rust/src/librustc_trans/trans/context.rs

// Copyright 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.

use llvm;
use llvm::{ContextRef, ModuleRef, ValueRef, BuilderRef};
use llvm::{TargetData};
use llvm::mk_target_data;
use metadata::common::LinkMeta;
use middle::resolve;
use middle::traits;
use trans::adt;
use trans::base;
use trans::builder::Builder;
use trans::common::{ExternMap,tydesc_info,BuilderRef_res};
use trans::debuginfo;
use trans::monomorphize::MonoId;
use trans::type_::{Type, TypeNames};
use middle::ty::{mod, Ty};
use session::config::NoDebugInfo;
use session::Session;
use util::ppaux::Repr;
use util::sha2::Sha256;
use util::nodemap::{NodeMap, NodeSet, DefIdMap, FnvHashMap, FnvHashSet};

use std::cell::{Cell, RefCell};
use std::c_str::ToCStr;
use std::ptr;
use std::rc::Rc;
use syntax::ast;
use syntax::parse::token::InternedString;

pub struct Stats {
    pub n_static_tydescs: Cell<uint>,
    pub n_glues_created: Cell<uint>,
    pub n_null_glues: Cell<uint>,
    pub n_real_glues: Cell<uint>,
    pub n_fns: Cell<uint>,
    pub n_monos: Cell<uint>,
    pub n_inlines: Cell<uint>,
    pub n_closures: Cell<uint>,
    pub n_llvm_insns: Cell<uint>,
    pub llvm_insns: RefCell<FnvHashMap<String, uint>>,
    // (ident, llvm-instructions)
    pub fn_stats: RefCell<Vec<(String, uint)> >,
}

/// The shared portion of a `CrateContext`.  There is one `SharedCrateContext`
/// per crate.  The data here is shared between all compilation units of the
/// crate, so it must not contain references to any LLVM data structures
/// (aside from metadata-related ones).
pub struct SharedCrateContext<'tcx> {
    local_ccxs: Vec<LocalCrateContext<'tcx>>,

    metadata_llmod: ModuleRef,
    metadata_llcx: ContextRef,

    exp_map2: resolve::ExportMap2,
    reachable: NodeSet,
    item_symbols: RefCell<NodeMap<String>>,
    link_meta: LinkMeta,
    symbol_hasher: RefCell<Sha256>,
    tcx: ty::ctxt<'tcx>,
    stats: Stats,

    available_monomorphizations: RefCell<FnvHashSet<String>>,
    available_drop_glues: RefCell<FnvHashMap<Ty<'tcx>, String>>,
}

/// The local portion of a `CrateContext`.  There is one `LocalCrateContext`
/// per compilation unit.  Each one has its own LLVM `ContextRef` so that
/// several compilation units may be optimized in parallel.  All other LLVM
/// data structures in the `LocalCrateContext` are tied to that `ContextRef`.
pub struct LocalCrateContext<'tcx> {
    llmod: ModuleRef,
    llcx: ContextRef,
    td: TargetData,
    tn: TypeNames,
    externs: RefCell<ExternMap>,
    item_vals: RefCell<NodeMap<ValueRef>>,
    drop_glues: RefCell<FnvHashMap<Ty<'tcx>, ValueRef>>,
    tydescs: RefCell<FnvHashMap<Ty<'tcx>, Rc<tydesc_info<'tcx>>>>,
    /// Set when running emit_tydescs to enforce that no more tydescs are
    /// created.
    finished_tydescs: Cell<bool>,
    /// Track mapping of external ids to local items imported for inlining
    external: RefCell<DefIdMap<Option<ast::NodeId>>>,
    /// Backwards version of the `external` map (inlined items to where they
    /// came from)
    external_srcs: RefCell<NodeMap<ast::DefId>>,
    /// Cache instances of monomorphized functions
    monomorphized: RefCell<FnvHashMap<MonoId<'tcx>, ValueRef>>,
    monomorphizing: RefCell<DefIdMap<uint>>,
    /// Cache generated vtables
    vtables: RefCell<FnvHashMap<(Ty<'tcx>, Rc<ty::TraitRef<'tcx>>), ValueRef>>,
    /// Cache of constant strings,
    const_cstr_cache: RefCell<FnvHashMap<InternedString, ValueRef>>,

    /// Reverse-direction for const ptrs cast from globals.
    /// Key is an int, cast from a ValueRef holding a *T,
    /// Val is a ValueRef holding a *[T].
    ///
    /// Needed because LLVM loses pointer->pointee association
    /// when we ptrcast, and we have to ptrcast during translation
    /// of a [T] const because we form a slice, a [*T,int] pair, not
    /// a pointer to an LLVM array type.
    const_globals: RefCell<FnvHashMap<int, ValueRef>>,

