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[Bug middle-end/79209] [5/6/7 Regression] AArch64: Inconsistent packed volatile bitfield accesses
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 12 Apr 2017 07:30:28 +0000
- Subject: [Bug middle-end/79209] [5/6/7 Regression] AArch64: Inconsistent packed volatile bitfield accesses
- Auto-submitted: auto-generated
- References: <bug-79209-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79209
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jakub at gcc dot gnu.org
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So shouldn't this be closed as invalid?
The documentation says:
"In some cases, such as when the @code{packed} attribute is applied to a
structure field, it may not be possible to access the field with a single
read or write that is correctly aligned for the target machine. In this
case GCC falls back to generating multiple accesses rather than code that
will fault or truncate the result at run time."
So with packed attribute, all bets are off, don't do it if you want something
consistent.