Disable broken Field event construction

The Field event instrumentation is broken because it does not distinguish between identical field indices at different depths, e.g., x.1.2 and x.2 will emit an identical Field(&x, 2) event.
immunant · May 18, 2024 · 2b30b48 · 2b30b48
1 parent d9b3be9
commit 2b30b48
Showing 1 changed file with 34 additions and 30 deletions.
diff --git a/dynamic_instrumentation/src/instrument.rs b/dynamic_instrumentation/src/instrument.rs
@@ -11,7 +11,7 @@ use rustc_index::vec::Idx;
 use rustc_middle::mir::visit::{MutVisitor, MutatingUseContext, PlaceContext, Visitor};
 use rustc_middle::mir::{
     BasicBlock, BasicBlockData, Body, BorrowKind, ClearCrossCrate, HasLocalDecls, Local, LocalDecl,
-    Location, Operand, Place, PlaceElem, ProjectionElem, Rvalue, Safety, SourceInfo, SourceScope,
+    Location, Operand, Place, ProjectionElem, Rvalue, Safety, SourceInfo, SourceScope,
     SourceScopeData, Statement, StatementKind, Terminator, TerminatorKind, START_BLOCK,
 };
 use rustc_middle::ty::{self, Ty, TyCtxt};
@@ -340,35 +340,39 @@ impl<'tcx> MutVisitor<'tcx> for RewriteAddressTakenLocals<'tcx> {
 }
 
 impl<'tcx> Visitor<'tcx> for CollectInstrumentationPoints<'_, 'tcx> {
-    fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location: Location) {
-        self.super_place(place, context, location);
-
-        let field_fn = self.hooks().find("ptr_field");
-
-        let base_ty = self.local_decls()[place.local].ty;
-
-        // Instrument field projections on raw-ptr places
-        if is_region_or_unsafe_ptr(base_ty) && context.is_use() {
-            for (base, elem) in place.iter_projections() {
-                if let PlaceElem::Field(field, _) = elem {
-                    let proj_dest = || {
-                        // Only the last field projection gets a destination
-                        self.assignment()
-                            .as_ref()
-                            .map(|(dest, _)| dest)
-                            .copied()
-                            .filter(|_| base.projection.len() == place.projection.len() - 1)
-                    };
-                    self.loc(location, location, field_fn)
-                        .arg_var(place.local)
-                        .arg_index_of(field)
-                        .source(place)
-                        .dest_from(proj_dest)
-                        .add_to(self);
-                }
-            }
-        }
-    }
+// TODO(ahomescu): this is completely broken and needs a rewrite
+// One problem is that it does not distinguish between the depth
+// of a field, e.g., x.1.2 and x.2 will generate the same event
+// Field(&x, 2) for the .2 projection.
+//    fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location: Location) {
+//        self.super_place(place, context, location);
+//
+//        let field_fn = self.hooks().find("ptr_field");
+//
+//        let base_ty = self.local_decls()[place.local].ty;
+//
+//        // Instrument field projections on raw-ptr places
+//        if is_region_or_unsafe_ptr(base_ty) && context.is_use() {
+//            for (base, elem) in place.iter_projections() {
+//                if let PlaceElem::Field(field, _) = elem {
+//                    let proj_dest = || {
+//                        // Only the last field projection gets a destination
+//                        self.assignment()
+//                            .as_ref()
+//                            .map(|(dest, _)| dest)
+//                            .copied()
+//                            .filter(|_| base.projection.len() == place.projection.len() - 1)
+//                    };
+//                    self.loc(location, location, field_fn)
+//                        .arg_var(place.local)
+//                        .arg_index_of(field)
+//                        .source(place)
+//                        .dest_from(proj_dest)
+//                        .add_to(self);
+//                }
+//            }
+//        }
+//    }
 
     fn visit_assign(&mut self, dest: &Place<'tcx>, value: &Rvalue<'tcx>, location: Location) {
         let copy_fn = self.hooks().find("ptr_copy");