540 lines
20 KiB
Rust
540 lines
20 KiB
Rust
import libc::c_uint;
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import syntax::ast;
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import syntax::ast_util;
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import lib::llvm::llvm;
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import lib::llvm::{ValueRef, TypeRef};
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import common::*;
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import build::*;
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import base::*;
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import type_of::*;
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import type_of::type_of; // Issue #1873
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import back::abi;
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import syntax::codemap::span;
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import syntax::print::pprust::expr_to_str;
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import back::link::{
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mangle_internal_name_by_path,
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mangle_internal_name_by_path_and_seq};
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import util::ppaux::ty_to_str;
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import syntax::ast_map::{path, path_mod, path_name};
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import driver::session::session;
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import std::map::hashmap;
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import dvec::extensions;
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// ___Good to know (tm)__________________________________________________
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//
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// The layout of a closure environment in memory is
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// roughly as follows:
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//
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// struct rust_opaque_box { // see rust_internal.h
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// unsigned ref_count; // only used for fn@()
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// type_desc *tydesc; // describes closure_data struct
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// rust_opaque_box *prev; // (used internally by memory alloc)
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// rust_opaque_box *next; // (used internally by memory alloc)
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// struct closure_data {
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// type_desc *bound_tdescs[]; // bound descriptors
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// struct {
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// upvar1_t upvar1;
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// ...
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// upvarN_t upvarN;
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// } bound_data;
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// }
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// };
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//
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// Note that the closure is itself a rust_opaque_box. This is true
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// even for fn~ and fn&, because we wish to keep binary compatibility
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// between all kinds of closures. The allocation strategy for this
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// closure depends on the closure type. For a sendfn, the closure
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// (and the referenced type descriptors) will be allocated in the
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// exchange heap. For a fn, the closure is allocated in the task heap
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// and is reference counted. For a block, the closure is allocated on
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// the stack.
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//
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// ## Opaque closures and the embedded type descriptor ##
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//
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// One interesting part of closures is that they encapsulate the data
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// that they close over. So when I have a ptr to a closure, I do not
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// know how many type descriptors it contains nor what upvars are
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// captured within. That means I do not know precisely how big it is
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// nor where its fields are located. This is called an "opaque
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// closure".
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//
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// Typically an opaque closure suffices because we only manipulate it
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// by ptr. The routine common::T_opaque_box_ptr() returns an
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// appropriate type for such an opaque closure; it allows access to
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// the box fields, but not the closure_data itself.
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//
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// But sometimes, such as when cloning or freeing a closure, we need
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// to know the full information. That is where the type descriptor
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// that defines the closure comes in handy. We can use its take and
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// drop glue functions to allocate/free data as needed.
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//
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// ## Subtleties concerning alignment ##
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//
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// It is important that we be able to locate the closure data *without
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// knowing the kind of data that is being bound*. This can be tricky
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// because the alignment requirements of the bound data affects the
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// alignment requires of the closure_data struct as a whole. However,
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// right now this is a non-issue in any case, because the size of the
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// rust_opaque_box header is always a mutiple of 16-bytes, which is
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// the maximum alignment requirement we ever have to worry about.
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//
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// The only reason alignment matters is that, in order to learn what data
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// is bound, we would normally first load the type descriptors: but their
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// location is ultimately depend on their content! There is, however, a
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// workaround. We can load the tydesc from the rust_opaque_box, which
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// describes the closure_data struct and has self-contained derived type
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// descriptors, and read the alignment from there. It's just annoying to
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// do. Hopefully should this ever become an issue we'll have monomorphized
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// and type descriptors will all be a bad dream.
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//
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// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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enum environment_value {
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// Copy the value from this llvm ValueRef into the environment.
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env_copy(ValueRef, ty::t, lval_kind),
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// Move the value from this llvm ValueRef into the environment.
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env_move(ValueRef, ty::t, lval_kind),
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// Access by reference (used for blocks).
