src/librustc_trans/trans/asm.rs

   1 // Copyright 2012-2015 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 //! # Translation of inline assembly.
  12
  13 use llvm;
  14 use trans::build::*;
  15 use trans::callee;
  16 use trans::common::*;
  17 use trans::cleanup;
  18 use trans::cleanup::CleanupMethods;
  19 use trans::expr;
  20 use trans::type_of;
  21 use trans::type_::Type;
  22
  23 use rustc_front::hir as ast;
  24 use std::ffi::CString;
  25 use syntax::ast::AsmDialect;
  26 use libc::{c_uint, c_char};
  27
  28 // Take an inline assembly expression and splat it out via LLVM
  29 pub fn trans_inline_asm<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, ia: &ast::InlineAsm)
  30                                     -> Block<'blk, 'tcx> {
  31     let fcx = bcx.fcx;
  32     let mut bcx = bcx;
  33     let mut constraints = Vec::new();
  34     let mut output_types = Vec::new();
  35
  36     let temp_scope = fcx.push_custom_cleanup_scope();
  37
  38     let mut ext_inputs = Vec::new();
  39     let mut ext_constraints = Vec::new();
  40
  41     // Prepare the output operands
  42     let mut outputs = Vec::new();
  43     let mut inputs = Vec::new();
  44     for (i, out) in ia.outputs.iter().enumerate() {
  45         constraints.push(out.constraint.clone());
  46
  47         let out_datum = unpack_datum!(bcx, expr::trans(bcx, &out.expr));
  48         if out.is_indirect {
  49             bcx = callee::trans_arg_datum(bcx,
  50                                           expr_ty(bcx, &out.expr),
  51                                           out_datum,
  52                                           cleanup::CustomScope(temp_scope),
  53                                           callee::DontAutorefArg,
  54                                           &mut inputs);
  55             if out.is_rw {
  56                 ext_inputs.push(*inputs.last().unwrap());
  57                 ext_constraints.push(i.to_string());
  58             }
  59         } else {
  60             output_types.push(type_of::type_of(bcx.ccx(), out_datum.ty));
  61             outputs.push(out_datum.val);
  62             if out.is_rw {
  63                 bcx = callee::trans_arg_datum(bcx,
  64                                               expr_ty(bcx, &out.expr),
  65                                               out_datum,
  66                                               cleanup::CustomScope(temp_scope),
  67                                               callee::DontAutorefArg,
  68                                               &mut ext_inputs);
  69                 ext_constraints.push(i.to_string());
  70             }
  71         }
  72     }
  73
  74     // Now the input operands
  75     for &(ref c, ref input) in &ia.inputs {
  76         constraints.push((*c).clone());
  77
  78         let in_datum = unpack_datum!(bcx, expr::trans(bcx, &input));
  79         bcx = callee::trans_arg_datum(bcx,
  80                                     expr_ty(bcx, &input),
  81                                     in_datum,
  82                                     cleanup::CustomScope(temp_scope),
  83                                     callee::DontAutorefArg,
  84                                     &mut inputs);
  85     }
  86     inputs.extend_from_slice(&ext_inputs[..]);
  87
  88     // no failure occurred preparing operands, no need to cleanup
  89     fcx.pop_custom_cleanup_scope(temp_scope);
  90
  91     let clobbers = ia.clobbers.iter()
  92                               .map(|s| format!("~{{{}}}", &s));
  93
  94     // Default per-arch clobbers
  95     // Basically what clang does
  96     let arch_clobbers = match &bcx.sess().target.target.arch[..] {
  97         "x86" | "x86_64" => vec!("~{dirflag}", "~{fpsr}", "~{flags}"),
  98         _                => Vec::new()
  99     };
 100
 101     let all_constraints= constraints.iter()
 102                                     .map(|s| s.to_string())
 103                                     .chain(ext_constraints)
 104                                     .chain(clobbers)
 105                                     .chain(arch_clobbers.iter()
 106                                                .map(|s| s.to_string()))
 107                                     .collect::<Vec<String>>()
 108                                     .join(",");
 109
 110     debug!("Asm Constraints: {}", &all_constraints[..]);
 111
 112     // Depending on how many outputs we have, the return type is different
 113     let num_outputs = outputs.len();
 114     let output_type = match num_outputs {
 115         0 => Type::void(bcx.ccx()),
 116         1 => output_types[0],
 117         _ => Type::struct_(bcx.ccx(), &output_types[..], false)
 118     };
 119
 120     let dialect = match ia.dialect {
 121         AsmDialect::Att   => llvm::AD_ATT,
 122         AsmDialect::Intel => llvm::AD_Intel
 123     };
 124
 125     let asm = CString::new(ia.asm.as_bytes()).unwrap();
 126     let constraint_cstr = CString::new(all_constraints).unwrap();
 127     let r = InlineAsmCall(bcx,
 128                           asm.as_ptr(),
 129                           constraint_cstr.as_ptr(),
 130                           &inputs,
 131                           output_type,
 132                           ia.volatile,
 133                           ia.alignstack,
 134                           dialect);
 135
 136     // Again, based on how many outputs we have
 137     if num_outputs == 1 {
 138         Store(bcx, r, outputs[0]);
 139     } else {
 140         for (i, o) in outputs.iter().enumerate() {
 141             let v = ExtractValue(bcx, r, i);
 142             Store(bcx, v, *o);
 143         }
 144     }
 145
 146     // Store expn_id in a metadata node so we can map LLVM errors
 147     // back to source locations.  See #17552.
 148     unsafe {
 149         let key = "srcloc";
 150         let kind = llvm::LLVMGetMDKindIDInContext(bcx.ccx().llcx(),
 151             key.as_ptr() as *const c_char, key.len() as c_uint);
 152
 153         let val: llvm::ValueRef = C_i32(bcx.ccx(), ia.expn_id.into_u32() as i32);
 154
 155         llvm::LLVMSetMetadata(r, kind,
 156             llvm::LLVMMDNodeInContext(bcx.ccx().llcx(), &val, 1));
 157     }
 158
 159     return bcx;
 160
 161 }