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Re: Problems with i386_register_convert_to_virtual
- To: Eli Zaretskii <eliz at is dot elta dot co dot il>
- Subject: Re: Problems with i386_register_convert_to_virtual
- From: Robert Hoehne <robert dot hoehne at gmx dot net>
- Date: Sun, 6 Aug 2000 10:52:41 +0200
- CC: gdb-patches at sourceware dot cygnus dot com
- Organization: none provided
- References: <200008052252.AAA22962@robby.dittmannsdorf.de> (message from Robert Hoehne on Sun, 6 Aug 2000 00:54:05 +0200)
> > From: Robert Hoehne <robert.hoehne@gmx.net>
> > Date: Sun, 6 Aug 2000 00:54:05 +0200
> >
> > void
> > i386_register_convert_to_virtual (int regnum, struct type *type,
> > char *from, char *to)
> > {
> > /* Copy straight over, but take care of the padding. */
> > memcpy (to, from, FPU_REG_RAW_SIZE);
> > memset (to + FPU_REG_RAW_SIZE, 0, TYPE_LENGTH (type) - FPU_REG_RAW_SIZE);
> > }
> >
> > -- snip --
> >
> > When I see correct, this function assumes only to be called
> > for long double types.
>
> Yes.
>
> > But since this function is called using the
> > REGISTER_CONVERT_TO_VIRTUAL macro, it can get be called for any
> > (register) type.
>
> Do we have any other registers that have different virtual and raw
> representations? I thought that FP registers were the only ones.
>
> I agree that it would be good to have some protection against invalid
> use of REGISTER_CONVERT_TO_VIRTUAL, but the case you are describing
> looks like a call to the wrong function, which valid code should not
> do.
>
After more searching in the GDB code and docs, I found the macro
REGISTER_CONVERTIBLE which tells, if a register have different
raw and virtual sizes. This macro is also used for instance in findvar.c
to decide, if REGISTER_CONVERT_TO_VIRTUAL is called or a
simple memcpy is done. In my Opionion either this should be documented
in the description for REGISTER_CONVERT_TO_VIRTUAL that
this macro should be called only, when REGISTER_CONVERTIBLE
returns true, or that logic should be included in the convert macro.
Robert
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