[U-Boot] [PATCH 2/3] md5: Fix gcc-4.7 build problem in md5

[Wolfgang Denk <wd@denx.de>]

Dear Pavel,

In message <20121105200340.GA15821@xo-6d-61-c0.localdomain> you wrote:
> 
> > > >  	/* Append length in bits and transform */
> > > > -	ctx->in32[14] = ctx->bits[0];
> > > > -	ctx->in32[15] = ctx->bits[1];
> > > > +	memcpy(ctx->in + 14 * sizeof(__u32), ctx->bits, 2 * sizeof(__u32));
> > > 
> > > This makes the code actually unreadable.  Please add at least a
> > > comment what this is doing.
> > 
> > Actually I think this shoul dbe split into two memcpy commands, using
> > the addresses of the respective array elements directly, without such
> > manual pointer arithmetics.
> 
> I guess bigger question is: why does gcc miscompile that, and is it
> guaranteed that it will not miscompile the memcpy?

I did not see Simon mentioning anythin about incorrect compilation.
My understanding was that it's just the usual "dereferencing
type-punned pointer" warnings issue.


Simon, what was the actual problem this was supposed to fix?

Best regards,

Wolfgang Denk

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