Automatic #[inline] for trivial wrappers

Author: saethlin

compiler/rustc_mir_transform/src/cross_crate_inline.rs

@@ -53,11 +53,19 @@ fn cross_crate_inlinable(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
     let mut checker =
         CostChecker { tcx, callee_body: mir, calls: 0, statements: 0, landing_pads: 0, resumes: 0 };
     checker.visit_body(mir);
-    checker.calls == 0
+    let is_leaf = checker.calls == 0
         && checker.resumes == 0
         && checker.landing_pads == 0
         && checker.statements
-            <= tcx.sess.opts.unstable_opts.cross_crate_inline_threshold.unwrap_or(100)
+            <= tcx.sess.opts.unstable_opts.cross_crate_inline_threshold.unwrap_or(100);
+
+    let is_wrapper = checker.calls == 1
+        && checker.resumes == 0
+        && checker.landing_pads == 0
+        && checker.statements == 0
+        && mir.basic_blocks.len() == 2;
+
+    is_leaf || is_wrapper
 }
 
 struct CostChecker<'b, 'tcx> {

tests/codegen-units/item-collection/implicit-panic-call.rs

@@ -48,6 +48,7 @@ impl Div for i32 {
 }
 
 #[allow(unconditional_panic)]
+#[inline(never)]
 pub fn foo() {
     // This implicitly generates a panic call.
     let _ = 1 / 0;

tests/codegen/call-metadata.rs

@@ -5,6 +5,7 @@
 
 #![crate_type = "lib"]
 
+#[inline(never)]
 pub fn test() {
     // CHECK: call noundef i8 @some_true(){{( #[0-9]+)?}}, !range [[R0:![0-9]+]]
     // CHECK: [[R0]] = !{i8 0, i8 3}

tests/codegen/cffi/ffi-const.rs

@@ -2,6 +2,7 @@
 #![crate_type = "lib"]
 #![feature(ffi_const)]
 
+#[inline(never)]
 pub fn bar() { unsafe { foo() } }
 
 extern "C" {

tests/codegen/cffi/ffi-pure.rs

@@ -2,6 +2,7 @@
 #![crate_type = "lib"]
 #![feature(ffi_pure)]
 
+#[inline(never)]
 pub fn bar() { unsafe { foo() } }
 
 extern "C" {

tests/codegen/cffi/ffi-returns-twice.rs

@@ -2,6 +2,7 @@
 #![crate_type = "lib"]
 #![feature(ffi_returns_twice)]
 
+#[inline(never)]
 pub fn bar() { unsafe { foo() } }
 
 extern "C" {

tests/codegen/sanitizer/cfi-emit-type-metadata-itanium-cxx-abi-generalized.rs

@@ -5,20 +5,23 @@
 
 #![crate_type="lib"]
 
+#[inline(never)]
 pub fn foo(f: fn(i32) -> i32, arg: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}foo
     // CHECK-SAME:  {{.*}}!type ![[TYPE1:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}}
     // CHECK:       call i1 @llvm.type.test(ptr {{%f|%0}}, metadata !"_ZTSFu3i32S_E.generalized")
     f(arg)
 }
 
+#[inline(never)]
 pub fn bar(f: fn(i32, i32) -> i32, arg1: i32, arg2: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}bar
     // CHECK-SAME:  {{.*}}!type ![[TYPE2:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}}
     // CHECK:       call i1 @llvm.type.test(ptr {{%f|%0}}, metadata !"_ZTSFu3i32S_S_E.generalized")
     f(arg1, arg2)
 }
 
+#[inline(never)]
 pub fn baz(f: fn(i32, i32, i32) -> i32, arg1: i32, arg2: i32, arg3: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}baz
     // CHECK-SAME:  {{.*}}!type ![[TYPE3:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}}

tests/codegen/sanitizer/cfi-emit-type-metadata-itanium-cxx-abi-normalized-generalized.rs

@@ -5,20 +5,23 @@
 
 #![crate_type="lib"]
 
+#[inline(never)]
 pub fn foo(f: fn(i32) -> i32, arg: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}foo
     // CHECK-SAME:  {{.*}}![[TYPE1:[0-9]+]]
     // CHECK:       call i1 @llvm.type.test(ptr {{%f|%0}}, metadata !"_ZTSFu3i32S_E.normalized.generalized")
     f(arg)
 }
 
+#[inline(never)]
 pub fn bar(f: fn(i32, i32) -> i32, arg1: i32, arg2: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}bar
     // CHECK-SAME:  {{.*}}![[TYPE2:[0-9]+]]
     // CHECK:       call i1 @llvm.type.test(ptr {{%f|%0}}, metadata !"_ZTSFu3i32S_S_E.normalized.generalized")
     f(arg1, arg2)
 }
 
+#[inline(never)]
 pub fn baz(f: fn(i32, i32, i32) -> i32, arg1: i32, arg2: i32, arg3: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}baz
     // CHECK-SAME:  {{.*}}![[TYPE3:[0-9]+]]

tests/codegen/sanitizer/cfi-emit-type-metadata-itanium-cxx-abi-normalized.rs

@@ -5,20 +5,23 @@
 
 #![crate_type="lib"]
 
+#[inline(never)]
 pub fn foo(f: fn(i32) -> i32, arg: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}foo
     // CHECK-SAME:  {{.*}}!type ![[TYPE1:[0-9]+]] !type !{{[0-9]+}}
     // CHECK:       call i1 @llvm.type.test(ptr {{%f|%0}}, metadata !"_ZTSFu3i32S_E.normalized")
     f(arg)
 }
 
+#[inline(never)]
 pub fn bar(f: fn(i32, i32) -> i32, arg1: i32, arg2: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}bar
     // CHECK-SAME:  {{.*}}!type ![[TYPE2:[0-9]+]] !type !{{[0-9]+}}
     // CHECK:       call i1 @llvm.type.test(ptr {{%f|%0}}, metadata !"_ZTSFu3i32S_S_E.normalized")
     f(arg1, arg2)
 }
 
+#[inline(never)]
 pub fn baz(f: fn(i32, i32, i32) -> i32, arg1: i32, arg2: i32, arg3: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}baz
     // CHECK-SAME:  {{.*}}!type ![[TYPE3:[0-9]+]] !type !{{[0-9]+}}

tests/codegen/sanitizer/cfi-emit-type-metadata-itanium-cxx-abi.rs

@@ -5,20 +5,23 @@
 
 #![crate_type="lib"]
 
+#[inline(never)]
 pub fn foo(f: fn(i32) -> i32, arg: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}foo
     // CHECK-SAME:  {{.*}}!type ![[TYPE1:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
     // CHECK:       call i1 @llvm.type.test(ptr {{%f|%0}}, metadata !"_ZTSFu3i32S_E")
     f(arg)
 }
 
+#[inline(never)]
 pub fn bar(f: fn(i32, i32) -> i32, arg1: i32, arg2: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}bar
     // CHECK-SAME:  {{.*}}!type ![[TYPE2:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
     // CHECK:       call i1 @llvm.type.test(ptr {{%f|%0}}, metadata !"_ZTSFu3i32S_S_E")
     f(arg1, arg2)
 }
 
+#[inline(never)]
 pub fn baz(f: fn(i32, i32, i32) -> i32, arg1: i32, arg2: i32, arg3: i32) -> i32 {
     // CHECK-LABEL: define{{.*}}baz
     // CHECK-SAME:  {{.*}}!type ![[TYPE3:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}