Re: Modifying the "StgHeader" struct

Hello Adithya, This sounds just like what has been implemented as the default mode for eras profiling: https://well-typed.com/blog/2024/01/ghc-eras-profiling — which tracks an “era” for each heap object — and, by default, uses a major garbage collection as the increment trigger. Could you check it out and see if it would supersede what you are trying to do? Cheers, Rodrigo

On 25 Feb 2024, at 12:58, Adithya Kumar wrote:

Hello,

I want to add a field for collecting information about the number of GCs a particular heap object survived.

I've done the following to implement this: - Add a field "StgWord gc_id" to struct "StgHeader" and "StgThunkHeader" - Update "SET_HDR" macro in "ClosureMacros.h" to update the "gc_id" - Update the "closureTypeHeaderSize" function in "Heap/ClosureTypes.hs" to account for that 1 extra word.

Compilation leads to a segmentation fault. The stage 2 compiler is built. But usage of it leads to a segmentation fault.

Build output: ``` chmod +x inplace/bin/ghc-stage2 "inplace/bin/ghc-stage2" -hisuf dyn_hi -osuf dyn_o -hcsuf dyn_hc -fPIC -dynamic -O0 -H64m -Wall -hide-all-packages -package-env - -i -iutils/check-api-annotations/. -iutils/check-api-annotations/dist-install/build -Iutils/check-api-annotations/dist-install/build -iutils/check-api-annotations/dist-install/build/check-api-annotations/autogen -Iutils/check-api-annotations/dist-install/build/check-api-annotations/autogen -optP-include -optPutils/check-api-annotations/dist-install/build/check-api-annotations/autogen/cabal_macros.h -package-id Cabal-3.2.1.0 -package-id base-4.14.3.0 -package-id containers-0.6.5.1 -package-id directory-1.3.6.0 -package-id ghc-8.10.7.20240224 -Wall -XHaskell2010 -no-user-package-db -rtsopts -Wnoncanonical-monad-instances -outputdir utils/check-api-annotations/dist-install/build -c utils/check-api-annotations/./Main.hs -o utils/check-api-annotations/dist-install/build/Main.dyn_o utils/check-api-annotations/ghc.mk:18 http://ghc.mk:18/: recipe for target 'utils/check-api-annotations/dist-install/build/Main.dyn_o' failed make[1]: *** [utils/check-api-annotations/dist-install/build/Main.dyn_o] Segmentation fault (core dumped) Makefile:123: recipe for target 'all' failed make: *** [all] Error 2 ```

Is there any other place I've missed follow-up modifications?

I appreciate any help provided.

Best, Adithya _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs