From f918fec3ac1bc34eaedc73126c0b2cbcf429d9d3 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Thu, 4 Sep 2025 09:33:56 +0900
Subject: [PATCH 01/23] ci: add dynamic build/test matrix (DYNAMIC=0/1) and
 restrict push trigger to stable-ghc-9.14

---
 .github/workflows/ci.yml | 59 +++++++++++++++++++++++++---------------
 1 file changed, 37 insertions(+), 22 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9c4b65f3c27..0a62582985f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,30 +1,45 @@
-name: CI
+name: Nix CI
 
-# Trigger the workflow on push or pull request, but only for the master branch
 on:
   pull_request:
-    types:
-      - opened
-      - synchronize
+    types: [opened, synchronize]
   push:
-    branches: [master]
-
+    branches: [stable-ghc-9.14]
   workflow_dispatch:
 
 jobs:
   cabal:
-    name: ${{ matrix.plat }} / ghc ${{ matrix.ghc }}
-    runs-on: "${{ fromJSON('{\"x86_64-linux\": \"ubuntu-24.04\", \"aarch64-linux\": \"ubuntu-24.04-arm\", \"x86_64-darwin\": \"macos-latest\", \"aarch64-darwin\": \"macos-latest\"}')[matrix.plat] }}"
-
     strategy:
       fail-fast: false
       matrix:
-        plat:
-          - x86_64-linux
-          # - aarch64-linux  # disabled: waiting for devx images to be fixed
-          # - x86_64-darwin  # disabled: waiting for devx images to be fixed
-          - aarch64-darwin
-        ghc: ['98'] # bootstrapping compiler
+        include:
+          - plat: x86_64-linux
+            runner: ubuntu-24.04
+            ghc: '98'
+            dynamic: 0
+          - plat: x86_64-linux
+            runner: ubuntu-24.04
+            ghc: '98'
+            dynamic: 1
+          # - plat: aarch64-linux  # disabled: waiting for devx images to be fixed
+          #   runner: ubuntu-24.04-arm
+          #   ghc: '98'
+          #   dynamic: 0
+          # - plat: aarch64-linux
+          #   runner: ubuntu-24.04-arm
+          #   ghc: '98'
+          #   dynamic: 1
+          - plat: aarch64-darwin
+            runner: macos-latest
+            ghc: '98'
+            dynamic: 0
+          - plat: aarch64-darwin
+            runner: macos-latest
+            ghc: '98'
+            dynamic: 1
+
+    name: "${{ matrix.plat }} / ghc ${{ matrix.ghc }} / dynamic=${{ matrix.dynamic }}"
+    runs-on: ${{ matrix.runner }}
 
     steps:
     - uses: actions/checkout@v4
@@ -50,25 +65,25 @@ jobs:
     #   shell: devx {0}
     #   run: ./configure
 
-    - name: Build the bindist
+    - name: Build the bindist (dynamic=${{ matrix.dynamic }})
       shell: devx {0}
-      run: make CABAL=$PWD/_build/stage0/bin/cabal
+      run: make CABAL=$PWD/_build/stage0/bin/cabal DYNAMIC=${{ matrix.dynamic }}
 
     - name: Upload artifacts
       uses: actions/upload-artifact@v4
       with:
-        name: ${{ matrix.plat }}-bindist
+        name: ${{ matrix.plat }}-dynamic${{ matrix.dynamic }}-bindist
         path: _build/bindist
 
-    - name: Run the testsuite
+    - name: Run the testsuite (dynamic=${{ matrix.dynamic }})
       shell: devx {0}
-      run: make test CABAL=$PWD/_build/stage0/bin/cabal
+      run: make test CABAL=$PWD/_build/stage0/bin/cabal DYNAMIC=${{ matrix.dynamic }}
 
     - name: Upload test results
       uses: actions/upload-artifact@v4
       if: ${{ !cancelled() }} # upload test results even if the testsuite failed to pass
       with:
-        name: ${{ matrix.plat }}-testsuite-results
+        name: ${{ matrix.plat }}-dynamic${{ matrix.dynamic }}-testsuite-results
         path: |
           _build/test-perf.csv
           _build/test-summary.txt

From 6131ef0a87aa7845b4e1f0b0c27fda8a996dbb3d Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Thu, 4 Sep 2025 09:36:30 +0900
Subject: [PATCH 02/23] ci: trigger also on stable-master branch

---
 .github/workflows/ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0a62582985f..6da30bfba00 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -4,7 +4,7 @@ on:
   pull_request:
     types: [opened, synchronize]
   push:
-    branches: [stable-ghc-9.14]
+    branches: [stable-ghc-9.14, stable-master]
   workflow_dispatch:
 
 jobs:

From 9d770e44b41d10ded26f3afaacb03f3fa9b20937 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Fri, 12 Sep 2025 10:59:44 +0900
Subject: [PATCH 03/23] Add the geenrated stage2.settings file to .gitignore.

---
 .gitignore | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.gitignore b/.gitignore
index f6d6b0bc900..3393551070c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -259,3 +259,4 @@ ghc.nix/
 # clangd
 .clangd
 dist-newstyle/
+cabal.project.stage2.settings

From 86f0f5764426b31eabe8fbfb7962eb05e7f9668a Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Fri, 12 Sep 2025 11:00:06 +0900
Subject: [PATCH 04/23] makefile: Stop rebuilding everything when running the
 test-suite

---
 Makefile | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 20837cbea96..454f3e18e11 100644
--- a/Makefile
+++ b/Makefile
@@ -1033,13 +1033,11 @@ CANONICAL_TEST_HC_OPTS = \
 	-Werror=compat -dno-debug-output
 
 # Build timeout utility (needed for some tests) if not already built.
-.PHONY: testsuite-timeout
-testsuite-timeout:
+testsuite/timeout/install-inplace/bin/timeout:
 	$(MAKE) -C testsuite/timeout
 
-
 # --- Test Target ---
-test: _build/bindist testsuite-timeout
+test: $(TEST_GHC) $(TEST_GHC_PKG) $(TEST_HP2PS) $(TEST_HPC) $(TEST_RUN_GHC) testsuite/timeout/install-inplace/bin/timeout
 	@echo "::group::Running tests with THREADS=$(THREADS)" >&2
 	# If any required tool is missing, testsuite logic will skip related tests.
 	TEST_HC='$(TEST_GHC)' \

From 66e260ca8b5580083fa99fc1056c5af146fbbe92 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Mon, 15 Sep 2025 10:31:18 +0900
Subject: [PATCH 05/23] Do not auto-link unlit (which is effectively a .c only
 utility.

---
 utils/hp2ps/hp2ps.cabal | 7 +++++++
 utils/unlit/unlit.cabal | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/utils/hp2ps/hp2ps.cabal b/utils/hp2ps/hp2ps.cabal
index 482ea772b93..ea071266a64 100644
--- a/utils/hp2ps/hp2ps.cabal
+++ b/utils/hp2ps/hp2ps.cabal
@@ -23,3 +23,10 @@ Executable hp2ps
        HpFile.c Marks.c Scale.c TraceElement.c
        Axes.c Dimensions.c Key.c PsFile.c Shade.c
        Utilities.c
+    ghc-options:
+        -- We do _not_ want to auto-link this against rts, base, ...
+        -- otherwise we end up with broken dependencies.  E.g. unlit
+        -- depending on libHSrts, which then depends on the libHSrts
+        -- implementation sublib, due to the -u,... flags from the
+        -- rts.
+        -no-auto-link-packages
\ No newline at end of file
diff --git a/utils/unlit/unlit.cabal b/utils/unlit/unlit.cabal
index 770567be3a8..696516dd8f5 100644
--- a/utils/unlit/unlit.cabal
+++ b/utils/unlit/unlit.cabal
@@ -10,5 +10,12 @@ Executable unlit
     cc-options:       -DFS_NAMESPACE=rts
     Default-Language: Haskell2010
     Main-Is: unlit.c
+    ghc-options:
+        -- We do _not_ want to auto-link this against rts, base, ...
+        -- otherwise we end up with broken dependencies.  E.g. unlit
+        -- depending on libHSrts, which then depends on the libHSrts
+        -- implementation sublib, due to the -u,... flags from the
+        -- rts.
+        -no-auto-link-packages
     build-depends:
         rts-fs

