2 use rustc::middle::allocator::AllocatorKind;
3 use smallvec::{smallvec, SmallVec};
6 self, Arg, Attribute, Crate, Expr, FnHeader, Generics, Ident, Item, ItemKind,
7 Mac, Mod, Mutability, Ty, TyKind, Unsafety, VisibilityKind,
11 respan, ExpnInfo, MacroAttribute,
14 base::{ExtCtxt, Resolver},
16 expand::ExpansionConfig,
17 hygiene::{Mark, SyntaxContext},
19 mut_visit::{self, MutVisitor},
22 symbol::{kw, sym, Symbol}
26 use crate::{AllocatorMethod, AllocatorTy, ALLOCATOR_METHODS};
30 resolver: &mut dyn Resolver,
33 handler: &rustc_errors::Handler,
35 ExpandAllocatorDirectives {
40 crate_name: Some(crate_name),
41 in_submod: -1, // -1 to account for the "root" module
45 struct ExpandAllocatorDirectives<'a> {
47 handler: &'a rustc_errors::Handler,
49 resolver: &'a mut dyn Resolver,
50 crate_name: Option<String>,
52 // For now, we disallow `global_allocator` in submodules because hygiene is hard. Keep track of
53 // whether we are in a submodule or not. If `in_submod > 0` we are in a submodule.
57 impl MutVisitor for ExpandAllocatorDirectives<'_> {
58 fn flat_map_item(&mut self, item: P<Item>) -> SmallVec<[P<Item>; 1]> {
59 debug!("in submodule {}", self.in_submod);
61 let name = if attr::contains_name(&item.attrs, sym::global_allocator) {
64 return mut_visit::noop_flat_map_item(item, self);
67 ItemKind::Static(..) => {}
70 .span_err(item.span, "allocators must be statics");
71 return smallvec![item];
75 if self.in_submod > 0 {
77 .span_err(item.span, "`global_allocator` cannot be used in submodules");
78 return smallvec![item];
83 .span_err(item.span, "cannot define more than one #[global_allocator]");
84 return smallvec![item];
88 // Create a fresh Mark for the new macro expansion we are about to do
89 let mark = Mark::fresh(Mark::root());
90 mark.set_expn_info(ExpnInfo {
91 call_site: item.span, // use the call site of the static
93 format: MacroAttribute(Symbol::intern(name)),
94 allow_internal_unstable: Some(vec![sym::rustc_attrs].into()),
95 allow_internal_unsafe: false,
96 local_inner_macros: false,
97 edition: self.sess.edition,
100 // Tie the span to the macro expansion info we just created
101 let span = item.span.with_ctxt(SyntaxContext::empty().apply_mark(mark));
103 // Create an expansion config
104 let ecfg = ExpansionConfig::default(self.crate_name.take().unwrap());
106 // Generate a bunch of new items using the AllocFnFactory
107 let mut f = AllocFnFactory {
109 kind: AllocatorKind::Global,
111 core: Ident::with_empty_ctxt(sym::core),
112 cx: ExtCtxt::new(self.sess, ecfg, self.resolver),
115 // We will generate a new submodule. To `use` the static from that module, we need to get
116 // the `super::...` path.
117 let super_path = f.cx.path(f.span, vec![Ident::with_empty_ctxt(kw::Super), f.global]);
119 // Generate the items in the submodule
120 let mut items = vec![
121 // import `core` to use allocators
122 f.cx.item_extern_crate(f.span, f.core),
123 // `use` the `global_allocator` in `super`
124 f.cx.item_use_simple(
126 respan(f.span.shrink_to_lo(), VisibilityKind::Inherited),
131 // Add the allocator methods to the submodule
135 .map(|method| f.allocator_fn(method)),
138 // Generate the submodule itself
139 let name = f.kind.fn_name("allocator_abi");
140 let allocator_abi = Ident::from_str(&name).gensym();
141 let module = f.cx.item_mod(span, span, allocator_abi, Vec::new(), items);
142 let module = f.cx.monotonic_expander().flat_map_item(module).pop().unwrap();
144 // Return the item and new submodule
145 smallvec![item, module]
148 // If we enter a submodule, take note.
149 fn visit_mod(&mut self, m: &mut Mod) {
150 debug!("enter submodule");
152 mut_visit::noop_visit_mod(m, self);
154 debug!("exit submodule");
157 // `visit_mac` is disabled by default. Enable it here.
