1 use crate::util::check_builtin_macro_attribute;
3 use rustc_ast::ast::{self, Attribute, Expr, FnHeader, FnSig, Generics, Param};
4 use rustc_ast::ast::{ItemKind, Mutability, Stmt, Ty, TyKind, Unsafe};
5 use rustc_ast::expand::allocator::{
6 AllocatorKind, AllocatorMethod, AllocatorTy, ALLOCATOR_METHODS,
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 not_static = |item: Annotatable| {
22 ecx.parse_sess.span_diagnostic.span_err(item.span(), "allocators must be statics");
25 let item = match item {
26 Annotatable::Item(item) => match item.kind {
27 ItemKind::Static(..) => item,
28 _ => return not_static(Annotatable::Item(item)),
30 _ => return not_static(item),
33 // Generate a bunch of new items using the AllocFnFactory
34 let span = ecx.with_def_site_ctxt(item.span);
35 let f = AllocFnFactory { span, kind: AllocatorKind::Global, global: item.ident, cx: ecx };
37 // Generate item statements for the allocator methods.
38 let stmts = ALLOCATOR_METHODS.iter().map(|method| f.allocator_fn(method)).collect();
40 // Generate anonymous constant serving as container for the allocator methods.
41 let const_ty = ecx.ty(span, TyKind::Tup(Vec::new()));
42 let const_body = ecx.expr_block(ecx.block(span, stmts));
43 let const_item = ecx.item_const(span, Ident::new(kw::Underscore, span), const_ty, const_body);
45 // Return the original item and the new methods.
46 vec![Annotatable::Item(item), Annotatable::Item(const_item)]
49 struct AllocFnFactory<'a, 'b> {
56 impl AllocFnFactory<'_, '_> {
57 fn allocator_fn(&self, method: &AllocatorMethod) -> Stmt {
58 let mut abi_args = Vec::new();
61 let name = self.cx.ident_of(&format!("arg{}", i), self.span);
65 let args = method.inputs.iter().map(|ty| self.arg_ty(ty, &mut abi_args, &mut mk)).collect();
66 let result = self.call_allocator(method.name, args);
67 let (output_ty, output_expr) = self.ret_ty(&method.output, result);
68 let decl = self.cx.fn_decl(abi_args, ast::FnRetTy::Ty(output_ty));
69 let header = FnHeader { unsafety: Unsafe::Yes(self.span), ..FnHeader::default() };
70 let sig = FnSig { decl, header };
71 let block = Some(self.cx.block_expr(output_expr));
72 let kind = ItemKind::Fn(ast::Defaultness::Final, sig, Generics::default(), block);
73 let item = self.cx.item(
75 self.cx.ident_of(&self.kind.fn_name(method.name), self.span),
79 self.cx.stmt_item(self.span, item)
82 fn call_allocator(&self, method: Symbol, mut args: Vec<P<Expr>>) -> P<Expr> {
83 let method = self.cx.std_path(&[sym::alloc, sym::GlobalAlloc, method]);
84 let method = self.cx.expr_path(self.cx.path(self.span, method));
85 let allocator = self.cx.path_ident(self.span, self.global);
86 let allocator = self.cx.expr_path(allocator);
87 let allocator = self.cx.expr_addr_of(self.span, allocator);
88 args.insert(0, allocator);
90 self.cx.expr_call(self.span, method, args)
93 fn attrs(&self) -> Vec<Attribute> {
94 let special = sym::rustc_std_internal_symbol;
95 let special = self.cx.meta_word(self.span, special);
96 vec![self.cx.attribute(special)]
102 args: &mut Vec<Param>,
103 ident: &mut dyn FnMut() -> Ident,
106 AllocatorTy::Layout => {
107 let usize = self.cx.path_ident(self.span, Ident::new(sym::usize, self.span));
108 let ty_usize = self.cx.ty_path(usize);
111 args.push(self.cx.param(self.span, size, ty_usize.clone()));
112 args.push(self.cx.param(self.span, align, ty_usize));
115 self.cx.std_path(&[sym::alloc, sym::Layout, sym::from_size_align_unchecked]);
116 let layout_new = self.cx.expr_path(self.cx.path(self.span, layout_new));
117 let size = self.cx.expr_ident(self.span, size);
118 let align = self.cx.expr_ident(self.span, align);
119 let layout = self.cx.expr_call(self.span, layout_new, vec![size, align]);
123 AllocatorTy::Ptr => {
125 args.push(self.cx.param(self.span, ident, self.ptr_u8()));
126 let arg = self.cx.expr_ident(self.span, ident);
127 self.cx.expr_cast(self.span, arg, self.ptr_u8())
130 AllocatorTy::Usize => {
132 args.push(self.cx.param(self.span, ident, self.usize()));
133 self.cx.expr_ident(self.span, ident)
136 AllocatorTy::ResultPtr | AllocatorTy::Unit => {
137 panic!("can't convert AllocatorTy to an argument")
142 fn ret_ty(&self, ty: &AllocatorTy, expr: P<Expr>) -> (P<Ty>, P<Expr>) {
144 AllocatorTy::ResultPtr => {
149 let expr = self.cx.expr_cast(self.span, expr, self.ptr_u8());
150 (self.ptr_u8(), expr)
153 AllocatorTy::Unit => (self.cx.ty(self.span, TyKind::Tup(Vec::new())), expr),
155 AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
156 panic!("can't convert `AllocatorTy` to an output")
161 fn usize(&self) -> P<Ty> {
162 let usize = self.cx.path_ident(self.span, Ident::new(sym::usize, self.span));
163 self.cx.ty_path(usize)
166 fn ptr_u8(&self) -> P<Ty> {
167 let u8 = self.cx.path_ident(self.span, Ident::new(sym::u8, self.span));
168 let ty_u8 = self.cx.ty_path(u8);
169 self.cx.ty_ptr(self.span, ty_u8, Mutability::Mut)