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};
8 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
9 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
10 fn handle_miri_backtrace_size(
14 args: &[OpTy<'tcx, Provenance>],
15 dest: &PlaceTy<'tcx, Provenance>,
16 ) -> InterpResult<'tcx> {
17 let this = self.eval_context_mut();
18 let [flags] = this.check_shim(abi, Abi::Rust, link_name, args)?;
20 let flags = this.read_scalar(flags)?.to_u64()?;
22 throw_unsup_format!("unknown `miri_backtrace_size` flags {}", flags);
25 let frame_count = this.active_thread_stack().len();
27 this.write_scalar(Scalar::from_machine_usize(frame_count.try_into().unwrap(), this), dest)
30 fn handle_miri_get_backtrace(
34 args: &[OpTy<'tcx, Provenance>],
35 dest: &PlaceTy<'tcx, Provenance>,
36 ) -> InterpResult<'tcx> {
37 let this = self.eval_context_mut();
40 let flags = if let Some(flags_op) = args.get(0) {
41 this.read_scalar(flags_op)?.to_u64()?
43 throw_ub_format!("expected at least 1 argument")
46 let mut data = Vec::new();
47 for frame in this.active_thread_stack().iter().rev() {
48 let mut span = frame.current_span();
49 // Match the behavior of runtime backtrace spans
50 // by using a non-macro span in our backtrace. See `FunctionCx::debug_loc`.
51 if span.from_expansion() && !tcx.sess.opts.unstable_opts.debug_macros {
52 span = rustc_span::hygiene::walk_chain(span, frame.body.span.ctxt())
54 data.push((frame.instance, span.lo()));
57 let ptrs: Vec<_> = data
59 .map(|(instance, pos)| {
60 // We represent a frame pointer by using the `span.lo` value
61 // as an offset into the function's allocation. This gives us an
62 // opaque pointer that we can return to user code, and allows us
63 // to reconstruct the needed frame information in `handle_miri_resolve_frame`.
64 // Note that we never actually read or write anything from/to this pointer -
65 // all of the data is represented by the pointer value itself.
66 let fn_ptr = this.create_fn_alloc_ptr(FnVal::Instance(instance));
67 fn_ptr.wrapping_offset(Size::from_bytes(pos.0), this)
71 let len: u64 = ptrs.len().try_into().unwrap();
73 let ptr_ty = this.machine.layouts.mut_raw_ptr.ty;
74 let array_layout = this.layout_of(tcx.mk_array(ptr_ty, len)).unwrap();
77 // storage for pointers is allocated by miri
78 // deallocating the slice is undefined behavior with a custom global allocator
80 let [_flags] = this.check_shim(abi, Abi::Rust, link_name, args)?;
82 let alloc = this.allocate(array_layout, MiriMemoryKind::Rust.into())?;
84 // Write pointers into array
85 for (i, ptr) in ptrs.into_iter().enumerate() {
86 let place = this.mplace_index(&alloc, i as u64)?;
88 this.write_pointer(ptr, &place.into())?;
92 Immediate::new_slice(Scalar::from_maybe_pointer(alloc.ptr, this), len, this),
96 // storage for pointers is allocated by the caller
98 let [_flags, buf] = this.check_shim(abi, Abi::Rust, link_name, args)?;
100 let buf_place = this.deref_operand(buf)?;
102 let ptr_layout = this.layout_of(ptr_ty)?;
104 for (i, ptr) in ptrs.into_iter().enumerate() {
105 let offset = ptr_layout.size * i.try_into().unwrap();
107 let op_place = buf_place.offset(offset, ptr_layout, this)?;
109 this.write_pointer(ptr, &op_place.into())?;
112 _ => throw_unsup_format!("unknown `miri_get_backtrace` flags {}", flags),
118 fn resolve_frame_pointer(
120 ptr: &OpTy<'tcx, Provenance>,
121 ) -> InterpResult<'tcx, (Instance<'tcx>, Loc, String, String)> {
122 let this = self.eval_context_mut();
124 let ptr = this.read_pointer(ptr)?;
125 // Take apart the pointer, we need its pieces. The offset encodes the span.
126 let (alloc_id, offset, _prov) = this.ptr_get_alloc_id(ptr)?;
128 // This has to be an actual global fn ptr, not a dlsym function.
129 let fn_instance = if let Some(GlobalAlloc::Function(instance)) =
130 this.tcx.try_get_global_alloc(alloc_id)
134 throw_ub_format!("expected static 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, Provenance>],
151 dest: &PlaceTy<'tcx, Provenance>,
152 ) -> InterpResult<'tcx> {
153 let this = self.eval_context_mut();
154 let [ptr, 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.create_fn_alloc_ptr(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 // `u32` is not enough to fit line/colno, which can be `usize`. It seems unlikely that a
175 // file would have more than 2^32 lines or columns, but whatever, just default to 0.
176 let lineno: u32 = u32::try_from(lo.line).unwrap_or(0);
177 // `lo.col` is 0-based - add 1 to make it 1-based for the caller.
178 let colno: u32 = u32::try_from(lo.col.0.saturating_add(1)).unwrap_or(0);
180 let dest = this.force_allocation(dest)?;
181 if let ty::Adt(adt, _) = dest.layout.ty.kind() {
184 "miri_resolve_frame must be declared with a `#[repr(C)]` return type"
191 // These are "mutable" allocations as we consider them to be owned by the callee.
193 this.allocate_str(&name, MiriMemoryKind::Rust.into(), Mutability::Mut);
195 this.allocate_str(&filename, MiriMemoryKind::Rust.into(), Mutability::Mut);
197 this.write_immediate(
198 name_alloc.to_ref(this),
199 &this.mplace_field(&dest, 0)?.into(),
201 this.write_immediate(
202 filename_alloc.to_ref(this),
203 &this.mplace_field(&dest, 1)?.into(),
208 Scalar::from_machine_usize(name.len().try_into().unwrap(), this),
209 &this.mplace_field(&dest, 0)?.into(),
212 Scalar::from_machine_usize(filename.len().try_into().unwrap(), this),
213 &this.mplace_field(&dest, 1)?.into(),
216 _ => throw_unsup_format!("unknown `miri_resolve_frame` flags {}", flags),
219 this.write_scalar(Scalar::from_u32(lineno), &this.mplace_field(&dest, 2)?.into())?;
220 this.write_scalar(Scalar::from_u32(colno), &this.mplace_field(&dest, 3)?.into())?;
222 // Support a 4-field struct for now - this is deprecated
223 // and slated for removal.
225 this.write_pointer(fn_ptr, &this.mplace_field(&dest, 4)?.into())?;
231 fn handle_miri_resolve_frame_names(
235 args: &[OpTy<'tcx, Provenance>],
236 ) -> InterpResult<'tcx> {
237 let this = self.eval_context_mut();
239 let [ptr, flags, name_ptr, filename_ptr] =
240 this.check_shim(abi, Abi::Rust, link_name, args)?;
242 let flags = this.read_scalar(flags)?.to_u64()?;
244 throw_unsup_format!("unknown `miri_resolve_frame_names` flags {}", flags);
247 let (_, _, name, filename) = this.resolve_frame_pointer(ptr)?;
249 this.write_bytes_ptr(this.read_pointer(name_ptr)?, name.bytes())?;
250 this.write_bytes_ptr(this.read_pointer(filename_ptr)?, filename.bytes())?;