Auto merge of #41920 - arielb1:inline-drop, r=eddyb

remove the #[inline] attribute from drop_in_place

Apparently LLVM has exponential code growth while inlining landing pads
if that attribute is present.

Fixes #41696.

beta-nominating  because regression.
r? @eddyb

src/libcore/ptr.rs

@@ -56,7 +56,6 @@ pub use intrinsics::write_bytes;
 /// invalid pointers, types, and double drops.
 #[stable(feature = "drop_in_place", since = "1.8.0")]
 #[lang="drop_in_place"]
-#[inline]
 #[allow(unconditional_recursion)]
 pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
     // Code here does not matter - this is replaced by the

src/librustc_trans/common.rs

@@ -537,6 +537,12 @@ pub fn requests_inline<'a, 'tcx>(
     if is_inline_instance(tcx, instance) {
         return true
     }
+    if let ty::InstanceDef::DropGlue(..) = instance.def {
+        // Drop glue wants to be instantiated at every translation
+        // unit, but without an #[inline] hint. We should make this
+        // available to normal end-users.
+        return true
+    }
     attr::requests_inline(&instance.def.attrs(tcx)[..])
 }
 

src/test/run-pass/issue-41696.rs

@@ -0,0 +1,61 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// this used to cause exponential code-size blowup during LLVM passes.
+// min-llvm-version 3.9
+
+#![feature(test)]
+
+extern crate test;
+
+struct MayUnwind;
+
+impl Drop for MayUnwind {
+    fn drop(&mut self) {
+        if test::black_box(false) {
+            panic!()
+        }
+    }
+}
+
+struct DS<U> {
+    may_unwind: MayUnwind,
+    name: String,
+    next: U,
+}
+
+fn add<U>(ds: DS<U>, name: String) -> DS<DS<U>> {
+    DS {
+        may_unwind: MayUnwind,
+        name: "?".to_owned(),
+        next: ds,
+    }
+}
+
+fn main() {
+    let deserializers = DS { may_unwind: MayUnwind, name: "?".to_owned(), next: () };
+    let deserializers = add(deserializers, "?".to_owned());
+    let deserializers = add(deserializers, "?".to_owned());
+    let deserializers = add(deserializers, "?".to_owned());
+    let deserializers = add(deserializers, "?".to_owned());
+    let deserializers = add(deserializers, "?".to_owned());
+    let deserializers = add(deserializers, "?".to_owned());
+    let deserializers = add(deserializers, "?".to_owned()); // 0.7s
+    let deserializers = add(deserializers, "?".to_owned()); // 1.3s
+    let deserializers = add(deserializers, "?".to_owned()); // 2.4s
+    let deserializers = add(deserializers, "?".to_owned()); // 6.7s
+    let deserializers = add(deserializers, "?".to_owned()); // 26.0s
+    let deserializers = add(deserializers, "?".to_owned()); // 114.0s
+    let deserializers = add(deserializers, "?".to_owned()); // 228.0s
+    let deserializers = add(deserializers, "?".to_owned()); // 400.0s
+    let deserializers = add(deserializers, "?".to_owned()); // 800.0s
+    let deserializers = add(deserializers, "?".to_owned()); // 1600.0s
+    let deserializers = add(deserializers, "?".to_owned()); // 3200.0s
+}