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Re^12: Perl 5 Optimizing Compiler, Part 4: LLVM Backend?

by dave_the_m (Prior)
on Aug 29, 2012 at 20:47 UTC ( #990566=note: print w/replies, xml ) Need Help??


in reply to Re^11: Perl 5 Optimizing Compiler, Part 4: LLVM Backend?
in thread Perl 5 Optimizing Compiler, Part 4: LLVM Backend?

I really do not understand why the perl context cannot be retrieved from TLS when it is needed, rather than passed around like a baton?
Because on linux pthreads at least, retrieving a value from TLS is very expensive (using the "match the SP to a thread" trick). Passing an extra parameter is a lot quicker.

As to why they don't reserve a register for it, you'd have to ask them. But I would speculate that it boils down to the fact that you can't assume that all code from all libraries compiled by all the different possible compilers on all the different platforms all know and agree that they're not allowed to touch register X. If this had been agreed on day 1, then maybe; not so much now.

Dave.

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[LanX]: M-x untabify
[choroba]: I don't think they're multiple people. I was told "he or she" sounds old-fashioned and "they" is the way to say it
[pryrt]: Those others were definitely offensive or unequivocably rude, I agree.
[choroba]: (well, it comes from the 14th century, so labelling it as "modern" doesn't seem appropriate)
[Your Mother]: "They" is becoming accepted but it irritates me sometimes. I tend to just pick she or he randomly or try to use "one."
LanX thinks it is appropriate here :)
[Your Mother]: They would think so.
[jdporter]: ok, I need a recipe for piping lines "through" an external program which is itself a filter
[jdporter]: without using a tmp file
[1nickt]: tobyink perl -MTypes::Standard= is_Int -Mstrict -wE 'say 1 if is_Int 1.0'

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