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env_ref(ValueRef, ty::t, lval_kind),
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}
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fn ev_to_str(ccx: @crate_ctxt, ev: environment_value) -> ~str {
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alt ev {
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env_copy(v, t, lk) { fmt!{"copy(%s,%s)", val_str(ccx.tn, v),
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ty_to_str(ccx.tcx, t)} }
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env_move(v, t, lk) { fmt!{"move(%s,%s)", val_str(ccx.tn, v),
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ty_to_str(ccx.tcx, t)} }
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env_ref(v, t, lk) { fmt!{"ref(%s,%s)", val_str(ccx.tn, v),
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ty_to_str(ccx.tcx, t)} }
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}
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}
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fn mk_tuplified_uniq_cbox_ty(tcx: ty::ctxt, cdata_ty: ty::t) -> ty::t {
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let cbox_ty = tuplify_box_ty(tcx, cdata_ty);
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ret ty::mk_imm_uniq(tcx, cbox_ty);
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}
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// Given a closure ty, emits a corresponding tuple ty
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fn mk_closure_tys(tcx: ty::ctxt,
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bound_values: ~[environment_value])
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-> ty::t {
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let mut bound_tys = ~[];
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// Compute the closed over data
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for vec::each(bound_values) |bv| {
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vec::push(bound_tys, alt bv {
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env_copy(_, t, _) { t }
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env_move(_, t, _) { t }
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env_ref(_, t, _) { t }
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});
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}
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let cdata_ty = ty::mk_tup(tcx, bound_tys);
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debug!{"cdata_ty=%s", ty_to_str(tcx, cdata_ty)};
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ret cdata_ty;
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}
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fn allocate_cbox(bcx: block,
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ck: ty::closure_kind,
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cdata_ty: ty::t)
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-> result {
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let _icx = bcx.insn_ctxt(~"closure::allocate_cbox");
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let ccx = bcx.ccx(), tcx = ccx.tcx;
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fn nuke_ref_count(bcx: block, llbox: ValueRef) {
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let _icx = bcx.insn_ctxt(~"closure::nuke_ref_count");
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// Initialize ref count to arbitrary value for debugging:
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let ccx = bcx.ccx();
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let llbox = PointerCast(bcx, llbox, T_opaque_box_ptr(ccx));
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let ref_cnt = GEPi(bcx, llbox, ~[0u, abi::box_field_refcnt]);
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let rc = C_int(ccx, 0x12345678);
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Store(bcx, rc, ref_cnt);
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}
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// Allocate and initialize the box:
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let {bcx, val} = alt ck {
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ty::ck_box {
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malloc_raw(bcx, cdata_ty, heap_shared)
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}
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ty::ck_uniq {
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malloc_raw(bcx, cdata_ty, heap_exchange)
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}
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ty::ck_block {
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let cbox_ty = tuplify_box_ty(tcx, cdata_ty);
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let llbox = base::alloc_ty(bcx, cbox_ty);
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nuke_ref_count(bcx, llbox);
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{bcx: bcx, val: llbox}
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}
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};
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ret {bcx: bcx, val: val};
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}
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type closure_result = {
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llbox: ValueRef, // llvalue of ptr to closure
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cdata_ty: ty::t, // type of the closure data
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bcx: block // final bcx
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};
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// Given a block context and a list of tydescs and values to bind
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// construct a closure out of them. If copying is true, it is a
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// heap allocated closure that copies the upvars into environment.
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// Otherwise, it is stack allocated and copies pointers to the upvars.
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fn store_environment(bcx: block,
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bound_values: ~[environment_value],
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ck: ty::closure_kind) -> closure_result {
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let _icx = bcx.insn_ctxt(~"closure::store_environment");
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let ccx = bcx.ccx(), tcx = ccx.tcx;
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// compute the shape of the closure
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let cdata_ty = mk_closure_tys(tcx, bound_values);
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// allocate closure in the heap
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let {bcx: bcx, val: llbox} = allocate_cbox(bcx, ck, cdata_ty);
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let mut temp_cleanups = ~[];
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// cbox_ty has the form of a tuple: (a, b, c) we want a ptr to a
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// tuple. This could be a ptr in uniq or a box or on stack,
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// whatever.
