2 use rustc_ast::ast::Mutability;
3 use rustc_middle::ty::layout::LayoutOf as _;
4 use rustc_middle::ty::{self, Instance};
5 use rustc_span::{BytePos, Loc, Symbol};
6 use rustc_target::{abi::Size, spec::abi::Abi};
7 use std::convert::TryInto as _;
9 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
10 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
11 fn handle_miri_backtrace_size(
15 args: &[OpTy<'tcx, Tag>],
16 dest: &PlaceTy<'tcx, Tag>,
17 ) -> InterpResult<'tcx> {
18 let this = self.eval_context_mut();
19 let &[ref flags] = this.check_shim(abi, Abi::Rust, link_name, args)?;
21 let flags = this.read_scalar(flags)?.to_u64()?;
23 throw_unsup_format!("unknown `miri_backtrace_size` flags {}", flags);
26 let frame_count = this.active_thread_stack().len();
28 this.write_scalar(Scalar::from_machine_usize(frame_count.try_into().unwrap(), this), dest)
31 fn handle_miri_get_backtrace(
35 args: &[OpTy<'tcx, Tag>],
36 dest: &PlaceTy<'tcx, Tag>,
37 ) -> InterpResult<'tcx> {
38 let this = self.eval_context_mut();
41 let flags = if let Some(flags_op) = args.get(0) {
42 this.read_scalar(flags_op)?.to_u64()?
44 throw_ub_format!("expected at least 1 argument")
47 let mut data = Vec::new();
48 for frame in this.active_thread_stack().iter().rev() {
49 let mut span = frame.current_span();
50 // Match the behavior of runtime backtrace spans
51 // by using a non-macro span in our backtrace. See `FunctionCx::debug_loc`.
52 if span.from_expansion() && !tcx.sess.opts.debugging_opts.debug_macros {
53 span = rustc_span::hygiene::walk_chain(span, frame.body.span.ctxt())
55 data.push((frame.instance, span.lo()));
58 let ptrs: Vec<_> = data
60 .map(|(instance, pos)| {
61 // We represent a frame pointer by using the `span.lo` value
62 // as an offset into the function's allocation. This gives us an
63 // opaque pointer that we can return to user code, and allows us
64 // to reconstruct the needed frame information in `handle_miri_resolve_frame`.
65 // Note that we never actually read or write anything from/to this pointer -
66 // all of the data is represented by the pointer value itself.
67 let fn_ptr = this.memory.create_fn_alloc(FnVal::Instance(instance));
68 fn_ptr.wrapping_offset(Size::from_bytes(pos.0), this)
72 let len: u64 = ptrs.len().try_into().unwrap();
74 let ptr_ty = this.machine.layouts.mut_raw_ptr.ty;
75 let array_layout = this.layout_of(tcx.mk_array(ptr_ty, len)).unwrap();
78 // storage for pointers is allocated by miri
79 // deallocating the slice is undefined behavior with a custom global allocator
81 let &[_flags] = this.check_shim(abi, Abi::Rust, link_name, args)?;
83 let alloc = this.allocate(array_layout, MiriMemoryKind::Rust.into())?;
85 // Write pointers into array
86 for (i, ptr) in ptrs.into_iter().enumerate() {
87 let place = this.mplace_index(&alloc, i as u64)?;
89 this.write_pointer(ptr, &place.into())?;
93 Immediate::new_slice(Scalar::from_maybe_pointer(alloc.ptr, this), len, this),
97 // storage for pointers is allocated by the caller
99 let &[_flags, ref buf] = this.check_shim(abi, Abi::Rust, link_name, args)?;
101 let buf_place = this.deref_operand(buf)?;
103 let ptr_layout = this.layout_of(ptr_ty)?;
105 for (i, ptr) in ptrs.into_iter().enumerate() {
106 let offset = ptr_layout.size * i.try_into().unwrap();
109 buf_place.offset(offset, MemPlaceMeta::None, ptr_layout, this)?;
111 this.write_pointer(ptr, &op_place.into())?;
114 _ => throw_unsup_format!("unknown `miri_get_backtrace` flags {}", flags),
120 fn resolve_frame_pointer(
122 ptr: &OpTy<'tcx, Tag>,
123 ) -> InterpResult<'tcx, (Instance<'tcx>, Loc, String, String)> {
124 let this = self.eval_context_mut();
126 let ptr = this.read_pointer(ptr)?;
127 // Take apart the pointer, we need its pieces.
