Compute quoted args for debuginfo at most once per session

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -16,13 +16,13 @@ use rustc_codegen_ssa::back::write::{
     TargetMachineFactoryFn,
 };
 use rustc_codegen_ssa::base::wants_wasm_eh;
-use rustc_codegen_ssa::debuginfo::command_line_args::quote_command_line_args;
 use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{CompiledModule, ModuleCodegen, ModuleKind};
 use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::small_c_str::SmallCStr;
 use rustc_errors::{DiagCtxtHandle, Level};
 use rustc_fs_util::{link_or_copy, path_to_c_string};
+use rustc_middle::middle::debuginfo::CommandLineArgsForDebuginfo;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
 use rustc_session::config::{
@@ -108,7 +108,11 @@ pub(crate) fn create_informational_target_machine(
     sess: &Session,
     only_base_features: bool,
 ) -> OwnedTargetMachine {
-    let config = TargetMachineFactoryConfig { split_dwarf_file: None, output_obj_file: None };
+    let config = TargetMachineFactoryConfig {
+        split_dwarf_file: None,
+        output_obj_file: None,
+        args_for_debuginfo: None,
+    };
     // Can't use query system here quite yet because this function is invoked before the query
     // system/tcx is set up.
     let features = llvm_util::global_llvm_features(sess, false, only_base_features);
@@ -133,7 +137,12 @@ pub(crate) fn create_target_machine(tcx: TyCtxt<'_>, mod_name: &str) -> OwnedTar
         mod_name,
         tcx.sess.invocation_temp.as_deref(),
     ));
-    let config = TargetMachineFactoryConfig { split_dwarf_file, output_obj_file };
+
+    let config = TargetMachineFactoryConfig {
+        split_dwarf_file,
+        output_obj_file,
+        args_for_debuginfo: Some(Arc::clone(tcx.args_for_debuginfo())),
+    };
 
     target_machine_factory(
         tcx.sess,
@@ -253,19 +262,6 @@ pub(crate) fn target_machine_factory(
 
     let use_emulated_tls = matches!(sess.tls_model(), TlsModel::Emulated);
 
-    // Command-line information to be included in the target machine.
-    // This seems to only be used for embedding in PDB debuginfo files.
-    // FIXME(Zalathar): Maybe skip this for non-PDB targets?
-    let argv0 = std::env::current_exe()
-        .unwrap_or_default()
-        .into_os_string()
-        .into_string()
-        .unwrap_or_default();
-    let command_line_args = quote_command_line_args(&sess.expanded_args);
-    // Self-profile counter for the number of bytes produced by command-line quoting.
-    // Values are summed, so the summary result is cumulative across all TM factories.
-    sess.prof.artifact_size("quoted_command_line_args", "-", command_line_args.len() as u64);
-
     let debuginfo_compression = sess.opts.debuginfo_compression.to_string();
     match sess.opts.debuginfo_compression {
         rustc_session::config::DebugInfoCompression::Zlib => {
@@ -304,6 +300,14 @@ pub(crate) fn target_machine_factory(
         let split_dwarf_file = path_to_cstring_helper(config.split_dwarf_file);
         let output_obj_file = path_to_cstring_helper(config.output_obj_file);
 
+        let (argv0, quoted_args) = config
+            .args_for_debuginfo
+            .as_deref()
+            .map(|CommandLineArgsForDebuginfo { argv0, quoted_args }| {
+                (argv0.as_str(), quoted_args.as_str())
+            })
+            .unwrap_or_default();
+
         OwnedTargetMachine::new(
             &triple,
             &cpu,
@@ -326,8 +330,8 @@ pub(crate) fn target_machine_factory(
             &output_obj_file,
             &debuginfo_compression,
             use_emulated_tls,
-            &argv0,
-            &command_line_args,
+            argv0,
+            quoted_args,
             use_wasm_eh,
         )
     })

