Help with reload bug, please

[Jeff Law]

On 01/23/15 14:46, Andrew Stubbs wrote:
>
> SECONDARY_INPUT_RELOAD_CLASS is another missed opportunity. Just like
> the legitimate address stuff, this has checks for the various VFP
> classes, but reload detects the class in the same flawed way, so an
> integer reload gives GENERAL_REGS even when the destination is VFP.
> Within the macro there's no way to see the whole insn.
You have to be conservative here. It's part of the fundamental design 
issue you're trying to work around.
>
>> We may have used special constraints as well to allow loads/stores of
>> integer registers in FP modes to use the larger offset.
>
> Do you have an example?
The entire PA port? :-)

Note this was a huge issue on the PA because integer multiply was 
implemented in the FP unit, so we regularly had integer mode accesses to 
FP registers.  If you don't have similar needs, I think there's some 
further macros you can define to discourage that behaviour.  I just 
can't remember what they are.

I'd focus on the bits that determine that an address is legitimate or 
not and the secondary reload mechanism.

Also note that the allowed offsets were increased in the PA 2.0 so you 
have to filter out that while you're reading.

Jeff