On 05/15/2015 09:17 PM, Simon Peyton Jones wrote:
Good idea. I think it’d great if Jost (or someone else) felt able to
update those wiki pages with the info in his email.
Sure, will do that.
I am not sure whether either of those pages is the best place for
information about the GHC ways. Maybe there is already a page about them
in the commentary - I will take a look tomorrow and add the information
about ways from the mail. If no page exists I'll add a page, and link to
it from the Debugging/RuntimeSystem page.
A few years ago, I wrote one page specifically about the parallel ways,
http://ghc.haskell.org/trac/ghc/wiki/GpHEden/CompilerWays
but the information is outdated.
/ Jost
thanks!
Simon
*From:*ghc-devs [mailto:[email protected]] *On Behalf Of
*Lennart Kolmodin
*Sent:* 15 May 2015 11:31
*To:* Jost Berthold
*Cc:* [email protected]
*Subject:* Re: Debugging the RTS
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
<[email protected]
<mailto:[email protected]>>:
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 <http://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 <http://build.mk> (also see mk/config.mk
<http://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, [email protected]
<mailto:[email protected]> wrote:
Date: Thu, 14 May 2015 18:36:04 +1000
From: Erik de Castro Lopo <[email protected]
<mailto:mle%[email protected]>>
To: [email protected] <mailto:[email protected]>
Subject: Debugging the RTS
Message-ID:
<[email protected]
<mailto:[email protected]>>
Content-Type: text/plain; charset=US-ASCII
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 <http://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
<http://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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