src/librustc_trans/trans/mir/rvalue.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 rustc::middle::ty::Ty;
  14 use rustc_front::hir;
  15 use rustc_mir::repr as mir;
  16
  17 use trans::asm;
  18 use trans::base;
  19 use trans::build;
  20 use trans::common::{self, Block, Result};
  21 use trans::debuginfo::DebugLoc;
  22 use trans::declare;
  23 use trans::machine;
  24 use trans::type_::Type;
  25 use trans::type_of;
  26 use trans::tvec;
  27
  28 use super::MirContext;
  29 use super::operand::OperandRef;
  30
  31 impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
  32     pub fn trans_rvalue(&mut self,
  33                         bcx: Block<'bcx, 'tcx>,
  34                         lldest: ValueRef,
  35                         rvalue: &mir::Rvalue<'tcx>)
  36                         -> Block<'bcx, 'tcx>
  37     {
  38         debug!("trans_rvalue(lldest={}, rvalue={:?})",
  39                bcx.val_to_string(lldest),
  40                rvalue);
  41
  42         match *rvalue {
  43             mir::Rvalue::Use(ref operand) => {
  44                 self.trans_operand_into(bcx, lldest, operand);
  45                 bcx
  46             }
  47
  48             mir::Rvalue::Cast(..) => {
  49                 unimplemented!()
  50             }
  51
  52             mir::Rvalue::Repeat(..) => {
  53                 unimplemented!()
  54             }
  55
  56             mir::Rvalue::Aggregate(_, ref operands) => {
  57                 for (i, operand) in operands.iter().enumerate() {
  58                     let lldest_i = build::GEPi(bcx, lldest, &[0, i]);
  59                     self.trans_operand_into(bcx, lldest_i, operand);
  60                 }
  61                 bcx
  62             }
  63
  64             mir::Rvalue::Slice { ref input, from_start, from_end } => {
  65                 let ccx = bcx.ccx();
  66                 let input = self.trans_lvalue(bcx, input);
  67                 let (llbase, lllen) = tvec::get_base_and_len(bcx,
  68                                                              input.llval,
  69                                                              input.ty.to_ty(bcx.tcx()));
  70                 let llbase1 = build::GEPi(bcx, llbase, &[from_start]);
  71                 let adj = common::C_uint(ccx, from_start + from_end);
  72                 let lllen1 = build::Sub(bcx, lllen, adj, DebugLoc::None);
  73                 build::Store(bcx, llbase1, build::GEPi(bcx, lldest, &[0, abi::FAT_PTR_ADDR]));
  74                 build::Store(bcx, lllen1, build::GEPi(bcx, lldest, &[0, abi::FAT_PTR_EXTRA]));
  75                 bcx
  76             }
  77
  78             mir::Rvalue::InlineAsm(inline_asm) => {
  79                 asm::trans_inline_asm(bcx, inline_asm)
  80             }
  81
  82             _ => {
  83                 assert!(rvalue_creates_operand(rvalue));
  84                 let (bcx, temp) = self.trans_rvalue_operand(bcx, rvalue);
  85                 build::Store(bcx, temp.llval, lldest);
  86                 bcx
  87             }
  88         }
  89     }
  90
  91     pub fn trans_rvalue_operand(&mut self,
  92                                 bcx: Block<'bcx, 'tcx>,
  93                                 rvalue: &mir::Rvalue<'tcx>)
  94                                 -> (Block<'bcx, 'tcx>, OperandRef<'tcx>)
  95     {
  96         assert!(rvalue_creates_operand(rvalue), "cannot trans {:?} to operand", rvalue);
  97
  98         match *rvalue {
  99             mir::Rvalue::Use(ref operand) => {
 100                 let operand = self.trans_operand(bcx, operand);
 101                 (bcx, operand)
 102             }
 103
 104             mir::Rvalue::Cast(..) => {
 105                 unimplemented!()
 106             }
 107
 108             mir::Rvalue::Ref(_, _, ref lvalue) => {
 109                 let tr_lvalue = self.trans_lvalue(bcx, lvalue);
 110
 111                 // Note: lvalues are indirect, so storing the `llval` into the
 112                 // destination effectively creates a reference.
