Auto merge of rust-lang#133929 - saethlin:remove-inline-in-all-cgus, r=nnethercote

Remove -Zinline-in-all-cgus and clean up tests/codegen-units/

Implementation of rust-lang/compiler-team#814

I've taken some liberties with cleaning up the CGU partitioning tests, because that's the only place this flag was used and also mattered. I've often fought a lot with the contents of `tests/codegen-units` and it has never been clear to me when a test failure indicates a problem with my changes as opposed to a test just needing to be manually blessed. Hopefully the combination of the new README, new comments, and using `-Zprint-mono-items=lazy` in the partitioning tests improves that.

I've also deleted some of the `tests/run-make/sepcomp` tests. I think all the "sepcomp" tests have been obviated for years by better-designed (less flaky, clearer failures) test suites, but here I'm just deleting the ones I'm confident in.

Author: bors

compiler/rustc_interface/src/tests.rs

@@ -797,7 +797,6 @@ fn test_unstable_options_tracking_hash() {
     tracked!(function_sections, Some(false));
     tracked!(human_readable_cgu_names, true);
     tracked!(incremental_ignore_spans, true);
-    tracked!(inline_in_all_cgus, Some(true));
     tracked!(inline_mir, Some(true));
     tracked!(inline_mir_hint_threshold, Some(123));
     tracked!(inline_mir_threshold, Some(123));

compiler/rustc_middle/src/mir/mono.rs

@@ -91,13 +91,8 @@ impl<'tcx> MonoItem<'tcx> {
     }
 
     pub fn instantiation_mode(&self, tcx: TyCtxt<'tcx>) -> InstantiationMode {
-        let generate_cgu_internal_copies = tcx
-            .sess
-            .opts
-            .unstable_opts
-            .inline_in_all_cgus
-            .unwrap_or_else(|| tcx.sess.opts.optimize != OptLevel::No)
-            && !tcx.sess.link_dead_code();
+        let generate_cgu_internal_copies =
+            (tcx.sess.opts.optimize != OptLevel::No) && !tcx.sess.link_dead_code();
 
         match *self {
             MonoItem::Fn(ref instance) => {
@@ -121,8 +116,8 @@ impl<'tcx> MonoItem<'tcx> {
                 }
 
                 // At this point we don't have explicit linkage and we're an
-                // inlined function. If we're inlining into all CGUs then we'll
-                // be creating a local copy per CGU.
+                // inlined function. If this crate's build settings permit,
+                // we'll be creating a local copy per CGU.
                 if generate_cgu_internal_copies {
                     return InstantiationMode::LocalCopy;
                 }

compiler/rustc_session/src/options.rs

@@ -1870,8 +1870,6 @@ options! {
         "verify extended properties for incr. comp. (default: no):
         - hashes of green query instances
         - hash collisions of query keys"),
-    inline_in_all_cgus: Option<bool> = (None, parse_opt_bool, [TRACKED],
-        "control whether `#[inline]` functions are in all CGUs"),
     inline_llvm: bool = (true, parse_bool, [TRACKED],
         "enable LLVM inlining (default: yes)"),
     inline_mir: Option<bool> = (None, parse_opt_bool, [TRACKED],

tests/codegen-units/item-collection/drop_in_place_intrinsic.rs

@@ -1,7 +1,6 @@
-//
 //@ compile-flags:-Zprint-mono-items=eager
-//@ compile-flags:-Zinline-in-all-cgus
 //@ compile-flags:-Zinline-mir=no
+//@ compile-flags: -O
 
 #![crate_type = "lib"]
 

tests/codegen-units/item-collection/generic-drop-glue.rs

@@ -1,6 +1,5 @@
-//
 //@ compile-flags:-Zprint-mono-items=eager
-//@ compile-flags:-Zinline-in-all-cgus
+//@ compile-flags: -O
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/instantiation-through-vtable.rs

@@ -1,5 +1,4 @@
-//
-//@ compile-flags:-Zprint-mono-items=eager -Zinline-in-all-cgus -Zmir-opt-level=0
+//@ compile-flags:-Zprint-mono-items=eager -Zmir-opt-level=0
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/non-generic-drop-glue.rs

@@ -1,6 +1,5 @@
-//
 //@ compile-flags:-Zprint-mono-items=eager
-//@ compile-flags:-Zinline-in-all-cgus
+//@ compile-flags: -O
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/transitive-drop-glue.rs

@@ -1,6 +1,5 @@
-//
 //@ compile-flags:-Zprint-mono-items=eager
-//@ compile-flags:-Zinline-in-all-cgus
+//@ compile-flags: -O
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/tuple-drop-glue.rs

@@ -1,6 +1,5 @@
-//
 //@ compile-flags:-Zprint-mono-items=eager
-//@ compile-flags:-Zinline-in-all-cgus
+//@ compile-flags: -O
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/unsizing.rs

@@ -1,5 +1,4 @@
 //@ compile-flags:-Zprint-mono-items=eager
-//@ compile-flags:-Zinline-in-all-cgus
 //@ compile-flags:-Zmir-opt-level=0
 
 #![deny(dead_code)]