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -25,6 +25,7 @@ use rustc_incremental::{
 use rustc_metadata::fs::copy_to_stdout;
 use rustc_middle::bug;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
+use rustc_middle::middle::debuginfo::CommandLineArgsForDebuginfo;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
 use rustc_session::config::{
@@ -283,6 +284,10 @@ pub struct TargetMachineFactoryConfig {
     /// The name of the output object file. Used for setting OutputFilenames in target options
     /// so that LLVM can emit the CodeView S_OBJNAME record in pdb files
     pub output_obj_file: Option<PathBuf>,
+
+    /// Contains a copy of [`TyCtxt::args_for_debuginfo`] for codegen,
+    /// or `None` if the target machine is informational only.
+    pub args_for_debuginfo: Option<Arc<CommandLineArgsForDebuginfo>>,
 }
 
 impl TargetMachineFactoryConfig {
@@ -306,7 +311,12 @@ impl TargetMachineFactoryConfig {
             module_name,
             cgcx.invocation_temp.as_deref(),
         ));
-        TargetMachineFactoryConfig { split_dwarf_file, output_obj_file }
+
+        TargetMachineFactoryConfig {
+            split_dwarf_file,
+            output_obj_file,
+            args_for_debuginfo: Some(Arc::clone(&cgcx.args_for_debuginfo)),
+        }
     }
 }
 
@@ -350,7 +360,7 @@ pub struct CodegenContext<B: WriteBackendMethods> {
     /// This will only be used within debug info, e.g. in the pdb file on windows
     /// This is mainly useful for other tools that reads that debuginfo to figure out
     /// how to call the compiler with the same arguments.
-    pub expanded_args: Vec<String>,
+    pub args_for_debuginfo: Arc<CommandLineArgsForDebuginfo>,
 
     /// Emitter to use for diagnostics produced during codegen.
     pub diag_emitter: SharedEmitter,
@@ -1153,7 +1163,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
         remark: sess.opts.cg.remark.clone(),
         remark_dir,
         incr_comp_session_dir: sess.incr_comp_session_dir_opt().map(|r| r.clone()),
-        expanded_args: tcx.sess.expanded_args.clone(),
+        args_for_debuginfo: Arc::clone(tcx.args_for_debuginfo()),
         diag_emitter: shared_emitter.clone(),
         output_filenames: Arc::clone(tcx.output_filenames(())),
         module_config: regular_config,

compiler/rustc_codegen_ssa/src/debuginfo/command_line_args/mod.rs

@@ -1,12 +1,42 @@
+use std::sync::Arc;
+
+use rustc_middle::middle::debuginfo::CommandLineArgsForDebuginfo;
+use rustc_middle::ty::TyCtxt;
+use rustc_middle::util::Providers;
+
 #[cfg(test)]
 mod tests;
 
+pub(crate) fn provide(providers: &mut Providers) {
+    providers.hooks.args_for_debuginfo = args_for_debuginfo;
+}
+
+/// Hook implementation for [`TyCtxt::args_for_debuginfo`].
+fn args_for_debuginfo<'tcx>(tcx: TyCtxt<'tcx>) -> &'tcx Arc<CommandLineArgsForDebuginfo> {
+    tcx.args_for_debuginfo_cache.get_or_init(|| {
+        // Command-line information to be included in the target machine.
+        // This seems to only be used for embedding in PDB debuginfo files.
+        // FIXME(Zalathar): Maybe skip this for non-PDB targets?
+        let argv0 = std::env::current_exe()
+            .unwrap_or_default()
+            .into_os_string()
+            .into_string()
+            .unwrap_or_default();
+        let quoted_args = quote_command_line_args(&tcx.sess.expanded_args);
+
+        // Self-profile counter for the number of bytes produced by command-line quoting.
+        tcx.prof.artifact_size("quoted_command_line_args", "-", quoted_args.len() as u64);
+
+        Arc::new(CommandLineArgsForDebuginfo { argv0, quoted_args })
+    })
+}
+
 /// Joins command-line arguments into a single space-separated string, quoting
 /// and escaping individual arguments as necessary.
 ///
 /// The result is intended to be informational, for embedding in debug metadata,
 /// and might not be properly quoted/escaped for actual command-line use.
-pub fn quote_command_line_args(args: &[String]) -> String {
+fn quote_command_line_args(args: &[String]) -> String {
     // Start with a decent-sized buffer, since rustc invocations tend to be long.
     let mut buf = String::with_capacity(128);
 

compiler/rustc_codegen_ssa/src/debuginfo/mod.rs

@@ -3,7 +3,7 @@ use rustc_middle::bug;
 use rustc_middle::ty::layout::{IntegerExt, PrimitiveExt, TyAndLayout};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 
-pub mod command_line_args;
+pub(crate) mod command_line_args;
 pub mod type_names;
 