 113                 (bcx, OperandRef {
 114                     llval: tr_lvalue.llval,
 115                     ty: tr_lvalue.ty.to_ty(bcx.tcx()),
 116                 })
 117             }
 118
 119             mir::Rvalue::Len(ref lvalue) => {
 120                 let tr_lvalue = self.trans_lvalue(bcx, lvalue);
 121                 let (_, lllen) = tvec::get_base_and_len(bcx,
 122                                                         tr_lvalue.llval,
 123                                                         tr_lvalue.ty.to_ty(bcx.tcx()));
 124                 (bcx, OperandRef {
 125                     llval: lllen,
 126                     ty: bcx.tcx().types.usize,
 127                 })
 128             }
 129
 130             mir::Rvalue::BinaryOp(op, ref lhs, ref rhs) => {
 131                 let lhs = self.trans_operand(bcx, lhs);
 132                 let rhs = self.trans_operand(bcx, rhs);
 133                 let is_float = lhs.ty.is_fp();
 134                 let is_signed = lhs.ty.is_signed();
 135                 let binop_debug_loc = DebugLoc::None;
 136                 let llval = match op {
 137                     mir::BinOp::Add => if is_float {
 138                         build::FAdd(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 139                     } else {
 140                         build::Add(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 141                     },
 142                     mir::BinOp::Sub => if is_float {
 143                         build::FSub(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 144                     } else {
 145                         build::Sub(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 146                     },
 147                     mir::BinOp::Mul => if is_float {
 148                         build::FMul(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 149                     } else {
 150                         build::Mul(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 151                     },
 152                     mir::BinOp::Div => if is_float {
 153                         build::FDiv(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 154                     } else if is_signed {
 155                         build::SDiv(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 156                     } else {
 157                         build::UDiv(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 158                     },
 159                     mir::BinOp::Rem => if is_float {
 160                         // LLVM currently always lowers the `frem` instructions appropriate
 161                         // library calls typically found in libm. Notably f64 gets wired up
 162                         // to `fmod` and f32 gets wired up to `fmodf`. Inconveniently for
 163                         // us, 32-bit MSVC does not actually have a `fmodf` symbol, it's
 164                         // instead just an inline function in a header that goes up to a
 165                         // f64, uses `fmod`, and then comes back down to a f32.
 166                         //
 167                         // Although LLVM knows that `fmodf` doesn't exist on MSVC, it will
 168                         // still unconditionally lower frem instructions over 32-bit floats
 169                         // to a call to `fmodf`. To work around this we special case MSVC
 170                         // 32-bit float rem instructions and instead do the call out to
 171                         // `fmod` ourselves.
 172                         //
 173                         // Note that this is currently duplicated with src/libcore/ops.rs
 174                         // which does the same thing, and it would be nice to perhaps unify
 175                         // these two implementations one day! Also note that we call `fmod`
 176                         // for both 32 and 64-bit floats because if we emit any FRem
 177                         // instruction at all then LLVM is capable of optimizing it into a
 178                         // 32-bit FRem (which we're trying to avoid).
 179                         let tcx = bcx.tcx();
 180                         let use_fmod = tcx.sess.target.target.options.is_like_msvc &&
 181                             tcx.sess.target.target.arch == "x86";
 182                         if use_fmod {
 183                             let f64t = Type::f64(bcx.ccx());
 184                             let fty = Type::func(&[f64t, f64t], &f64t);
 185                             let llfn = declare::declare_cfn(bcx.ccx(), "fmod", fty,
 186                                                             tcx.types.f64);
 187                             if lhs.ty == tcx.types.f32 {
 188                                 let lllhs = build::FPExt(bcx, lhs.llval, f64t);
 189                                 let llrhs = build::FPExt(bcx, rhs.llval, f64t);
 190                                 let llres = build::Call(bcx, llfn, &[lllhs, llrhs],
 191                                                         None, binop_debug_loc);
 192                                 build::FPTrunc(bcx, llres, Type::f32(bcx.ccx()))
 193                             } else {
 194                                 build::Call(bcx, llfn, &[lhs.llval, rhs.llval],
 195                                             None, binop_debug_loc)
 196                             }
 197                         } else {
 198                             build::FRem(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 199                         }
 200                     } else if is_signed {
