Assertion failed: !NodePtr->isKnownSentinel() with boost::intrusive_ptr on Windows

[atnnn]

Bugzilla Link	45033
Resolution	FIXED
Resolved on	Mar 02, 2020 02:43
Version	trunk
OS	Windows NT
Blocks	#43900
Attachments	Minimal example, Build log, Run script
CC	@DougGregor,@zmodem,@zygoloid,@rnk

Extended Description

The following code seems to cause clang and clang-cl, 9.0.0 and trunk, to crash:

intrusive_ptr<C> a;
try {
    a = mk();
    mk();
}
catch (...) {
}

Debug logs show

INSTCOMBINE ITERATION #​1 on ?crash@@YAXXZ
IC: ADDING: 27 instrs to worklist
IC: Visiting:   %call1 = invoke %struct.C* @"?mk@@YAPEAUC@@XZ"()
          to label %invoke.cont2 unwind label %catch.dispatch
IC: Visiting:   %a.sroa.0.0 = phi i64 [ %0, %invoke.cont2 ], [ 0, %entry ]
IC: Visiting:   %1 = catchswitch within none [label %catch] unwind label %ehcleanup
IC: Visiting:   %2 = catchpad within %1 [i8* null, i32 64, i8* null]
IC: Visiting:   catchret from %2 to label %try.cont
IC: Visiting:   %a.sroa.0.1 = phi i64 [ %0, %invoke.cont2 ], [ %a.sroa.0.0, %catch ]
IC: ADD:   %a.sroa.0.1.ptr = phi %struct.C* 
Assertion failed: !NodePtr->isKnownSentinel(), file C:\src\llvm_package_2663a25f\llvm-project\llvm\include\llvm/ADT/ilist_iterator.h, line 139

I've attached the logs and full trimmed down source.

Thanks.

[rnk]

I suspect the problematic code was introduced here (2017):
https://reviews.llvm.org/D37832#inline-686315

It assumes getFirstInsertionPt always points to an Instruction*, and not an end iterator.

[rnk]

Proposed fix: https://reviews.llvm.org/D75381

[rnk]

Pushed as 1adbe86.

Marked as a 10.0 blocker to see if Hans wants to merge it. I think it's fairly safe, it adds some conditions in which instcombine will not attempt to do a transform.

[zmodem]

Pushed as 1adbe86.

Marked as a 10.0 blocker to see if Hans wants to merge it. I think it's
fairly safe, it adds some conditions in which instcombine will not attempt
to do a transform.

Okay, it seems safe enough. Pushed to 10.x as 0bf4795.

Please let me know if there are any follow-ups.