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...e problem arises because after changing %b to %a in LLVM, the load from virtual pointer can be devirtualized to different type. %vtable_a = load %a, !invariant.group;;;; %a == %b%bool = icmp %a, %bbr %bool, %if, %afterif:; if this will be changed to %a, then the optimizer will be able to replace ; %vtable_b with %vtable_a%vtable_b = load %b, !invariant.groupFor other corner cases check out appendix.SolutionThe proposed solution is to model pointers to dynamic types as “fat pointers”. We can think of them as pointers that also store the current dynamic type. Virtual calls would consist of virtual point...

...VM, the load from virtual pointer can be devirtualized to different type. > > %vtable_a = load %a, !invariant.group > ;;; > ; %a == %b > %bool = icmp %a, %b > br %bool, %if, %after > if: > ; if this will be changed to %a, then the optimizer will be able to replace > ; %vtable_b with %vtable_a > %vtable_b = load %b, !invariant.group > > For other corner cases check out appendix. > Solution > The proposed solution is to model pointers to dynamic types as “fat pointers”. We can think of them as pointers that also store the current dynamic type. Virtual calls...

...ause after changing %b to %a in LLVM, the load from virtual pointer can > be devirtualized to different type. %vtable_a = load %a, > !invariant.group;;;; %a == %b%bool = icmp %a, %bbr %bool, %if, %afterif:; > if this will be changed to %a, then the optimizer will be able to replace ; > %vtable_b with %vtable_a%vtable_b = load %b, !invariant.groupFor other > corner cases check out appendix.SolutionThe proposed solution is to model > pointers to dynamic types as “fat pointers”. We can think of them as > pointers that also store the current dynamic type. Virtual calls would > cons...