Searching for online resources brought me to
https://ghc.haskell.org/trac/ghc/wiki/Debugging and
https://ghc.haskell.org/trac/ghc/wiki/Debugging/RuntimeSystem
This mail seems to be a more detailed description than available on the
wiki. That page refers to GHC 6.12.
Would it make sense to add some info to the RuntimeSystem
https://ghc.haskell.org/trac/ghc/wiki/Debugging/RuntimeSystem page?
2015-05-14 16:21 GMT+02:00 Jost Berthold : Hi Eric, definitely not bit-rotted - the #if DEBUG code is what you get when you
compile with -debug. Short roadmap: In general, GHC is built in many "ways", the -debug way is one.
Some ways (like -threaded, -eventlog, -debug) are RTS-only, others (like
-prof) lead to different library code. Ways are defined in compiler/main/DynFlags.hs as a Haskell data structure.
In _dynamic_flags_, the actual flag strings for the ghc invocation are
defined (like -prof, -threaded), they will activate the respective _Way_.
_wayTag_, in turn, defines short names used as a suffix for *.o and *.a
files, for instance *.p_o for profiling, *.l_o for eventlog.
A number of other functions in there customise behaviour depending on the
ways. Note _wayOptc_ which sets some options for the C compiler, like
-DTRACING for the -eventlog way. However, it does not define DEBUG for the
debug way! In mk/ways.mk you will find all the short names, and some more options
are defined (WAY_*_HC_OPTS). These definitions are for the driver script,
and pass on the right (long-name) options to the Haskell compiler to
activate what is inside DynFlags (like -prof for WAY_p_HC_OPTS).
Here we find
WAY_debug_HC_OPTS= -static -optc-DDEBUG -ticky -DTICKY_TICKY
which is what you were looking for To build a GHC with debug-way RTS, you need to add GhcRtsWays += debug to
your build.mk (also see mk/config.mk{.in}, which gathers the default ways
to build depending on platform and build configuration).
I guess this might produce quite a number of new warnings and errors if
you do it on a new platform... Once you have built this, you can compile with -debug and pass RTS options
to get debug traces and activate sanity checks, like so:
ghc -debug -myprogram.hs -o myprogramDebug
./myprogramDebug +RTS -Ds -DS
(-DS = sanity checks on, -Ds = scheduler tracing)
The usage message (see /rts/RtsFlags.c) tells you more options you can use. Happy debugging!
/ Jost On 05/14/2015 10:00 PM, ghc-devs-request@haskell.org wrote: Date: Thu, 14 May 2015 18:36:04 +1000
From: Erik de Castro Lopo Hi all, I'm trying to debug a AArch64/Linux specific RTS issue and digging
around in the rts C code, I see a large amount of code wrapped in
"#if DEBUG" type statements, but no way to enable in either
mk/build.mk or it seems in any of the other build related settings
files in the mk/ directory. The only way I have found to enable this debug code that actually
works is to enable this DEBUG code is to edit mk/ghc.mk as follows: -STANDARD_OPTS += -DCOMPILING_RTS
+STANDARD_OPTS += -DCOMPILING_RTS -DDEBUG However, once I do that I get a bunch of C synatx errors. I am doing this wrong or has the DEBUG code bit rotted? Cheers,
Erik _______________________________________________
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