rustc_codegen_llvm/
allocator.rs

1use libc::c_uint;
2use rustc_ast::expand::allocator::{
3    ALLOCATOR_METHODS, AllocatorKind, AllocatorTy, NO_ALLOC_SHIM_IS_UNSTABLE,
4    alloc_error_handler_name, default_fn_name, global_fn_name,
5};
6use rustc_codegen_ssa::traits::BaseTypeCodegenMethods as _;
7use rustc_middle::bug;
8use rustc_middle::ty::TyCtxt;
9use rustc_session::config::{DebugInfo, OomStrategy};
10use rustc_symbol_mangling::mangle_internal_symbol;
11use smallvec::SmallVec;
12
13use crate::builder::SBuilder;
14use crate::declare::declare_simple_fn;
15use crate::llvm::{self, FALSE, TRUE, Type, Value};
16use crate::{SimpleCx, attributes, debuginfo, llvm_util};
17
18pub(crate) unsafe fn codegen(
19    tcx: TyCtxt<'_>,
20    cx: SimpleCx<'_>,
21    module_name: &str,
22    kind: AllocatorKind,
23    alloc_error_handler_kind: AllocatorKind,
24) {
25    let usize = match tcx.sess.target.pointer_width {
26        16 => cx.type_i16(),
27        32 => cx.type_i32(),
28        64 => cx.type_i64(),
29        tws => bug!("Unsupported target word size for int: {}", tws),
30    };
31    let i8 = cx.type_i8();
32    let i8p = cx.type_ptr();
33
34    if kind == AllocatorKind::Default {
35        for method in ALLOCATOR_METHODS {
36            let mut args = Vec::with_capacity(method.inputs.len());
37            for input in method.inputs.iter() {
38                match input.ty {
39                    AllocatorTy::Layout => {
40                        args.push(usize); // size
41                        args.push(usize); // align
42                    }
43                    AllocatorTy::Ptr => args.push(i8p),
44                    AllocatorTy::Usize => args.push(usize),
45
46                    AllocatorTy::ResultPtr | AllocatorTy::Unit => panic!("invalid allocator arg"),
47                }
48            }
49            let output = match method.output {
50                AllocatorTy::ResultPtr => Some(i8p),
51                AllocatorTy::Unit => None,
52
53                AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
54                    panic!("invalid allocator output")
55                }
56            };
57
58            let from_name = mangle_internal_symbol(tcx, &global_fn_name(method.name));
59            let to_name = mangle_internal_symbol(tcx, &default_fn_name(method.name));
60
61            create_wrapper_function(tcx, &cx, &from_name, Some(&to_name), &args, output, false);
62        }
63    }
64
65    // rust alloc error handler
66    create_wrapper_function(
67        tcx,
68        &cx,
69        &mangle_internal_symbol(tcx, "__rust_alloc_error_handler"),
70        Some(&mangle_internal_symbol(tcx, alloc_error_handler_name(alloc_error_handler_kind))),
71        &[usize, usize], // size, align
72        None,
73        true,
74    );
75
76    unsafe {
77        // __rust_alloc_error_handler_should_panic_v2
78        create_const_value_function(
79            tcx,
80            &cx,
81            &mangle_internal_symbol(tcx, OomStrategy::SYMBOL),
82            &i8,
83            &llvm::LLVMConstInt(i8, tcx.sess.opts.unstable_opts.oom.should_panic() as u64, FALSE),
84        );
85
86        // __rust_no_alloc_shim_is_unstable_v2
87        create_wrapper_function(
88            tcx,
89            &cx,
90            &mangle_internal_symbol(tcx, NO_ALLOC_SHIM_IS_UNSTABLE),
91            None,
92            &[],
93            None,
94            false,
95        );
96    }
97
98    if tcx.sess.opts.debuginfo != DebugInfo::None {
99        let dbg_cx = debuginfo::CodegenUnitDebugContext::new(cx.llmod);
100        debuginfo::metadata::build_compile_unit_di_node(tcx, module_name, &dbg_cx);
101        dbg_cx.finalize(tcx.sess);
102    }
