adt::trans_set_discr(bcx,
  69                                          &repr,
  70                                         lvalue_transed.llval,
  71                                         Disr::from(variant_index))
  72                 );
  73                 bcx
  74             }
  75             mir::StatementKind::StorageLive(ref lvalue) => {
  76                 self.trans_storage_liveness(bcx, lvalue, base::Lifetime::Start)
  77             }
  78             mir::StatementKind::StorageDead(ref lvalue) => {
  79                 self.trans_storage_liveness(bcx, lvalue, base::Lifetime::End)
  80             }
  81         }
  82     }
  83
  84     fn trans_storage_liveness(&self,
  85                               bcx: BlockAndBuilder<'bcx, 'tcx>,
  86                               lvalue: &mir::Lvalue<'tcx>,
  87                               intrinsic: base::Lifetime)
  88                               -> BlockAndBuilder<'bcx, 'tcx> {
  89         if let Some(index) = self.mir.local_index(lvalue) {
  90             if let LocalRef::Lvalue(tr_lval) = self.locals[index] {
  91                 intrinsic.call(&bcx, tr_lval.llval);
  92             }
  93         }
  94         bcx
  95     }
  96 }