rust/src/librustc/middle/trans/asm.rs

// Copyright 2012-2013 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 core::prelude::*;

use lib;
use middle::trans::build::*;
use middle::trans::callee;
use middle::trans::common::*;
use middle::ty;

use middle::trans::type_::Type;

use core::str;
use syntax::ast;

// Take an inline assembly expression and splat it out via LLVM
pub fn trans_inline_asm(bcx: block, ia: &ast::inline_asm) -> block {

    let mut bcx = bcx;
    let mut constraints = ~[];
    let mut cleanups = ~[];
    let mut aoutputs = ~[];

    // Prepare the output operands
    let outputs = do ia.outputs.map |&(c, out)| {
        constraints.push(c);

        aoutputs.push(unpack_result!(bcx, {
            callee::trans_arg_expr(bcx,
                                   expr_ty(bcx, out),
                                   ty::ByCopy,
                                   ast::sty_static,
                                   out,
                                   &mut cleanups,
                                   None,
                                   callee::DontAutorefArg)
        }));

        let e = match out.node {
            ast::expr_addr_of(_, e) => e,
            _ => fail!("Expression must be addr of")
        };

        unpack_result!(bcx, {
            callee::trans_arg_expr(bcx,
                                   expr_ty(bcx, e),
                                   ty::ByCopy,
                                   ast::sty_static,
                                   e,
                                   &mut cleanups,
                                   None,
                                   callee::DontAutorefArg)
        })

    };

    for cleanups.iter().advance |c| {
        revoke_clean(bcx, *c);
    }
    cleanups.clear();

    // Now the input operands
    let inputs = do ia.inputs.map |&(c, in)| {
        constraints.push(c);

        unpack_result!(bcx, {
            callee::trans_arg_expr(bcx,
                                   expr_ty(bcx, in),
                                   ty::ByCopy,
                                   ast::sty_static,
                                   in,
                                   &mut cleanups,
                                   None,
                                   callee::DontAutorefArg)
        })

    };

    for cleanups.iter().advance |c| {
        revoke_clean(bcx, *c);
    }

    let mut constraints = constraints.connect(",");

    let mut clobbers = getClobbers();
    if !ia.clobbers.is_empty() && !clobbers.is_empty() {
        clobbers = fmt!("%s,%s", ia.clobbers, clobbers);
    } else {
        clobbers.push_str(ia.clobbers);
    };

    // Add the clobbers to our constraints list
    if clobbers.len() != 0 && constraints.len() != 0 {
        constraints.push_char(',');
        constraints.push_str(clobbers);
    } else {
        constraints.push_str(clobbers);
    }

    debug!("Asm Constraints: %?", constraints);

    let numOutputs = outputs.len();

    // Depending on how many outputs we have, the return type is different
    let output = if numOutputs == 0 {
        Type::void()
    } else if numOutputs == 1 {
        val_ty(outputs[0])
    } else {
        Type::struct_(outputs.map(|o| val_ty(*o)), false)
    };

    let dialect = match ia.dialect {
        ast::asm_att   => lib::llvm::AD_ATT,
        ast::asm_intel => lib::llvm::AD_Intel
    };

    let r = do str::as_c_str(ia.asm) |a| {
        do str::as_c_str(constraints) |c| {
            InlineAsmCall(bcx, a, c, inputs, output, ia.volatile, ia.alignstack, dialect)
        }
    };

    // Again, based on how many outputs we have
    if numOutputs == 1 {
        let op = PointerCast(bcx, aoutputs[0], val_ty(outputs[0]).ptr_to());
        Store(bcx, r, op);
    } else {
        for aoutputs.iter().enumerate().advance |(i, o)| {
            let v = ExtractValue(bcx, r, i);
            let op = PointerCast(bcx, *o, val_ty(outputs[i]).ptr_to());
            Store(bcx, v, op);
        }
    }

    return bcx;

}

// Default per-arch clobbers
// Basically what clang does

#[cfg(target_arch = "arm")]
#[cfg(target_arch = "mips")]
fn getClobbers() -> ~str {
    ~""
}

#[cfg(target_arch = "x86")]
#[cfg(target_arch = "x86_64")]
fn getClobbers() -> ~str {
    ~"~{dirflag},~{fpsr},~{flags}"
}