rust/src/librustc_trans/asm.rs
2017-04-12 19:12:49 -05:00

135 lines
4.3 KiB
Rust

// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! # Translation of inline assembly.
use llvm::{self, ValueRef};
use base;
use common::*;
use type_of;
use type_::Type;
use builder::Builder;
use rustc::hir;
use rustc::ty::Ty;
use mir::lvalue::Alignment;
use std::ffi::CString;
use syntax::ast::AsmDialect;
use libc::{c_uint, c_char};
// Take an inline assembly expression and splat it out via LLVM
pub fn trans_inline_asm<'a, 'tcx>(
bcx: &Builder<'a, 'tcx>,
ia: &hir::InlineAsm,
outputs: Vec<(ValueRef, Ty<'tcx>)>,
mut inputs: Vec<ValueRef>
) {
let mut ext_constraints = vec![];
let mut output_types = vec![];
// Prepare the output operands
let mut indirect_outputs = vec![];
for (i, (out, &(val, ty))) in ia.outputs.iter().zip(&outputs).enumerate() {
let val = if out.is_rw || out.is_indirect {
Some(base::load_ty(bcx, val, Alignment::Packed, ty))
} else {
None
};
if out.is_rw {
inputs.push(val.unwrap());
ext_constraints.push(i.to_string());
}
if out.is_indirect {
indirect_outputs.push(val.unwrap());
} else {
output_types.push(type_of::type_of(bcx.ccx, ty));
}
}
if !indirect_outputs.is_empty() {
indirect_outputs.extend_from_slice(&inputs);
inputs = indirect_outputs;
}
let clobbers = ia.clobbers.iter()
.map(|s| format!("~{{{}}}", &s));
// Default per-arch clobbers
// Basically what clang does
let arch_clobbers = match &bcx.sess().target.target.arch[..] {
"x86" | "x86_64" => vec!["~{dirflag}", "~{fpsr}", "~{flags}"],
_ => Vec::new()
};
let all_constraints =
ia.outputs.iter().map(|out| out.constraint.to_string())
.chain(ia.inputs.iter().map(|s| s.to_string()))
.chain(ext_constraints)
.chain(clobbers)
.chain(arch_clobbers.iter().map(|s| s.to_string()))
.collect::<Vec<String>>().join(",");
debug!("Asm Constraints: {}", &all_constraints);
// Depending on how many outputs we have, the return type is different
let num_outputs = output_types.len();
let output_type = match num_outputs {
0 => Type::void(bcx.ccx),
1 => output_types[0],
_ => Type::struct_(bcx.ccx, &output_types, false)
};
let dialect = match ia.dialect {
AsmDialect::Att => llvm::AsmDialect::Att,
AsmDialect::Intel => llvm::AsmDialect::Intel,
};
let asm = CString::new(ia.asm.as_str().as_bytes()).unwrap();
let constraint_cstr = CString::new(all_constraints).unwrap();
let r = bcx.inline_asm_call(
asm.as_ptr(),
constraint_cstr.as_ptr(),
&inputs,
output_type,
ia.volatile,
ia.alignstack,
dialect
);
// Again, based on how many outputs we have
let outputs = ia.outputs.iter().zip(&outputs).filter(|&(ref o, _)| !o.is_indirect);
for (i, (_, &(val, _))) in outputs.enumerate() {
let v = if num_outputs == 1 { r } else { bcx.extract_value(r, i) };
bcx.store(v, val, None);
}
// Store mark in a metadata node so we can map LLVM errors
// back to source locations. See #17552.
unsafe {
let key = "srcloc";
let kind = llvm::LLVMGetMDKindIDInContext(bcx.ccx.llcx(),
key.as_ptr() as *const c_char, key.len() as c_uint);
let val: llvm::ValueRef = C_i32(bcx.ccx, ia.ctxt.outer().as_u32() as i32);
llvm::LLVMSetMetadata(r, kind,
llvm::LLVMMDNodeInContext(bcx.ccx.llcx(), &val, 1));
}
}
pub fn trans_global_asm<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
ga: &hir::GlobalAsm) {
let asm = CString::new(ga.asm.as_str().as_bytes()).unwrap();
unsafe {
llvm::LLVMRustAppendModuleInlineAsm(ccx.llmod(), asm.as_ptr());
}
}