Auto merge of #88243 - nikic:newpm-2, r=nagisa

Enable new pass manager with LLVM 13

The new pass manager is enabled by default in clang since Clang/LLVM 13. Per the recent discussion on llvm-dev (https://lists.llvm.org/pipermail/llvm-dev/2021-August/152305.html) the legacy pass manager will be unmaintained in LLVM 14 and removed entirely in LLVM 15.

This switches us to use the new pass manager if LLVM >= 13 is used. It's possible to still use the old pass manager using `-Z new-llvm-pass-manager=no`.

1 files changed, 10 insertions, 5 deletions

diff --git a/src/test/codegen/panic-in-drop-abort.rs b/src/test/codegen/panic-in-drop-abort.rs
index 62d093507dd..39f73c4e396 100644
--- a/src/test/codegen/panic-in-drop-abort.rs
+++ b/src/test/codegen/panic-in-drop-abort.rs
@@ -1,8 +1,17 @@
-// compile-flags: -Z panic-in-drop=abort -O
+// compile-flags: -Z panic-in-drop=abort -O -Z new-llvm-pass-manager=no
 
 // Ensure that unwinding code paths are eliminated from the output after
 // optimization.
 
+// This test uses -Z new-llvm-pass-manager=no, because the expected optimization does not happen
+// on targets using SEH exceptions (i.e. MSVC) anymore. The core issue is that Rust promises that
+// the drop_in_place() function can't unwind, but implements it in a way that *can*, because we
+// currently go out of our way to allow longjmps, which also use the unwinding mechanism on MSVC
+// targets. We should either forbid longjmps, or not assume nounwind, making this optimization
+// incompatible with the current behavior of running cleanuppads on longjmp unwinding.
+
+// CHECK-NOT: {{(call|invoke).*}}should_not_appear_in_output
+
 #![crate_type = "lib"]
 use std::any::Any;
 use std::mem::forget;
@@ -35,8 +44,6 @@ impl Drop for AssertNeverDrop {
     }
 }
 
-// CHECK-LABEL: normal_drop
-// CHECK-NOT: should_not_appear_in_output
 #[no_mangle]
 pub fn normal_drop(x: ExternDrop) {
     let guard = AssertNeverDrop;
@@ -44,8 +51,6 @@ pub fn normal_drop(x: ExternDrop) {
     forget(guard);
 }
 
-// CHECK-LABEL: indirect_drop
-// CHECK-NOT: should_not_appear_in_output
 #[no_mangle]
 pub fn indirect_drop(x: Box<dyn Any>) {
     let guard = AssertNeverDrop;