On 08/11/16 06:30, Dennis wrote:
Gennady Agranov wrote:
Hi,

I have submitted a bug - http://bugs.freepascal.org/view.php?id=30872
(misaligned data exception on ARMv7)

And this big was resolved as "won't fix"

1. I understand that one has to work really hard to encounter this bug
- and there are easy workarounds, but it there are also different ways
to resolve this bug - e.g. just giving a hint would suffice - IMHO

a compiler warning or hint would be nice.

Alignment was a major issue back when SPARC was still a realistically viable platform.

The Solaris and C communities appeared to take the line that a correct compiler "could not" generate unaligned accesses, although they held off clarifying whether "could" in that context means "if it does it's an error" or "it must rearrange data to avoid an error".

I believe that Solaris and in some cases Linux can handle unaligned accesses in the kernel, although there's obviously a significant performance penalty.

Working on the principle that the FPC community would do well to avoid antagonising people with expectations derived from experience with other compilers and languages, I'd suggest that a warning when potentially-misaligned code is generated is in order.

--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]
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