Re: [PATCH] tree-optimization/107833 - invariant motion of uninit uses

[Jeff Law <jeffreyalaw@gmail.com>]

On 12/2/22 07:30, Richard Biener via Gcc-patches wrote:
> The following fixes a wrong-code bug caused by loop invariant motion
> hoisting an expression using an uninitialized value outside of its
> controlling condition causing IVOPTs to use that to rewrite a defined
> value.  PR107839 is a similar case involving a bogus uninit diagnostic.
> 
> Bootstrapped and tested on x86_64-unknown-linux-gnu.
> 
> OK?
> 
> Thanks,
> Richard.
> 
> 	PR tree-optimization/107833
> 	PR tree-optimization/107839
> 	* cfghooks.cc: Include tree.h.
> 	* tree-ssa-loop-im.cc (movement_possibility): Wrap and
> 	make stmts using any ssa_name_maybe_undef_p operand
> 	to preserve execution.
> 	(loop_invariant_motion_in_fun): Call mark_ssa_maybe_undefs
> 	to init maybe-undefined status.
> 	* tree-ssa-loop-ivopts.cc (ssa_name_maybe_undef_p,
> 	ssa_name_set_maybe_undef, ssa_name_any_use_dominates_bb_p,
> 	mark_ssa_maybe_undefs): Move ...
> 	* tree-ssa.cc: ... here.
> 	* tree-ssa.h (ssa_name_any_use_dominates_bb_p,
> 	mark_ssa_maybe_undefs): Declare.
> 	(ssa_name_maybe_undef_p, ssa_name_set_maybe_undef): Define.
> 
> 	* gcc.dg/torture/pr107833.c: New testcase.
> 	* gcc.dg/uninit-pr107839.c: Likewise.
OK.

Jeff