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use std::convert::TryFrom;
use rustc_ast::Mutability;
use rustc_hir::lang_items::LangItem;
use rustc_middle::mir::TerminatorKind;
use rustc_middle::ty::layout::LayoutOf;
use rustc_middle::ty::subst::Subst;
use rustc_span::{Span, Symbol};
use crate::interpret::{
intrinsics::{InterpCx, Machine},
MPlaceTy, MemoryKind, Scalar,
};
impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
/// Walks up the callstack from the intrinsic's callsite, searching for the first callsite in a
/// frame which is not `#[track_caller]`.
pub(crate) fn find_closest_untracked_caller_location(&self) -> Span {
for frame in self.stack().iter().rev() {
debug!("find_closest_untracked_caller_location: checking frame {:?}", frame.instance);
// Assert that the frame we look at is actually executing code currently
// (`loc` is `Err` when we are unwinding and the frame does not require cleanup).
let loc = frame.loc.unwrap();
// This could be a non-`Call` terminator (such as `Drop`), or not a terminator at all
// (such as `box`). Use the normal span by default.
let mut source_info = *frame.body.source_info(loc);
// If this is a `Call` terminator, use the `fn_span` instead.
let block = &frame.body.basic_blocks()[loc.block];
if loc.statement_index == block.statements.len() {
debug!(
"find_closest_untracked_caller_location: got terminator {:?} ({:?})",
block.terminator(),
block.terminator().kind
);
if let TerminatorKind::Call { fn_span, .. } = block.terminator().kind {
source_info.span = fn_span;
}
}
// Walk up the `SourceScope`s, in case some of them are from MIR inlining.
// If so, the starting `source_info.span` is in the innermost inlined
// function, and will be replaced with outer callsite spans as long
// as the inlined functions were `#[track_caller]`.
loop {
let scope_data = &frame.body.source_scopes[source_info.scope];
if let Some((callee, callsite_span)) = scope_data.inlined {
// Stop inside the most nested non-`#[track_caller]` function,
// before ever reaching its caller (which is irrelevant).
if !callee.def.requires_caller_location(*self.tcx) {
return source_info.span;
}
source_info.span = callsite_span;
}
// Skip past all of the parents with `inlined: None`.
match scope_data.inlined_parent_scope {
Some(parent) => source_info.scope = parent,
None => break,
}
}
// Stop inside the most nested non-`#[track_caller]` function,
// before ever reaching its caller (which is irrelevant).
if !frame.instance.def.requires_caller_location(*self.tcx) {
return source_info.span;
}
}
span_bug!(self.cur_span(), "no non-`#[track_caller]` frame found")
}
/// Allocate a `const core::panic::Location` with the provided filename and line/column numbers.
pub(crate) fn alloc_caller_location(
&mut self,
filename: Symbol,
line: u32,
col: u32,
) -> MPlaceTy<'tcx, M::Provenance> {
let loc_details = &self.tcx.sess.opts.unstable_opts.location_detail;
let file = if loc_details.file {
self.allocate_str(filename.as_str(), MemoryKind::CallerLocation, Mutability::Not)
} else {
// FIXME: This creates a new allocation each time. It might be preferable to
// perform this allocation only once, and re-use the `MPlaceTy`.
// See https://github.com/rust-lang/rust/pull/89920#discussion_r730012398
self.allocate_str("<redacted>", MemoryKind::CallerLocation, Mutability::Not)
};
let line = if loc_details.line { Scalar::from_u32(line) } else { Scalar::from_u32(0) };
let col = if loc_details.column { Scalar::from_u32(col) } else { Scalar::from_u32(0) };
// Allocate memory for `CallerLocation` struct.
let loc_ty = self
.tcx
.bound_type_of(self.tcx.require_lang_item(LangItem::PanicLocation, None))
.subst(*self.tcx, self.tcx.mk_substs([self.tcx.lifetimes.re_erased.into()].iter()));
let loc_layout = self.layout_of(loc_ty).unwrap();
// This can fail if rustc runs out of memory right here. Trying to emit an error would be
// pointless, since that would require allocating more memory than a Location.
let location = self.allocate(loc_layout, MemoryKind::CallerLocation).unwrap();
// Initialize fields.
self.write_immediate(file.to_ref(self), &self.mplace_field(&location, 0).unwrap().into())
.expect("writing to memory we just allocated cannot fail");
self.write_scalar(line, &self.mplace_field(&location, 1).unwrap().into())
.expect("writing to memory we just allocated cannot fail");
self.write_scalar(col, &self.mplace_field(&location, 2).unwrap().into())
.expect("writing to memory we just allocated cannot fail");
location
}
pub(crate) fn location_triple_for_span(&self, span: Span) -> (Symbol, u32, u32) {
let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
let caller = self.tcx.sess.source_map().lookup_char_pos(topmost.lo());
(
Symbol::intern(&caller.file.name.prefer_remapped().to_string_lossy()),
u32::try_from(caller.line).unwrap(),
u32::try_from(caller.col_display).unwrap().checked_add(1).unwrap(),
)
}
pub fn alloc_caller_location_for_span(&mut self, span: Span) -> MPlaceTy<'tcx, M::Provenance> {
let (file, line, column) = self.location_triple_for_span(span);
self.alloc_caller_location(file, line, column)
}
}
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