Build gcc question

Build gcc question

[Gary Oblock]

I've got a really amazingly bizarre bug, when running my modified
gcc under gdb, I see some bewildering behavior. So, before I start
debugging at the assembly level, I'd like to see some .s files.
This led me to try adding "-save-temps" to the CFLAGS and
CXXFLAGS on the make command line. This in turn led to plethora
of different assembly errors. Is this supposed to happen
and is there another way to preserve .s files?

Thanks,

Gary


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Re: s390 port

[Joe Monk]

It is unclear how this would even work.

For instance, the LA instruction clears the top bit.

Also, instructions like LPR, LNR, BXLE, BXH all treat the value in the
register as signed, so the top bit is not available.

Joe

Re: s390 port

[Paul Edwards]

Hi Joe.

Thanks for your comments.

> It is unclear how this would even work. 

> For instance, the LA instruction clears the top bit.

In AM64, LA does not clear any bits.

> Also, instructions like LPR, LNR,

These operate on data registers, not addresses,
and will continue to work unchanged.

> BXLE, BXH all treat the value in the register as signed,
> so the top bit is not available.

These are already a problem if you are putting
addresses in them and it is approaching the 2 GiB
mark. The POP has a special mention of that.

Fun fact: The z/Arch POP has the same problem with
the G version of those instructions, when it hits the
63-bit mark, but the POP incorrectly states that the
problem occurs near the 64-bit mark. I reported the
problem with the POP but nothing seems to have
been done.

The solution is to drop these instructions from the
repertoire. C-generated assembler for both i370 and
s390 targets does not use these.

BFN. Paul.