    /// Cache of emitted const values
    const_values: RefCell<NodeMap<ValueRef>>,

    /// Cache of emitted static values
    static_values: RefCell<NodeMap<ValueRef>>,

    /// Cache of external const values
    extern_const_values: RefCell<DefIdMap<ValueRef>>,

    impl_method_cache: RefCell<FnvHashMap<(ast::DefId, ast::Name), ast::DefId>>,

    /// Cache of closure wrappers for bare fn's.
    closure_bare_wrapper_cache: RefCell<FnvHashMap<ValueRef, ValueRef>>,

    lltypes: RefCell<FnvHashMap<Ty<'tcx>, Type>>,
    llsizingtypes: RefCell<FnvHashMap<Ty<'tcx>, Type>>,
    adt_reprs: RefCell<FnvHashMap<Ty<'tcx>, Rc<adt::Repr<'tcx>>>>,
    type_hashcodes: RefCell<FnvHashMap<Ty<'tcx>, String>>,
    all_llvm_symbols: RefCell<FnvHashSet<String>>,
    int_type: Type,
    opaque_vec_type: Type,
    builder: BuilderRef_res,

    /// Holds the LLVM values for closure IDs.
    unboxed_closure_vals: RefCell<FnvHashMap<MonoId<'tcx>, ValueRef>>,

    dbg_cx: Option<debuginfo::CrateDebugContext<'tcx>>,

    eh_personality: RefCell<Option<ValueRef>>,

    intrinsics: RefCell<FnvHashMap<&'static str, ValueRef>>,

    /// Number of LLVM instructions translated into this `LocalCrateContext`.
    /// This is used to perform some basic load-balancing to keep all LLVM
    /// contexts around the same size.
    n_llvm_insns: Cell<uint>,

    trait_cache: RefCell<FnvHashMap<Rc<ty::TraitRef<'tcx>>,
                                    traits::Vtable<'tcx, ()>>>,
}

pub struct CrateContext<'a, 'tcx: 'a> {
    shared: &'a SharedCrateContext<'tcx>,
    local: &'a LocalCrateContext<'tcx>,
    /// The index of `local` in `shared.local_ccxs`.  This is used in
    /// `maybe_iter(true)` to identify the original `LocalCrateContext`.
    index: uint,
}

pub struct CrateContextIterator<'a, 'tcx: 'a> {
    shared: &'a SharedCrateContext<'tcx>,
    index: uint,
}

impl<'a, 'tcx> Iterator<CrateContext<'a, 'tcx>> for CrateContextIterator<'a,'tcx> {
    fn next(&mut self) -> Option<CrateContext<'a, 'tcx>> {
        if self.index >= self.shared.local_ccxs.len() {
            return None;
        }

        let index = self.index;
        self.index += 1;

        Some(CrateContext {
            shared: self.shared,
            local: &self.shared.local_ccxs[index],
            index: index,
        })
    }
}

/// The iterator produced by `CrateContext::maybe_iter`.
pub struct CrateContextMaybeIterator<'a, 'tcx: 'a> {
    shared: &'a SharedCrateContext<'tcx>,
    index: uint,
    single: bool,
    origin: uint,
}

impl<'a, 'tcx> Iterator<(CrateContext<'a, 'tcx>, bool)> for CrateContextMaybeIterator<'a, 'tcx> {
    fn next(&mut self) -> Option<(CrateContext<'a, 'tcx>, bool)> {
        if self.index >= self.shared.local_ccxs.len() {
            return None;
        }

        let index = self.index;
        self.index += 1;
        if self.single {
            self.index = self.shared.local_ccxs.len();
        }

        let ccx = CrateContext {
            shared: self.shared,
            local: &self.shared.local_ccxs[index],
            index: index,
        };
        Some((ccx, index == self.origin))
    }
}


unsafe fn create_context_and_module(sess: &Session, mod_name: &str) -> (ContextRef, ModuleRef) {
    let llcx = llvm::LLVMContextCreate();
    let llmod = mod_name.with_c_str(|buf| {
        llvm::LLVMModuleCreateWithNameInContext(buf, llcx)
    });
    sess.target
        .target
        .data_layout
        .as_slice()
        .with_c_str(|buf| {
        llvm::LLVMSetDataLayout(llmod, buf);
    });
    sess.target
        .target
        .llvm_target
        .as_slice()
        .with_c_str(|buf| {
        llvm::LLVMRustSetNormalizedTarget(llmod, buf);
    });
    (llcx, llmod)
}

impl<'tcx> SharedCrateContext<'tcx> {
    pub fn new(crate_name: &str,
               local_count: uint,
               tcx: ty::ctxt<'tcx>,
               emap2: resolve::ExportMap2,
               symbol_hasher: Sha256,
               link_meta: LinkMeta,
               reachable: NodeSet)
               -> SharedCrateContext<'tcx> {
        let (metadata_llcx, metadata_llmod) = unsafe {
            create_context_and_module(&tcx.sess, "metadata")
        };

