[Bug target/109535] internal compiler error: in finalize_new_accesses, at rtl-ssa/changes.cc:471

["pan2.li at intel dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109535

Li Pan <pan2.li at intel dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |pan2.li at intel dot com

--- Comment #6 from Li Pan <pan2.li at intel dot com> ---
(In reply to rsandifo@gcc.gnu.org from comment #2)
> The assert in question fires if the pass creates an instruction
> whose pattern uses a register or memory and if the pass doesn't
> provide associated use information.  Let me know if it looks like
> a bug in rtl-ssa rather than a bug in the vsetvl pass.

Just sync with juzhe for the assertion failure. It tries to find the regno=8 in
the shared_uses=[0, 66, 67] in function_info::finalize_new_accesses. And then
it will hit the NOT_NULL assert.

While in the pass_vsetvl::cleanup_insns, it will clean up the AVL use similar
as below.

AVL regno 8
Before Uses Reg Nums => [0,8,66,67,]
After  Uses Reg Nums => [0,66,67,]

After vsetvl, the avl-related use, aka use Regno=8 will be removed, because the
instruction pattern in RVV will eliminate the dependencies of the operand.

Juzhe can help to correct me if any misleading or misunderstanding.

Thanks.