128 let (alloc_id, offset, ptr) = this.memory.ptr_get_alloc(ptr)?;
131 if let Some(GlobalAlloc::Function(instance)) = this.tcx.get_global_alloc(alloc_id) {
134 throw_ub_format!("expected function pointer, found {:?}", ptr);
138 this.tcx.sess.source_map().lookup_char_pos(BytePos(offset.bytes().try_into().unwrap()));
140 let name = fn_instance.to_string();
141 let filename = lo.file.name.prefer_remapped().to_string();
143 Ok((fn_instance, lo, name, filename))
146 fn handle_miri_resolve_frame(
150 args: &[OpTy<'tcx, Tag>],
151 dest: &PlaceTy<'tcx, Tag>,
152 ) -> InterpResult<'tcx> {
153 let this = self.eval_context_mut();
154 let &[ref ptr, ref flags] = this.check_shim(abi, Abi::Rust, link_name, args)?;
156 let flags = this.read_scalar(flags)?.to_u64()?;
158 let (fn_instance, lo, name, filename) = this.resolve_frame_pointer(ptr)?;
160 // Reconstruct the original function pointer,
161 // which we pass to user code.
162 let fn_ptr = this.memory.create_fn_alloc(FnVal::Instance(fn_instance));
164 let num_fields = dest.layout.fields.count();
166 if !(4..=5).contains(&num_fields) {
167 // Always mention 5 fields, since the 4-field struct
168 // is deprecated and slated for removal.
170 "bad declaration of miri_resolve_frame - should return a struct with 5 fields"
174 let lineno: u32 = lo.line as u32;
175 // `lo.col` is 0-based - add 1 to make it 1-based for the caller.
176 let colno: u32 = lo.col.0 as u32 + 1;
178 let dest = this.force_allocation(dest)?;
179 if let ty::Adt(adt, _) = dest.layout.ty.kind() {
182 "miri_resolve_frame must be declared with a `#[repr(C)]` return type"
189 // These are "mutable" allocations as we consider them to be owned by the callee.
191 this.allocate_str(&name, MiriMemoryKind::Rust.into(), Mutability::Mut);
193 this.allocate_str(&filename, MiriMemoryKind::Rust.into(), Mutability::Mut);
195 this.write_immediate(
196 name_alloc.to_ref(this),
197 &this.mplace_field(&dest, 0)?.into(),
199 this.write_immediate(
200 filename_alloc.to_ref(this),
201 &this.mplace_field(&dest, 1)?.into(),
206 Scalar::from_machine_usize(name.len().try_into().unwrap(), this),
207 &this.mplace_field(&dest, 0)?.into(),
210 Scalar::from_machine_usize(filename.len().try_into().unwrap(), this),
211 &this.mplace_field(&dest, 1)?.into(),
214 _ => throw_unsup_format!("unknown `miri_resolve_frame` flags {}", flags),
217 this.write_scalar(Scalar::from_u32(lineno), &this.mplace_field(&dest, 2)?.into())?;
218 this.write_scalar(Scalar::from_u32(colno), &this.mplace_field(&dest, 3)?.into())?;
220 // Support a 4-field struct for now - this is deprecated
221 // and slated for removal.
223 this.write_pointer(fn_ptr, &this.mplace_field(&dest, 4)?.into())?;
229 fn handle_miri_resolve_frame_names(
233 args: &[OpTy<'tcx, Tag>],
234 ) -> InterpResult<'tcx> {
235 let this = self.eval_context_mut();
237 let &[ref ptr, ref flags, ref name_ptr, ref filename_ptr] =
238 this.check_shim(abi, Abi::Rust, link_name, args)?;
240 let flags = this.read_scalar(flags)?.to_u64()?;
242 throw_unsup_format!("unknown `miri_resolve_frame_names` flags {}", flags);
245 let (_, _, name, filename) = this.resolve_frame_pointer(ptr)?;
247 this.memory.write_bytes(this.read_pointer(name_ptr)?, name.bytes())?;
248 this.memory.write_bytes(this.read_pointer(filename_ptr)?, filename.bytes())?;