[Bug middle-end/104550] bogus warning from -Wuninitialized + -ftrivial-auto-var-init=pattern

[qinzhao at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104550

--- Comment #9 from qinzhao at gcc dot gnu.org ---
(In reply to Jakub Jelinek from comment #8)
> Well, for the .DEFERRED_INIT case if the var ends up in memory, I really
> don't see the point in any clear_padding, .DEFERRED_INIT expansion should
> just initialize the whole DECL_RTL MEM_P slot with the pattern it wants,
> trying to initialize only the non-padding bits and then only the padding
> bits next to each other is a waste of CPU cycles.
__builtin_clear_padding is ONLY emitted for pattern init to set the paddings to
zero. for zero init, the .DEFERRED_INIT expansion should block set all the
memory to
zero already. no __builtin_clear_padding is added for zero init. 

that's the reason why this bug is only exposed with
-ftrivial-auto-var-init=pattern