8500 loader: need __divmoddi4 and __udivmoddi4 | Review Request

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Information
Submitter:	Toomas Soome
Repository:	illumos-gate
Branch:
Bugs:	8500
Depends On:
Commit:	b8ca630...
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Groups:	general
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Description

8500 loader: need __divmoddi4 and __udivmoddi4

Testing Done

no targeted test, just boot. Need to devise something better, likely some nice forth script:)

Issues

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All Issues: 1

Description	From	Last Updated
So, the implementation of __divmoddi4 matches most of those that we find in other compiler runtimes. However, in most of ...	Robert Mustacchi	Sept. 18, 2017, 8:36 a.m.

usr/src/boot/lib/libstand/qdivrem.c (Diff revision 1)

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So, the implementation of __divmoddi4 matches most of those that we find in other compiler runtimes. However, in most of the others, __udivmoddi4 seems more complicated. Is that because the hard work is actually all in __qdivrem()? I haven't quite convinced myself that they are logically equivalent to say the llvm compiler-rt one.

Yuri Pankov July 15, 2017, 10:32 p.m.

I did look at compiler-rt ones when just saw this review and they are exactly the same. Are we looking at the different source?

Robert Mustacchi July 15, 2017, 10:35 p.m.

Hmm. I'm now suspicious that the one I found was from a much older version of llvm, as this came from apple.com. Yuri, where did you find the one you were looking at?

Toomas Soome July 15, 2017, 10:42 p.m.

at least one most certainly did look like the same but I did not spend too much time on it.

Toomas Soome Sept. 18, 2017, 8:35 a.m.

Yes, one confusion is about where is the actual "worker" implemented - I did rename __qdivrem to __udivmoddi4 to fix it + we do not really need the extra small wrapper. There seem to be alternate references, one is referring to implementation in PPC manual (https://cr.yp.to/2005-590/powerpc-cwg.pdf), another is referring directly to Knuth's vol. 2.