Remove mono item collection strategy override from -Zprint-mono-items

Previously `-Zprint-mono-items` would override the mono item collection strategy. When debugging one doesn't want to change the behaviour, so this was counter productive. Additionally, the produced behaviour was artificial and might never arise without using the option in the first place (`-Zprint-mono-items=eager` without `-Clink-dead-code`). Finally, the option was incorrectly marked as `UNTRACKED`. Resolve those issues, by turning `-Zprint-mono-items` into a boolean flag that prints results of mono item collection without changing the behaviour of mono item collection. For codegen-units test incorporate `-Zprint-mono-items` flag directly into compiletest tool. Test changes are mechanical. `-Zprint-mono-items=lazy` was removed without additional changes, and `-Zprint-mono-items=eager` was turned into `-Clink-dead-code`. Linking dead code disables internalization, so tests have been updated accordingly.

Author: tmiasko

compiler/rustc_interface/src/tests.rs

@@ -720,7 +720,7 @@ fn test_unstable_options_tracking_hash() {
  untracked!(pre_link_args, vec![String::from("abc"), String::from("def")]);
  untracked!(print_codegen_stats, true);
  untracked!(print_llvm_passes, true);
- untracked!(print_mono_items, Some(String::from("abc")));
+ untracked!(print_mono_items, true);
  untracked!(print_type_sizes, true);
  untracked!(proc_macro_backtrace, true);
  untracked!(proc_macro_execution_strategy, ProcMacroExecutionStrategy::CrossThread);

compiler/rustc_monomorphize/messages.ftl

@@ -60,9 +60,6 @@ monomorphize_start_not_found = using `fn main` requires the standard library
 
 monomorphize_symbol_already_defined = symbol `{$symbol}` is already defined
 
-monomorphize_unknown_cgu_collection_mode =
- unknown codegen-item collection mode '{$mode}', falling back to 'lazy' mode
-
 monomorphize_wasm_c_abi_transition =
  this function {$is_call ->
  [true] call

compiler/rustc_monomorphize/src/errors.rs

@@ -64,12 +64,6 @@ pub(crate) struct EncounteredErrorWhileInstantiating {
 #[help]
 pub(crate) struct StartNotFound;
 
-#[derive(Diagnostic)]
-#[diag(monomorphize_unknown_cgu_collection_mode)]
-pub(crate) struct UnknownCguCollectionMode<'a> {
- pub mode: &'a str,
-}
-
 #[derive(Diagnostic)]
 #[diag(monomorphize_abi_error_disabled_vector_type)]
 #[help]

compiler/rustc_monomorphize/src/partitioning.rs

@@ -124,7 +124,7 @@ use rustc_target::spec::SymbolVisibility;
 use tracing::debug;
 
 use crate::collector::{self, MonoItemCollectionStrategy, UsageMap};
-use crate::errors::{CouldntDumpMonoStats, SymbolAlreadyDefined, UnknownCguCollectionMode};
+use crate::errors::{CouldntDumpMonoStats, SymbolAlreadyDefined};
 
 struct PartitioningCx<'a, 'tcx> {
  tcx: TyCtxt<'tcx>,
@@ -1127,27 +1127,10 @@ where
 }
 
 fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> MonoItemPartitions<'_> {
- let collection_strategy = match tcx.sess.opts.unstable_opts.print_mono_items {
- Some(ref s) => {
- let mode = s.to_lowercase();
- let mode = mode.trim();
- if mode == "eager" {
- MonoItemCollectionStrategy::Eager
- } else {
- if mode != "lazy" {
- tcx.dcx().emit_warn(UnknownCguCollectionMode { mode });
- }
-
- MonoItemCollectionStrategy::Lazy
- }
- }
- None => {
- if tcx.sess.link_dead_code() {
- MonoItemCollectionStrategy::Eager
- } else {
- MonoItemCollectionStrategy::Lazy
- }
- }
+ let collection_strategy = if tcx.sess.link_dead_code() {
+ MonoItemCollectionStrategy::Eager
+ } else {
+ MonoItemCollectionStrategy::Lazy
  };
 
  let (items, usage_map) = collector::collect_crate_mono_items(tcx, collection_strategy);
@@ -1209,7 +1192,7 @@ fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> MonoItemPartitio
  }
  }
 
