Multi target support #35

hasufell · 2025-07-29T05:35:08Z

As well as being invoked via triplet symlink.

angerman

I guess we'll need to overhaul this program completely at some point.

This change looks good. I've left a few comments with ideas.

utils/ghc-pkg/Main.hs

angerman · 2025-07-29T08:39:56Z

Oof, CI also tells us we don't really test this program at all on its own, just as part of the whole 😅 nothing to fix now, just an observation.

hsyl20 · 2025-07-29T11:18:25Z

utils/ghc-pkg/Main.hs

+                     mt <- getTarget my_flags
+                     dir <- case mt of
+                              Nothing -> pure dir'
+                              Just target -> pure (dir' </> "targets" </> target </> "lib")


This path should be kept in sync with ghc: perhaps add a helper function where getBaseDir is? If it's not possible because of staging, some comment would be useful to remember this.

The code in GHC is a bit different:

ghc/ghc/Main.hs

Lines 142 to 161 in 1c9db51

targettopdir <- Just <$> do

topdir <- findTopDir mbMinusB

let targets_dir = topdir </> "targets"

-- list targets when asked

when list_targets $ do

putStrLn $ "Installed targets (in " ++ targets_dir ++ "):"

doesDirectoryExist targets_dir >>= \case

True -> do

ds <- listDirectory targets_dir

forM_ ds (\d -> putStrLn $ " - " ++ d)

False -> pure ()

exitSuccess

-- otherwise select the appropriate target

case mbTarget of

Nothing -> pure topdir

Just target -> do

let r = targets_dir </> target </> "lib"

doesDirectoryExist r >>= \case

True -> pure r

False -> throwGhcException (UsageError $ "Couldn't find specific target `" ++ target ++ "' in `" ++ r ++ "'")

What did you have in mind?

I was thinking about something like getTargetDir :: FilePath -> String -> IO FilePath taking the topdir and the target name and returning the target dir.

utils/ghc-pkg/Main.hs

As well as being invoked via triplet symlink.

hasufell · 2025-08-04T09:36:44Z

Instructions to test:

checkout this branch
run: make CABAL=_build/stage0/bin/cabal
make sure emscripten is installed and the emscripten env script has been sourced: https://emscripten.org/docs/getting_started/downloads.html
run: make CABAL=_build/stage0/bin/cabal stage2-javascript-unknown-ghcjs
clone miso example from https://github.com/haskell-miso/miso-counter.git
compile miso example via something like (example from my machine) /home/hasufell/git/ghc/_build/stage0/bin/cabal build -W /home/hasufell/git/ghc/_build/stage2/bin/ghc -w /home/hasufell/git/ghc/_build/stage2/bin/javascript-unknown-ghcjs-ghc --with-gcc=emcc --allow-newer=ghc-bignum

angerman

👏 This is great work! I've left a few comments with throughts.

angerman · 2025-08-06T02:10:24Z

rts/rts.cabal

+          AutoApply_V32.cmm
+          AutoApply_V64.cmm
+
+common ghcjs


This should really be called rts-javascript, or rts-ghcjs or something like that.

To align with the other common stanzas: rts-js-sources being the best?

angerman · 2025-08-06T02:11:45Z

rts/rts.cabal

+          AutoApply_V32.cmm
+          AutoApply_V64.cmm
+
+common ghcjs
    import: rts-base-config


This seems to deviate from how other common stanzas are done? This should just be in the conditional below: rts-base-config, rts-ghcjs, or similar.

angerman · 2025-08-06T02:13:12Z

rts/rts.cabal

    visibility: public
-    build-depends: rts


Good! This is an oversignt, and already part of rts-base-config.

angerman · 2025-08-06T02:15:20Z

cabal.project.stage2

+  utils/genprimopcode
+  utils/deriveConstants
+
+if !arch(javascript)


Suggested change

if !arch(javascript)

-- We do not want to compile the utilities to javascript. Also terminfo (and haskeline) don't make sense for javascript.

