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how to implement pipeline errata?
- From: Spundun Bhatt <spundun at ISI dot EDU>
- To: gcc at gcc dot gnu dot org
- Date: 20 Mar 2003 16:20:40 -0800
- Subject: how to implement pipeline errata?
- Organization:
Hi gcc
I am looking to implement a workaround in gcc backend to avoid an
instruction sequence which produces erroneous output due to an error in
pipeline forwarding.
Namely if I have an arithmatic instruciont
'arith Rd, R1,R2'
then I can not use instruction
'ST Rd,R3,offset' in the next to instruction slots.
>From what I read, peep-hole,splits and function unit definitions seem to
work for optimizations and only try to avoid these occurances rather
than force to avoid the sequence at any cost, which is what I want.
I thought about define_delay as an alternative but that looks so
complecated because of the huge number of arithmatic instructions.. I
will have to "semi-handcode" nops at all the places...
I am sure all architectures have gone through similar erroneous chips,
so I was hoping gcc might have some provision for it.
Thanx again for your help
Spundun