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