From b103d8246b96302a01ff99919932681080064d92 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Mon, 15 Sep 2025 16:03:33 +0900
Subject: [PATCH 06/23] compiler/rts: prelink archive threshold

---
 compiler/GHC/Driver/DynFlags.hs |   4 +
 compiler/GHC/Driver/Session.hs  |  11 +-
 compiler/cbits/cutils.c         |  12 ++
 rts/Linker.c                    | 217 ++++++++++++++++++++++++++++++++
 rts/RtsFlags.c                  |  23 ++++
 rts/include/rts/Flags.h         |   2 +
 6 files changed, 268 insertions(+), 1 deletion(-)

diff --git a/compiler/GHC/Driver/DynFlags.hs b/compiler/GHC/Driver/DynFlags.hs
index 4377094a98c..13786cc03e7 100644
--- a/compiler/GHC/Driver/DynFlags.hs
+++ b/compiler/GHC/Driver/DynFlags.hs
@@ -196,6 +196,9 @@ data DynFlags = DynFlags {
 
   enableTimeStats       :: Bool,        -- ^ Enable RTS timing statistics?
   ghcHeapSize           :: Maybe Int,   -- ^ The heap size to set.
+  -- | Threshold (in bytes) above which GHCi will pre-link archives (ld -r)
+  -- before loading. A value of 0 disables pre-linking.
+  ghciPrelinkArchiveThreshold :: Maybe Integer,
 
   maxRelevantBinds      :: Maybe Int,   -- ^ Maximum number of bindings from the type envt
                                         --   to show in type error messages
@@ -583,6 +586,7 @@ defaultDynFlags mySettings =
 
         enableTimeStats         = False,
         ghcHeapSize             = Nothing,
+        ghciPrelinkArchiveThreshold = Nothing,
 
         importPaths             = ["."],
         mainModuleNameIs        = mAIN_NAME,
diff --git a/compiler/GHC/Driver/Session.hs b/compiler/GHC/Driver/Session.hs
index 0ca58c33866..38e9a8c5e3a 100644
--- a/compiler/GHC/Driver/Session.hs
+++ b/compiler/GHC/Driver/Session.hs
@@ -295,6 +295,8 @@ import qualified Data.Map as Map
 import qualified Data.Set as Set
 import Data.Word
 import System.FilePath
+-- no env tweaks needed here
+import Data.Int (Int64)
 import Text.ParserCombinators.ReadP hiding (char)
 import Text.ParserCombinators.ReadP as R
 
@@ -884,7 +886,7 @@ parseDynamicFlagsFull activeFlags cmdline logger dflags0 args = do
     map ((rdr . ppr . getLoc &&& unLoc) . errMsg) $ errs
 
   -- check for disabled flags in safe haskell
-  let (dflags2, sh_warns) = safeFlagCheck cmdline dflags1
+            let (dflags2, sh_warns) = safeFlagCheck cmdline dflags1
       theWays = ways dflags2
 
   unless (allowed_combination theWays) $ liftIO $
@@ -899,6 +901,10 @@ parseDynamicFlagsFull activeFlags cmdline logger dflags0 args = do
     Just x -> liftIO (setHeapSize x)
     _      -> return ()
 
+  case ghciPrelinkArchiveThreshold dflags3 of
+    Just n  -> liftIO (setGhciPrelinkArchiveThreshold (fromIntegral (n :: Integer)))
+    _       -> return ()
+
   liftIO $ setUnsafeGlobalDynFlags dflags3
 
   -- create message envelopes using final DynFlags: #23402
@@ -1075,6 +1081,8 @@ dynamic_flags_deps = [
     -- RTS options -------------------------------------------------------------
   , make_ord_flag defFlag "H"           (HasArg (\s -> upd (\d ->
           d { ghcHeapSize = Just $ fromIntegral (decodeSize s)})))
+  , make_ord_flag defGhcFlag "ghci-prelink-archive-threshold"
+          (HasArg (\s -> upd (\d -> d { ghciPrelinkArchiveThreshold = Just (decodeSize s) })))
 
   , make_ord_flag defFlag "Rghc-timing" (NoArg (upd (\d ->
                                                d { enableTimeStats = True })))
@@ -3808,6 +3816,7 @@ decodeSize str
 
 foreign import ccall unsafe "setHeapSize"       setHeapSize       :: Int -> IO ()
 foreign import ccall unsafe "enableTimingStats" enableTimingStats :: IO ()
+foreign import ccall unsafe "setGhciPrelinkArchiveThreshold" setGhciPrelinkArchiveThreshold :: Int64 -> IO ()
 
 outputFile :: DynFlags -> Maybe String
 outputFile dflags
diff --git a/compiler/cbits/cutils.c b/compiler/cbits/cutils.c
index fb7e3f7335b..0091dfa767e 100644
--- a/compiler/cbits/cutils.c
+++ b/compiler/cbits/cutils.c
@@ -7,6 +7,11 @@ places in the GHC library.
 
 #include <HsFFI.h>
 
+/* Prototype for FFI-callable helper */
+void enableTimingStats( void );
+void setHeapSize( HsInt size );
+void setGhciPrelinkArchiveThreshold( HsInt64 bytes );
+
 void
 enableTimingStats( void )       /* called from the driver */
 {
@@ -22,3 +27,10 @@ setHeapSize( HsInt size )
         RtsFlags.GcFlags.maxHeapSize = RtsFlags.GcFlags.heapSizeSuggestion;
     }
 }
+
+/* Configure GHCi pre-link archive threshold (in bytes). 0 disables. */
+void
+setGhciPrelinkArchiveThreshold( HsInt64 bytes )
+{
+    RtsFlags.MiscFlags.linkerPrelinkArchiveThreshold = (StgInt64) bytes;
+}
diff --git a/rts/Linker.c b/rts/Linker.c
index dc9a3a336c6..3ee3545f865 100644
--- a/rts/Linker.c
+++ b/rts/Linker.c
@@ -35,6 +35,7 @@
 #include "PathUtils.h"
 #include "CheckUnload.h" // createOCSectionIndices
 #include "ReportMemoryMap.h"
+#include "xxhash.h"
 
 #if !defined(mingw32_HOST_OS) && defined(HAVE_SIGNAL_H)
 #include "posix/Signals.h"
@@ -444,6 +445,176 @@ void initLinker (void)
     initLinker_(1);
 }
 
