Don't add inlinehint to big closures

Author: saethlin

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -337,12 +337,14 @@ pub fn from_fn_attrs<'ll, 'tcx>(
         OptimizeAttr::Speed => {}
     }
 
-    let inline =
-        if codegen_fn_attrs.inline == InlineAttr::None && instance.def.requires_inline(cx.tcx) {
-            InlineAttr::Hint
-        } else {
-            codegen_fn_attrs.inline
-        };
+    let inline = if codegen_fn_attrs.inline == InlineAttr::None
+        && (cx.tcx.cross_crate_inlinable(instance.def_id())
+            || matches!(instance.def, rustc_middle::ty::InstanceKind::CloneShim(..)))
+    {
+        InlineAttr::Hint
+    } else {
+        codegen_fn_attrs.inline
+    };
     to_add.extend(inline_attr(cx, inline));
 
     // The `uwtable` attribute according to LLVM is:

compiler/rustc_middle/src/ty/instance.rs

@@ -300,10 +300,7 @@ impl<'tcx> InstanceKind<'tcx> {
             ty::InstanceKind::ThreadLocalShim(_) => return false,
             _ => return true,
         };
-        matches!(
-            tcx.def_key(def_id).disambiguated_data.data,
-            DefPathData::Ctor | DefPathData::Closure
-        )
+        matches!(tcx.def_key(def_id).disambiguated_data.data, DefPathData::Ctor)
     }
 
     /// Returns `true` if the machine code for this instance is instantiated in

compiler/rustc_mir_transform/src/cross_crate_inline.rs

@@ -25,8 +25,8 @@ fn cross_crate_inlinable(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
 
     // This just reproduces the logic from Instance::requires_inline.
     match tcx.def_kind(def_id) {
-        DefKind::Ctor(..) | DefKind::Closure => return true,
-        DefKind::Fn | DefKind::AssocFn => {}
+        DefKind::Ctor(..) => return true,
+        DefKind::Fn | DefKind::AssocFn | DefKind::Closure => {}
         _ => return false,
     }
 

tests/coverage/closure.cov-map

@@ -31,18 +31,16 @@ Number of file 0 mappings: 24
     = (c0 - c1)
 - Code(Counter(0)) at (prev + 1, 5) to (start + 3, 2)
 
-Function name: closure::main::{closure#0}
-Raw bytes (26): 0x[01, 01, 01, 01, 05, 04, 01, 28, 05, 02, 14, 05, 02, 15, 02, 0a, 02, 02, 0a, 00, 0b, 01, 01, 09, 01, 06]
+Function name: closure::main::{closure#0} (unused)
+Raw bytes (24): 0x[01, 01, 00, 04, 00, 28, 05, 02, 14, 00, 02, 15, 02, 0a, 00, 02, 0a, 00, 0b, 00, 01, 09, 01, 06]
 Number of files: 1
 - file 0 => global file 1
-Number of expressions: 1
-- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
+Number of expressions: 0
 Number of file 0 mappings: 4
-- Code(Counter(0)) at (prev + 40, 5) to (start + 2, 20)
-- Code(Counter(1)) at (prev + 2, 21) to (start + 2, 10)
-- Code(Expression(0, Sub)) at (prev + 2, 10) to (start + 0, 11)
-    = (c0 - c1)
-- Code(Counter(0)) at (prev + 1, 9) to (start + 1, 6)
+- Code(Zero) at (prev + 40, 5) to (start + 2, 20)
+- Code(Zero) at (prev + 2, 21) to (start + 2, 10)
+- Code(Zero) at (prev + 2, 10) to (start + 0, 11)
+- Code(Zero) at (prev + 1, 9) to (start + 1, 6)
 
 Function name: closure::main::{closure#10} (unused)
 Raw bytes (10): 0x[01, 01, 00, 01, 00, 9b, 01, 07, 00, 21]