158 fn visit_mac(&mut self, mac: &mut Mac) {
159 mut_visit::noop_visit_mac(mac, self)
163 struct AllocFnFactory<'a> {
171 impl AllocFnFactory<'_> {
172 fn allocator_fn(&self, method: &AllocatorMethod) -> P<Item> {
173 let mut abi_args = Vec::new();
175 let ref mut mk = || {
176 let name = Ident::from_str(&format!("arg{}", i));
183 .map(|ty| self.arg_ty(ty, &mut abi_args, mk))
185 let result = self.call_allocator(method.name, args);
186 let (output_ty, output_expr) = self.ret_ty(&method.output, result);
187 let kind = ItemKind::Fn(
188 self.cx.fn_decl(abi_args, ast::FunctionRetTy::Ty(output_ty)),
190 unsafety: Unsafety::Unsafe,
191 ..FnHeader::default()
194 self.cx.block_expr(output_expr),
198 Ident::from_str(&self.kind.fn_name(method.name)),
204 fn call_allocator(&self, method: &str, mut args: Vec<P<Expr>>) -> P<Expr> {
205 let method = self.cx.path(
209 Ident::from_str("alloc"),
210 Ident::from_str("GlobalAlloc"),
211 Ident::from_str(method),
214 let method = self.cx.expr_path(method);
215 let allocator = self.cx.path_ident(self.span, self.global);
216 let allocator = self.cx.expr_path(allocator);
217 let allocator = self.cx.expr_addr_of(self.span, allocator);
218 args.insert(0, allocator);
220 self.cx.expr_call(self.span, method, args)
223 fn attrs(&self) -> Vec<Attribute> {
224 let special = sym::rustc_std_internal_symbol;
225 let special = self.cx.meta_word(self.span, special);
226 vec![self.cx.attribute(self.span, special)]
233 ident: &mut dyn FnMut() -> Ident,
236 AllocatorTy::Layout => {
237 let usize = self.cx.path_ident(self.span, Ident::with_empty_ctxt(sym::usize));
238 let ty_usize = self.cx.ty_path(usize);
241 args.push(self.cx.arg(self.span, size, ty_usize.clone()));
242 args.push(self.cx.arg(self.span, align, ty_usize));
244 let layout_new = self.cx.path(
248 Ident::from_str("alloc"),
249 Ident::from_str("Layout"),
250 Ident::from_str("from_size_align_unchecked"),
253 let layout_new = self.cx.expr_path(layout_new);
254 let size = self.cx.expr_ident(self.span, size);
255 let align = self.cx.expr_ident(self.span, align);
256 let layout = self.cx.expr_call(self.span, layout_new, vec![size, align]);
260 AllocatorTy::Ptr => {
262 args.push(self.cx.arg(self.span, ident, self.ptr_u8()));
263 let arg = self.cx.expr_ident(self.span, ident);
264 self.cx.expr_cast(self.span, arg, self.ptr_u8())
267 AllocatorTy::Usize => {
269 args.push(self.cx.arg(self.span, ident, self.usize()));
270 self.cx.expr_ident(self.span, ident)
273 AllocatorTy::ResultPtr | AllocatorTy::Unit => {
274 panic!("can't convert AllocatorTy to an argument")
279 fn ret_ty(&self, ty: &AllocatorTy, expr: P<Expr>) -> (P<Ty>, P<Expr>) {
281 AllocatorTy::ResultPtr => {
286 let expr = self.cx.expr_cast(self.span, expr, self.ptr_u8());
287 (self.ptr_u8(), expr)
290 AllocatorTy::Unit => (self.cx.ty(self.span, TyKind::Tup(Vec::new())), expr),
292 AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
293 panic!("can't convert AllocatorTy to an output")
298 fn usize(&self) -> P<Ty> {
299 let usize = self.cx.path_ident(self.span, Ident::with_empty_ctxt(sym::usize));
300 self.cx.ty_path(usize)
303 fn ptr_u8(&self) -> P<Ty> {
304 let u8 = self.cx.path_ident(self.span, Ident::with_empty_ctxt(sym::u8));
305 let ty_u8 = self.cx.ty_path(u8);
306 self.cx.ty_ptr(self.span, ty_u8, Mutability::Mutable)