+// Helper to pre-link big archives into a temporary object file so the
+// internal linker can load a single .o instead of many members.
+#if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <limits.h>
+#include <time.h>
+
+static const char *ghci_basename_posix(const char *p)
+{
+    const char *last = p;
+    if (!p) return p;
+    for (const char *s = p; *s; ++s) {
+        if (*s == '/') last = s + 1;
+    }
+    return last;
+}
+
+static const char *ghci_tmpdir(void)
+{
+    const char *t = getenv("TMPDIR");
+    return t && *t ? t : "/tmp";
+}
+
+static bool ghci_read_file_prefix(const char *path, char *buf, size_t bufsz)
+{
+    FILE *f = fopen(path, "rb");
+    if (!f) return false;
+    size_t n = fread(buf, 1, bufsz - 1, f);
+    buf[n] = '\0';
+    fclose(f);
+    return true;
+}
+
+static bool ghci_compute_cache_key(const char *path, char out_hex[65])
+{
+    FILE *f = fopen(path, "rb");
+    if (!f) return false;
+    XXH64_state_t* st = XXH64_createState();
+    if (!st) { fclose(f); return false; }
+    if (XXH64_reset(st, 0) != XXH_OK) { XXH64_freeState(st); fclose(f); return false; }
+    unsigned char buf[256 * 1024];
+    size_t n;
+    while ((n = fread(buf, 1, sizeof(buf), f)) > 0) {
+        if (XXH64_update(st, buf, n) != XXH_OK) {
+            XXH64_freeState(st); fclose(f); return false;
+        }
+    }
+    fclose(f);
+    XXH64_hash_t hv = XXH64_digest(st);
+    XXH64_freeState(st);
+    // render as 16-char hex (zero-padded)
+    // use unsigned long long to satisfy printf on most platforms
+    unsigned long long v = (unsigned long long)hv;
+    // ensure buffer large enough; we reserved 65 earlier
+    snprintf(out_hex, 65, "%016llx", v);
+    return true;
+}
+
+static pathchar *ghci_prelink_archive_to_tmp(pathchar *archivePath, size_t threshold)
+{
+    struct_stat st;
+    if (pathstat(archivePath, &st) != 0) return NULL;
+    if (threshold == 0 || (size_t)st.st_size < threshold) return NULL;
+
+    // Build cache target name using SHA-256 and include basename for readability
+    char hex[65];
+    if (!ghci_compute_cache_key((const char *)archivePath, hex)) {
+        return NULL;
+    }
+
+    const char *tmpdir = ghci_tmpdir();
+    const char *base = ghci_basename_posix((const char *)archivePath);
+    int target_needed = snprintf(NULL, 0, "%s/ghc-prelink-%s-%s.o", tmpdir, base, hex);
+    pathchar *target = stgMallocBytes((target_needed + 1) * pathsize, "ghci_prelink(target)");
+    snprintf((char *)target, target_needed + 1, "%s/ghc-prelink-%s-%s.o", tmpdir, base, hex);
+
+    // If cached object exists, use it
+    struct stat sb;
+    if (stat((const char *)target, &sb) == 0 && sb.st_size > 0) {
+        return target;
+    }
+
+    // Cross-process lock using a directory
+    char lock_path[PATH_MAX];
+    snprintf(lock_path, sizeof(lock_path), "%s/ghc-prelink-%s-%s.building", tmpdir, base, hex);
+    if (mkdir(lock_path, 0700) == 0) {
+        // We are the builder
+        int tmp_needed = snprintf(NULL, 0, "%s/ghc-prelink-%d-%s.tmp.o", tmpdir, (int)getpid(), base);
+        pathchar *tmp_out = stgMallocBytes((tmp_needed + 1) * pathsize, "ghci_prelink(tmp)");
+        snprintf((char *)tmp_out, tmp_needed + 1, "%s/ghc-prelink-%d-%s.tmp.o", tmpdir, (int)getpid(), base);
+
+        // Log for diagnostics
+        char log_path[PATH_MAX];
+        snprintf(log_path, sizeof(log_path), "%s/ghc-prelink-%s.log", tmpdir, hex);
+
+    const char *cc = getenv("CC");
+        if (!cc || !*cc) cc = "cc";
+    const char *ldflags = getenv("LDFLAGS");
+    if (!ldflags) ldflags = "";
+        char cmd[4096];
+#  if defined(OBJFORMAT_ELF)
+        int n = snprintf(cmd, sizeof(cmd),
+             "%s %s -nostdlib -Wl,-r -Wl,--whole-archive '%s' -Wl,--no-whole-archive -o '%s' >'%s' 2>&1",
+             cc, ldflags, (const char *)archivePath, (const char *)tmp_out, log_path);
+#  elif defined(OBJFORMAT_MACHO)
+        int n = snprintf(cmd, sizeof(cmd),
+             "%s %s -nostdlib -Wl,-r -Wl,-all_load '%s' -o '%s' >'%s' 2>&1",
+             cc, ldflags, (const char *)archivePath, (const char *)tmp_out, log_path);
+#  endif
+        if (n < 0 || (size_t)n >= sizeof(cmd)) {
+            errorBelch("prelink: command too long while building cache for %s", base);
+            stgFree(tmp_out);
+            rmdir(lock_path);
+            stgFree(target);
+            return NULL;
+        }
+
+        IF_DEBUG(linker, debugBelch("prelinking large archive: %" PATH_FMT " -> %s (cc=%s)\n", archivePath, (char *)tmp_out, cc));
+        int rc = system(cmd);
+        if (rc != 0) {
+            char buf[1024];
+            buf[0] = '\0';
+            if (ghci_read_file_prefix(log_path, buf, sizeof(buf))) {
+                errorBelch("prelink failed (rc=%d) for %s; command: %s\n%s", rc, base, cmd, buf);
+            } else {
+                errorBelch("prelink failed (rc=%d) for %s; command: %s", rc, base, cmd);
+            }
+            unlink((const char *)tmp_out);
+            unlink(log_path);
+            rmdir(lock_path);
+            stgFree(tmp_out);
+            stgFree(target);
+            return NULL;
+        }
+
+        // Atomically move into place
+        if (rename((const char *)tmp_out, (const char *)target) != 0) {
+            errorBelch("prelink: failed to rename '%s' to '%s' (errno=%d)", (char *)tmp_out, (char *)target, errno);
+            unlink((const char *)tmp_out);
+            unlink(log_path);
+            rmdir(lock_path);
+            stgFree(tmp_out);
+            stgFree(target);
+            return NULL;
+        }
+        unlink(log_path);
+        rmdir(lock_path);
+        stgFree(tmp_out);
+        return target;
+    } else {
+        // Someone else is building; wait for target to appear
+        const int max_ms = 30000; // 30 seconds
+        int waited = 0;
+        while (waited < max_ms) {
+            if (stat((const char *)target, &sb) == 0 && sb.st_size > 0) {
+                return target;
+            }
+            struct timespec ts = {0, 100 * 1000 * 1000}; // 100ms
+            nanosleep(&ts, NULL);
+            waited += 100;
+        }
+        // Give up
+        stgFree(target);
+        return NULL;
+    }
+}
+#endif
+
 void
 initLinker_ (int retain_cafs)
 {
@@ -1468,9 +1639,55 @@ static HsInt loadObj_ (pathchar *path)
        return 1; // success
    }
 
