Auto merge of #115964 - bjorn3:cgu_reuse_tracker_global_state, r=cjgillot

Remove cgu_reuse_tracker from Session

This removes a bit of global mutable state.

It will now miss post-lto cgu reuse when ThinLTO determines that a cgu doesn't get changed, but there weren't any tests for this anyway and a test for it would be fragile to the exact implementation of ThinLTO in LLVM.

1 files changed, 37 insertions, 61 deletions

diff --git a/compiler/rustc_codegen_cranelift/src/driver/aot.rs b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
index cc2f5d72714..49f51f9f956 100644
--- a/compiler/rustc_codegen_cranelift/src/driver/aot.rs
+++ b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
@@ -7,14 +7,15 @@ use std::sync::Arc;
 use std::thread::JoinHandle;
 
 use cranelift_object::{ObjectBuilder, ObjectModule};
+use rustc_codegen_ssa::assert_module_sources::CguReuse;
 use rustc_codegen_ssa::back::metadata::create_compressed_metadata_file;
+use rustc_codegen_ssa::base::determine_cgu_reuse;
 use rustc_codegen_ssa::{CodegenResults, CompiledModule, CrateInfo, ModuleKind};
 use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_middle::mir::mono::{CodegenUnit, MonoItem};
-use rustc_session::cgu_reuse_tracker::CguReuse;
 use rustc_session::config::{DebugInfo, OutputFilenames, OutputType};
 use rustc_session::Session;
 
@@ -374,43 +375,47 @@ pub(crate) fn run_aot(
         }
     }
 
+    // Calculate the CGU reuse
+    let cgu_reuse = tcx.sess.time("find_cgu_reuse", || {
+        cgus.iter().map(|cgu| determine_cgu_reuse(tcx, &cgu)).collect::<Vec<_>>()
+    });
+
+    rustc_codegen_ssa::assert_module_sources::assert_module_sources(tcx, &|cgu_reuse_tracker| {
+        for (i, cgu) in cgus.iter().enumerate() {
+            let cgu_reuse = cgu_reuse[i];
+            cgu_reuse_tracker.set_actual_reuse(cgu.name().as_str(), cgu_reuse);
+        }
+    });
+
     let global_asm_config = Arc::new(crate::global_asm::GlobalAsmConfig::new(tcx));
 
     let mut concurrency_limiter = ConcurrencyLimiter::new(tcx.sess, cgus.len());
 
     let modules = tcx.sess.time("codegen mono items", || {
         cgus.iter()
-            .map(|cgu| {
-                let cgu_reuse = if backend_config.disable_incr_cache {
-                    CguReuse::No
-                } else {
-                    determine_cgu_reuse(tcx, cgu)
-                };
-                tcx.sess.cgu_reuse_tracker.set_actual_reuse(cgu.name().as_str(), cgu_reuse);
-
-                match cgu_reuse {
-                    CguReuse::No => {
-                        let dep_node = cgu.codegen_dep_node(tcx);
-                        tcx.dep_graph
-                            .with_task(
-                                dep_node,
-                                tcx,
-                                (
-                                    backend_config.clone(),
-                                    global_asm_config.clone(),
-                                    cgu.name(),
-                                    concurrency_limiter.acquire(tcx.sess.diagnostic()),
-                                ),
-                                module_codegen,
-                                Some(rustc_middle::dep_graph::hash_result),
-                            )
-                            .0
-                    }
-                    CguReuse::PreLto => unreachable!(),
-                    CguReuse::PostLto => {
-                        concurrency_limiter.job_already_done();
-                        OngoingModuleCodegen::Sync(reuse_workproduct_for_cgu(tcx, cgu))
-                    }
+            .enumerate()
+            .map(|(i, cgu)| match cgu_reuse[i] {
+                CguReuse::No => {
+                    let dep_node = cgu.codegen_dep_node(tcx);
+                    tcx.dep_graph
+                        .with_task(
+                            dep_node,
+                            tcx,
+                            (
+                                backend_config.clone(),
+                                global_asm_config.clone(),
+                                cgu.name(),
+                                concurrency_limiter.acquire(tcx.sess.diagnostic()),
+                            ),
+                            module_codegen,
+                            Some(rustc_middle::dep_graph::hash_result),
+                        )
+                        .0
+                }
+                CguReuse::PreLto => unreachable!("LTO not yet supported"),
+                CguReuse::PostLto => {
+                    concurrency_limiter.job_already_done();
+                    OngoingModuleCodegen::Sync(reuse_workproduct_for_cgu(tcx, cgu))
                 }
             })
             .collect::<Vec<_>>()
@@ -489,32 +494,3 @@ pub(crate) fn run_aot(
         concurrency_limiter,
     })
 }
-
-// Adapted from https://github.com/rust-lang/rust/blob/303d8aff6092709edd4dbd35b1c88e9aa40bf6d8/src/librustc_codegen_ssa/base.rs#L922-L953
-fn determine_cgu_reuse<'tcx>(tcx: TyCtxt<'tcx>, cgu: &CodegenUnit<'tcx>) -> CguReuse {
-    if !tcx.dep_graph.is_fully_enabled() {
-        return CguReuse::No;
-    }
-
-    let work_product_id = &cgu.work_product_id();
-    if tcx.dep_graph.previous_work_product(work_product_id).is_none() {
-        // We don't have anything cached for this CGU. This can happen
-        // if the CGU did not exist in the previous session.
-        return CguReuse::No;
-    }
-
-    // Try to mark the CGU as green. If it we can do so, it means that nothing
-    // affecting the LLVM module has changed and we can re-use a cached version.
-    // If we compile with any kind of LTO, this means we can re-use the bitcode
-    // of the Pre-LTO stage (possibly also the Post-LTO version but we'll only
-    // know that later). If we are not doing LTO, there is only one optimized
-    // version of each module, so we re-use that.
-    let dep_node = cgu.codegen_dep_node(tcx);
-    assert!(
-        !tcx.dep_graph.dep_node_exists(&dep_node),
-        "CompileCodegenUnit dep-node for CGU `{}` already exists before marking.",
-        cgu.name()
-    );
-
-    if tcx.try_mark_green(&dep_node) { CguReuse::PostLto } else { CguReuse::No }
-}