src/librustc_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::{self, ValueRef};
  14 use base;
  15 use build::*;
  16 use common::*;
  17 use type_of;
  18 use type_::Type;
  19
  20 use rustc::hir;
  21 use rustc::ty::Ty;
  22
  23 use std::ffi::CString;
  24 use syntax::ast::AsmDialect;
  25 use libc::{c_uint, c_char};
  26
  27 // Take an inline assembly expression and splat it out via LLVM
  28 pub fn trans_inline_asm<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
  29                                     ia: &hir::InlineAsm,
  30                                     outputs: Vec<(ValueRef, Ty<'tcx>)>,
  31                                     mut inputs: Vec<ValueRef>) {
  32     let mut ext_constraints = vec![];
  33     let mut output_types = vec![];
  34
  35     // Prepare the output operands
  36     let mut indirect_outputs = vec![];
  37     for (i, (out, &(val, ty))) in ia.outputs.iter().zip(&outputs).enumerate() {
  38         let val = if out.is_rw || out.is_indirect {
  39             Some(base::load_ty(bcx, val, ty))
  40         } else {
  41             None
  42         };
  43         if out.is_rw {
  44             inputs.push(val.unwrap());
  45             ext_constraints.push(i.to_string());
  46         }
  47         if out.is_indirect {
  48             indirect_outputs.push(val.unwrap());
  49         } else {
  50             output_types.push(type_of::type_of(bcx.ccx(), ty));
  51         }
  52     }
  53     if !indirect_outputs.is_empty() {
  54         indirect_outputs.extend_from_slice(&inputs);
  55         inputs = indirect_outputs;
  56     }
  57
  58     let clobbers = ia.clobbers.iter()
  59                               .map(|s| format!("~{{{}}}", &s));
  60
  61     // Default per-arch clobbers
  62     // Basically what clang does
  63     let arch_clobbers = match &bcx.sess().target.target.arch[..] {
  64         "x86" | "x86_64" => vec!["~{dirflag}", "~{fpsr}", "~{flags}"],
  65         _                => Vec::new()
  66     };
  67
  68     let all_constraints =
  69         ia.outputs.iter().map(|out| out.constraint.to_string())
  70           .chain(ia.inputs.iter().map(|s| s.to_string()))
  71           .chain(ext_constraints)
  72           .chain(clobbers)
  73           .chain(arch_clobbers.iter().map(|s| s.to_string()))
  74           .collect::<Vec<String>>().join(",");
  75
  76     debug!("Asm Constraints: {}", &all_constraints[..]);
  77
  78     // Depending on how many outputs we have, the return type is different
  79     let num_outputs = output_types.len();
  80     let output_type = match num_outputs {
  81         0 => Type::void(bcx.ccx()),
  82         1 => output_types[0],
  83         _ => Type::struct_(bcx.ccx(), &output_types[..], false)
  84     };
  85
  86     let dialect = match ia.dialect {
  87         AsmDialect::Att   => llvm::AsmDialect::Att,
  88         AsmDialect::Intel => llvm::AsmDialect::Intel,
  89     };
  90
  91     let asm = CString::new(ia.asm.as_bytes()).unwrap();
  92     let constraint_cstr = CString::new(all_constraints).unwrap();
  93     let r = InlineAsmCall(bcx,
  94                           asm.as_ptr(),
  95                           constraint_cstr.as_ptr(),
  96                           &inputs,
  97                           output_type,
  98                           ia.volatile,
  99                           ia.alignstack,
 100                           dialect);
 101
 102     // Again, based on how many outputs we have
 103     let outputs = ia.outputs.iter().zip(&outputs).filter(|&(ref o, _)| !o.is_indirect);
 104     for (i, (_, &(val, _))) in outputs.enumerate() {
 105         let v = if num_outputs == 1 { r } else { ExtractValue(bcx, r, i) };
 106         Store(bcx, v, val);
 107     }
 108
 109     // Store expn_id in a metadata node so we can map LLVM errors
 110     // back to source locations.  See #17552.
 111     unsafe {
 112         let key = "srcloc";
 113         let kind = llvm::LLVMGetMDKindIDInContext(bcx.ccx().llcx(),
 114             key.as_ptr() as *const c_char, key.len() as c_uint);
 115
 116         let val: llvm::ValueRef = C_i32(bcx.ccx(), ia.expn_id.into_u32() as i32);
 117
 118         llvm::LLVMSetMetadata(r, kind,
 119             llvm::LLVMMDNodeInContext(bcx.ccx().llcx(), &val, 1));
 120     }
 121 }