        let mut shared_ccx = SharedCrateContext {
            local_ccxs: Vec::with_capacity(local_count),
            metadata_llmod: metadata_llmod,
            metadata_llcx: metadata_llcx,
            exp_map2: emap2,
            reachable: reachable,
            item_symbols: RefCell::new(NodeMap::new()),
            link_meta: link_meta,
            symbol_hasher: RefCell::new(symbol_hasher),
            tcx: tcx,
            stats: Stats {
                n_static_tydescs: Cell::new(0u),
                n_glues_created: Cell::new(0u),
                n_null_glues: Cell::new(0u),
                n_real_glues: Cell::new(0u),
                n_fns: Cell::new(0u),
                n_monos: Cell::new(0u),
                n_inlines: Cell::new(0u),
                n_closures: Cell::new(0u),
                n_llvm_insns: Cell::new(0u),
                llvm_insns: RefCell::new(FnvHashMap::new()),
                fn_stats: RefCell::new(Vec::new()),
            },
            available_monomorphizations: RefCell::new(FnvHashSet::new()),
            available_drop_glues: RefCell::new(FnvHashMap::new()),
        };

        for i in range(0, local_count) {
            // Append ".rs" to crate name as LLVM module identifier.
            //
            // LLVM code generator emits a ".file filename" directive
            // for ELF backends. Value of the "filename" is set as the
            // LLVM module identifier.  Due to a LLVM MC bug[1], LLVM
            // crashes if the module identifier is same as other symbols
            // such as a function name in the module.
            // 1. http://llvm.org/bugs/show_bug.cgi?id=11479
            let llmod_id = format!("{}.{}.rs", crate_name, i);
            let local_ccx = LocalCrateContext::new(&shared_ccx, llmod_id.as_slice());
            shared_ccx.local_ccxs.push(local_ccx);
        }

        shared_ccx
    }

    pub fn iter<'a>(&'a self) -> CrateContextIterator<'a, 'tcx> {
        CrateContextIterator {
            shared: self,
            index: 0,
        }
    }

    pub fn get_ccx<'a>(&'a self, index: uint) -> CrateContext<'a, 'tcx> {
        CrateContext {
            shared: self,
            local: &self.local_ccxs[index],
            index: index,
        }
    }

    fn get_smallest_ccx<'a>(&'a self) -> CrateContext<'a, 'tcx> {
        let (local_ccx, index) =
            self.local_ccxs
                .iter()
                .zip(range(0, self.local_ccxs.len()))
                .min_by(|&(local_ccx, _idx)| local_ccx.n_llvm_insns.get())
                .unwrap();
        CrateContext {
            shared: self,
            local: local_ccx,
            index: index,
        }
    }


    pub fn metadata_llmod(&self) -> ModuleRef {
        self.metadata_llmod
    }

    pub fn metadata_llcx(&self) -> ContextRef {
        self.metadata_llcx
    }

    pub fn exp_map2<'a>(&'a self) -> &'a resolve::ExportMap2 {
        &self.exp_map2
    }

    pub fn reachable<'a>(&'a self) -> &'a NodeSet {
        &self.reachable
    }

    pub fn item_symbols<'a>(&'a self) -> &'a RefCell<NodeMap<String>> {
        &self.item_symbols
    }

    pub fn link_meta<'a>(&'a self) -> &'a LinkMeta {
        &self.link_meta
    }

    pub fn symbol_hasher<'a>(&'a self) -> &'a RefCell<Sha256> {
        &self.symbol_hasher
    }

    pub fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx> {
        &self.tcx
    }

    pub fn take_tcx(self) -> ty::ctxt<'tcx> {
        self.tcx
    }

    pub fn sess<'a>(&'a self) -> &'a Session {
        &self.tcx.sess
    }

    pub fn stats<'a>(&'a self) -> &'a Stats {
        &self.stats
    }
}

impl<'tcx> LocalCrateContext<'tcx> {
    fn new(shared: &SharedCrateContext<'tcx>,
           name: &str)
           -> LocalCrateContext<'tcx> {
        unsafe {
            let (llcx, llmod) = create_context_and_module(&shared.tcx.sess, name);

            let td = mk_target_data(shared.tcx
                                          .sess
                                          .target
                                          .target
                                          .data_layout
                                          .as_slice());

            let dbg_cx = if shared.tcx.sess.opts.debuginfo != NoDebugInfo {
                Some(debuginfo::CrateDebugContext::new(llmod))
            } else {
                None
            };

