Heisenbug in v2.0.3
- From: Pierre-Yves Gérardy <pygy79@xxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Wed, 1 Apr 2015 01:00:11 +0200
Hello Mike, hello list,
I encounter a problem with LuaJIT v2.0.3 that disappears when I try to debug it.
To test LuLPeg, I use a modified version of the LPeg test suite, with
`assert` modified to gather stats rather than crashing on error.
The following line† errors out three times (out of 550) when run as follows:
git clone https://github.com/pygy/LuLPeg.git
cd LuLPeg
git checkout 9855c3d85e9 # the master HEAD as of this post
luajit tests/lpeg.0.12.test.lua lulpeg abcdefgh
But this works fine:
luajit tests/lpeg.0.12.test.lua lulpeg abcdefg
Note that the last parameter (abcdefg(h)) is not used by the program.
(When I say that it works fine, I mean that it errors out 70 times out
of 6000+, as expected for now).
I've tried to narrow down the issue, but slight modifications make the
bug go away. It doesn't happen with -joff.
I'm using MacOS 10.8.5, and that LuaJIT version was installed through
Homebrew. These optimisations are enabled: JIT: ON CMOV SSE2 SSE3
SSE4.1 fold cse dce fwd dse narrow loop abc sink fuse
LuLPeg compiles patterns to Lua code using a parser combinator
approach, which are a pain to debug :-). Hopefully you can guide me in
providing you more useful information.
—Pierre-Yves
† https://github.com/pygy/LuLPeg/blob/master/tests/lpeg.0.12.test.lua#L240
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