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let cbox_ty = tuplify_box_ty(tcx, cdata_ty);
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let cboxptr_ty = ty::mk_ptr(tcx, {ty:cbox_ty, mutbl:ast::m_imm});
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let llbox = PointerCast(bcx, llbox, type_of(ccx, cboxptr_ty));
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debug!{"tuplify_box_ty = %s", ty_to_str(tcx, cbox_ty)};
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// Copy expr values into boxed bindings.
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let mut bcx = bcx;
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do vec::iteri(bound_values) |i, bv| {
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debug!{"Copy %s into closure", ev_to_str(ccx, bv)};
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if !ccx.sess.no_asm_comments() {
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add_comment(bcx, fmt!{"Copy %s into closure",
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ev_to_str(ccx, bv)});
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}
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let bound_data = GEPi(bcx, llbox,
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~[0u, abi::box_field_body, i]);
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alt bv {
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env_copy(val, ty, lv_owned) {
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let val1 = load_if_immediate(bcx, val, ty);
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bcx = base::copy_val(bcx, INIT, bound_data, val1, ty);
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}
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env_copy(val, ty, lv_owned_imm) {
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bcx = base::copy_val(bcx, INIT, bound_data, val, ty);
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}
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env_copy(_, _, lv_temporary) {
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fail ~"cannot capture temporary upvar";
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}
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env_move(val, ty, kind) {
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let src = {bcx:bcx, val:val, kind:kind};
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bcx = move_val(bcx, INIT, bound_data, src, ty);
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}
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env_ref(val, ty, lv_owned) {
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debug!{"> storing %s into %s",
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val_str(bcx.ccx().tn, val),
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val_str(bcx.ccx().tn, bound_data)};
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Store(bcx, val, bound_data);
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}
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env_ref(val, ty, lv_owned_imm) {
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let addr = do_spill_noroot(bcx, val);
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Store(bcx, addr, bound_data);
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}
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env_ref(_, _, lv_temporary) {
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fail ~"cannot capture temporary upvar";
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}
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}
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}
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for vec::each(temp_cleanups) |cleanup| { revoke_clean(bcx, cleanup); }
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ret {llbox: llbox, cdata_ty: cdata_ty, bcx: bcx};
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}
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// Given a context and a list of upvars, build a closure. This just
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// collects the upvars and packages them up for store_environment.
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fn build_closure(bcx0: block,
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cap_vars: ~[capture::capture_var],
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ck: ty::closure_kind,
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id: ast::node_id,
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include_ret_handle: option<ValueRef>) -> closure_result {
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let _icx = bcx0.insn_ctxt(~"closure::build_closure");
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// If we need to, package up the iterator body to call
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let mut env_vals = ~[];
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let mut bcx = bcx0;
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let ccx = bcx.ccx(), tcx = ccx.tcx;
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// Package up the captured upvars
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do vec::iter(cap_vars) |cap_var| {
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debug!{"Building closure: captured variable %?", cap_var};
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let lv = trans_local_var(bcx, cap_var.def);
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let nid = ast_util::def_id_of_def(cap_var.def).node;
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debug!{"Node id is %s",
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syntax::ast_map::node_id_to_str(bcx.ccx().tcx.items, nid)};
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let mut ty = node_id_type(bcx, nid);
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alt cap_var.mode {
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capture::cap_ref {
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assert ck == ty::ck_block;
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ty = ty::mk_mut_ptr(tcx, ty);
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vec::push(env_vals, env_ref(lv.val, ty, lv.kind));
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}
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capture::cap_copy {
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let mv = alt check ccx.maps.last_use_map.find(id) {
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none { false }
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some(vars) { (*vars).contains(nid) }
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};
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if mv { vec::push(env_vals, env_move(lv.val, ty, lv.kind)); }
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else { vec::push(env_vals, env_copy(lv.val, ty, lv.kind)); }
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}
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capture::cap_move {
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vec::push(env_vals, env_move(lv.val, ty, lv.kind));
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}
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capture::cap_drop {
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assert lv.kind == lv_owned;
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bcx = drop_ty(bcx, lv.val, ty);
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bcx = zero_mem(bcx, lv.val, ty);
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}
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}
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}
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do option::iter(include_ret_handle) |flagptr| {
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let our_ret = alt bcx.fcx.loop_ret {
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some({retptr, _}) { retptr }
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none { bcx.fcx.llretptr }
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};
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let nil_ret = PointerCast(bcx, our_ret, T_ptr(T_nil()));
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vec::push(env_vals,
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env_ref(flagptr,
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ty::mk_mut_ptr(tcx, ty::mk_bool(tcx)), lv_owned));
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vec::push(env_vals,
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env_ref(nil_ret, ty::mk_nil_ptr(tcx), lv_owned));
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}
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ret store_environment(bcx, env_vals, ck);
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}
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// Given an enclosing block context, a new function context, a closure type,
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// and a list of upvars, generate code to load and populate the environment
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// with the upvars and type descriptors.