            let mut local_ccx = LocalCrateContext {
                llmod: llmod,
                llcx: llcx,
                td: td,
                tn: TypeNames::new(),
                externs: RefCell::new(FnvHashMap::new()),
                item_vals: RefCell::new(NodeMap::new()),
                drop_glues: RefCell::new(FnvHashMap::new()),
                tydescs: RefCell::new(FnvHashMap::new()),
                finished_tydescs: Cell::new(false),
                external: RefCell::new(DefIdMap::new()),
                external_srcs: RefCell::new(NodeMap::new()),
                monomorphized: RefCell::new(FnvHashMap::new()),
                monomorphizing: RefCell::new(DefIdMap::new()),
                vtables: RefCell::new(FnvHashMap::new()),
                const_cstr_cache: RefCell::new(FnvHashMap::new()),
                const_globals: RefCell::new(FnvHashMap::new()),
                const_values: RefCell::new(NodeMap::new()),
                static_values: RefCell::new(NodeMap::new()),
                extern_const_values: RefCell::new(DefIdMap::new()),
                impl_method_cache: RefCell::new(FnvHashMap::new()),
                closure_bare_wrapper_cache: RefCell::new(FnvHashMap::new()),
                lltypes: RefCell::new(FnvHashMap::new()),
                llsizingtypes: RefCell::new(FnvHashMap::new()),
                adt_reprs: RefCell::new(FnvHashMap::new()),
                type_hashcodes: RefCell::new(FnvHashMap::new()),
                all_llvm_symbols: RefCell::new(FnvHashSet::new()),
                int_type: Type::from_ref(ptr::null_mut()),
                opaque_vec_type: Type::from_ref(ptr::null_mut()),
                builder: BuilderRef_res(llvm::LLVMCreateBuilderInContext(llcx)),
                unboxed_closure_vals: RefCell::new(FnvHashMap::new()),
                dbg_cx: dbg_cx,
                eh_personality: RefCell::new(None),
                intrinsics: RefCell::new(FnvHashMap::new()),
                n_llvm_insns: Cell::new(0u),
                trait_cache: RefCell::new(FnvHashMap::new()),
            };

            local_ccx.int_type = Type::int(&local_ccx.dummy_ccx(shared));
            local_ccx.opaque_vec_type = Type::opaque_vec(&local_ccx.dummy_ccx(shared));

            // Done mutating local_ccx directly.  (The rest of the
            // initialization goes through RefCell.)
            {
                let ccx = local_ccx.dummy_ccx(shared);

                let mut str_slice_ty = Type::named_struct(&ccx, "str_slice");
                str_slice_ty.set_struct_body(&[Type::i8p(&ccx), ccx.int_type()], false);
                ccx.tn().associate_type("str_slice", &str_slice_ty);

                ccx.tn().associate_type("tydesc", &Type::tydesc(&ccx, str_slice_ty));

                if ccx.sess().count_llvm_insns() {
                    base::init_insn_ctxt()
                }
            }

            local_ccx
        }
    }

    /// Create a dummy `CrateContext` from `self` and  the provided
    /// `SharedCrateContext`.  This is somewhat dangerous because `self` may
    /// not actually be an element of `shared.local_ccxs`, which can cause some
    /// operations to panic unexpectedly.
    ///
    /// This is used in the `LocalCrateContext` constructor to allow calling
    /// functions that expect a complete `CrateContext`, even before the local
    /// portion is fully initialized and attached to the `SharedCrateContext`.
    fn dummy_ccx<'a>(&'a self, shared: &'a SharedCrateContext<'tcx>)
                     -> CrateContext<'a, 'tcx> {
        CrateContext {
            shared: shared,
            local: self,
            index: -1 as uint,
        }
    }
}

impl<'b, 'tcx> CrateContext<'b, 'tcx> {
    pub fn shared(&self) -> &'b SharedCrateContext<'tcx> {
        self.shared
    }

    pub fn local(&self) -> &'b LocalCrateContext<'tcx> {
        self.local
    }


    /// Get a (possibly) different `CrateContext` from the same
    /// `SharedCrateContext`.
    pub fn rotate(&self) -> CrateContext<'b, 'tcx> {
        self.shared.get_smallest_ccx()
    }

    /// Either iterate over only `self`, or iterate over all `CrateContext`s in
    /// the `SharedCrateContext`.  The iterator produces `(ccx, is_origin)`
    /// pairs, where `is_origin` is `true` if `ccx` is `self` and `false`
    /// otherwise.  This method is useful for avoiding code duplication in
    /// cases where it may or may not be necessary to translate code into every
    /// context.
    pub fn maybe_iter(&self, iter_all: bool) -> CrateContextMaybeIterator<'b, 'tcx> {
        CrateContextMaybeIterator {
            shared: self.shared,
            index: if iter_all { 0 } else { self.index },
            single: !iter_all,
            origin: self.index,
        }
    }


    pub fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx> {
        &self.shared.tcx
    }