+   // Optionally pre-link large archives into a temporary .o to speed up loading.
+   // Runtime configuration precedence:
+   //   1) +RTS --linker-prelink-archive-threshold=<size>
+   //   2) env GHCI_PRELINK_ARCHIVE_THRESHOLD=<size>
+   //   3) default 100M
+   static size_t ghci_prelink_threshold = (size_t)-1;
+   if (ghci_prelink_threshold == (size_t)-1) {
+       // Env var takes precedence over the RTS field
+       size_t val;
+       const char *env = getenv("GHCI_PRELINK_ARCHIVE_THRESHOLD");
+       if (env && *env) {
+           char *endp = NULL;
+           unsigned long long n = strtoull(env, &endp, 10);
+           if (endp && (*endp == 'K' || *endp == 'k')) {
+               val = (size_t)n * 1024ULL;
+           } else if (endp && (*endp == 'M' || *endp == 'm')) {
+               val = (size_t)n * 1024ULL * 1024ULL;
+           } else if (endp && (*endp == 'G' || *endp == 'g')) {
+               val = (size_t)n * 1024ULL * 1024ULL * 1024ULL;
+           } else {
+               val = (size_t)n;
+           }
+       } else {
+           // use the RTS field (set by +RTS or defaulted)
+           val = (size_t)RtsFlags.MiscFlags.linkerPrelinkArchiveThreshold;
+       }
+       ghci_prelink_threshold = val;
+   }
+
    // Things that look like object files (e.g. end in `.o`) may nevertheless be
    // archives, as noted in Note [Object merging] in GHC.Driver.Pipeline.Execute.
    if (isArchive(path)) {
+       // Try pre-linking if the archive is large enough
+    pathchar *tmp_o = NULL;
+#if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
+    tmp_o = ghci_prelink_archive_to_tmp(path, ghci_prelink_threshold);
+#endif
+       if (tmp_o != NULL) {
+           HsInt ok = loadObj_(tmp_o);
+           if (!ok) {
+               IF_DEBUG(linker, debugBelch("prelinked loading failed for %" PATH_FMT ", falling back to archive loader\n", path));
+               // Fall back to archive loader
+               stgFree(tmp_o);
+           } else {
+               // Keep the temp file on disk to allow later unload/debug. Do not free oc->fileName here.
+               stgFree(tmp_o);
+               return 1;
+           }
+       }
        if (loadArchive_(path)) {
             return 1; // success
        } else {
diff --git a/rts/RtsFlags.c b/rts/RtsFlags.c
index 214255c590d..048addef099 100644
--- a/rts/RtsFlags.c
+++ b/rts/RtsFlags.c
@@ -272,6 +272,8 @@ void initRtsFlagsDefaults(void)
     RtsFlags.MiscFlags.linkerOptimistic        = false;
     RtsFlags.MiscFlags.linkerMemBase           = 0;
     RtsFlags.MiscFlags.ioManager               = IO_MNGR_FLAG_AUTO;
+    /* Default to 100 MiB; can be overridden by env or +RTS */
+    RtsFlags.MiscFlags.linkerPrelinkArchiveThreshold = (int64_t)(100ULL * 1024ULL * 1024ULL);
 #if defined(THREADED_RTS) && defined(mingw32_HOST_OS)
     RtsFlags.MiscFlags.numIoWorkerThreads      = getNumberOfProcessors();
 #else
@@ -555,6 +557,9 @@ usage_text[] = {
 "  -xm        Base address to mmap memory in the GHCi linker",
 "             (hex; must be <80000000)",
 #endif
+"  --linker-prelink-archive-threshold=<size>",
+"             Pre-link large .a archives to a temporary .o before loading.",
+"             Units: K, M, G. 0 disables. Default: 100M (if not set via env)",
 "  -xq        The allocation limit given to a thread after it receives",
 "             an AllocationLimitExceeded exception. (default: 100k)",
 "",
@@ -1005,6 +1010,24 @@ error = true;
                        OPTION_UNSAFE;
                        RtsFlags.MiscFlags.linkerOptimistic = true;
                   }
+                  else if (!strncmp("linker-prelink-archive-threshold=",
+                               &rts_argv[arg][2], 33)) {
+                      OPTION_UNSAFE;
+                      /* rts_argv[arg] is like "--linker-prelink-archive-threshold=<size>" */
+                      /* The value begins after the '=' which is at index 36 of the string */
+                      /* We can't easily compute the offset robustly from here; instead find '=' */
+                      const char* full = rts_argv[arg];
+                      const char* eq = strchr(full, '=');
+                      if (eq == NULL) {
+                          errorBelch("%s: missing value", rts_argv[arg]);
+                          error = true;
+                      } else {
+                          /* decodeSize expects the full flag and an offset to the value within it */
+                          uint32_t off = (uint32_t)(eq - full + 1);
+                          StgWord64 bytes = decodeSize(full, off, 0, HS_WORD64_MAX);
+                          RtsFlags.MiscFlags.linkerPrelinkArchiveThreshold = (int64_t)bytes;
+                      }
+                  }
                   else if (strequal("null-eventlog-writer",
                                &rts_argv[arg][2])) {
                       OPTION_UNSAFE;
diff --git a/rts/include/rts/Flags.h b/rts/include/rts/Flags.h
index 3d5b3aa22af..cf36f81689b 100644
--- a/rts/include/rts/Flags.h
+++ b/rts/include/rts/Flags.h
@@ -272,6 +272,8 @@ typedef struct _MISC_FLAGS {
                                   * for the linker, NULL ==> off */
     IO_MANAGER_FLAG ioManager;   /* The I/O manager to use.  */
     uint32_t numIoWorkerThreads; /* Number of I/O worker threads to use.  */
+    /* Pre-link large archives before loading into the RTS linker. */
+    int64_t linkerPrelinkArchiveThreshold; /* bytes; default set in RtsFlags; 0 = disable */
 } MISC_FLAGS;
 
 /* See Note [Synchronization of flags and base APIs] */

From 81b1580e92c12c4cdefd02c6bce87bca0316c8ca Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Mon, 15 Sep 2025 16:03:50 +0900
Subject: [PATCH 07/23] Revert "compiler/rts: prelink archive threshold"

This reverts commit d82107487ee83f1b27cf77a7e9398c4fd624457b.
---
 compiler/GHC/Driver/DynFlags.hs |   4 -
 compiler/GHC/Driver/Session.hs  |  11 +-
 compiler/cbits/cutils.c         |  12 --
 rts/Linker.c                    | 217 --------------------------------
 rts/RtsFlags.c                  |  23 ----
 rts/include/rts/Flags.h         |   2 -
 6 files changed, 1 insertion(+), 268 deletions(-)

diff --git a/compiler/GHC/Driver/DynFlags.hs b/compiler/GHC/Driver/DynFlags.hs
index 13786cc03e7..4377094a98c 100644
--- a/compiler/GHC/Driver/DynFlags.hs
+++ b/compiler/GHC/Driver/DynFlags.hs
@@ -196,9 +196,6 @@ data DynFlags = DynFlags {
 
   enableTimeStats       :: Bool,        -- ^ Enable RTS timing statistics?
   ghcHeapSize           :: Maybe Int,   -- ^ The heap size to set.
-  -- | Threshold (in bytes) above which GHCi will pre-link archives (ld -r)
-  -- before loading. A value of 0 disables pre-linking.
-  ghciPrelinkArchiveThreshold :: Maybe Integer,
 
   maxRelevantBinds      :: Maybe Int,   -- ^ Maximum number of bindings from the type envt
                                         --   to show in type error messages
@@ -586,7 +583,6 @@ defaultDynFlags mySettings =
 
         enableTimeStats         = False,
         ghcHeapSize             = Nothing,
-        ghciPrelinkArchiveThreshold = Nothing,
 
         importPaths             = ["."],
         mainModuleNameIs        = mAIN_NAME,
diff --git a/compiler/GHC/Driver/Session.hs b/compiler/GHC/Driver/Session.hs
index 38e9a8c5e3a..0ca58c33866 100644
--- a/compiler/GHC/Driver/Session.hs
+++ b/compiler/GHC/Driver/Session.hs
@@ -295,8 +295,6 @@ import qualified Data.Map as Map
 import qualified Data.Set as Set
 import Data.Word
 import System.FilePath
--- no env tweaks needed here
-import Data.Int (Int64)
 import Text.ParserCombinators.ReadP hiding (char)
 import Text.ParserCombinators.ReadP as R
 
@@ -886,7 +884,7 @@ parseDynamicFlagsFull activeFlags cmdline logger dflags0 args = do
     map ((rdr . ppr . getLoc &&& unLoc) . errMsg) $ errs
 
   -- check for disabled flags in safe haskell
-            let (dflags2, sh_warns) = safeFlagCheck cmdline dflags1
+  let (dflags2, sh_warns) = safeFlagCheck cmdline dflags1
       theWays = ways dflags2
 
   unless (allowed_combination theWays) $ liftIO $
@@ -901,10 +899,6 @@ parseDynamicFlagsFull activeFlags cmdline logger dflags0 args = do
     Just x -> liftIO (setHeapSize x)
     _      -> return ()
 
-  case ghciPrelinkArchiveThreshold dflags3 of
-    Just n  -> liftIO (setGhciPrelinkArchiveThreshold (fromIntegral (n :: Integer)))
-    _       -> return ()
-
   liftIO $ setUnsafeGlobalDynFlags dflags3
 
   -- create message envelopes using final DynFlags: #23402
@@ -1081,8 +1075,6 @@ dynamic_flags_deps = [
     -- RTS options -------------------------------------------------------------
   , make_ord_flag defFlag "H"           (HasArg (\s -> upd (\d ->
           d { ghcHeapSize = Just $ fromIntegral (decodeSize s)})))
-  , make_ord_flag defGhcFlag "ghci-prelink-archive-threshold"
-          (HasArg (\s -> upd (\d -> d { ghciPrelinkArchiveThreshold = Just (decodeSize s) })))
 
   , make_ord_flag defFlag "Rghc-timing" (NoArg (upd (\d ->
                                                d { enableTimeStats = True })))
@@ -3816,7 +3808,6 @@ decodeSize str
 
 foreign import ccall unsafe "setHeapSize"       setHeapSize       :: Int -> IO ()
 foreign import ccall unsafe "enableTimingStats" enableTimingStats :: IO ()
-foreign import ccall unsafe "setGhciPrelinkArchiveThreshold" setGhciPrelinkArchiveThreshold :: Int64 -> IO ()
 
 outputFile :: DynFlags -> Maybe String
 outputFile dflags
diff --git a/compiler/cbits/cutils.c b/compiler/cbits/cutils.c
index 0091dfa767e..fb7e3f7335b 100644
--- a/compiler/cbits/cutils.c
+++ b/compiler/cbits/cutils.c
@@ -7,11 +7,6 @@ places in the GHC library.
 
