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Re: m68k reloc types
Roman Zippel <email@example.com> writes:
> It's not the same, gcc can use it to access local variables without
> creating a got entry. m68k currently doesn't do it, but it would be nice,
> if we could. Simply compare the generated code for something like
> "puts("foo");" for i386 and m68k.
For strings or other read-only data you can just use pc-relative
> Anyway, the cost of a memory indirect accesses depends on the cpu,
> 6800 would benefit from this.
Are you sure about that? AFAIK especially on the 040 and 060 the memory
indirect addressing modes are slower than going through a temporary
register. For example on the 68040, for `add Rn,([bd,BR,Xn])' calculating
the destination address takes a whopping 10 cycles and additionally 9
cycles to execute the insn, whereas for simple addressing modes at most 2
cycles are needed for both. Thus memory indirect is a major loss. On the
060 the difference is much smaller, but still significant.
Andreas Schwab, SuSE Labs, firstname.lastname@example.org
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
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