Auto merge of #53963 - michaelwoerister:incr-comp-no-cgu-split, r=<try>

[experimental] Don't partition generic and non-generic code into different CGUs during incr. comp.

At the moment we are splitting generic and non-generic code into different CGUs when partitioning the crate during incremental compilation. The reasoning behind this is that generic code might change more often than non-generic code. That reasoning was never properly validated though. Since it's simple to just not split things, let's give it a try and see how it performs.

Author: bors

src/librustc_mir/monomorphize/partitioning.rs

@@ -303,7 +303,6 @@ fn place_root_mono_items<'a, 'tcx, I>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 {
     let mut roots = FxHashSet();
     let mut codegen_units = FxHashMap();
-    let is_incremental_build = tcx.sess.opts.incremental.is_some();
     let mut internalization_candidates = FxHashSet();
 
     // Determine if monomorphizations instantiated in this crate will be made
@@ -323,14 +322,11 @@ fn place_root_mono_items<'a, 'tcx, I>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
         }
 
         let characteristic_def_id = characteristic_def_id_of_mono_item(tcx, mono_item);
-        let is_volatile = is_incremental_build &&
-                          mono_item.is_generic_fn();
 
         let codegen_unit_name = match characteristic_def_id {
             Some(def_id) => compute_codegen_unit_name(tcx,
                                                       cgu_name_builder,
                                                       def_id,
-                                                      is_volatile,
                                                       cgu_name_cache),
             None => fallback_cgu_name(cgu_name_builder),
         };
@@ -794,12 +790,11 @@ fn characteristic_def_id_of_mono_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     }
 }
 
-type CguNameCache = FxHashMap<(DefId, bool), InternedString>;
+type CguNameCache = FxHashMap<DefId, InternedString>;
 
 fn compute_codegen_unit_name(tcx: TyCtxt,
                              name_builder: &mut CodegenUnitNameBuilder,
                              def_id: DefId,
-                             volatile: bool,
                              cache: &mut CguNameCache)
                              -> InternedString {
     // Find the innermost module that is not nested within a function
@@ -838,21 +833,16 @@ fn compute_codegen_unit_name(tcx: TyCtxt,
 
     let cgu_def_id = cgu_def_id.unwrap();
 
-    cache.entry((cgu_def_id, volatile)).or_insert_with(|| {
+    cache.entry(cgu_def_id).or_insert_with(|| {
         let def_path = tcx.def_path(cgu_def_id);
 
         let components = def_path
             .data
             .iter()
             .map(|part| part.data.as_interned_str());
 
-        let volatile_suffix = if volatile {
-            Some("volatile")
-        } else {
-            None
-        };
-
-        name_builder.build_cgu_name(def_path.krate, components, volatile_suffix)
+        let suffix: Option<&str> = None;
+        name_builder.build_cgu_name(def_path.krate, components, suffix)
     }).clone()
 }
 

src/test/codegen-units/partitioning/extern-generic.rs

@@ -58,5 +58,5 @@ mod mod3 {
 
 // Make sure the two generic functions from the extern crate get instantiated
 // once for the current crate
-//~ MONO_ITEM fn cgu_generic_function::foo[0]<&str> @@ cgu_generic_function.volatile[External]
-//~ MONO_ITEM fn cgu_generic_function::bar[0]<&str> @@ cgu_generic_function.volatile[External]
+//~ MONO_ITEM fn cgu_generic_function::foo[0]<&str> @@ cgu_generic_function[External]
+//~ MONO_ITEM fn cgu_generic_function::bar[0]<&str> @@ cgu_generic_function[External]

src/test/codegen-units/partitioning/local-generic.rs

@@ -16,10 +16,10 @@
 #![allow(dead_code)]
 #![crate_type="lib"]
 
-//~ MONO_ITEM fn local_generic::generic[0]<u32> @@ local_generic.volatile[External]
-//~ MONO_ITEM fn local_generic::generic[0]<u64> @@ local_generic.volatile[External]
-//~ MONO_ITEM fn local_generic::generic[0]<char> @@ local_generic.volatile[External]
-//~ MONO_ITEM fn local_generic::generic[0]<&str> @@ local_generic.volatile[External]
+//~ MONO_ITEM fn local_generic::generic[0]<u32> @@ local_generic[External]
+//~ MONO_ITEM fn local_generic::generic[0]<u64> @@ local_generic[External]
+//~ MONO_ITEM fn local_generic::generic[0]<char> @@ local_generic[External]
+//~ MONO_ITEM fn local_generic::generic[0]<&str> @@ local_generic[External]
 pub fn generic<T>(x: T) -> T { x }
 
 //~ MONO_ITEM fn local_generic::user[0] @@ local_generic[Internal]

src/test/codegen-units/partitioning/shared-generics.rs

@@ -19,7 +19,7 @@ extern crate shared_generics_aux;
 //~ MONO_ITEM fn shared_generics::foo[0]
 pub fn foo() {
 
-    //~ MONO_ITEM fn shared_generics_aux::generic_fn[0]<u16> @@ shared_generics_aux.volatile[External]
+    //~ MONO_ITEM fn shared_generics_aux::generic_fn[0]<u16> @@ shared_generics_aux[External]
     let _ = shared_generics_aux::generic_fn(0u16, 1u16);
 
     // This should not generate a monomorphization because it's already

src/test/codegen-units/partitioning/vtable-through-const.rs

@@ -78,20 +78,20 @@ fn start(_: isize, _: *const *const u8) -> isize {
     // Since Trait1::do_something() is instantiated via its default implementation,
     // it is considered a generic and is instantiated here only because it is
     // referenced in this module.
-    //~ MONO_ITEM fn vtable_through_const::mod1[0]::Trait1[0]::do_something_else[0]<u32> @@ vtable_through_const-mod1.volatile[External]
+    //~ MONO_ITEM fn vtable_through_const::mod1[0]::Trait1[0]::do_something_else[0]<u32> @@ vtable_through_const-mod1[External]
 
     // Although it is never used, Trait1::do_something_else() has to be
     // instantiated locally here too, otherwise the <&u32 as &Trait1> vtable
     // could not be fully constructed.
-    //~ MONO_ITEM fn vtable_through_const::mod1[0]::Trait1[0]::do_something[0]<u32> @@ vtable_through_const-mod1.volatile[External]
+    //~ MONO_ITEM fn vtable_through_const::mod1[0]::Trait1[0]::do_something[0]<u32> @@ vtable_through_const-mod1[External]
     mod1::TRAIT1_REF.do_something();
 
     // Same as above
-    //~ MONO_ITEM fn vtable_through_const::mod1[0]::{{impl}}[1]::do_something[0]<u8> @@ vtable_through_const-mod1.volatile[External]
-    //~ MONO_ITEM fn vtable_through_const::mod1[0]::{{impl}}[1]::do_something_else[0]<u8> @@ vtable_through_const-mod1.volatile[External]
+    //~ MONO_ITEM fn vtable_through_const::mod1[0]::{{impl}}[1]::do_something[0]<u8> @@ vtable_through_const-mod1[External]
+    //~ MONO_ITEM fn vtable_through_const::mod1[0]::{{impl}}[1]::do_something_else[0]<u8> @@ vtable_through_const-mod1[External]
     mod1::TRAIT1_GEN_REF.do_something(0u8);
 
-    //~ MONO_ITEM fn vtable_through_const::mod1[0]::id[0]<char> @@ vtable_through_const-mod1.volatile[External]
+    //~ MONO_ITEM fn vtable_through_const::mod1[0]::id[0]<char> @@ vtable_through_const-mod1[External]
     mod1::ID_CHAR('x');
 
     0