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fn load_environment(fcx: fn_ctxt,
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cdata_ty: ty::t,
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cap_vars: ~[capture::capture_var],
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load_ret_handle: bool,
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ck: ty::closure_kind) {
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let _icx = fcx.insn_ctxt(~"closure::load_environment");
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let bcx = raw_block(fcx, false, fcx.llloadenv);
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// Load a pointer to the closure data, skipping over the box header:
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let llcdata = base::opaque_box_body(bcx, cdata_ty, fcx.llenv);
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// Populate the upvars from the environment.
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let mut i = 0u;
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do vec::iter(cap_vars) |cap_var| {
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alt cap_var.mode {
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capture::cap_drop { /* ignore */ }
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_ {
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let mut upvarptr =
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GEPi(bcx, llcdata, ~[0u, i]);
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alt ck {
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ty::ck_block { upvarptr = Load(bcx, upvarptr); }
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ty::ck_uniq | ty::ck_box { }
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}
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let def_id = ast_util::def_id_of_def(cap_var.def);
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fcx.llupvars.insert(def_id.node, upvarptr);
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i += 1u;
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}
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}
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}
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if load_ret_handle {
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let flagptr = Load(bcx, GEPi(bcx, llcdata,
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~[0u, i]));
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let retptr = Load(bcx,
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GEPi(bcx, llcdata,
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~[0u, i+1u]));
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fcx.loop_ret = some({flagptr: flagptr, retptr: retptr});
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}
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}
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fn trans_expr_fn(bcx: block,
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proto: ast::proto,
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decl: ast::fn_decl,
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body: ast::blk,
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id: ast::node_id,
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cap_clause: ast::capture_clause,
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is_loop_body: option<option<ValueRef>>,
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dest: dest) -> block {
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let _icx = bcx.insn_ctxt(~"closure::trans_expr_fn");
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if dest == ignore { ret bcx; }
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let ccx = bcx.ccx();
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let fty = node_id_type(bcx, id);
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let llfnty = type_of_fn_from_ty(ccx, fty);
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let sub_path = vec::append_one(bcx.fcx.path, path_name(@~"anon"));
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let s = mangle_internal_name_by_path(ccx, sub_path);
