1 use crate::util::check_builtin_macro_attribute;
3 use rustc_ast::expand::allocator::{
4 AllocatorKind, AllocatorMethod, AllocatorTy, ALLOCATOR_METHODS,
7 use rustc_ast::{self as ast, Attribute, Expr, FnHeader, FnSig, Generics, Param, StmtKind};
8 use rustc_ast::{FnKind, ItemKind, Mutability, Stmt, Ty, TyKind, Unsafe};
9 use rustc_expand::base::{Annotatable, ExtCtxt};
10 use rustc_span::symbol::{kw, sym, Ident, Symbol};
14 ecx: &mut ExtCtxt<'_>,
16 meta_item: &ast::MetaItem,
18 ) -> Vec<Annotatable> {
19 check_builtin_macro_attribute(ecx, meta_item, sym::global_allocator);
21 let orig_item = item.clone();
23 ecx.sess.parse_sess.span_diagnostic.span_err(item.span(), "allocators must be statics");
24 vec![orig_item.clone()]
27 // Allow using `#[global_allocator]` on an item statement
28 // FIXME - if we get deref patterns, use them to reduce duplication here
29 let (item, is_stmt) = match &item {
30 Annotatable::Item(item) => match item.kind {
31 ItemKind::Static(..) => (item, false),
32 _ => return not_static(),
34 Annotatable::Stmt(stmt) => match &stmt.kind {
35 StmtKind::Item(item_) => match item_.kind {
36 ItemKind::Static(..) => (item_, true),
37 _ => return not_static(),
39 _ => return not_static(),
41 _ => return not_static(),
44 // Generate a bunch of new items using the AllocFnFactory
45 let span = ecx.with_def_site_ctxt(item.span);
46 let f = AllocFnFactory { span, kind: AllocatorKind::Global, global: item.ident, cx: ecx };
48 // Generate item statements for the allocator methods.
49 let stmts = ALLOCATOR_METHODS.iter().map(|method| f.allocator_fn(method)).collect();
51 // Generate anonymous constant serving as container for the allocator methods.
52 let const_ty = ecx.ty(span, TyKind::Tup(Vec::new()));
53 let const_body = ecx.expr_block(ecx.block(span, stmts));
54 let const_item = ecx.item_const(span, Ident::new(kw::Underscore, span), const_ty, const_body);
55 let const_item = if is_stmt {
56 Annotatable::Stmt(P(ecx.stmt_item(span, const_item)))
58 Annotatable::Item(const_item)
61 // Return the original item and the new methods.
62 vec![orig_item, const_item]
65 struct AllocFnFactory<'a, 'b> {
72 impl AllocFnFactory<'_, '_> {
73 fn allocator_fn(&self, method: &AllocatorMethod) -> Stmt {
74 let mut abi_args = Vec::new();
77 let name = Ident::from_str_and_span(&format!("arg{}", i), self.span);
81 let args = method.inputs.iter().map(|ty| self.arg_ty(ty, &mut abi_args, &mut mk)).collect();
82 let result = self.call_allocator(method.name, args);
83 let (output_ty, output_expr) = self.ret_ty(&method.output, result);
84 let decl = self.cx.fn_decl(abi_args, ast::FnRetTy::Ty(output_ty));
85 let header = FnHeader { unsafety: Unsafe::Yes(self.span), ..FnHeader::default() };
86 let sig = FnSig { decl, header, span: self.span };
87 let block = Some(self.cx.block_expr(output_expr));
89 ItemKind::Fn(box FnKind(ast::Defaultness::Final, sig, Generics::default(), block));
90 let item = self.cx.item(
92 Ident::from_str_and_span(&self.kind.fn_name(method.name), self.span),
96 self.cx.stmt_item(self.span, item)
99 fn call_allocator(&self, method: Symbol, mut args: Vec<P<Expr>>) -> P<Expr> {
100 let method = self.cx.std_path(&[sym::alloc, sym::GlobalAlloc, method]);
101 let method = self.cx.expr_path(self.cx.path(self.span, method));
102 let allocator = self.cx.path_ident(self.span, self.global);
103 let allocator = self.cx.expr_path(allocator);
104 let allocator = self.cx.expr_addr_of(self.span, allocator);
105 args.insert(0, allocator);
107 self.cx.expr_call(self.span, method, args)
110 fn attrs(&self) -> Vec<Attribute> {
111 let special = sym::rustc_std_internal_symbol;
112 let special = self.cx.meta_word(self.span, special);
113 vec![self.cx.attribute(special)]
119 args: &mut Vec<Param>,
120 ident: &mut dyn FnMut() -> Ident,
123 AllocatorTy::Layout => {
124 let usize = self.cx.path_ident(self.span, Ident::new(sym::usize, self.span));
125 let ty_usize = self.cx.ty_path(usize);
128 args.push(self.cx.param(self.span, size, ty_usize.clone()));
129 args.push(self.cx.param(self.span, align, ty_usize));
132 self.cx.std_path(&[sym::alloc, sym::Layout, sym::from_size_align_unchecked]);
133 let layout_new = self.cx.expr_path(self.cx.path(self.span, layout_new));
134 let size = self.cx.expr_ident(self.span, size);
135 let align = self.cx.expr_ident(self.span, align);
136 let layout = self.cx.expr_call(self.span, layout_new, vec![size, align]);
140 AllocatorTy::Ptr => {
142 args.push(self.cx.param(self.span, ident, self.ptr_u8()));
143 let arg = self.cx.expr_ident(self.span, ident);
144 self.cx.expr_cast(self.span, arg, self.ptr_u8())
147 AllocatorTy::Usize => {
149 args.push(self.cx.param(self.span, ident, self.usize()));
150 self.cx.expr_ident(self.span, ident)
153 AllocatorTy::ResultPtr | AllocatorTy::Unit => {
154 panic!("can't convert AllocatorTy to an argument")
159 fn ret_ty(&self, ty: &AllocatorTy, expr: P<Expr>) -> (P<Ty>, P<Expr>) {
161 AllocatorTy::ResultPtr => {
166 let expr = self.cx.expr_cast(self.span, expr, self.ptr_u8());
167 (self.ptr_u8(), expr)
170 AllocatorTy::Unit => (self.cx.ty(self.span, TyKind::Tup(Vec::new())), expr),
172 AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
173 panic!("can't convert `AllocatorTy` to an output")
178 fn usize(&self) -> P<Ty> {
179 let usize = self.cx.path_ident(self.span, Ident::new(sym::usize, self.span));
180 self.cx.ty_path(usize)
183 fn ptr_u8(&self) -> P<Ty> {
184 let u8 = self.cx.path_ident(self.span, Ident::new(sym::u8, self.span));
185 let ty_u8 = self.cx.ty_path(u8);
186 self.cx.ty_ptr(self.span, ty_u8, Mutability::Mut)