#5615: [with patch, not ready for review] use labels-as-values for fast_callable
under gcc
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Reporter: cwitty | Owner: cwitty
Type: enhancement | Status: new
Priority: major | Milestone: sage-wishlist
Component: basic arithmetic | Keywords:
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This patch uses gcc's labels-as-values extension to (theoretically) speed
up the instruction dispatch. Unfortunately, on my 32-bit x86 laptop, it's
about the same speed as before the patch (maybe a little slower). I think
this is due to poor instruction scheduling (that gcc can't fix with -fno-
strict-aliasing), but trying to move the instructions around by hand makes
the problem worse (it adds register pressure, which makes the register
allocator do very bad things on 32-bit x86).
Doctests do NOT pass, and the patch is not fully documented. (I believe
the patch works; the doctests that fail are looking at fast_callable
internals that changed.)
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5615>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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