Make drop-glue take advantage of -Zshare-generics.

1 files changed, 20 insertions, 8 deletions

diff --git a/src/librustc_codegen_ssa/back/symbol_export.rs b/src/librustc_codegen_ssa/back/symbol_export.rs
index 12b82633245..7e888a271e3 100644
--- a/src/librustc_codegen_ssa/back/symbol_export.rs
+++ b/src/librustc_codegen_ssa/back/symbol_export.rs
@@ -5,7 +5,7 @@ use rustc::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc::middle::exported_symbols::{metadata_symbol_name, ExportedSymbol, SymbolExportLevel};
 use rustc::session::config::{self, Sanitizer};
 use rustc::ty::query::Providers;
-use rustc::ty::subst::SubstsRef;
+use rustc::ty::subst::{GenericArgKind, SubstsRef};
 use rustc::ty::Instance;
 use rustc::ty::{SymbolName, TyCtxt};
 use rustc_codegen_utils::symbol_names;
@@ -248,19 +248,31 @@ fn exported_symbols_provider_local(
                 continue;
             }
 
-            if let &MonoItem::Fn(Instance { def: InstanceDef::Item(def_id), substs }) = mono_item {
-                if substs.non_erasable_generics().next().is_some() {
-                    symbols
-                        .push((ExportedSymbol::Generic(def_id, substs), SymbolExportLevel::Rust));
+            match *mono_item {
+                MonoItem::Fn(Instance { def: InstanceDef::Item(def_id), substs }) => {
+                    if substs.non_erasable_generics().next().is_some() {
+                        let symbol = ExportedSymbol::Generic(def_id, substs);
+                        symbols.push((symbol, SymbolExportLevel::Rust));
+                    }
+                }
+                MonoItem::Fn(Instance { def: InstanceDef::DropGlue(def_id, Some(ty)), substs }) => {
+                    // A little sanity-check
+                    debug_assert_eq!(
+                        substs.non_erasable_generics().next(),
+                        Some(GenericArgKind::Type(ty))
+                    );
+                    let symbol = ExportedSymbol::Generic(def_id, substs);
+                    symbols.push((symbol, SymbolExportLevel::Rust));
+                }
+                _ => {
+                    // Any other symbols don't qualify for sharing
                 }
             }
         }
     }
 
     // Sort so we get a stable incr. comp. hash.
-    symbols.sort_unstable_by(|&(ref symbol1, ..), &(ref symbol2, ..)| {
-        symbol1.compare_stable(tcx, symbol2)
-    });
+    symbols.sort_by_cached_key(|s| s.0.symbol_name_for_local_instance(tcx));
 
     Arc::new(symbols)
 }