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From: "david at westcontrol dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/105523] Wrong warning array subscript [0] is outside
 array bounds
Date: Tue, 25 Apr 2023 07:30:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105523

--- Comment #21 from David Brown <david at westcontrol dot com> ---
(In reply to Andrew Pinski from comment #1)
> --param=3Dmin-pagesize=3D should be set to 0 for avr as zero is a valid a=
ddress.

Is there any convenient description of "min-pagesize" ?  The user manual is
unhelpful: "Minimum page size for warning purposes."  Your comment here
suggests it is connected to whether zero is a valid address or not, which d=
oes
not sound at all related to the issue here.  (But you are correct that for =
the
AVR, and many embedded systems, accessing memory at address zero is valid.)

Testing (on godbolt) shows that setting "--param=3Dmin-pagesize=3D0" does s=
top this
warning triggering.  But this is an issue that affects all systems for which
the user might want to convert a fixed value to an address - i.e., all embe=
dded
systems, and perhaps device drivers or other low-level code on bigger syste=
ms.=20
Is setting "min-pagesize" to 0 actually a fix, or is it a workaround, and w=
ill
it have other effects on static warning checks and/or code generation?

A workaround is, of course, helpful - especially since this can be added to
peoples CFLAGS list.=