about summary refs log tree commit diff
diff options
context:
space:
mode:
-rw-r--r--compiler/rustc_middle/src/mir/mono.rs23
-rw-r--r--tests/ui/intrinsics/non-integer-atomic.stderr80
2 files changed, 60 insertions, 43 deletions
diff --git a/compiler/rustc_middle/src/mir/mono.rs b/compiler/rustc_middle/src/mir/mono.rs
index 0e6f797b1e4..533066bdef9 100644
--- a/compiler/rustc_middle/src/mir/mono.rs
+++ b/compiler/rustc_middle/src/mir/mono.rs
@@ -548,10 +548,27 @@ impl<'tcx> CodegenUnit<'tcx> {
 
         let mut items: Vec<_> = self.items().iter().map(|(&i, &data)| (i, data)).collect();
         if !tcx.sess.opts.unstable_opts.codegen_source_order {
-            // It's already deterministic, so we can just use it.
-            return items;
+            // In this case, we do not need to keep the items in any specific order, as the input
+            // is already deterministic.
+            //
+            // However, it seems that moving related things (such as different
+            // monomorphizations of the same function) close to one another is actually beneficial
+            // for LLVM performance.
+            // LLVM will codegen the items in the order we pass them to it, and when it handles
+            // similar things in succession, it seems that it leads to better cache utilization,
+            // less branch mispredictions and in general to better performance.
+            // For example, if we have functions `a`, `c::<u32>`, `b`, `c::<i16>`, `d` and
+            // `c::<bool>`, it seems that it helps LLVM's performance to codegen the three `c`
+            // instantiations right after one another, as they will likely reference similar types,
+            // call similar functions, etc.
+            //
+            // See https://github.com/rust-lang/rust/pull/145358 for more details.
+            //
+            // Sorting by symbol name should not incur any new non-determinism.
+            items.sort_by_cached_key(|&(i, _)| i.symbol_name(tcx));
+        } else {
+            items.sort_by_cached_key(|&(i, _)| item_sort_key(tcx, i));
         }
-        items.sort_by_cached_key(|&(i, _)| item_sort_key(tcx, i));
         items
     }
 
diff --git a/tests/ui/intrinsics/non-integer-atomic.stderr b/tests/ui/intrinsics/non-integer-atomic.stderr
index 330d313639d..c27013c0de2 100644
--- a/tests/ui/intrinsics/non-integer-atomic.stderr
+++ b/tests/ui/intrinsics/non-integer-atomic.stderr
@@ -4,20 +4,20 @@ error[E0511]: invalid monomorphization of `atomic_load` intrinsic: expected basi
 LL |     intrinsics::atomic_load::<_, { SeqCst }>(p);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+error[E0511]: invalid monomorphization of `atomic_xchg` intrinsic: expected basic integer or pointer type, found `&dyn Fn()`
+  --> $DIR/non-integer-atomic.rs:65:5
+   |
+LL |     intrinsics::atomic_xchg::<_, { SeqCst }>(p, v);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 error[E0511]: invalid monomorphization of `atomic_load` intrinsic: expected basic integer or pointer type, found `Foo`
   --> $DIR/non-integer-atomic.rs:35:5
    |
 LL |     intrinsics::atomic_load::<_, { SeqCst }>(p);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `atomic_store` intrinsic: expected basic integer or pointer type, found `&dyn Fn()`
-  --> $DIR/non-integer-atomic.rs:60:5
-   |
-LL |     intrinsics::atomic_store::<_, { SeqCst }>(p, v);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error[E0511]: invalid monomorphization of `atomic_xchg` intrinsic: expected basic integer or pointer type, found `[u8; 100]`
-  --> $DIR/non-integer-atomic.rs:85:5
+error[E0511]: invalid monomorphization of `atomic_xchg` intrinsic: expected basic integer or pointer type, found `Foo`
+  --> $DIR/non-integer-atomic.rs:45:5
    |
 LL |     intrinsics::atomic_xchg::<_, { SeqCst }>(p, v);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -28,71 +28,71 @@ error[E0511]: invalid monomorphization of `atomic_cxchg` intrinsic: expected bas
 LL |     intrinsics::atomic_cxchg::<_, { SeqCst }, { SeqCst }>(p, v, v);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `atomic_store` intrinsic: expected basic integer or pointer type, found `Foo`
-  --> $DIR/non-integer-atomic.rs:40:5
+error[E0511]: invalid monomorphization of `atomic_store` intrinsic: expected basic integer or pointer type, found `&dyn Fn()`
+  --> $DIR/non-integer-atomic.rs:60:5
    |
