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 outputs = ia.outputs.iter().enumerate().map(|(i, &(ref c, ref out, is_rw))| {
  43         constraints.push((*c).clone());
  44
  45         let out_datum = unpack_datum!(bcx, expr::trans(bcx, &**out));
  46         output_types.push(type_of::type_of(bcx.ccx(), out_datum.ty));
  47         let val = out_datum.val;
  48         if is_rw {
  49             bcx = callee::trans_arg_datum(bcx,
  50                                           expr_ty(bcx, &**out),
  51                                           out_datum,
  52                                           cleanup::CustomScope(temp_scope),
  53                                           callee::DontAutorefArg,
  54                                           &mut ext_inputs);
  55             ext_constraints.push(i.to_string());
  56         }
  57         val
  58
  59     }).collect::<Vec<_>>();
  60
  61     // Now the input operands
  62     let mut inputs = Vec::new();
  63     for &(ref c, ref input) in &ia.inputs {
  64         constraints.push((*c).clone());
  65
  66         let in_datum = unpack_datum!(bcx, expr::trans(bcx, &**input));
  67         bcx = callee::trans_arg_datum(bcx,
  68                                     expr_ty(bcx, &**input),
  69                                     in_datum,
  70                                     cleanup::CustomScope(temp_scope),
  71                                     callee::DontAutorefArg,
  72                                     &mut inputs);
  73     }
  74     inputs.extend_from_slice(&ext_inputs[..]);
  75
  76     // no failure occurred preparing operands, no need to cleanup
  77     fcx.pop_custom_cleanup_scope(temp_scope);
  78
  79     let clobbers = ia.clobbers.iter()
  80                               .map(|s| format!("~{{{}}}", &s));
  81
  82     // Default per-arch clobbers
  83     // Basically what clang does
  84     let arch_clobbers = match &bcx.sess().target.target.arch[..] {
  85         "x86" | "x86_64" => vec!("~{dirflag}", "~{fpsr}", "~{flags}"),
  86         _                => Vec::new()
  87     };
  88
  89     let all_constraints= constraints.iter()
  90                                     .map(|s| s.to_string())
  91                                     .chain(ext_constraints)
  92                                     .chain(clobbers)
  93                                     .chain(arch_clobbers.iter()
  94                                                .map(|s| s.to_string()))
  95                                     .collect::<Vec<String>>()
  96                                     .join(",");
  97
  98     debug!("Asm Constraints: {}", &all_constraints[..]);
  99
 100     // Depending on how many outputs we have, the return type is different
 101     let num_outputs = outputs.len();
 102     let output_type = match num_outputs {
 103         0 => Type::void(bcx.ccx()),
 104         1 => output_types[0],
 105         _ => Type::struct_(bcx.ccx(), &output_types[..], false)
 106     };
 107
 108     let dialect = match ia.dialect {
 109         AsmDialect::Att   => llvm::AD_ATT,
 110         AsmDialect::Intel => llvm::AD_Intel
 111     };
 112
 113     let asm = CString::new(ia.asm.as_bytes()).unwrap();
 114     let constraint_cstr = CString::new(all_constraints).unwrap();
 115     let r = InlineAsmCall(bcx,
 116                           asm.as_ptr(),
 117                           constraint_cstr.as_ptr(),
 118                           &inputs,
 119                           output_type,
 120                           ia.volatile,
 121                           ia.alignstack,
 122                           dialect);
 123
 124     // Again, based on how many outputs we have
 125     if num_outputs == 1 {
 126         Store(bcx, r, outputs[0]);
 127     } else {
 128         for (i, o) in outputs.iter().enumerate() {
 129             let v = ExtractValue(bcx, r, i);
 130             Store(bcx, v, *o);
 131         }
 132     }
 133
 134     // Store expn_id in a metadata node so we can map LLVM errors
 135     // back to source locations.  See #17552.
 136     unsafe {
 137         let key = "srcloc";
 138         let kind = llvm::LLVMGetMDKindIDInContext(bcx.ccx().llcx(),
 139             key.as_ptr() as *const c_char, key.len() as c_uint);
 140
 141         let val: llvm::ValueRef = C_i32(bcx.ccx(), ia.expn_id.into_u32() as i32);
 142
 143         llvm::LLVMSetMetadata(r, kind,
 144             llvm::LLVMMDNodeInContext(bcx.ccx().llcx(), &val, 1));
 145     }
 146
 147     return bcx;
 148
 149 }
 150