    pub fn sess<'a>(&'a self) -> &'a Session {
        &self.shared.tcx.sess
    }

    pub fn builder<'a>(&'a self) -> Builder<'a, 'tcx> {
        Builder::new(self)
    }

    pub fn raw_builder<'a>(&'a self) -> BuilderRef {
        self.local.builder.b
    }

    pub fn tydesc_type(&self) -> Type {
        self.local.tn.find_type("tydesc").unwrap()
    }

    pub fn get_intrinsic(&self, key: & &'static str) -> ValueRef {
        if let Some(v) = self.intrinsics().borrow().get(key).cloned() {
            return v;
        }
        match declare_intrinsic(self, key) {
            Some(v) => return v,
            None => panic!()
        }
    }

    pub fn is_split_stack_supported(&self) -> bool {
        self.sess().target.target.options.morestack
    }


    pub fn llmod(&self) -> ModuleRef {
        self.local.llmod
    }

    pub fn llcx(&self) -> ContextRef {
        self.local.llcx
    }

    pub fn td<'a>(&'a self) -> &'a TargetData {
        &self.local.td
    }

    pub fn tn<'a>(&'a self) -> &'a TypeNames {
        &self.local.tn
    }

    pub fn externs<'a>(&'a self) -> &'a RefCell<ExternMap> {
        &self.local.externs
    }

    pub fn item_vals<'a>(&'a self) -> &'a RefCell<NodeMap<ValueRef>> {
        &self.local.item_vals
    }

    pub fn exp_map2<'a>(&'a self) -> &'a resolve::ExportMap2 {
        &self.shared.exp_map2
    }

    pub fn reachable<'a>(&'a self) -> &'a NodeSet {
        &self.shared.reachable
    }

    pub fn item_symbols<'a>(&'a self) -> &'a RefCell<NodeMap<String>> {
        &self.shared.item_symbols
    }

    pub fn link_meta<'a>(&'a self) -> &'a LinkMeta {
        &self.shared.link_meta
    }

    pub fn drop_glues<'a>(&'a self) -> &'a RefCell<FnvHashMap<Ty<'tcx>, ValueRef>> {
        &self.local.drop_glues
    }

    pub fn tydescs<'a>(&'a self) -> &'a RefCell<FnvHashMap<Ty<'tcx>, Rc<tydesc_info<'tcx>>>> {
        &self.local.tydescs
    }

    pub fn finished_tydescs<'a>(&'a self) -> &'a Cell<bool> {
        &self.local.finished_tydescs
    }

    pub fn external<'a>(&'a self) -> &'a RefCell<DefIdMap<Option<ast::NodeId>>> {
        &self.local.external
    }

    pub fn external_srcs<'a>(&'a self) -> &'a RefCell<NodeMap<ast::DefId>> {
        &self.local.external_srcs
    }

    pub fn monomorphized<'a>(&'a self) -> &'a RefCell<FnvHashMap<MonoId<'tcx>, ValueRef>> {
        &self.local.monomorphized
    }

    pub fn monomorphizing<'a>(&'a self) -> &'a RefCell<DefIdMap<uint>> {
        &self.local.monomorphizing
    }

    pub fn vtables<'a>(&'a self) -> &'a RefCell<FnvHashMap<(Ty<'tcx>, Rc<ty::TraitRef<'tcx>>),
                                                            ValueRef>> {
        &self.local.vtables
    }

    pub fn const_cstr_cache<'a>(&'a self) -> &'a RefCell<FnvHashMap<InternedString, ValueRef>> {
        &self.local.const_cstr_cache
    }

    pub fn const_globals<'a>(&'a self) -> &'a RefCell<FnvHashMap<int, ValueRef>> {
        &self.local.const_globals
    }

    pub fn const_values<'a>(&'a self) -> &'a RefCell<NodeMap<ValueRef>> {
        &self.local.const_values
    }

    pub fn static_values<'a>(&'a self) -> &'a RefCell<NodeMap<ValueRef>> {
        &self.local.static_values
    }

    pub fn extern_const_values<'a>(&'a self) -> &'a RefCell<DefIdMap<ValueRef>> {
        &self.local.extern_const_values
    }

    pub fn impl_method_cache<'a>(&'a self)
            -> &'a RefCell<FnvHashMap<(ast::DefId, ast::Name), ast::DefId>> {
        &self.local.impl_method_cache
    }

    pub fn closure_bare_wrapper_cache<'a>(&'a self) -> &'a RefCell<FnvHashMap<ValueRef, ValueRef>> {
        &self.local.closure_bare_wrapper_cache
    }

    pub fn lltypes<'a>(&'a self) -> &'a RefCell<FnvHashMap<Ty<'tcx>, Type>> {
        &self.local.lltypes
    }

    pub fn llsizingtypes<'a>(&'a self) -> &'a RefCell<FnvHashMap<Ty<'tcx>, Type>> {
        &self.local.llsizingtypes
    }