 #include <HsFFI.h>
 
-/* Prototype for FFI-callable helper */
-void enableTimingStats( void );
-void setHeapSize( HsInt size );
-void setGhciPrelinkArchiveThreshold( HsInt64 bytes );
-
 void
 enableTimingStats( void )       /* called from the driver */
 {
@@ -27,10 +22,3 @@ setHeapSize( HsInt size )
         RtsFlags.GcFlags.maxHeapSize = RtsFlags.GcFlags.heapSizeSuggestion;
     }
 }
-
-/* Configure GHCi pre-link archive threshold (in bytes). 0 disables. */
-void
-setGhciPrelinkArchiveThreshold( HsInt64 bytes )
-{
-    RtsFlags.MiscFlags.linkerPrelinkArchiveThreshold = (StgInt64) bytes;
-}
diff --git a/rts/Linker.c b/rts/Linker.c
index 3ee3545f865..dc9a3a336c6 100644
--- a/rts/Linker.c
+++ b/rts/Linker.c
@@ -35,7 +35,6 @@
 #include "PathUtils.h"
 #include "CheckUnload.h" // createOCSectionIndices
 #include "ReportMemoryMap.h"
-#include "xxhash.h"
 
 #if !defined(mingw32_HOST_OS) && defined(HAVE_SIGNAL_H)
 #include "posix/Signals.h"
@@ -445,176 +444,6 @@ void initLinker (void)
     initLinker_(1);
 }
 
-// Helper to pre-link big archives into a temporary object file so the
-// internal linker can load a single .o instead of many members.
-#if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
-#include <errno.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <limits.h>
-#include <time.h>
-
-static const char *ghci_basename_posix(const char *p)
-{
-    const char *last = p;
-    if (!p) return p;
-    for (const char *s = p; *s; ++s) {
-        if (*s == '/') last = s + 1;
-    }
-    return last;
-}
-
-static const char *ghci_tmpdir(void)
-{
-    const char *t = getenv("TMPDIR");
-    return t && *t ? t : "/tmp";
-}
-
-static bool ghci_read_file_prefix(const char *path, char *buf, size_t bufsz)
-{
-    FILE *f = fopen(path, "rb");
-    if (!f) return false;
-    size_t n = fread(buf, 1, bufsz - 1, f);
-    buf[n] = '\0';
-    fclose(f);
-    return true;
-}
-
-static bool ghci_compute_cache_key(const char *path, char out_hex[65])
-{
-    FILE *f = fopen(path, "rb");
-    if (!f) return false;
-    XXH64_state_t* st = XXH64_createState();
-    if (!st) { fclose(f); return false; }
-    if (XXH64_reset(st, 0) != XXH_OK) { XXH64_freeState(st); fclose(f); return false; }
-    unsigned char buf[256 * 1024];
-    size_t n;
-    while ((n = fread(buf, 1, sizeof(buf), f)) > 0) {
-        if (XXH64_update(st, buf, n) != XXH_OK) {
-            XXH64_freeState(st); fclose(f); return false;
-        }
-    }
-    fclose(f);
-    XXH64_hash_t hv = XXH64_digest(st);
-    XXH64_freeState(st);
-    // render as 16-char hex (zero-padded)
-    // use unsigned long long to satisfy printf on most platforms
-    unsigned long long v = (unsigned long long)hv;
-    // ensure buffer large enough; we reserved 65 earlier
-    snprintf(out_hex, 65, "%016llx", v);
-    return true;
-}
-
-static pathchar *ghci_prelink_archive_to_tmp(pathchar *archivePath, size_t threshold)
-{
-    struct_stat st;
-    if (pathstat(archivePath, &st) != 0) return NULL;
-    if (threshold == 0 || (size_t)st.st_size < threshold) return NULL;
-
-    // Build cache target name using SHA-256 and include basename for readability
-    char hex[65];
-    if (!ghci_compute_cache_key((const char *)archivePath, hex)) {
-        return NULL;
-    }
-
-    const char *tmpdir = ghci_tmpdir();
-    const char *base = ghci_basename_posix((const char *)archivePath);
-    int target_needed = snprintf(NULL, 0, "%s/ghc-prelink-%s-%s.o", tmpdir, base, hex);
-    pathchar *target = stgMallocBytes((target_needed + 1) * pathsize, "ghci_prelink(target)");
-    snprintf((char *)target, target_needed + 1, "%s/ghc-prelink-%s-%s.o", tmpdir, base, hex);
-
-    // If cached object exists, use it
-    struct stat sb;
-    if (stat((const char *)target, &sb) == 0 && sb.st_size > 0) {
-        return target;
-    }
-
-    // Cross-process lock using a directory
-    char lock_path[PATH_MAX];
-    snprintf(lock_path, sizeof(lock_path), "%s/ghc-prelink-%s-%s.building", tmpdir, base, hex);
-    if (mkdir(lock_path, 0700) == 0) {
-        // We are the builder
-        int tmp_needed = snprintf(NULL, 0, "%s/ghc-prelink-%d-%s.tmp.o", tmpdir, (int)getpid(), base);
-        pathchar *tmp_out = stgMallocBytes((tmp_needed + 1) * pathsize, "ghci_prelink(tmp)");
-        snprintf((char *)tmp_out, tmp_needed + 1, "%s/ghc-prelink-%d-%s.tmp.o", tmpdir, (int)getpid(), base);
-
-        // Log for diagnostics
-        char log_path[PATH_MAX];
-        snprintf(log_path, sizeof(log_path), "%s/ghc-prelink-%s.log", tmpdir, hex);
-
-    const char *cc = getenv("CC");
-        if (!cc || !*cc) cc = "cc";
-    const char *ldflags = getenv("LDFLAGS");
-    if (!ldflags) ldflags = "";
-        char cmd[4096];
-#  if defined(OBJFORMAT_ELF)
-        int n = snprintf(cmd, sizeof(cmd),
-             "%s %s -nostdlib -Wl,-r -Wl,--whole-archive '%s' -Wl,--no-whole-archive -o '%s' >'%s' 2>&1",
-             cc, ldflags, (const char *)archivePath, (const char *)tmp_out, log_path);
-#  elif defined(OBJFORMAT_MACHO)
-        int n = snprintf(cmd, sizeof(cmd),
-             "%s %s -nostdlib -Wl,-r -Wl,-all_load '%s' -o '%s' >'%s' 2>&1",
-             cc, ldflags, (const char *)archivePath, (const char *)tmp_out, log_path);
-#  endif
-        if (n < 0 || (size_t)n >= sizeof(cmd)) {
-            errorBelch("prelink: command too long while building cache for %s", base);
-            stgFree(tmp_out);
-            rmdir(lock_path);
-            stgFree(target);
-            return NULL;
-        }
-
-        IF_DEBUG(linker, debugBelch("prelinking large archive: %" PATH_FMT " -> %s (cc=%s)\n", archivePath, (char *)tmp_out, cc));
-        int rc = system(cmd);
-        if (rc != 0) {
-            char buf[1024];
-            buf[0] = '\0';
-            if (ghci_read_file_prefix(log_path, buf, sizeof(buf))) {
-                errorBelch("prelink failed (rc=%d) for %s; command: %s\n%s", rc, base, cmd, buf);
-            } else {
-                errorBelch("prelink failed (rc=%d) for %s; command: %s", rc, base, cmd);
-            }
-            unlink((const char *)tmp_out);
-            unlink(log_path);
-            rmdir(lock_path);
-            stgFree(tmp_out);
-            stgFree(target);
-            return NULL;
-        }
-
-        // Atomically move into place
-        if (rename((const char *)tmp_out, (const char *)target) != 0) {
-            errorBelch("prelink: failed to rename '%s' to '%s' (errno=%d)", (char *)tmp_out, (char *)target, errno);
-            unlink((const char *)tmp_out);
-            unlink(log_path);
-            rmdir(lock_path);
-            stgFree(tmp_out);
-            stgFree(target);
-            return NULL;
-        }
-        unlink(log_path);
-        rmdir(lock_path);
-        stgFree(tmp_out);
-        return target;
-    } else {
-        // Someone else is building; wait for target to appear
-        const int max_ms = 30000; // 30 seconds
-        int waited = 0;
-        while (waited < max_ms) {
-            if (stat((const char *)target, &sb) == 0 && sb.st_size > 0) {
-                return target;
-            }
-            struct timespec ts = {0, 100 * 1000 * 1000}; // 100ms
-            nanosleep(&ts, NULL);
-            waited += 100;
-        }
-        // Give up
-        stgFree(target);
-        return NULL;
-    }
-}
-#endif
-
 void
 initLinker_ (int retain_cafs)
 {
@@ -1639,55 +1468,9 @@ static HsInt loadObj_ (pathchar *path)
        return 1; // success
    }
 