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let llfn = decl_internal_cdecl_fn(ccx.llmod, s, llfnty);
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let trans_closure_env = fn@(ck: ty::closure_kind) -> result {
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let cap_vars = capture::compute_capture_vars(
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ccx.tcx, id, proto, cap_clause);
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let ret_handle = alt is_loop_body { some(x) { x } none { none } };
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let {llbox, cdata_ty, bcx} = build_closure(bcx, cap_vars, ck, id,
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ret_handle);
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trans_closure(ccx, sub_path, decl, body, llfn, no_self,
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bcx.fcx.param_substs, id, |fcx| {
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load_environment(fcx, cdata_ty, cap_vars,
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option::is_some(ret_handle), ck);
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}, |bcx| {
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if option::is_some(is_loop_body) {
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Store(bcx, C_bool(true), bcx.fcx.llretptr);
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}
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});
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{bcx: bcx, val: llbox}
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};
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let {bcx: bcx, val: closure} = alt proto {
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ast::proto_any | ast::proto_block { trans_closure_env(ty::ck_block) }
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ast::proto_box { trans_closure_env(ty::ck_box) }
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ast::proto_uniq { trans_closure_env(ty::ck_uniq) }
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ast::proto_bare {
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trans_closure(ccx, sub_path, decl, body, llfn, no_self, none,
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id, |_fcx| { }, |_bcx| { });
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{bcx: bcx, val: C_null(T_opaque_box_ptr(ccx))}
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}
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};
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fill_fn_pair(bcx, get_dest_addr(dest), llfn, closure);
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ret bcx;
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}
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fn make_fn_glue(
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cx: block,
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v: ValueRef,
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t: ty::t,
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glue_fn: fn@(block, v: ValueRef, t: ty::t) -> block)
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-> block {
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let _icx = cx.insn_ctxt(~"closure::make_fn_glue");
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let bcx = cx;
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let tcx = cx.tcx();
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let fn_env = fn@(ck: ty::closure_kind) -> block {
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let box_cell_v = GEPi(cx, v, ~[0u, abi::fn_field_box]);
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let box_ptr_v = Load(cx, box_cell_v);
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do with_cond(cx, IsNotNull(cx, box_ptr_v)) |bcx| {
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let closure_ty = ty::mk_opaque_closure_ptr(tcx, ck);
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glue_fn(bcx, box_cell_v, closure_ty)
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}
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};
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ret alt ty::get(t).struct {
