2 use helpers::check_arg_count;
3 use rustc_middle::ty::{self, TypeAndMut};
4 use rustc_ast::ast::Mutability;
5 use rustc_span::BytePos;
6 use rustc_target::abi::Size;
7 use std::convert::TryInto as _;
8 use crate::rustc_target::abi::LayoutOf as _;
10 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
11 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
13 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] = check_arg_count(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.into_iter().map(|(instance, pos)| {
39 // We represent a frame pointer by using the `span.lo` value
40 // as an offset into the function's allocation. This gives us an
41 // opaque pointer that we can return to user code, and allows us
42 // to reconstruct the needed frame information in `handle_miri_resolve_frame`.
43 // Note that we never actually read or write anything from/to this pointer -
44 // all of the data is represented by the pointer value itself.
45 let mut fn_ptr = this.memory.create_fn_alloc(FnVal::Instance(instance));
46 fn_ptr.offset = Size::from_bytes(pos.0);
52 let ptr_ty = tcx.mk_ptr(TypeAndMut {
54 mutbl: Mutability::Mut
57 let array_ty = tcx.mk_array(ptr_ty, ptrs.len().try_into().unwrap());
59 // Write pointers into array
60 let alloc = 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_immediate_to_mplace(ptr.into(), &place)?;
66 this.write_immediate(Immediate::new_slice(alloc.ptr.into(), len.try_into().unwrap(), this), dest)?;
70 fn handle_miri_resolve_frame(
72 args: &[OpTy<'tcx, Tag>],
73 dest: &PlaceTy<'tcx, Tag>
74 ) -> InterpResult<'tcx> {
75 let this = self.eval_context_mut();
77 let &[ref ptr, ref flags] = check_arg_count(args)?;
79 let flags = this.read_scalar(flags)?.to_u64()?;
81 throw_unsup_format!("unknown `miri_resolve_frame` flags {}", flags);
84 let ptr = this.force_ptr(this.read_scalar(ptr)?.check_init()?)?;
86 let fn_instance = if let Some(GlobalAlloc::Function(instance)) = this.tcx.get_global_alloc(ptr.alloc_id) {
89 throw_ub_format!("expected function pointer, found {:?}", ptr);
92 // Reconstruct the original function pointer,
93 // which we pass to user code.
95 fn_ptr.offset = Size::from_bytes(0);
96 let fn_ptr = Scalar::Ptr(fn_ptr);
98 let num_fields = dest.layout.layout.fields.count();
100 if !(4..=5).contains(&num_fields) {
101 // Always mention 5 fields, since the 4-field struct
102 // is deprecated and slated for removal.
103 throw_ub_format!("bad declaration of miri_resolve_frame - should return a struct with 5 fields");
106 let pos = BytePos(ptr.offset.bytes().try_into().unwrap());
107 let name = fn_instance.to_string();
109 let lo = tcx.sess.source_map().lookup_char_pos(pos);
111 let filename = lo.file.name.to_string();
112 let lineno: u32 = lo.line as u32;
113 // `lo.col` is 0-based - add 1 to make it 1-based for the caller.
114 let colno: u32 = lo.col.0 as u32 + 1;
116 let name_alloc = this.allocate_str(&name, MiriMemoryKind::Rust.into());
117 let filename_alloc = this.allocate_str(&filename, MiriMemoryKind::Rust.into());
118 let lineno_alloc = Scalar::from_u32(lineno);
119 let colno_alloc = Scalar::from_u32(colno);
121 let dest = this.force_allocation(dest)?;
122 if let ty::Adt(adt, _) = dest.layout.ty.kind() {
124 throw_ub_format!("miri_resolve_frame must be declared with a `#[repr(C)]` return type");
128 this.write_immediate(name_alloc.to_ref(), &this.mplace_field(&dest, 0)?.into())?;
129 this.write_immediate(filename_alloc.to_ref(), &this.mplace_field(&dest, 1)?.into())?;
130 this.write_scalar(lineno_alloc, &this.mplace_field(&dest, 2)?.into())?;
131 this.write_scalar(colno_alloc, &this.mplace_field(&dest, 3)?.into())?;
133 // Support a 4-field struct for now - this is deprecated
134 // and slated for removal.
136 this.write_scalar(fn_ptr, &this.mplace_field(&dest, 4)?.into())?;