if !arch(javascript)

angerman · 2025-08-06T02:16:35Z

cabal.project.stage2

+if arch(javascript)
+  constraints:
+    Cabal source,
+    Cabal-syntax source,
+    array source,
+    base source,
+    binary source,
+    bytestring source,
+    containers source,
+    deepseq source,
+    directory source,
+    exceptions source,
+	file-io source,
+    filepath source,
+    hpc source,
+    integer-gmp source,
+    mtl source,
+	os-string source,
+    parsec source,
+    pretty source,
+    process source,
+    rts source,
+    rts-headers source,
+	rts-fs source,
+    stm source,
+    system-cxx-std-lib source,
+    template-haskell source,
+    text source,
+    time source,
+    transformers source,
+    unix source,
+    xhtml source,
+	Win32 source


The indentation is meant to signify dependencies?

Why do we need the source constraint here? We should have acomment explaining why this is done, and if this is a cabal defect that needs to be rectified or something else.

angerman · 2025-08-06T02:18:03Z

Makefile

+	$(call run_and_log, HADRIAN_SETTINGS='$(HADRIAN_SETTINGS)' \
+		PATH=$(PWD)/_build/stage1/bin:$(PATH) \
+		$(CABAL_BUILD) --ghc-options="-ghcversion-file=$(abspath ./rts/include/ghcversion.h)" -W $(GHC0) rts:nonthreaded-nodebug )


This really feels like a bug, why do we need to build this explicitly here, why is this not brought into scope automatically?

angerman · 2025-08-06T02:19:16Z

Makefile

+javascript-unknown-ghcjs-libs: private CC=emcc
+javascript-unknown-ghcjs-libs: _build/stage2/bin/javascript-unknown-ghcjs-ghc-pkg _build/stage2/bin/javascript-unknown-ghcjs-ghc _build/stage2/lib/targets/javascript-unknown-ghcjs/lib/settings _build/stage2/lib/targets/javascript-unknown-ghcjs/bin/unlit _build/stage2/lib/targets/javascript-unknown-ghcjs/lib/package.conf.d
+	# Force cabal to replan
+	rm -rf _build/stage2/javascript-unknown-ghcjs/cache


Wow, this seems ... odd? @andreabedini what's going on here?

angerman · 2025-08-06T02:20:03Z

Makefile

+	rm -rf _build/stage2/javascript-unknown-ghcjs/cache
+	$(call run_and_log, HADRIAN_SETTINGS='$(HADRIAN_SETTINGS)' \
+		PATH=$(PWD)/_build/stage2/bin:$(PATH) \
+		$(CABAL_BUILD) -W $(GHC2) --happy-options="--template=$(abspath _build/stage2/src/happy-lib-2.1.5/data/)" rts:nonthreaded-nodebug )


Do you remember what the underlying reason for the happy-lib-... path thing was? Can we add a comment to remember why this was needed?

angerman · 2025-08-06T02:20:53Z

Makefile

+		$(CABAL_BUILD) -W $(GHC2) --happy-options="--template=$(abspath _build/stage2/src/happy-lib-2.1.5/data/)" rts:nonthreaded-nodebug )
+	$(call run_and_log, HADRIAN_SETTINGS='$(HADRIAN_SETTINGS)' \
+		PATH=$(PWD)/_build/stage2/bin:$(PATH) \
+		$(CABAL_BUILD) -W $(GHC2) --happy-options="--template=$(abspath _build/stage2/src/happy-lib-2.1.5/data/)" $(STAGE2_TARGET_LIBS) )


Can't the STAGE2_CROSS_TARET_LIBS contain rts:nonthreaded-nodebug? If not, why not?

angerman · 2025-08-06T02:21:16Z

Makefile

@@ -176,6 +182,33 @@ STAGE2_UTIL_EXECUTABLES := \
 	runghc \
 	unlit

+STAGE2_TARGET_LIBS := \


This is for the CROSS compiler, right? Can we rename it to STAGE2_CROSS_TARET_LIBS then?

hasufell · 2025-08-07T09:47:52Z

I've stage3-ified this and added musl cross compiler support.

hsyl20 · 2025-08-11T13:20:28Z

Updated build instructions afaict:

