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From: "qinzhao at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug middle-end/104550] bogus warning from -Wuninitialized +
 -ftrivial-auto-var-init=pattern
Date: Wed, 16 Feb 2022 16:57:55 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104550

--- Comment #11 from qinzhao at gcc dot gnu.org ---
(In reply to Jakub Jelinek from comment #10)
> Even in that case, filling the memory with pattern & mask instead of fill=
ing
> the memory with pattern + __builtin_clear_padding afterwards seems like a
> win.

So, you mean It's better to do the following for pattern init:

1. add call to .DEFERRED_INIT(, pattern, ) during gimplification;
2. during RTL expansion, fill the memory with pattern & mask if the variabl=
e is
in memory.=20

how to implement "fill the memory with pattern & mask" during RTL expansion?
currently, we use memset to fill the memory when the variable is in memory,
pattern & mask might not fit to a BYTE-repeatable pattern that can be used =
for
memset?=