[Issue 16513] Speed up TemplateInstance.findExistingInstance, hash by mangling

2016-10-11 Thread via Digitalmars-d-bugs 
https://issues.dlang.org/show_bug.cgi?id=16513

ZombineDev  changed:

   What|Removed |Added

 CC||petar.p.ki...@gmail.com

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[Issue 16513] Speed up TemplateInstance.findExistingInstance, hash by mangling

2016-09-20 Thread via Digitalmars-d-bugs 
https://issues.dlang.org/show_bug.cgi?id=16513

--- Comment #4 from Martin Nowak  ---
(In reply to uplink.coder from comment #2)
> Hash collisions will happen!
> We need a way to speed up those equals compares in rootObject.
> I'll look if I can find a good way to gradually remove the virtual calls.

This whole RootObject hashing/comparison is a kludge when we can cheaply
generate a unique string.

>   IsVariable!(Simulated_Object_966)
>   IsMemberVariable!(Simulated_Object_975)
>   isSomeFunction!(Simulated_Object_573)
> 
> Those SHOULD produce the same hash they work on the same types!

Yes right, only the arguments are part of the hash.

> I am of the impression that template-inlining can help here.

True for isSomeFunction and it does work, the other 2 take alias parameters
(via variadic arguments) and create one instance per object (w/ the same hash).

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[Issue 16513] Speed up TemplateInstance.findExistingInstance, hash by mangling

2016-09-20 Thread via Digitalmars-d-bugs 
https://issues.dlang.org/show_bug.cgi?id=16513

--- Comment #3 from Martin Nowak  ---
Managed to speed up the test case from 1.8s to 1.2s, almost completely
eliminating the lookup cost.
Still need to fix a few issues, the cppmangler thinks member variables are
static, we might not want to fill the idPool with unused identifiers (would
save some memory to just compute the hash), needs some more testing whether the
mangling is really bijective, if so we could only hash the string and ditch the
TemplateInstance.compare code.

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[Issue 16513] Speed up TemplateInstance.findExistingInstance, hash by mangling

2016-09-20 Thread via Digitalmars-d-bugs 
https://issues.dlang.org/show_bug.cgi?id=16513

--- Comment #2 from uplink.co...@googlemail.com ---
Hash collisions will happen!
We need a way to speed up those equals compares in rootObject.
I'll look if I can find a good way to gradually remove the virtual calls. 

  IsVariable!(Simulated_Object_966)
  IsMemberVariable!(Simulated_Object_975)
  isSomeFunction!(Simulated_Object_573)

Those SHOULD produce the same hash they work on the same types!
I am of the impression that template-inlining can help here.

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[Issue 16513] Speed up TemplateInstance.findExistingInstance, hash by mangling

2016-09-20 Thread via Digitalmars-d-bugs 
https://issues.dlang.org/show_bug.cgi?id=16513

Martin Nowak  changed:

   What|Removed |Added

 CC||goober...@gmail.com,
   ||uplink.co...@googlemail.com

--- Comment #1 from Martin Nowak  ---
It's the horrible hash that is causing the performance issue.
Arguments as widely different than

  genericIndexOf!(CPPMethods, ushort, int, uint, long, ulong)
  genericIndexOf!(VTable, ushort, int, uint, long, ulong)

produce the same hash.

>From the 88.3K lookups, 7900 have the hash 1 (one).

The test code that triggered the issue contains 1K instances of

  VariableDescriptor!(tonsofsimulatedobjects, SimulatedEntity,
"Simulated_Object_1063")
  VariableDescriptor!(tonsofsimulatedobjects, SimulatedEntity,
"Simulated_Object_1064")

and lots of instances like

  IsVariable!(Simulated_Object_963)
  IsMemberVariable!(Simulated_Object_973)
  isSomeFunction!(Simulated_Object_571)
  IsVariable!(Simulated_Object_964)
  IsMemberVariable!(Simulated_Object_974)
  isSomeFunction!(Simulated_Object_572)
  IsVariable!(Simulated_Object_966)
  IsMemberVariable!(Simulated_Object_975)
  isSomeFunction!(Simulated_Object_573)

all producing the same hash.
With such a crappy hash the behavior degrades back to the old linear search.

I'll try to replace this with the mangling suffix (.getIdent) instead which
should be both simpler and effective, given that all mangling bugs are fixed.

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