Replace locals in debuginfo records during ref_prop

Author: dianqk

compiler/rustc_mir_transform/src/ref_prop.rs

@@ -407,6 +407,20 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'tcx> {
         self.super_var_debug_info(debuginfo);
     }
 
+    fn visit_statement_debuginfo(
+        &mut self,
+        stmt_debuginfo: &mut StmtDebugInfo<'tcx>,
+        location: Location,
+    ) {
+        if let StmtDebugInfo::AssignRef(local, _) = stmt_debuginfo
+            && let Value::Pointer(target, _) = self.targets[*local]
+        {
+            *local = target.local;
+            self.any_replacement = true;
+        }
+        self.super_statement_debuginfo(stmt_debuginfo, location);
+    }
+
     fn visit_place(&mut self, place: &mut Place<'tcx>, ctxt: PlaceContext, loc: Location) {
         loop {
             let Some((&PlaceElem::Deref, rest)) = place.projection.split_first() else { return };

tests/mir-opt/debuginfo/ref_prop.remap_debuginfo_locals.ReferencePropagation.diff

@@ -25,7 +25,7 @@
 -         StorageDead(_2);
 -         StorageDead(_3);
 -         StorageDead(_1);
-+         // DBG: _1 = &(*_5);
++         // DBG: _5 = &(*_5);
           _0 = const ();
           return;
       }

tests/mir-opt/debuginfo/ref_prop.rs

@@ -1,4 +1,3 @@
-// skip-filecheck
 //@ test-mir-pass: ReferencePropagation
 //@ compile-flags: -g -Zub_checks=false -Zinline-mir -Zmir-enable-passes=+DeadStoreElimination-initial
 
@@ -9,6 +8,11 @@ use std::intrinsics::mir::*;
 
 // EMIT_MIR ref_prop.remap_debuginfo_locals.ReferencePropagation.diff
 pub fn remap_debuginfo_locals() {
+    // CHECK-LABEL: fn remap_debuginfo_locals()
+    // CHECK: debug a => [[a:_.*]];
+    // CHECK: bb0:
+    // CHECK-NEXT: [[a]] = const
+    // CHECK-NEXT: DBG: [[a]] = &(*[[a]]);
     foo(&0);
 }
 

tests/crashes/147485.rs renamed to tests/ui/debuginfo/ref_prop_debuginfo-147485.rs

@@ -1,6 +1,8 @@
-//@ known-bug: #147485
+//@ build-pass
 //@ compile-flags: -g -O
 
+// Regression test for #147485.
+
 #![crate_type = "lib"]
 
 pub fn f(x: *const usize) -> &'static usize {