-   // Optionally pre-link large archives into a temporary .o to speed up loading.
-   // Runtime configuration precedence:
-   //   1) +RTS --linker-prelink-archive-threshold=<size>
-   //   2) env GHCI_PRELINK_ARCHIVE_THRESHOLD=<size>
-   //   3) default 100M
-   static size_t ghci_prelink_threshold = (size_t)-1;
-   if (ghci_prelink_threshold == (size_t)-1) {
-       // Env var takes precedence over the RTS field
-       size_t val;
-       const char *env = getenv("GHCI_PRELINK_ARCHIVE_THRESHOLD");
-       if (env && *env) {
-           char *endp = NULL;
-           unsigned long long n = strtoull(env, &endp, 10);
-           if (endp && (*endp == 'K' || *endp == 'k')) {
-               val = (size_t)n * 1024ULL;
-           } else if (endp && (*endp == 'M' || *endp == 'm')) {
-               val = (size_t)n * 1024ULL * 1024ULL;
-           } else if (endp && (*endp == 'G' || *endp == 'g')) {
-               val = (size_t)n * 1024ULL * 1024ULL * 1024ULL;
-           } else {
-               val = (size_t)n;
-           }
-       } else {
-           // use the RTS field (set by +RTS or defaulted)
-           val = (size_t)RtsFlags.MiscFlags.linkerPrelinkArchiveThreshold;
-       }
-       ghci_prelink_threshold = val;
-   }
-
    // Things that look like object files (e.g. end in `.o`) may nevertheless be
    // archives, as noted in Note [Object merging] in GHC.Driver.Pipeline.Execute.
    if (isArchive(path)) {
-       // Try pre-linking if the archive is large enough
-    pathchar *tmp_o = NULL;
-#if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
-    tmp_o = ghci_prelink_archive_to_tmp(path, ghci_prelink_threshold);
-#endif
-       if (tmp_o != NULL) {
-           HsInt ok = loadObj_(tmp_o);
-           if (!ok) {
-               IF_DEBUG(linker, debugBelch("prelinked loading failed for %" PATH_FMT ", falling back to archive loader\n", path));
-               // Fall back to archive loader
-               stgFree(tmp_o);
-           } else {
-               // Keep the temp file on disk to allow later unload/debug. Do not free oc->fileName here.
-               stgFree(tmp_o);
-               return 1;
-           }
-       }
        if (loadArchive_(path)) {
             return 1; // success
        } else {
diff --git a/rts/RtsFlags.c b/rts/RtsFlags.c
index 048addef099..214255c590d 100644
--- a/rts/RtsFlags.c
+++ b/rts/RtsFlags.c
@@ -272,8 +272,6 @@ void initRtsFlagsDefaults(void)
     RtsFlags.MiscFlags.linkerOptimistic        = false;
     RtsFlags.MiscFlags.linkerMemBase           = 0;
     RtsFlags.MiscFlags.ioManager               = IO_MNGR_FLAG_AUTO;
-    /* Default to 100 MiB; can be overridden by env or +RTS */
-    RtsFlags.MiscFlags.linkerPrelinkArchiveThreshold = (int64_t)(100ULL * 1024ULL * 1024ULL);
 #if defined(THREADED_RTS) && defined(mingw32_HOST_OS)
     RtsFlags.MiscFlags.numIoWorkerThreads      = getNumberOfProcessors();
 #else
@@ -557,9 +555,6 @@ usage_text[] = {
 "  -xm        Base address to mmap memory in the GHCi linker",
 "             (hex; must be <80000000)",
 #endif
-"  --linker-prelink-archive-threshold=<size>",
-"             Pre-link large .a archives to a temporary .o before loading.",
-"             Units: K, M, G. 0 disables. Default: 100M (if not set via env)",
 "  -xq        The allocation limit given to a thread after it receives",
 "             an AllocationLimitExceeded exception. (default: 100k)",
 "",
@@ -1010,24 +1005,6 @@ error = true;
                        OPTION_UNSAFE;
                        RtsFlags.MiscFlags.linkerOptimistic = true;
                   }
-                  else if (!strncmp("linker-prelink-archive-threshold=",
-                               &rts_argv[arg][2], 33)) {
-                      OPTION_UNSAFE;
-                      /* rts_argv[arg] is like "--linker-prelink-archive-threshold=<size>" */
-                      /* The value begins after the '=' which is at index 36 of the string */
-                      /* We can't easily compute the offset robustly from here; instead find '=' */
-                      const char* full = rts_argv[arg];
-                      const char* eq = strchr(full, '=');
-                      if (eq == NULL) {
-                          errorBelch("%s: missing value", rts_argv[arg]);
-                          error = true;
-                      } else {
-                          /* decodeSize expects the full flag and an offset to the value within it */
-                          uint32_t off = (uint32_t)(eq - full + 1);
-                          StgWord64 bytes = decodeSize(full, off, 0, HS_WORD64_MAX);
-                          RtsFlags.MiscFlags.linkerPrelinkArchiveThreshold = (int64_t)bytes;
-                      }
-                  }
                   else if (strequal("null-eventlog-writer",
                                &rts_argv[arg][2])) {
                       OPTION_UNSAFE;
diff --git a/rts/include/rts/Flags.h b/rts/include/rts/Flags.h
index cf36f81689b..3d5b3aa22af 100644
--- a/rts/include/rts/Flags.h
+++ b/rts/include/rts/Flags.h
@@ -272,8 +272,6 @@ typedef struct _MISC_FLAGS {
                                   * for the linker, NULL ==> off */
     IO_MANAGER_FLAG ioManager;   /* The I/O manager to use.  */
     uint32_t numIoWorkerThreads; /* Number of I/O worker threads to use.  */
-    /* Pre-link large archives before loading into the RTS linker. */
-    int64_t linkerPrelinkArchiveThreshold; /* bytes; default set in RtsFlags; 0 = disable */
 } MISC_FLAGS;
 
 /* See Note [Synchronization of flags and base APIs] */

From 20f14f1276b020cc73b98298b545d2d422f4ef1f Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Mon, 15 Sep 2025 16:26:25 +0900
Subject: [PATCH 08/23] rts: move cmm sources into common section, and move
 them into sublibs

---
 rts/rts.cabal | 63 ++++++++++++++++++++++++++-------------------------
 1 file changed, 32 insertions(+), 31 deletions(-)

diff --git a/rts/rts.cabal b/rts/rts.cabal
index ad0674d5f10..5eeaf939f37 100644
--- a/rts/rts.cabal
+++ b/rts/rts.cabal
@@ -331,6 +331,34 @@ common rts-base-config
       rts-fs,
       rts
 
+common rts-cmm-sources-base
+    if !arch(javascript)
+      -- FIXME: by virtue of being part of the rts main library, these do not get
+      -- the flags (debug, threaded, ...) as the sub libraries.  Thus we are
+      -- likely missing -DDEBUG, -DTHREADED_RTS, etc.
+      -- One solution to this would be to turn all of these into `.h` files, and
+      -- then have the `AutoApply.cmm` in `rts-c-sources-base` include them.  This
+      -- would mean they are included in the sublibraries which will in turn apply
+      -- the sublibrary specific (c)flags.
+      autogen-cmm-sources:
+        AutoApply.cmm
+        AutoApply_V16.cmm
+
+      if arch(x86_64)
+        cmm-sources:
+          Jumps_V32.cmm (-mavx2)
+          Jumps_V64.cmm (-mavx512f)
+        autogen-cmm-sources:
+          AutoApply_V32.cmm (-mavx2)
+          AutoApply_V64.cmm (-mavx512f)
+      else
+        cmm-sources:
+          Jumps_V32.cmm
+          Jumps_V64.cmm
+        autogen-cmm-sources:
+          AutoApply_V32.cmm
+          AutoApply_V64.cmm
+
 common rts-c-sources-base
     if !arch(javascript)
       cmm-sources:
@@ -694,33 +722,6 @@ library
       rts-headers,
       rts-fs
 