 /// Returns true if we want to generate a DW_TAG_enumeration_type description for

compiler/rustc_codegen_ssa/src/lib.rs

@@ -271,6 +271,7 @@ pub enum CodegenErrors {
 pub fn provide(providers: &mut Providers) {
     crate::back::symbol_export::provide(providers);
     crate::base::provide(providers);
+    crate::debuginfo::command_line_args::provide(providers);
     crate::target_features::provide(providers);
     crate::codegen_attrs::provide(providers);
     providers.queries.global_backend_features = |_tcx: TyCtxt<'_>, ()| vec![];

compiler/rustc_middle/src/hooks/mod.rs

@@ -3,11 +3,14 @@
 //! similar to queries, but queries come with a lot of machinery for caching and incremental
 //! compilation, whereas hooks are just plain function pointers without any of the query magic.
 
+use std::sync::Arc;
+
 use rustc_hir::def_id::{DefId, DefPathHash};
 use rustc_session::StableCrateId;
 use rustc_span::def_id::{CrateNum, LocalDefId};
 use rustc_span::{ExpnHash, ExpnId};
 
+use crate::middle::debuginfo::CommandLineArgsForDebuginfo;
 use crate::mir;
 use crate::ty::{Ty, TyCtxt};
 
@@ -102,6 +105,13 @@ declare_hooks! {
     /// Ensure the given scalar is valid for the given type.
     /// This checks non-recursive runtime validity.
     hook validate_scalar_in_layout(scalar: crate::ty::ScalarInt, ty: Ty<'tcx>) -> bool;
+
+    /// Builds a quoted form of _all_ command-line args, for inclusion in some
+    /// forms of debuginfo (specifically PDB).
+    ///
+    /// This needs to _not_ be a query, because it would ruin incremental
+    /// compilation for CGUs that would otherwise be considered up-to-date.
+    hook args_for_debuginfo() -> &'tcx Arc<CommandLineArgsForDebuginfo>;
 }
 
 #[cold]

compiler/rustc_middle/src/middle/debuginfo.rs

@@ -0,0 +1,5 @@
+#[derive(Debug)]
+pub struct CommandLineArgsForDebuginfo {
+    pub argv0: String,
+    pub quoted_args: String,
+}

compiler/rustc_middle/src/middle/mod.rs

@@ -1,5 +1,6 @@
 pub mod codegen_fn_attrs;
 pub mod debugger_visualizer;
+pub mod debuginfo;
 pub mod dependency_format;
 pub mod exported_symbols;
 pub mod lang_items;

compiler/rustc_middle/src/ty/context.rs

@@ -66,6 +66,7 @@ use crate::infer::canonical::{CanonicalParamEnvCache, CanonicalVarKind, Canonica
 use crate::lint::lint_level;
 use crate::metadata::ModChild;
 use crate::middle::codegen_fn_attrs::{CodegenFnAttrs, TargetFeature};
+use crate::middle::debuginfo::CommandLineArgsForDebuginfo;
 use crate::middle::resolve_bound_vars;
 use crate::mir::interpret::{self, Allocation, ConstAllocation};
 use crate::mir::{Body, Local, Place, PlaceElem, ProjectionKind, Promoted};
@@ -1593,6 +1594,10 @@ pub struct GlobalCtxt<'tcx> {
 
     /// A jobserver reference used to release then acquire a token while waiting on a query.
     pub jobserver_proxy: Arc<Proxy>,
+
+    /// Memoization slot for the [`TyCtxt::args_for_debuginfo`] hook, which needs
+    /// to not be a query, but should still be cached after being computed once.
+    pub args_for_debuginfo_cache: OnceLock<Arc<CommandLineArgsForDebuginfo>>,
 }
 
 impl<'tcx> GlobalCtxt<'tcx> {
@@ -1818,6 +1823,7 @@ impl<'tcx> TyCtxt<'tcx> {
             alloc_map: interpret::AllocMap::new(),
             current_gcx,
             jobserver_proxy,
+            args_for_debuginfo_cache: OnceLock::new(),
         });
 
         // This is a separate function to work around a crash with parallel rustc (#135870)