1 use crate::rustc_target::abi::LayoutOf as _;
3 use rustc_ast::ast::Mutability;
4 use rustc_middle::ty::{self, TypeAndMut};
5 use rustc_span::{BytePos, 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_get_backtrace(
15 args: &[OpTy<'tcx, Tag>],
16 dest: &PlaceTy<'tcx, Tag>,
17 ) -> InterpResult<'tcx> {
18 let this = self.eval_context_mut();
20 let &[ref flags] = this.check_shim(abi, Abi::Rust, link_name, args)?;
22 let flags = this.read_scalar(flags)?.to_u64()?;
24 throw_unsup_format!("unknown `miri_get_backtrace` flags {}", flags);
27 let mut data = Vec::new();
28 for frame in this.active_thread_stack().iter().rev() {
29 let mut span = frame.current_span();
30 // Match the behavior of runtime backtrace spans
31 // by using a non-macro span in our backtrace. See `FunctionCx::debug_loc`.
32 if span.from_expansion() && !tcx.sess.opts.debugging_opts.debug_macros {
33 span = rustc_span::hygiene::walk_chain(span, frame.body.span.ctxt())
35 data.push((frame.instance, span.lo()));
38 let ptrs: Vec<_> = data
40 .map(|(instance, pos)| {
41 // We represent a frame pointer by using the `span.lo` value
42 // as an offset into the function's allocation. This gives us an
43 // opaque pointer that we can return to user code, and allows us
44 // to reconstruct the needed frame information in `handle_miri_resolve_frame`.
45 // Note that we never actually read or write anything from/to this pointer -
46 // all of the data is represented by the pointer value itself.
47 let fn_ptr = this.memory.create_fn_alloc(FnVal::Instance(instance));
48 fn_ptr.wrapping_offset(Size::from_bytes(pos.0), this)
54 let ptr_ty = tcx.mk_ptr(TypeAndMut { ty: tcx.types.unit, mutbl: Mutability::Mut });
56 let array_ty = tcx.mk_array(ptr_ty, ptrs.len().try_into().unwrap());
58 // Write pointers into array
60 this.allocate(this.layout_of(array_ty).unwrap(), MiriMemoryKind::Rust.into())?;
61 for (i, ptr) in ptrs.into_iter().enumerate() {
62 let place = this.mplace_index(&alloc, i as u64)?;
63 this.write_pointer(ptr, &place.into())?;
68 Scalar::from_maybe_pointer(alloc.ptr, this),
69 len.try_into().unwrap(),
77 fn handle_miri_resolve_frame(
81 args: &[OpTy<'tcx, Tag>],
82 dest: &PlaceTy<'tcx, Tag>,
83 ) -> InterpResult<'tcx> {
84 let this = self.eval_context_mut();
86 let &[ref ptr, ref flags] = this.check_shim(abi, Abi::Rust, link_name, args)?;
88 let flags = this.read_scalar(flags)?.to_u64()?;
90 throw_unsup_format!("unknown `miri_resolve_frame` flags {}", flags);
93 let ptr = this.read_pointer(ptr)?;
94 // Take apart the pointer, we need its pieces.
95 let (alloc_id, offset, ptr) = this.memory.ptr_get_alloc(ptr)?;
98 if let Some(GlobalAlloc::Function(instance)) = this.tcx.get_global_alloc(alloc_id) {
101 throw_ub_format!("expected function pointer, found {:?}", ptr);
104 // Reconstruct the original function pointer,
105 // which we pass to user code.
106 let fn_ptr = this.memory.create_fn_alloc(FnVal::Instance(fn_instance));
108 let num_fields = dest.layout.layout.fields.count();
110 if !(4..=5).contains(&num_fields) {
111 // Always mention 5 fields, since the 4-field struct
112 // is deprecated and slated for removal.
114 "bad declaration of miri_resolve_frame - should return a struct with 5 fields"
118 let pos = BytePos(offset.bytes().try_into().unwrap());
119 let name = fn_instance.to_string();
121 let lo = tcx.sess.source_map().lookup_char_pos(pos);
123 let filename = lo.file.name.prefer_remapped().to_string();
124 let lineno: u32 = lo.line as u32;
125 // `lo.col` is 0-based - add 1 to make it 1-based for the caller.
126 let colno: u32 = lo.col.0 as u32 + 1;
128 // These are "mutable" allocations as we consider them to be owned by the callee.
129 let name_alloc = this.allocate_str(&name, MiriMemoryKind::Rust.into(), Mutability::Mut);
131 this.allocate_str(&filename, MiriMemoryKind::Rust.into(), Mutability::Mut);
132 let lineno_alloc = Scalar::from_u32(lineno);
133 let colno_alloc = Scalar::from_u32(colno);
135 let dest = this.force_allocation(dest)?;
136 if let ty::Adt(adt, _) = dest.layout.ty.kind() {
139 "miri_resolve_frame must be declared with a `#[repr(C)]` return type"
144 this.write_immediate(name_alloc.to_ref(this), &this.mplace_field(&dest, 0)?.into())?;
145 this.write_immediate(filename_alloc.to_ref(this), &this.mplace_field(&dest, 1)?.into())?;
146 this.write_scalar(lineno_alloc, &this.mplace_field(&dest, 2)?.into())?;
147 this.write_scalar(colno_alloc, &this.mplace_field(&dest, 3)?.into())?;
149 // Support a 4-field struct for now - this is deprecated
150 // and slated for removal.
152 this.write_pointer(fn_ptr, &this.mplace_field(&dest, 4)?.into())?;