[luajit] deep inspection on lightuserdata identity test?

[Daniel Klein <daniel.klein@...>]

Greetings!

We ran into an interesting situation while working with LuaJIT 2.0.0-beta8:

> require 'cdlua'

> =cd.GREEN

userdata: 0x0000ff00

> =cd.BLUE

userdata: 0x000000ff

> =cd.GREEN == cd.GREEN

true

> =cd.GREEN == cd.BLUE

PANIC: unprotected error in call to Lua API (4.4562912041821e-313)

This is using the CD library from tecgraf, and the cd.X are lightuserdata objects.

We're running Windows 7, x64 and the crash happens with beta8 and HEAD and with the JIT turned off and no optimisations enabled (-joff -O0)

I suspect this means that if the pointers are equal, the result comes back quickly, but if they're not there's some deep inspection of the pointers happening, and I wouldn't have expected that. In regular Lua, the result comes back as I would expect (false) and doesn't crash.

I haven't been able to track down exactly where this sort of thing is resolved (lj_obj.c?), so my question -- Is this expected behaviour or a bug?

Cheers,

Daniel M. Klein

s/w dev, Tornado Medical Systems, Inc.

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