-    if !arch(javascript)
-      -- FIXME: by virtue of being part of the rts main library, these do not get
-      -- the flags (debug, threaded, ...) as the sub libraries.  Thus we are
-      -- likely missing -DDEBUG, -DTHREADED_RTS, etc.
-      -- One solution to this would be to turn all of these into `.h` files, and
-      -- then have the `AutoApply.cmm` in `rts-c-sources-base` include them.  This
-      -- would mean they are included in the sublibraries which will in turn apply
-      -- the sublibrary specific (c)flags.
-      autogen-cmm-sources:
-        AutoApply.cmm
-        AutoApply_V16.cmm
-
-      if arch(x86_64)
-        cmm-sources:
-          Jumps_V32.cmm (-mavx2)
-          Jumps_V64.cmm (-mavx512f)
-        autogen-cmm-sources:
-          AutoApply_V32.cmm (-mavx2)
-          AutoApply_V64.cmm (-mavx512f)
-      else
-        cmm-sources:
-          Jumps_V32.cmm
-          Jumps_V64.cmm
-        autogen-cmm-sources:
-          AutoApply_V32.cmm
-          AutoApply_V64.cmm
-
 common ghcjs
     import: rts-base-config
 
@@ -767,7 +768,7 @@ library nonthreaded-nodebug
     if arch(javascript)
       import: ghcjs
     else
-      import: rts-base-config, rts-c-sources-base, rts-link-options, rts-global-build-flags
+      import: rts-base-config, rts-cmm-sources-base, rts-c-sources-base, rts-link-options, rts-global-build-flags
 
     visibility: public
 
@@ -775,21 +776,21 @@ library nonthreaded-nodebug
 
 
 library threaded-nodebug
-    import: rts-base-config, rts-c-sources-base, rts-link-options, rts-global-build-flags, rts-threaded-flags
+    import: rts-base-config, rts-cmm-sources-base, rts-c-sources-base, rts-link-options, rts-global-build-flags, rts-threaded-flags
     visibility: public
     build-depends: rts
     if arch(javascript)
       buildable: False
 
 library nonthreaded-debug
-    import: rts-base-config, rts-c-sources-base, rts-link-options, rts-global-build-flags, rts-debug-flags
+    import: rts-base-config, rts-cmm-sources-base, rts-c-sources-base, rts-link-options, rts-global-build-flags, rts-debug-flags
     visibility: public
     build-depends: rts
     if arch(javascript)
       buildable: False
 
 library threaded-debug
-    import: rts-base-config, rts-c-sources-base, rts-link-options, rts-global-build-flags, rts-threaded-flags, rts-debug-flags
+    import: rts-base-config, rts-cmm-sources-base, rts-c-sources-base, rts-link-options, rts-global-build-flags, rts-threaded-flags, rts-debug-flags
     visibility: public
     build-depends: rts
     if arch(javascript)

From 26a1007546672e31363657504ec5cf92c291d16a Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Mon, 15 Sep 2025 20:20:25 +0900
Subject: [PATCH 09/23] rts: Add no-ghc-internal flag

---
 compiler/GHC/Driver/DynFlags.hs |  3 ++-
 compiler/GHC/Driver/Flags.hs    |  1 +
 compiler/GHC/Driver/Session.hs  |  2 ++
 compiler/GHC/Unit/State.hs      | 11 +++++++++--
 4 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/compiler/GHC/Driver/DynFlags.hs b/compiler/GHC/Driver/DynFlags.hs
index 4377094a98c..9a3fa58603c 100644
--- a/compiler/GHC/Driver/DynFlags.hs
+++ b/compiler/GHC/Driver/DynFlags.hs
@@ -878,7 +878,8 @@ packageFlagsChanged idflags1 idflags0 =
      [ Opt_HideAllPackages
      , Opt_HideAllPluginPackages
      , Opt_AutoLinkPackages
-     , Opt_NoRts ]
+     , Opt_NoRts
+     , Opt_NoGhcInternal ]
 
 instance Outputable PackageFlag where
     ppr (ExposePackage n arg rn) = text n <> braces (ppr arg <+> ppr rn)
diff --git a/compiler/GHC/Driver/Flags.hs b/compiler/GHC/Driver/Flags.hs
index 58e80e41b40..a10670b9eff 100644
--- a/compiler/GHC/Driver/Flags.hs
+++ b/compiler/GHC/Driver/Flags.hs
@@ -863,6 +863,7 @@ data GeneralFlag
    -- temporary flags
    | Opt_AutoLinkPackages
    | Opt_NoRts
+   | Opt_NoGhcInternal
    | Opt_ImplicitImportQualified
 
    -- keeping stuff
diff --git a/compiler/GHC/Driver/Session.hs b/compiler/GHC/Driver/Session.hs
index 0ca58c33866..5f791ecc219 100644
--- a/compiler/GHC/Driver/Session.hs
+++ b/compiler/GHC/Driver/Session.hs
@@ -1314,6 +1314,8 @@ dynamic_flags_deps = [
         (NoArg (setGeneralFlag Opt_NoHsMain))
   , make_ord_flag defGhcFlag "no-rts"
         (NoArg (setGeneralFlag Opt_NoRts))
+  , make_ord_flag defGhcFlag "no-ghc-internal"
+        (NoArg (setGeneralFlag Opt_NoGhcInternal))
   , make_ord_flag defGhcFlag "fno-state-hack"
         (NoArg (setGeneralFlag Opt_G_NoStateHack))
   , make_ord_flag defGhcFlag "fno-opt-coercion"
diff --git a/compiler/GHC/Unit/State.hs b/compiler/GHC/Unit/State.hs
index ed8ea36db6d..43107587073 100644
--- a/compiler/GHC/Unit/State.hs
+++ b/compiler/GHC/Unit/State.hs
@@ -1636,7 +1636,11 @@ mkUnitState logger dflags cfg = do
   -- it modifies the unit ids of wired in packages, but when we process
   -- package arguments we need to key against the old versions.
   --
-  (pkgs2, wired_map) <- findWiredInUnits logger (rtsWayUnitId dflags:wiredInUnitIds) prec_map pkgs1 vis_map2
+  let wired_ids_all = rtsWayUnitId dflags : wiredInUnitIds
+      wired_ids
+        | gopt Opt_NoGhcInternal dflags = filter (/= ghcInternalUnitId) wired_ids_all
+        | otherwise                     = wired_ids_all
+  (pkgs2, wired_map) <- findWiredInUnits logger wired_ids prec_map pkgs1 vis_map2
 
   --
   -- Sanity check. If the rtsWayUnitId is not in the database, then we have a
@@ -1648,6 +1652,7 @@ mkUnitState logger dflags cfg = do
         , nest 2 $ vcat
             [ text "pkgs1_count =" <+> ppr (length pkgs1)
             , text "Opt_NoRts   =" <+> ppr (gopt Opt_NoRts dflags)
+            , text "Opt_NoGhcInternal =" <+> ppr (gopt Opt_NoGhcInternal dflags)
             , text "ghcLink     =" <+> text (show (ghcLink dflags))
             , text "platform    =" <+> text (show (targetPlatform dflags))
             , text "rtsWayUnitId=" <+> ppr (rtsWayUnitId dflags)
@@ -1664,7 +1669,9 @@ mkUnitState logger dflags cfg = do
       <> text " Please check your installation."
       <> text " If this target doesn't need the RTS (e.g. building a shared library), you can add -no-rts to the relevant package's ghc-options in cabal.project to bypass this check."
 
