Add move metadata into source info

Add a new MIR pass which changes the source filename
for statements with move operands to include information
about the types being moved.

Author: olivergillespie

compiler/rustc_mir_transform/src/add_move_metadata.rs

@@ -0,0 +1,129 @@
+//! This module provides a pass that modifies spans for statements with move operands,
+//! adding information about moved types and their sizes to the filename.
+
+use rustc_middle::mir::{Body, Operand, Rvalue, StatementKind};
+use rustc_middle::ty::{Ty, TyCtxt, TypingEnv};
+use rustc_span::{FileName, Span};
+use tracing::debug;
+
+pub(super) struct AddMoveMetadata;
+
+impl<'tcx> crate::MirPass<'tcx> for AddMoveMetadata {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+        for basic_block in body.basic_blocks.as_mut() {
+            for statement in basic_block.statements.iter_mut() {
+                if let StatementKind::Assign(box (place, rvalue)) = &statement.kind {
+                    if rvalue_has_move(rvalue) {
+                        let moved_types =
+                            get_moved_types_from_rvalue(rvalue, &body.local_decls, tcx);
+                        let mut moved_types_with_sizes: Vec<_> = moved_types
+                            .iter()
+                            .map(|ty| {
+                                let size = tcx
+                                    .layout_of(TypingEnv::fully_monomorphized().as_query_input(*ty))
+                                    .map(|layout| layout.size.bytes())
+                                    .unwrap_or(0);
+                                (*ty, size)
+                            })
+                            .collect();
+                        moved_types_with_sizes.sort_by(|a, b| b.1.cmp(&a.1));
+                        let old_span = statement.source_info.span;
+                        statement.source_info.span = modify_span_filename(
+                            statement.source_info.span,
+                            &moved_types_with_sizes,
+                            tcx,
+                        );
+                        for (ty, size) in &moved_types_with_sizes {
+                            debug!("Moved type: {} (size: {} bytes)", ty, size);
+                        }
+                        debug!(
+                            "Changed span from {:?} to {:?}, place: {:?}, rvalue: {:?}",
+                            old_span, statement.source_info.span, place, rvalue
+                        );
+                    }
+                }
+            }
+        }
+    }
+
+    fn is_required(&self) -> bool {
+        true
+    }
+}
+
+fn rvalue_has_move(rvalue: &Rvalue<'_>) -> bool {
+    match rvalue {
+        Rvalue::Use(operand)
+        | Rvalue::Repeat(operand, _)
+        | Rvalue::Cast(_, operand, _)
+        | Rvalue::UnaryOp(_, operand) => matches!(operand, Operand::Move(_)),
+        Rvalue::BinaryOp(_, box (left, right)) => {
+            matches!(left, Operand::Move(_)) || matches!(right, Operand::Move(_))
+        }
+        Rvalue::Aggregate(_, operands) => operands.iter().any(|op| matches!(op, Operand::Move(_))),
+        _ => false,
+    }
+}
+
+fn get_moved_types_from_rvalue<'tcx>(
+    rvalue: &Rvalue<'tcx>,
+    local_decls: &rustc_middle::mir::LocalDecls<'tcx>,
+    tcx: TyCtxt<'tcx>,
+) -> Vec<Ty<'tcx>> {
+    let mut types = Vec::new();
+    match rvalue {
+        Rvalue::Use(Operand::Move(place))
+        | Rvalue::Repeat(Operand::Move(place), _)
+        | Rvalue::Cast(_, Operand::Move(place), _)
+        | Rvalue::UnaryOp(_, Operand::Move(place)) => {
+            types.push(place.ty(local_decls, tcx).ty);
+        }
+        Rvalue::BinaryOp(_, box (left, right)) => {
+            if let Operand::Move(place) = left {
+                types.push(place.ty(local_decls, tcx).ty);
+            }
+            if let Operand::Move(place) = right {
+                types.push(place.ty(local_decls, tcx).ty);
+            }
+        }
+        Rvalue::Aggregate(_, operands) => {
+            for operand in operands {
+                if let Operand::Move(place) = operand {
+                    types.push(place.ty(local_decls, tcx).ty);
+                }
+            }
+        }
+        _ => {}
+    }
+    types
+}
+
+fn modify_span_filename<'tcx>(
+    span: Span,
+    moved_types_with_sizes: &[(Ty<'tcx>, u64)],
+    tcx: TyCtxt<'tcx>,
+) -> Span {
+    let source_map = tcx.sess.source_map();
+    let source_file = source_map.lookup_source_file(span.lo());
+    let filename = source_file.name.prefer_local().to_string();
+    let types_str = moved_types_with_sizes
+        .iter()
+        .map(|(ty, size)| format!("{}({} bytes)", ty, size))
+        .collect::<Vec<_>>()
+        .join(", ");
+    let new_filename = format!("{} Moved:[{}] Line:", filename, types_str);
+
+    let src = source_file.src.as_ref().map(|s| s.as_str()).unwrap_or("").to_string();
+    let new_source_file = source_map.new_source_file(
+        FileName::Real(rustc_span::RealFileName::LocalPath(std::path::PathBuf::from(new_filename))),
+        src,
+    );
+
+    let offset = span.lo() - source_file.start_pos;
+    Span::new(
+        new_source_file.start_pos + offset,
+        new_source_file.start_pos + offset + (span.hi() - span.lo()),
+        span.ctxt(),
+        span.parent(),
+    )
+}

compiler/rustc_mir_transform/src/lib.rs

@@ -123,6 +123,7 @@ declare_passes! {
     mod check_packed_ref : CheckPackedRef;
     // This pass is public to allow external drivers to perform MIR cleanup
     pub mod cleanup_post_borrowck : CleanupPostBorrowck;
+    mod add_move_metadata : AddMoveMetadata;
 
     mod copy_prop : CopyProp;
     mod coroutine : StateTransform;
@@ -578,6 +579,7 @@ pub fn run_analysis_to_runtime_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'
 fn run_analysis_cleanup_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
     let passes: &[&dyn MirPass<'tcx>] = &[
         &impossible_predicates::ImpossiblePredicates,
+        &add_move_metadata::AddMoveMetadata,
         &cleanup_post_borrowck::CleanupPostBorrowck,
         &remove_noop_landing_pads::RemoveNoopLandingPads,
         &simplify::SimplifyCfg::PostAnalysis,