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From: "hjl.tools at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c/53037] New: warn_if_not_aligned(X)
Date: Wed, 18 Apr 2012 22:59:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53037

             Bug #: 53037
           Summary: warn_if_not_aligned(X)
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: hjl.tools@gmail.com


What I'd like to have is an __attribute__((warn_if_not_aligned(X)))
which issues a warning if the object/type/field in question is not
aligned to X.  In particular, I'd like to build with:

typedef unsigned long long __u64
       __attribute__((aligned(4),warn_if_not_aligned(8)));

... in order to get a list of the places where we have misaligned 64-bit
data pieces in x86.  Then we can do Linus' requested cleanups which
ultimately aims to getting __u64 to be __attribute__((aligned(8))) even
on i386, with an explicit __compat_u64 for the places where we need to
be misaligned for legacy reasons.