src/librustc_trans/trans/mir/constant.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 back::abi;
  12 use llvm::ValueRef;
  13 use middle::subst::Substs;
  14 use middle::ty::{Ty, TypeFoldable};
  15 use rustc::middle::const_eval::ConstVal;
  16 use rustc::mir::repr as mir;
  17 use trans::common::{self, BlockAndBuilder, C_bool, C_bytes, C_floating_f64, C_integral,
  18                     C_str_slice};
  19 use trans::consts;
  20 use trans::expr;
  21 use trans::type_of;
  22
  23 use super::operand::{OperandRef, OperandValue};
  24 use super::MirContext;
  25
  26
  27 impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
  28     pub fn trans_constval(&mut self,
  29                           bcx: &BlockAndBuilder<'bcx, 'tcx>,
  30                           cv: &ConstVal,
  31                           ty: Ty<'tcx>)
  32                           -> OperandRef<'tcx>
  33     {
  34         let ccx = bcx.ccx();
  35         let val = self.trans_constval_inner(bcx, cv, ty, bcx.fcx().param_substs);
  36         let val = if common::type_is_immediate(ccx, ty) {
  37             OperandValue::Immediate(val)
  38         } else if common::type_is_fat_ptr(bcx.tcx(), ty) {
  39             let data = common::const_get_elt(ccx, val, &[abi::FAT_PTR_ADDR as u32]);
  40             let extra = common::const_get_elt(ccx, val, &[abi::FAT_PTR_EXTRA as u32]);
  41             OperandValue::FatPtr(data, extra)
  42         } else {
  43             OperandValue::Ref(val)
  44         };
  45
  46         assert!(!ty.has_erasable_regions());
  47
  48         OperandRef {
  49             ty: ty,
  50             val: val
  51         }
  52     }
  53
  54     /// Translate ConstVal into a bare LLVM ValueRef.
  55     fn trans_constval_inner(&mut self,
  56                             bcx: &BlockAndBuilder<'bcx, 'tcx>,
  57                             cv: &ConstVal,
  58                             ty: Ty<'tcx>,
  59                             param_substs: &'tcx Substs<'tcx>)
  60                             -> ValueRef
  61     {
  62         let ccx = bcx.ccx();
  63         let llty = type_of::type_of(ccx, ty);
  64         match *cv {
  65             ConstVal::Float(v) => C_floating_f64(v, llty),
  66             ConstVal::Bool(v) => C_bool(ccx, v),
  67             ConstVal::Int(v) => C_integral(llty, v as u64, true),
  68             ConstVal::Uint(v) => C_integral(llty, v, false),
  69             ConstVal::Str(ref v) => C_str_slice(ccx, v.clone()),
  70             ConstVal::ByteStr(ref v) => consts::addr_of(ccx, C_bytes(ccx, v), 1, "byte_str"),
  71             ConstVal::Struct(id) | ConstVal::Tuple(id) |
  72             ConstVal::Array(id, _) | ConstVal::Repeat(id, _) => {
  73                 let expr = bcx.tcx().map.expect_expr(id);
  74                 bcx.with_block(|bcx| {
  75                     expr::trans(bcx, expr).datum.val
  76                 })
  77             },
  78             ConstVal::Function(did) =>
  79                 self.trans_fn_ref(bcx, ty, param_substs, did).immediate()
  80         }
  81     }
  82
  83     pub fn trans_constant(&mut self,
  84                           bcx: &BlockAndBuilder<'bcx, 'tcx>,
  85                           constant: &mir::Constant<'tcx>)
  86                           -> OperandRef<'tcx>
  87     {
  88         match constant.literal {
  89             mir::Literal::Item { def_id, kind, substs } => {
  90                 let substs = bcx.tcx().mk_substs(bcx.monomorphize(&substs));
  91                 self.trans_item_ref(bcx, constant.ty, kind, substs, def_id)
  92             }
  93             mir::Literal::Value { ref value } => {
  94                 let ty = bcx.monomorphize(&constant.ty);
  95                 self.trans_constval(bcx, value, ty)
  96             }
  97         }
  98     }
  99 }