 LL |     intrinsics::atomic_store::<_, { SeqCst }>(p, v);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `atomic_cxchg` intrinsic: expected basic integer or pointer type, found `[u8; 100]`
-  --> $DIR/non-integer-atomic.rs:90:5
+error[E0511]: invalid monomorphization of `atomic_cxchg` intrinsic: expected basic integer or pointer type, found `Foo`
+  --> $DIR/non-integer-atomic.rs:50:5
    |
 LL |     intrinsics::atomic_cxchg::<_, { SeqCst }, { SeqCst }>(p, v, v);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `atomic_store` intrinsic: expected basic integer or pointer type, found `[u8; 100]`
-  --> $DIR/non-integer-atomic.rs:80:5
-   |
-LL |     intrinsics::atomic_store::<_, { SeqCst }>(p, v);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error[E0511]: invalid monomorphization of `atomic_store` intrinsic: expected basic integer or pointer type, found `bool`
-  --> $DIR/non-integer-atomic.rs:20:5
+error[E0511]: invalid monomorphization of `atomic_store` intrinsic: expected basic integer or pointer type, found `Foo`
+  --> $DIR/non-integer-atomic.rs:40:5
    |
 LL |     intrinsics::atomic_store::<_, { SeqCst }>(p, v);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `atomic_xchg` intrinsic: expected basic integer or pointer type, found `&dyn Fn()`
-  --> $DIR/non-integer-atomic.rs:65:5
-   |
-LL |     intrinsics::atomic_xchg::<_, { SeqCst }>(p, v);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
 error[E0511]: invalid monomorphization of `atomic_load` intrinsic: expected basic integer or pointer type, found `[u8; 100]`
   --> $DIR/non-integer-atomic.rs:75:5
    |
 LL |     intrinsics::atomic_load::<_, { SeqCst }>(p);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+error[E0511]: invalid monomorphization of `atomic_xchg` intrinsic: expected basic integer or pointer type, found `[u8; 100]`
+  --> $DIR/non-integer-atomic.rs:85:5
+   |
+LL |     intrinsics::atomic_xchg::<_, { SeqCst }>(p, v);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 error[E0511]: invalid monomorphization of `atomic_load` intrinsic: expected basic integer or pointer type, found `bool`
   --> $DIR/non-integer-atomic.rs:15:5
    |
 LL |     intrinsics::atomic_load::<_, { SeqCst }>(p);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `atomic_cxchg` intrinsic: expected basic integer or pointer type, found `bool`
-  --> $DIR/non-integer-atomic.rs:30:5
+error[E0511]: invalid monomorphization of `atomic_xchg` intrinsic: expected basic integer or pointer type, found `bool`
+  --> $DIR/non-integer-atomic.rs:25:5
    |
-LL |     intrinsics::atomic_cxchg::<_, { SeqCst }, { SeqCst }>(p, v, v);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     intrinsics::atomic_xchg::<_, { SeqCst }>(p, v);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `atomic_cxchg` intrinsic: expected basic integer or pointer type, found `Foo`
-  --> $DIR/non-integer-atomic.rs:50:5
+error[E0511]: invalid monomorphization of `atomic_cxchg` intrinsic: expected basic integer or pointer type, found `[u8; 100]`
+  --> $DIR/non-integer-atomic.rs:90:5
    |
 LL |     intrinsics::atomic_cxchg::<_, { SeqCst }, { SeqCst }>(p, v, v);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `atomic_xchg` intrinsic: expected basic integer or pointer type, found `Foo`
-  --> $DIR/non-integer-atomic.rs:45:5
+error[E0511]: invalid monomorphization of `atomic_store` intrinsic: expected basic integer or pointer type, found `[u8; 100]`
+  --> $DIR/non-integer-atomic.rs:80:5
    |
-LL |     intrinsics::atomic_xchg::<_, { SeqCst }>(p, v);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     intrinsics::atomic_store::<_, { SeqCst }>(p, v);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `atomic_xchg` intrinsic: expected basic integer or pointer type, found `bool`
-  --> $DIR/non-integer-atomic.rs:25:5
+error[E0511]: invalid monomorphization of `atomic_cxchg` intrinsic: expected basic integer or pointer type, found `bool`
+  --> $DIR/non-integer-atomic.rs:30:5
    |
-LL |     intrinsics::atomic_xchg::<_, { SeqCst }>(p, v);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     intrinsics::atomic_cxchg::<_, { SeqCst }, { SeqCst }>(p, v, v);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0511]: invalid monomorphization of `atomic_store` intrinsic: expected basic integer or pointer type, found `bool`
+  --> $DIR/non-integer-atomic.rs:20:5
+   |
+LL |     intrinsics::atomic_store::<_, { SeqCst }>(p, v);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 16 previous errors