Instructions to test:

checkout this branch
run: make CABAL=_build/stage0/bin/cabal twice. it should print "Binary distribution created."
optional: make sure emscripten is installed and the emscripten env script has been sourced: https://emscripten.org/docs/getting_started/downloads.html (not needed if globally installed, as with the ArchLinux package)
run: make CABAL=_build/stage0/bin/cabal stage3-javascript-unknown-ghcjs (stage3, not stage2)
install iserv for JS: cp ghc-interp.js _build/stage2/lib/targets/javascript-unknown-ghcjs/lib
clone miso example from https://github.com/haskell-miso/miso-counter.git
compile miso example via something like (example from my machine) /home/hasufell/git/ghc/_build/stage0/bin/cabal build -W /home/hasufell/git/ghc/_build/stage2/bin/ghc -w /home/hasufell/git/ghc/_build/stage3/bin/javascript-unknown-ghcjs-ghc --with-gcc=emcc --allow-newer=ghc-bignum (stage3, not stage2).

These instructions worked for me.

Note that replacing build with run in the last command rebuilds everything for some reason.

Then it fails with:

/home/hsyl20/projects/ghc/scratch/miso/miso-counter/dist-newstyle/build/host/javascript-ghcjs/ghc-9.13/miso-counter-0.1-app/build/app/app:163760
  var e = new WebAssembly.RuntimeError(what);
          ^

RuntimeError: Aborted('HEAP8' was not exported. add it to EXPORTED_RUNTIME_METHODS (see the Emscripten FAQ))

that someone reported (again? I've already seen it) 2 days ago: https://gitlab.haskell.org/ghc/ghc/-/issues/26290

hasufell requested a review from hsyl20 July 29, 2025 05:35

hasufell linked an issue Jul 29, 2025 that may be closed by this pull request

Multi-target support for GHC #30

Open

5 tasks

hasufell force-pushed the wip/multi-target-support branch from 5158146 to 8b1e18e Compare July 29, 2025 05:35

angerman approved these changes Jul 29, 2025

View reviewed changes

utils/ghc-pkg/Main.hs Show resolved Hide resolved

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hsyl20 requested changes Jul 29, 2025

View reviewed changes

feat: make ghc-pkg support '--target'

2de8dce

As well as being invoked via triplet symlink.

hasufell force-pushed the wip/multi-target-support branch from 8b1e18e to 2de8dce Compare July 29, 2025 11:38

hasufell added 2 commits August 1, 2025 21:35

Fix rts for javascript target

b82d383

Implement "stage2" javascript build

aca0750

hasufell changed the title ~~feat: make ghc-pkg support '--target'~~ Multi target support Aug 1, 2025

hasufell requested review from hsyl20 and angerman August 1, 2025 13:37

angerman approved these changes Aug 6, 2025

View reviewed changes

Stage3-ify

cd014e3

	targettopdir <- Just <$> do
	topdir <- findTopDir mbMinusB
	let targets_dir = topdir </> "targets"
	-- list targets when asked
	when list_targets $ do
	putStrLn $ "Installed targets (in " ++ targets_dir ++ "):"
	doesDirectoryExist targets_dir >>= \case
	True -> do
	ds <- listDirectory targets_dir
	forM_ ds (\d -> putStrLn $ " - " ++ d)
	False -> pure ()
	exitSuccess
	-- otherwise select the appropriate target
	case mbTarget of
	Nothing -> pure topdir
	Just target -> do
	let r = targets_dir </> target </> "lib"
	doesDirectoryExist r >>= \case
	True -> pure r
	False -> throwGhcException (UsageError $ "Couldn't find specific target `" ++ target ++ "' in `" ++ r ++ "'")

	if !arch(javascript)
	-- We do not want to compile the utilities to javascript. Also terminfo (and haskeline) don't make sense for javascript.
	if !arch(javascript)

Multi target support #35

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Multi target support #35

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hasufell commented Jul 29, 2025

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angerman commented Jul 29, 2025

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hasufell commented Aug 4, 2025

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hasufell commented Aug 7, 2025

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hsyl20 commented Aug 11, 2025

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