    pub fn adt_reprs<'a>(&'a self) -> &'a RefCell<FnvHashMap<Ty<'tcx>, Rc<adt::Repr<'tcx>>>> {
        &self.local.adt_reprs
    }

    pub fn symbol_hasher<'a>(&'a self) -> &'a RefCell<Sha256> {
        &self.shared.symbol_hasher
    }

    pub fn type_hashcodes<'a>(&'a self) -> &'a RefCell<FnvHashMap<Ty<'tcx>, String>> {
        &self.local.type_hashcodes
    }

    pub fn all_llvm_symbols<'a>(&'a self) -> &'a RefCell<FnvHashSet<String>> {
        &self.local.all_llvm_symbols
    }

    pub fn stats<'a>(&'a self) -> &'a Stats {
        &self.shared.stats
    }

    pub fn available_monomorphizations<'a>(&'a self) -> &'a RefCell<FnvHashSet<String>> {
        &self.shared.available_monomorphizations
    }

    pub fn available_drop_glues<'a>(&'a self) -> &'a RefCell<FnvHashMap<Ty<'tcx>, String>> {
        &self.shared.available_drop_glues
    }

    pub fn int_type(&self) -> Type {
        self.local.int_type
    }

    pub fn opaque_vec_type(&self) -> Type {
        self.local.opaque_vec_type
    }

    pub fn unboxed_closure_vals<'a>(&'a self) -> &'a RefCell<FnvHashMap<MonoId<'tcx>,ValueRef>> {
        &self.local.unboxed_closure_vals
    }

    pub fn dbg_cx<'a>(&'a self) -> &'a Option<debuginfo::CrateDebugContext<'tcx>> {
        &self.local.dbg_cx
    }

    pub fn eh_personality<'a>(&'a self) -> &'a RefCell<Option<ValueRef>> {
        &self.local.eh_personality
    }

    fn intrinsics<'a>(&'a self) -> &'a RefCell<FnvHashMap<&'static str, ValueRef>> {
        &self.local.intrinsics
    }

    pub fn count_llvm_insn(&self) {
        self.local.n_llvm_insns.set(self.local.n_llvm_insns.get() + 1);
    }

    pub fn trait_cache(&self) -> &RefCell<FnvHashMap<Rc<ty::TraitRef<'tcx>>,
                                                     traits::Vtable<'tcx, ()>>> {
        &self.local.trait_cache
    }

    /// Return exclusive upper bound on object size.
    ///
    /// The theoretical maximum object size is defined as the maximum positive `int` value. This
    /// ensures that the `offset` semantics remain well-defined by allowing it to correctly index
    /// every address within an object along with one byte past the end, along with allowing `int`
    /// to store the difference between any two pointers into an object.
    ///
    /// The upper bound on 64-bit currently needs to be lower because LLVM uses a 64-bit integer to
    /// represent object size in bits. It would need to be 1 << 61 to account for this, but is
    /// currently conservatively bounded to 1 << 47 as that is enough to cover the current usable
    /// address space on 64-bit ARMv8 and x86_64.
    pub fn obj_size_bound(&self) -> u64 {
        match self.sess().target.target.target_word_size[] {
            "32" => 1 << 31,
            "64" => 1 << 47,
            _ => unreachable!() // error handled by config::build_target_config
        }
    }

    pub fn report_overbig_object(&self, obj: Ty<'tcx>) -> ! {
        self.sess().fatal(
            format!("the type `{}` is too big for the current architecture",
                    obj.repr(self.tcx())).as_slice())
    }
}

fn declare_intrinsic(ccx: &CrateContext, key: & &'static str) -> Option<ValueRef> {
    macro_rules! ifn (
        ($name:expr fn() -> $ret:expr) => (
            if *key == $name {
                let f = base::decl_cdecl_fn(
                    ccx, $name, Type::func(&[], &$ret),
                    ty::mk_nil(ccx.tcx()));
                ccx.intrinsics().borrow_mut().insert($name, f.clone());
                return Some(f);
            }
        );
        ($name:expr fn($($arg:expr),*) -> $ret:expr) => (
            if *key == $name {
                let f = base::decl_cdecl_fn(ccx, $name,
                                  Type::func(&[$($arg),*], &$ret), ty::mk_nil(ccx.tcx()));
                ccx.intrinsics().borrow_mut().insert($name, f.clone());
                return Some(f);
            }
        )
    )
    macro_rules! mk_struct (
        ($($field_ty:expr),*) => (Type::struct_(ccx, &[$($field_ty),*], false))
    )

    let i8p = Type::i8p(ccx);
    let void = Type::void(ccx);
    let i1 = Type::i1(ccx);
    let t_i8 = Type::i8(ccx);
    let t_i16 = Type::i16(ccx);
    let t_i32 = Type::i32(ccx);
    let t_i64 = Type::i64(ccx);
    let t_f32 = Type::f32(ccx);
    let t_f64 = Type::f64(ccx);