 201                         build::SRem(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 202                     } else {
 203                         build::URem(bcx, lhs.llval, rhs.llval, binop_debug_loc)
 204                     },
 205                     mir::BinOp::BitOr => build::Or(bcx, lhs.llval, rhs.llval, binop_debug_loc),
 206                     mir::BinOp::BitAnd => build::And(bcx, lhs.llval, rhs.llval, binop_debug_loc),
 207                     mir::BinOp::BitXor => build::Xor(bcx, lhs.llval, rhs.llval, binop_debug_loc),
 208                     mir::BinOp::Shl => common::build_unchecked_lshift(bcx,
 209                                                                       lhs.llval,
 210                                                                       rhs.llval,
 211                                                                       binop_debug_loc),
 212                     mir::BinOp::Shr => common::build_unchecked_rshift(bcx,
 213                                                                       lhs.ty,
 214                                                                       lhs.llval,
 215                                                                       rhs.llval,
 216                                                                       binop_debug_loc),
 217                     mir::BinOp::Eq => base::compare_scalar_types(bcx, lhs.llval, rhs.llval, lhs.ty,
 218                                                                  hir::BiEq, binop_debug_loc),
 219                     mir::BinOp::Lt => base::compare_scalar_types(bcx, lhs.llval, rhs.llval, lhs.ty,
 220                                                                  hir::BiLt, binop_debug_loc),
 221                     mir::BinOp::Le => base::compare_scalar_types(bcx, lhs.llval, rhs.llval, lhs.ty,
 222                                                                  hir::BiLe, binop_debug_loc),
 223                     mir::BinOp::Ne => base::compare_scalar_types(bcx, lhs.llval, rhs.llval, lhs.ty,
 224                                                                  hir::BiNe, binop_debug_loc),
 225                     mir::BinOp::Ge => base::compare_scalar_types(bcx, lhs.llval, rhs.llval, lhs.ty,
 226                                                                  hir::BiGe, binop_debug_loc),
 227                     mir::BinOp::Gt => base::compare_scalar_types(bcx, lhs.llval, rhs.llval, lhs.ty,
 228                                                                  hir::BiGt, binop_debug_loc),
 229                 };
 230                 (bcx, OperandRef {
 231                     llval: llval,
 232                     ty: lhs.ty,
 233                 })
 234             }
 235
 236             mir::Rvalue::UnaryOp(op, ref operand) => {
 237                 let operand = self.trans_operand(bcx, operand);
 238                 let is_float = operand.ty.is_fp();
 239                 let debug_loc = DebugLoc::None;
 240                 let llval = match op {
 241                     mir::UnOp::Not => build::Not(bcx, operand.llval, debug_loc),
 242                     mir::UnOp::Neg => if is_float {
 243                         build::FNeg(bcx, operand.llval, debug_loc)
 244                     } else {
 245                         build::Neg(bcx, operand.llval, debug_loc)
 246                     }
 247                 };
 248                 (bcx, OperandRef {
 249                     llval: llval,
 250                     ty: operand.ty,
 251                 })
 252             }
 253
 254             mir::Rvalue::Box(content_ty) => {
 255                 let content_ty: Ty<'tcx> = bcx.monomorphize(&content_ty);
 256                 let llty = type_of::type_of(bcx.ccx(), content_ty);
 257                 let llsize = machine::llsize_of(bcx.ccx(), llty);
 258                 let align = type_of::align_of(bcx.ccx(), content_ty);
 259                 let llalign = common::C_uint(bcx.ccx(), align);
 260                 let llty_ptr = llty.ptr_to();
 261                 let box_ty = bcx.tcx().mk_box(content_ty);
 262                 let Result { bcx, val: llval } = base::malloc_raw_dyn(bcx,
 263                                                                       llty_ptr,
 264                                                                       box_ty,
 265                                                                       llsize,
 266                                                                       llalign,
 267                                                                       DebugLoc::None);
 268                 (bcx, OperandRef {
 269                     llval: llval,
 270                     ty: box_ty,
 271                 })
 272             }
 273
 274             mir::Rvalue::Repeat(..) |
 275             mir::Rvalue::Aggregate(..) |
 276             mir::Rvalue::Slice { .. } |
 277             mir::Rvalue::InlineAsm(..) => {
 278                 bcx.tcx().sess.bug(&format!("cannot generate operand from rvalue {:?}", rvalue));
 279             }
 280         }
 281     }
 282 }
 283
 284 pub fn rvalue_creates_operand<'tcx>(rvalue: &mir::Rvalue<'tcx>) -> bool {
 285     match *rvalue {
 286         mir::Rvalue::Use(..) | // (*)
 287         mir::Rvalue::Ref(..) |
 288         mir::Rvalue::Len(..) |
 289         mir::Rvalue::Cast(..) | // (*)
 290         mir::Rvalue::BinaryOp(..) |
 291         mir::Rvalue::UnaryOp(..) |
 292         mir::Rvalue::Box(..) =>
 293             true,
 294         mir::Rvalue::Repeat(..) |
 295         mir::Rvalue::Aggregate(..) |
 296         mir::Rvalue::Slice { .. } |
 297         mir::Rvalue::InlineAsm(..) =>
 298             false,
 299     }
 300
 301     // (*) this is only true if the type is suitable
 302 }