diff --git a/src/librustc_trans/trans/_match.rs b/src/librustc_trans/trans/_match.rs
index 0ad780fb0e4d..f46a7ea67b5f 100644
--- a/src/librustc_trans/trans/_match.rs
+++ b/src/librustc_trans/trans/_match.rs
@@ -1760,6 +1760,9 @@ fn mk_binding_alloca<'blk, 'tcx, A, F>(bcx: Block<'blk, 'tcx>,
     let lvalue = Lvalue::new_with_hint(caller_name, bcx, p_id, HintKind::DontZeroJustUse);
     let datum = Datum::new(llval, var_ty, lvalue);
 
+    debug!("mk_binding_alloca cleanup_scope={:?} llval={} var_ty={:?}",
+           cleanup_scope, bcx.ccx().tn().val_to_string(llval), var_ty);
+
     // Subtle: be sure that we *populate* the memory *before*
     // we schedule the cleanup.
     call_lifetime_start(bcx, llval);
diff --git a/src/librustc_trans/trans/adt.rs b/src/librustc_trans/trans/adt.rs
index e152e11a6a65..d22d619b9622 100644
--- a/src/librustc_trans/trans/adt.rs
+++ b/src/librustc_trans/trans/adt.rs
@@ -1281,7 +1281,11 @@ pub fn trans_drop_flag_ptr<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
             let scratch = unpack_datum!(bcx, datum::lvalue_scratch_datum(
                 bcx, tcx.dtor_type(), "drop_flag",
                 InitAlloca::Uninit("drop flag itself has no dtor"),
-                cleanup::CustomScope(custom_cleanup_scope), (), |_, bcx, _| bcx
+                cleanup::CustomScope(custom_cleanup_scope), (), |_, bcx, _| {
+                    debug!("no-op populate call for trans_drop_flag_ptr on dtor_type={:?}",
+                           tcx.dtor_type());
+                    bcx
+                }
             ));
             bcx = fold_variants(bcx, r, val, |variant_cx, st, value| {
                 let ptr = struct_field_ptr(variant_cx, st, MaybeSizedValue::sized(value),
diff --git a/src/librustc_trans/trans/base.rs b/src/librustc_trans/trans/base.rs
index b2bc7c2af933..1e5c60609b0b 100644
--- a/src/librustc_trans/trans/base.rs
+++ b/src/librustc_trans/trans/base.rs
@@ -1689,6 +1689,8 @@ pub fn create_datums_for_fn_args<'a, 'tcx>(mut bcx: Block<'a, 'tcx>,
     let fcx = bcx.fcx;
     let arg_scope_id = cleanup::CustomScope(arg_scope);
 
+    debug!("create_datums_for_fn_args");
+
     // Return an array wrapping the ValueRefs that we get from `get_param` for
     // each argument into datums.
     //
@@ -1723,6 +1725,9 @@ pub fn create_datums_for_fn_args<'a, 'tcx>(mut bcx: Block<'a, 'tcx>,
                 unpack_datum!(bcx, datum::lvalue_scratch_datum(bcx, arg_ty, "", uninit_reason,
                                                         arg_scope_id, (data, extra),
                                                         |(data, extra), bcx, dst| {
+                    debug!("populate call for create_datum_for_fn_args \
+                            early fat arg, on arg[{}] ty={:?}", i, arg_ty);
+
                     Store(bcx, data, expr::get_dataptr(bcx, dst));
                     Store(bcx, extra, expr::get_meta(bcx, dst));
                     bcx
@@ -1738,7 +1743,13 @@ pub fn create_datums_for_fn_args<'a, 'tcx>(mut bcx: Block<'a, 'tcx>,
                                                           uninit_reason,
                                                           arg_scope_id,
                                                           tmp,
-                                                          |tmp, bcx, dst| tmp.store_to(bcx, dst)))
+                                                          |tmp, bcx, dst| {
+
+                        debug!("populate call for create_datum_for_fn_args \
+                                early thin arg, on arg[{}] ty={:?}", i, arg_ty);
+
+                                                              tmp.store_to(bcx, dst)
+                                                          }))
             }
         } else {
             // FIXME(pcwalton): Reduce the amount of code bloat this is responsible for.
@@ -1753,7 +1764,9 @@ pub fn create_datums_for_fn_args<'a, 'tcx>(mut bcx: Block<'a, 'tcx>,
                                                               (),
                                                               |(),
                                                                mut bcx,
-                                                               llval| {
+                                                              llval| {
+                        debug!("populate call for create_datum_for_fn_args \
+                                tupled_args, on arg[{}] ty={:?}", i, arg_ty);
                         for (j, &tupled_arg_ty) in
                                     tupled_arg_tys.iter().enumerate() {
                             let lldest = StructGEP(bcx, llval, j);
diff --git a/src/librustc_trans/trans/datum.rs b/src/librustc_trans/trans/datum.rs
index 339b3f0f920d..6a033602adab 100644
--- a/src/librustc_trans/trans/datum.rs
+++ b/src/librustc_trans/trans/datum.rs
@@ -311,6 +311,8 @@ pub fn lvalue_scratch_datum<'blk, 'tcx, A, F>(bcx: Block<'blk, 'tcx>,
     // Very subtle: potentially initialize the scratch memory at point where it is alloca'ed.
     // (See discussion at Issue 30530.)
     let scratch = alloc_ty_init(bcx, ty, zero, name);
+    debug!("lvalue_scratch_datum scope={:?} scratch={} ty={:?}",
+           scope, bcx.ccx().tn().val_to_string(scratch), ty);
 
     // Subtle. Populate the scratch memory *before* scheduling cleanup.
     let bcx = populate(arg, bcx, scratch);
@@ -349,6 +351,8 @@ fn add_rvalue_clean<'a, 'tcx>(mode: RvalueMode,
                               scope: cleanup::ScopeId,
                               val: ValueRef,
                               ty: Ty<'tcx>) {
+    debug!("add_rvalue_clean scope={:?} val={} ty={:?}",
+           scope, fcx.ccx.tn().val_to_string(val), ty);
     match mode {
         ByValue => { fcx.schedule_drop_immediate(scope, val, ty); }
         ByRef => {
@@ -507,6 +511,8 @@ impl<'tcx> Datum<'tcx, Rvalue> {
                 lvalue_scratch_datum(
                     bcx, self.ty, name, InitAlloca::Dropped, scope, self,
                     |this, bcx, llval| {
+                        debug!("populate call for Datum::to_lvalue_datum_in_scope \
+                                self.ty={:?}", this.ty);
                         call_lifetime_start(bcx, llval);
                         let bcx = this.store_to(bcx, llval);
                         bcx.fcx.schedule_lifetime_end(scope, llval);
diff --git a/src/librustc_trans/trans/expr.rs b/src/librustc_trans/trans/expr.rs
index fb6f2190207e..57afd0b580f1 100644
--- a/src/librustc_trans/trans/expr.rs
+++ b/src/librustc_trans/trans/expr.rs
@@ -1487,6 +1487,8 @@ pub fn trans_adt<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
         }
     };
 
+    debug!("trans_adt");
+
     // This scope holds intermediates that must be cleaned should
     // panic occur before the ADT as a whole is ready.
     let custom_cleanup_scope = fcx.push_custom_cleanup_scope();