    ifn!("llvm.memcpy.p0i8.p0i8.i32" fn(i8p, i8p, t_i32, t_i32, i1) -> void);
    ifn!("llvm.memcpy.p0i8.p0i8.i64" fn(i8p, i8p, t_i64, t_i32, i1) -> void);
    ifn!("llvm.memmove.p0i8.p0i8.i32" fn(i8p, i8p, t_i32, t_i32, i1) -> void);
    ifn!("llvm.memmove.p0i8.p0i8.i64" fn(i8p, i8p, t_i64, t_i32, i1) -> void);
    ifn!("llvm.memset.p0i8.i32" fn(i8p, t_i8, t_i32, t_i32, i1) -> void);
    ifn!("llvm.memset.p0i8.i64" fn(i8p, t_i8, t_i64, t_i32, i1) -> void);

    ifn!("llvm.trap" fn() -> void);
    ifn!("llvm.debugtrap" fn() -> void);
    ifn!("llvm.frameaddress" fn(t_i32) -> i8p);

    ifn!("llvm.powi.f32" fn(t_f32, t_i32) -> t_f32);
    ifn!("llvm.powi.f64" fn(t_f64, t_i32) -> t_f64);
    ifn!("llvm.pow.f32" fn(t_f32, t_f32) -> t_f32);
    ifn!("llvm.pow.f64" fn(t_f64, t_f64) -> t_f64);

    ifn!("llvm.sqrt.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.sqrt.f64" fn(t_f64) -> t_f64);
    ifn!("llvm.sin.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.sin.f64" fn(t_f64) -> t_f64);
    ifn!("llvm.cos.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.cos.f64" fn(t_f64) -> t_f64);
    ifn!("llvm.exp.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.exp.f64" fn(t_f64) -> t_f64);
    ifn!("llvm.exp2.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.exp2.f64" fn(t_f64) -> t_f64);
    ifn!("llvm.log.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.log.f64" fn(t_f64) -> t_f64);
    ifn!("llvm.log10.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.log10.f64" fn(t_f64) -> t_f64);
    ifn!("llvm.log2.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.log2.f64" fn(t_f64) -> t_f64);

    ifn!("llvm.fma.f32" fn(t_f32, t_f32, t_f32) -> t_f32);
    ifn!("llvm.fma.f64" fn(t_f64, t_f64, t_f64) -> t_f64);

    ifn!("llvm.fabs.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.fabs.f64" fn(t_f64) -> t_f64);

    ifn!("llvm.floor.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.floor.f64" fn(t_f64) -> t_f64);
    ifn!("llvm.ceil.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.ceil.f64" fn(t_f64) -> t_f64);
    ifn!("llvm.trunc.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.trunc.f64" fn(t_f64) -> t_f64);

    ifn!("llvm.rint.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.rint.f64" fn(t_f64) -> t_f64);
    ifn!("llvm.nearbyint.f32" fn(t_f32) -> t_f32);
    ifn!("llvm.nearbyint.f64" fn(t_f64) -> t_f64);

    ifn!("llvm.ctpop.i8" fn(t_i8) -> t_i8);
    ifn!("llvm.ctpop.i16" fn(t_i16) -> t_i16);
    ifn!("llvm.ctpop.i32" fn(t_i32) -> t_i32);
    ifn!("llvm.ctpop.i64" fn(t_i64) -> t_i64);

    ifn!("llvm.ctlz.i8" fn(t_i8 , i1) -> t_i8);
    ifn!("llvm.ctlz.i16" fn(t_i16, i1) -> t_i16);
    ifn!("llvm.ctlz.i32" fn(t_i32, i1) -> t_i32);
    ifn!("llvm.ctlz.i64" fn(t_i64, i1) -> t_i64);

    ifn!("llvm.cttz.i8" fn(t_i8 , i1) -> t_i8);
    ifn!("llvm.cttz.i16" fn(t_i16, i1) -> t_i16);
    ifn!("llvm.cttz.i32" fn(t_i32, i1) -> t_i32);
    ifn!("llvm.cttz.i64" fn(t_i64, i1) -> t_i64);

    ifn!("llvm.bswap.i16" fn(t_i16) -> t_i16);
    ifn!("llvm.bswap.i32" fn(t_i32) -> t_i32);
    ifn!("llvm.bswap.i64" fn(t_i64) -> t_i64);

    ifn!("llvm.sadd.with.overflow.i8" fn(t_i8, t_i8) -> mk_struct!{t_i8, i1});
    ifn!("llvm.sadd.with.overflow.i16" fn(t_i16, t_i16) -> mk_struct!{t_i16, i1});
    ifn!("llvm.sadd.with.overflow.i32" fn(t_i32, t_i32) -> mk_struct!{t_i32, i1});
    ifn!("llvm.sadd.with.overflow.i64" fn(t_i64, t_i64) -> mk_struct!{t_i64, i1});

