http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46317
Summary: Incorrect construction vtable on ARM in case of
diamond shaped virtual inheritance
Product: gcc
Version: 4.2.1
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: end...@gmail.com
Created attachment 22295
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=22295
Code that triggers the issue on ARM
This problem appears on ARM (not x86), with -O > 0.
The register R1 holding the pointer to the construction vtable for the
Parent-in-Child is actually pointing to the wrong Parent-in-Child vtable:
Let's assume we have a virtual base class A, two derived class B and C
virtually inheriting from A and a final class D derived virtually from B and
normally from C.
When instantiating D, the CTOR for B is called with R1 pointing to the
construction vtable for B-in-D instead of the one for C-in-D, which thus make
the program crash since it tries to access an uninitialized element of the
vtable for B when trying to access elements in C.
A work-around for this issue is to compile with -fno-toplevel-reorder. It fixes
the problem for all optimizations level
This issue seems to be linked to #41354.
