[Bug translator/2438] Can't resolve $fd argument for sys_readv and sys_writev on ppc64

["fche at redhat dot com" <sourceware-bugzilla@sourceware.org>]

------- Additional Comments From fche at redhat dot com  2006-05-08 15:17 -------
(In reply to comment #3)
> It seems such case cannot be avoided completely. In powerpc, first
> arguments are always passed in registers, and there's no reason
> for the compiler to refuse to put a modification instruction at the 
> probe address.

You mean, there is no need to look for a prologue end?  Yes, we would
prefer not to, but that requires correct location list information from
the compiler to cover the function.


> the instruction at the "pc" address will modify the incoming argument 
> register therfore make related location list entry invalid, while it 
> was still valid at the preceding address "pc-4".

This sounds like a compiler bug.
 
> Since our pre-handler will be executed before this instruction
> at "pc", the location list entry should also be valid at that time.

The definition of the location list entry for an instruction address X
is that, at the beginning of the execution of that instruction, the
respective variables are at their respective locations.  So it should not
matter how large the breakpoint instructions are, or what the instruction
at X would have done.

Roland/Alex, please clarify / correct me.


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http://sourceware.org/bugzilla/show_bug.cgi?id=2438

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