    ifn!("llvm.uadd.with.overflow.i8" fn(t_i8, t_i8) -> mk_struct!{t_i8, i1});
    ifn!("llvm.uadd.with.overflow.i16" fn(t_i16, t_i16) -> mk_struct!{t_i16, i1});
    ifn!("llvm.uadd.with.overflow.i32" fn(t_i32, t_i32) -> mk_struct!{t_i32, i1});
    ifn!("llvm.uadd.with.overflow.i64" fn(t_i64, t_i64) -> mk_struct!{t_i64, i1});

    ifn!("llvm.ssub.with.overflow.i8" fn(t_i8, t_i8) -> mk_struct!{t_i8, i1});
    ifn!("llvm.ssub.with.overflow.i16" fn(t_i16, t_i16) -> mk_struct!{t_i16, i1});
    ifn!("llvm.ssub.with.overflow.i32" fn(t_i32, t_i32) -> mk_struct!{t_i32, i1});
    ifn!("llvm.ssub.with.overflow.i64" fn(t_i64, t_i64) -> mk_struct!{t_i64, i1});

    ifn!("llvm.usub.with.overflow.i8" fn(t_i8, t_i8) -> mk_struct!{t_i8, i1});
    ifn!("llvm.usub.with.overflow.i16" fn(t_i16, t_i16) -> mk_struct!{t_i16, i1});
    ifn!("llvm.usub.with.overflow.i32" fn(t_i32, t_i32) -> mk_struct!{t_i32, i1});
    ifn!("llvm.usub.with.overflow.i64" fn(t_i64, t_i64) -> mk_struct!{t_i64, i1});

    ifn!("llvm.smul.with.overflow.i8" fn(t_i8, t_i8) -> mk_struct!{t_i8, i1});
    ifn!("llvm.smul.with.overflow.i16" fn(t_i16, t_i16) -> mk_struct!{t_i16, i1});
    ifn!("llvm.smul.with.overflow.i32" fn(t_i32, t_i32) -> mk_struct!{t_i32, i1});
    ifn!("llvm.smul.with.overflow.i64" fn(t_i64, t_i64) -> mk_struct!{t_i64, i1});

    ifn!("llvm.umul.with.overflow.i8" fn(t_i8, t_i8) -> mk_struct!{t_i8, i1});
    ifn!("llvm.umul.with.overflow.i16" fn(t_i16, t_i16) -> mk_struct!{t_i16, i1});
    ifn!("llvm.umul.with.overflow.i32" fn(t_i32, t_i32) -> mk_struct!{t_i32, i1});
    ifn!("llvm.umul.with.overflow.i64" fn(t_i64, t_i64) -> mk_struct!{t_i64, i1});

    ifn!("llvm.lifetime.start" fn(t_i64,i8p) -> void);
    ifn!("llvm.lifetime.end" fn(t_i64, i8p) -> void);

    ifn!("llvm.expect.i1" fn(i1, i1) -> i1);
    ifn!("llvm.assume" fn(i1) -> void);

    // Some intrinsics were introduced in later versions of LLVM, but they have
    // fallbacks in libc or libm and such. Currently, all of these intrinsics
    // were introduced in LLVM 3.4, so we case on that.
    macro_rules! compatible_ifn (
        ($name:expr, $cname:ident ($($arg:expr),*) -> $ret:expr) => (
            if unsafe { llvm::LLVMVersionMinor() >= 4 } {
                // The `if key == $name` is already in ifn!
                ifn!($name fn($($arg),*) -> $ret);
            } else if *key == $name {
                let f = base::decl_cdecl_fn(ccx, stringify!($cname),
                                      Type::func(&[$($arg),*], &$ret),
                                      ty::mk_nil(ccx.tcx()));
                ccx.intrinsics().borrow_mut().insert($name, f.clone());
                return Some(f);
            }
        )
    )

    compatible_ifn!("llvm.copysign.f32", copysignf(t_f32, t_f32) -> t_f32);
    compatible_ifn!("llvm.copysign.f64", copysign(t_f64, t_f64) -> t_f64);
    compatible_ifn!("llvm.round.f32", roundf(t_f32) -> t_f32);
    compatible_ifn!("llvm.round.f64", round(t_f64) -> t_f64);


    if ccx.sess().opts.debuginfo != NoDebugInfo {
        ifn!("llvm.dbg.declare" fn(Type::metadata(ccx), Type::metadata(ccx)) -> void);
        ifn!("llvm.dbg.value" fn(Type::metadata(ccx), t_i64, Type::metadata(ccx)) -> void);
    }
    return None;
}