103}
104
105fn create_const_value_function(
106    tcx: TyCtxt<'_>,
107    cx: &SimpleCx<'_>,
108    name: &str,
109    output: &Type,
110    value: &Value,
111) {
112    let ty = cx.type_func(&[], output);
113    let llfn = declare_simple_fn(
114        &cx,
115        name,
116        llvm::CallConv::CCallConv,
117        llvm::UnnamedAddr::Global,
118        llvm::Visibility::from_generic(tcx.sess.default_visibility()),
119        ty,
120    );
121
122    attributes::apply_to_llfn(
123        llfn,
124        llvm::AttributePlace::Function,
125        &[llvm::AttributeKind::AlwaysInline.create_attr(cx.llcx)],
126    );
127
128    let llbb = unsafe { llvm::LLVMAppendBasicBlockInContext(cx.llcx, llfn, c"entry".as_ptr()) };
129    let mut bx = SBuilder::build(&cx, llbb);
130    bx.ret(value);
131}
132
133fn create_wrapper_function(
134    tcx: TyCtxt<'_>,
135    cx: &SimpleCx<'_>,
136    from_name: &str,
137    to_name: Option<&str>,
138    args: &[&Type],
139    output: Option<&Type>,
140    no_return: bool,
141) {
142    let ty = cx.type_func(args, output.unwrap_or_else(|| cx.type_void()));
143    let llfn = declare_simple_fn(
144        &cx,
145        from_name,
146        llvm::CallConv::CCallConv,
147        llvm::UnnamedAddr::Global,
148        llvm::Visibility::from_generic(tcx.sess.default_visibility()),
149        ty,
150    );
151
152    let mut attrs = SmallVec::<[_; 2]>::new();
153
154    let target_cpu = llvm_util::target_cpu(tcx.sess);
155    let target_cpu_attr = llvm::CreateAttrStringValue(cx.llcx, "target-cpu", target_cpu);
156
157    let tune_cpu_attr = llvm_util::tune_cpu(tcx.sess)
158        .map(|tune_cpu| llvm::CreateAttrStringValue(cx.llcx, "tune-cpu", tune_cpu));
159
160    attrs.push(target_cpu_attr);
161    attrs.extend(tune_cpu_attr);
162
163    attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &attrs);
164
165    let no_return = if no_return {
166        // -> ! DIFlagNoReturn
167        let no_return = llvm::AttributeKind::NoReturn.create_attr(cx.llcx);
168        attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &[no_return]);
169        Some(no_return)
170    } else {
171        None
172    };
173
174    if tcx.sess.must_emit_unwind_tables() {
175        let uwtable =
176            attributes::uwtable_attr(cx.llcx, tcx.sess.opts.unstable_opts.use_sync_unwind);
177        attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &[uwtable]);
178    }
179
180    let llbb = unsafe { llvm::LLVMAppendBasicBlockInContext(cx.llcx, llfn, c"entry".as_ptr()) };
181    let mut bx = SBuilder::build(&cx, llbb);
182
183    if let Some(to_name) = to_name {
184        let callee = declare_simple_fn(
185            &cx,
186            to_name,
187            llvm::CallConv::CCallConv,
188            llvm::UnnamedAddr::Global,
189            llvm::Visibility::Hidden,
190            ty,
191        );
192        if let Some(no_return) = no_return {
193            // -> ! DIFlagNoReturn
194            attributes::apply_to_llfn(callee, llvm::AttributePlace::Function, &[no_return]);
195        }
196        llvm::set_visibility(callee, llvm::Visibility::Hidden);
197
198        let args = args
199            .iter()
200            .enumerate()
201            .map(|(i, _)| llvm::get_param(llfn, i as c_uint))
202            .collect::<Vec<_>>();
203        let ret = bx.call(ty, callee, &args, None);
204        llvm::LLVMSetTailCall(ret, TRUE);
205        if output.is_some() {
206            bx.ret(ret);
207        } else {
208            bx.ret_void()
209        }
210    } else {
211        assert!(output.is_none());
212        bx.ret_void()
213    }
214}
rustc_codegen_llvm/allocator.rs

rustc_codegen_llvm/
allocator.rs