- if tcx.sess.opts.unstable_opts.print_mono_items.is_some() {
+ if tcx.sess.opts.unstable_opts.print_mono_items {
  let mut item_to_cgus: UnordMap<_, Vec<_>> = Default::default();
 
  for cgu in codegen_units {

compiler/rustc_session/src/options.rs

@@ -2408,10 +2408,8 @@ options! {
  "print codegen statistics (default: no)"),
  print_llvm_passes: bool = (false, parse_bool, [UNTRACKED],
  "print the LLVM optimization passes being run (default: no)"),
- print_mono_items: Option<String> = (None, parse_opt_string, [UNTRACKED],
- "print the result of the monomorphization collection pass. \
- Value `lazy` means to use normal collection; `eager` means to collect all items.
- Note that this overwrites the effect `-Clink-dead-code` has on collection!"),
+ print_mono_items: bool = (false, parse_bool, [UNTRACKED],
+ "print the result of the monomorphization collection pass (default: no)"),
  print_type_sizes: bool = (false, parse_bool, [UNTRACKED],
  "print layout information for each type encountered (default: no)"),
  proc_macro_backtrace: bool = (false, parse_bool, [UNTRACKED],

src/doc/rustc-dev-guide/src/tests/compiletest.md

@@ -325,12 +325,8 @@ The tests in [`tests/codegen-units`] test the
 [monomorphization](../backend/monomorph.md) collector and CGU partitioning.
 
 These tests work by running `rustc` with a flag to print the result of the
-monomorphization collection pass, and then special annotations in the file are
-used to compare against that.
-
-Each test should be annotated with the `//@
-compile-flags:-Zprint-mono-items=VAL` directive with the appropriate `VAL` to
-instruct `rustc` to print the monomorphization information.
+monomorphization collection pass, i.e., `-Zprint-mono-items`, and then special
+annotations in the file are used to compare against that.
 
 Then, the test should be annotated with comments of the form `//~ MONO_ITEM
 name` where `name` is the monomorphized string printed by rustc like `fn <u32 as

src/tools/compiletest/src/runtest.rs

@@ -1583,7 +1583,10 @@ impl<'test> TestCx<'test> {
  Crashes => {
  set_mir_dump_dir(&mut rustc);
  }
- Pretty | DebugInfo | Rustdoc | RustdocJson | RunMake | CodegenUnits | RustdocJs => {
+ CodegenUnits => {
+ rustc.arg("-Zprint-mono-items");
+ }
+ Pretty | DebugInfo | Rustdoc | RustdocJson | RunMake | RustdocJs => {
  // do not use JSON output
  }
  }

tests/codegen-units/item-collection/asm-sym.rs

@@ -1,5 +1,5 @@
 //@ needs-asm-support
-//@ compile-flags: -Ccodegen-units=1 -Zprint-mono-items=lazy --crate-type=lib
+//@ compile-flags: -Ccodegen-units=1 --crate-type=lib
 
 #[inline(always)]
 pub unsafe fn f() {

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

@@ -1,5 +1,5 @@
 //@ edition: 2021
-//@ compile-flags: -Zprint-mono-items=eager --crate-type=lib
+//@ compile-flags: -Clink-dead-code --crate-type=lib
 
 //~ MONO_ITEM fn async_fn @@
 //~ MONO_ITEM fn async_fn::{closure#0} @@

tests/codegen-units/item-collection/cross-crate-closures.rs

@@ -1,6 +1,6 @@
 // We need to disable MIR inlining in both this and its aux-build crate. The MIR inliner
 // will just inline everything into our start function if we let it. As it should.
-//@ compile-flags:-Zprint-mono-items=eager -Zinline-mir=no
+//@ compile-flags:-Clink-dead-code -Zinline-mir=no
 
 #![deny(dead_code)]
 #![no_main]
@@ -11,12 +11,12 @@ extern crate cgu_extern_closures;
 //~ MONO_ITEM fn main @@ cross_crate_closures-cgu.0[External]
 #[no_mangle]
 extern "C" fn main(_: core::ffi::c_int, _: *const *const u8) -> core::ffi::c_int {
- //~ MONO_ITEM fn cgu_extern_closures::inlined_fn @@ cross_crate_closures-cgu.0[Internal]
- //~ MONO_ITEM fn cgu_extern_closures::inlined_fn::{closure#0} @@ cross_crate_closures-cgu.0[Internal]
+ //~ MONO_ITEM fn cgu_extern_closures::inlined_fn @@ cross_crate_closures-cgu.0[External]
+ //~ MONO_ITEM fn cgu_extern_closures::inlined_fn::{closure#0} @@ cross_crate_closures-cgu.0[External]
  let _ = cgu_extern_closures::inlined_fn(1, 2);
 
- //~ MONO_ITEM fn cgu_extern_closures::inlined_fn_generic::<i32> @@ cross_crate_closures-cgu.0[Internal]
- //~ MONO_ITEM fn cgu_extern_closures::inlined_fn_generic::<i32>::{closure#0} @@ cross_crate_closures-cgu.0[Internal]
+ //~ MONO_ITEM fn cgu_extern_closures::inlined_fn_generic::<i32> @@ cross_crate_closures-cgu.0[External]
+ //~ MONO_ITEM fn cgu_extern_closures::inlined_fn_generic::<i32>::{closure#0} @@ cross_crate_closures-cgu.0[External]
  let _ = cgu_extern_closures::inlined_fn_generic(3, 4, 5i32);
 
  // Nothing should be generated for this call, we just link to the instance