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ty::ty_fn({proto: ast::proto_bare, _}) |
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ty::ty_fn({proto: ast::proto_block, _}) |
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ty::ty_fn({proto: ast::proto_any, _}) { bcx }
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ty::ty_fn({proto: ast::proto_uniq, _}) { fn_env(ty::ck_uniq) }
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ty::ty_fn({proto: ast::proto_box, _}) { fn_env(ty::ck_box) }
|
|
_ { fail ~"make_fn_glue invoked on non-function type" }
|
|
};
|
|
}
|
|
|
|
fn make_opaque_cbox_take_glue(
|
|
bcx: block,
|
|
ck: ty::closure_kind,
|
|
cboxptr: ValueRef) // ptr to ptr to the opaque closure
|
|
-> block {
|
|
// Easy cases:
|
|
let _icx = bcx.insn_ctxt(~"closure::make_opaque_cbox_take_glue");
|
|
alt ck {
|
|
ty::ck_block { ret bcx; }
|
|
ty::ck_box { incr_refcnt_of_boxed(bcx, Load(bcx, cboxptr)); ret bcx; }
|
|
ty::ck_uniq { /* hard case: */ }
|
|
}
|
|
|
|
// Hard case, a deep copy:
|
|
let ccx = bcx.ccx(), tcx = ccx.tcx;
|
|
let llopaquecboxty = T_opaque_box_ptr(ccx);
|
|
let cbox_in = Load(bcx, cboxptr);
|
|
do with_cond(bcx, IsNotNull(bcx, cbox_in)) |bcx| {
|
|
// Load the size from the type descr found in the cbox
|
|
let cbox_in = PointerCast(bcx, cbox_in, llopaquecboxty);
|
|
let tydescptr = GEPi(bcx, cbox_in, ~[0u, abi::box_field_tydesc]);
|
|
let tydesc = Load(bcx, tydescptr);
|
|
let tydesc = PointerCast(bcx, tydesc, T_ptr(ccx.tydesc_type));
|
|
let sz = Load(bcx, GEPi(bcx, tydesc, ~[0u, abi::tydesc_field_size]));
|
|
|
|
// Adjust sz to account for the rust_opaque_box header fields
|
|
let sz = Add(bcx, sz, shape::llsize_of(ccx, T_box_header(ccx)));
|
|
|
|
// Allocate memory, update original ptr, and copy existing data
|
|
let malloc = ~"exchange_malloc";
|
|
let opaque_tydesc = PointerCast(bcx, tydesc, T_ptr(T_i8()));
|
|
let rval = alloca_zeroed(bcx, T_ptr(T_i8()));
|
|
let bcx = trans_rtcall(bcx, malloc, ~[opaque_tydesc, sz],
|
|
save_in(rval));
|
|
let cbox_out = PointerCast(bcx, Load(bcx, rval), llopaquecboxty);
|
|
call_memmove(bcx, cbox_out, cbox_in, sz);
|
|
Store(bcx, cbox_out, cboxptr);
|
|
|
|
// Take the (deeply cloned) type descriptor
|
|
let tydesc_out = GEPi(bcx, cbox_out, ~[0u, abi::box_field_tydesc]);
|
|
let bcx = take_ty(bcx, tydesc_out, ty::mk_type(tcx));
|
|
|
|
// Take the data in the tuple
|
|
let cdata_out = GEPi(bcx, cbox_out, ~[0u, abi::box_field_body]);
|
|
call_tydesc_glue_full(bcx, cdata_out, tydesc,
|
|
abi::tydesc_field_take_glue, none);
|
|
bcx
|
|
}
|
|
}
|
|
|
|
fn make_opaque_cbox_drop_glue(
|
|
bcx: block,
|
|
ck: ty::closure_kind,
|
|
cboxptr: ValueRef) // ptr to the opaque closure
|
|
-> block {
|
|
let _icx = bcx.insn_ctxt(~"closure::make_opaque_cbox_drop_glue");
|
|
alt ck {
|
|
ty::ck_block { bcx }
|
|
ty::ck_box {
|
|
decr_refcnt_maybe_free(bcx, Load(bcx, cboxptr),
|
|
ty::mk_opaque_closure_ptr(bcx.tcx(), ck))
|
|
}
|
|
ty::ck_uniq {
|
|
free_ty(bcx, Load(bcx, cboxptr),
|
|
ty::mk_opaque_closure_ptr(bcx.tcx(), ck))
|
|
}
|
|
}
|
|
}
|
|
|
|
fn make_opaque_cbox_free_glue(
|
|
bcx: block,
|
|
ck: ty::closure_kind,
|
|
cbox: ValueRef) // ptr to the opaque closure
|
|
-> block {
|
|
let _icx = bcx.insn_ctxt(~"closure::make_opaque_cbox_free_glue");
|
|
alt ck {
|
|
ty::ck_block { ret bcx; }
|
|
ty::ck_box | ty::ck_uniq { /* hard cases: */ }
|
|
}
|
|
|
|
let ccx = bcx.ccx();
|
|
do with_cond(bcx, IsNotNull(bcx, cbox)) |bcx| {
|
|
// Load the type descr found in the cbox
|
|
let lltydescty = T_ptr(ccx.tydesc_type);
|
|
let cbox = PointerCast(bcx, cbox, T_opaque_cbox_ptr(ccx));
|
|
let tydescptr = GEPi(bcx, cbox, ~[0u, abi::box_field_tydesc]);
|
|
let tydesc = Load(bcx, tydescptr);
|
|
let tydesc = PointerCast(bcx, tydesc, lltydescty);
|
|
|
|
// Drop the tuple data then free the descriptor
|
|
let cdata = GEPi(bcx, cbox, ~[0u, abi::box_field_body]);
|
|
call_tydesc_glue_full(bcx, cdata, tydesc,
|
|
abi::tydesc_field_drop_glue, none);
|
|
|
|
// Free the ty descr (if necc) and the box itself
|
|
alt ck {
|
|
ty::ck_block { fail ~"Impossible"; }
|
|
ty::ck_box {
|
|
trans_free(bcx, cbox)
|
|
}
|
|
ty::ck_uniq {
|
|
trans_unique_free(bcx, cbox)
|
|
}
|
|
}
|
|
}
|
|
}
|