-  let pkgs3 = if gopt Opt_NoRts dflags && not (anyUniqMap (== ghcInternalUnitId) wired_map)
+  let pkgs3 = if gopt Opt_NoGhcInternal dflags
+         then pkgs2
+         else if gopt Opt_NoRts dflags && not (anyUniqMap (== ghcInternalUnitId) wired_map)
               then pkgs2
               else
               -- At this point we should have `ghcInternalUnitId`, and the `rtsWiredUnitId dflags`.

From b60cbda26faca97bb4152ea096152ec2ce9a21b7 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Mon, 15 Sep 2025 20:20:43 +0900
Subject: [PATCH 10/23] rts: Better AutoApply logic

---
 rts/AutoApply.cmm     |  1 +
 rts/AutoApply_V16.cmm |  1 +
 rts/AutoApply_V32.cmm |  1 +
 rts/AutoApply_V64.cmm |  1 +
 rts/configure.ac      | 24 ++++++++++++------------
 rts/rts.cabal         | 34 +++++++++++++++++++++++++++++-----
 6 files changed, 45 insertions(+), 17 deletions(-)
 create mode 100644 rts/AutoApply.cmm
 create mode 100644 rts/AutoApply_V16.cmm
 create mode 100644 rts/AutoApply_V32.cmm
 create mode 100644 rts/AutoApply_V64.cmm

diff --git a/rts/AutoApply.cmm b/rts/AutoApply.cmm
new file mode 100644
index 00000000000..22ed09ee02c
--- /dev/null
+++ b/rts/AutoApply.cmm
@@ -0,0 +1 @@
+#include <rts/AutoApply.cmm.h>
diff --git a/rts/AutoApply_V16.cmm b/rts/AutoApply_V16.cmm
new file mode 100644
index 00000000000..5cc5142317b
--- /dev/null
+++ b/rts/AutoApply_V16.cmm
@@ -0,0 +1 @@
+#include <rts/AutoApply_V16.cmm.h>
diff --git a/rts/AutoApply_V32.cmm b/rts/AutoApply_V32.cmm
new file mode 100644
index 00000000000..9a4427459b5
--- /dev/null
+++ b/rts/AutoApply_V32.cmm
@@ -0,0 +1 @@
+#include <rts/AutoApply_V32.cmm.h>
diff --git a/rts/AutoApply_V64.cmm b/rts/AutoApply_V64.cmm
new file mode 100644
index 00000000000..343853d6e16
--- /dev/null
+++ b/rts/AutoApply_V64.cmm
@@ -0,0 +1 @@
+#include <rts/AutoApply_V64.cmm.h>
diff --git a/rts/configure.ac b/rts/configure.ac
index ae110d76dce..7ee47bd4941 100644
--- a/rts/configure.ac
+++ b/rts/configure.ac
@@ -583,36 +583,36 @@ else
   AC_MSG_ERROR([Failed to run $DERIVE_CONSTANTS --gen-header ...])
 fi
 
-AC_MSG_CHECKING([for AutoApply.cmm])
-if $GENAPPLY include/DerivedConstants.h > AutoApply.cmm; then
+AC_MSG_CHECKING([for include/rts/AutoApply.cmm.h])
+if mkdir -p include/rts && $GENAPPLY include/DerivedConstants.h > include/rts/AutoApply.cmm.h; then
   AC_MSG_RESULT([created])
 else
   AC_MSG_RESULT([failed to create])
-  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h > AutoApply.cmm])
+  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h > include/rts/AutoApply.cmm.h])
 fi
 
-AC_MSG_CHECKING([for AutoApply_V16.cmm])
-if $GENAPPLY include/DerivedConstants.h -V16 > AutoApply_V16.cmm; then
+AC_MSG_CHECKING([for include/rts/AutoApply_V16.cmm.h])
+if mkdir -p include/rts && $GENAPPLY include/DerivedConstants.h -V16 > include/rts/AutoApply_V16.cmm.h; then
   AC_MSG_RESULT([created])
 else
   AC_MSG_RESULT([failed to create])
-  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V16 > AutoApply_V16.cmm])
+  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V16 > include/rts/AutoApply_V16.cmm.h])
 fi
 
-AC_MSG_CHECKING([for AutoApply_V32.cmm])
-if $GENAPPLY include/DerivedConstants.h -V32 > AutoApply_V32.cmm; then
+AC_MSG_CHECKING([for include/rts/AutoApply_V32.cmm.h])
+if mkdir -p include/rts && $GENAPPLY include/DerivedConstants.h -V32 > include/rts/AutoApply_V32.cmm.h; then
   AC_MSG_RESULT([created])
 else
   AC_MSG_RESULT([failed to create])
-  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V32 > AutoApply_V32.cmm])
+  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V32 > include/rts/AutoApply_V32.cmm.h])
 fi
 
-AC_MSG_CHECKING([for AutoApply_V64.cmm])
-if $GENAPPLY include/DerivedConstants.h -V64 > AutoApply_V64.cmm; then
+AC_MSG_CHECKING([for include/rts/AutoApply_V64.cmm.h])
+if mkdir -p include/rts && $GENAPPLY include/DerivedConstants.h -V64 > include/rts/AutoApply_V64.cmm.h; then
   AC_MSG_RESULT([created])
 else
   AC_MSG_RESULT([failed to create])
-  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V64 > AutoApply_V64.cmm])
+  AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V64 > include/rts/AutoApply_V64.cmm.h])
 fi
 
 AC_MSG_CHECKING([for include/rts/EventLogConstants.h])
diff --git a/rts/rts.cabal b/rts/rts.cabal
index 5eeaf939f37..46acc0ba0b4 100644
--- a/rts/rts.cabal
+++ b/rts/rts.cabal
@@ -340,7 +340,7 @@ common rts-cmm-sources-base
       -- then have the `AutoApply.cmm` in `rts-c-sources-base` include them.  This
       -- would mean they are included in the sublibraries which will in turn apply
       -- the sublibrary specific (c)flags.
-      autogen-cmm-sources:
+      cmm-sources:
         AutoApply.cmm
         AutoApply_V16.cmm
 
@@ -348,17 +348,20 @@ common rts-cmm-sources-base
         cmm-sources:
           Jumps_V32.cmm (-mavx2)
           Jumps_V64.cmm (-mavx512f)
-        autogen-cmm-sources:
           AutoApply_V32.cmm (-mavx2)
           AutoApply_V64.cmm (-mavx512f)
       else
         cmm-sources:
           Jumps_V32.cmm
           Jumps_V64.cmm
-        autogen-cmm-sources:
           AutoApply_V32.cmm
           AutoApply_V64.cmm
 
+    -- this is required so we don't have ghc inject ghc-internal (which depends on the rts)
+    -- during the build phase of this library.
+    ghc-options: -no-ghc-internal
+
+
 common rts-c-sources-base
     if !arch(javascript)
       cmm-sources:
@@ -637,12 +640,31 @@ library
     ghc-options: -this-unit-id rts -ghcversion-file=include/ghcversion.h -optc-DFS_NAMESPACE=rts
     cmm-options: -this-unit-id rts
 
+    -- [The AutoApply story]
+    --
+    -- We use GenApply to generate the AutoApply[_V{16,32,64}].cmm files.
+    -- However cabal will run the ./configure script only for the main library.
+    -- To work around this shortcoming, we'll generate .cmm.h files (same
+    -- content as .cmm), and create AutoApply*.cmm files that just
+    --
+    --   #include <rts/AutoApply_...cmm.h>
+    --
+    -- This way each sublib has it's own properly parameterized .cmm file, while
+    -- we only generate them once and stick them into the rts library.
+    --
+    -- This is a hack, and it would be great if sublibs had access to their
+    -- parent libraries auto-gen folders, however as sublibs are supposed to be
+    -- separate components, this is a non-trivial (impossible?) task to resolve.
     autogen-includes:
       ghcautoconf.h
       ghcplatform.h
       DerivedConstants.h
       rts/EventLogConstants.h
       rts/EventTypes.h
+      AutoApply.cmm.h
+      AutoApply_V16.cmm.h
+      AutoApply_V32.cmm.h
+      AutoApply_V64.cmm.h
 
     install-includes:
       ghcautoconf.h
@@ -650,6 +672,10 @@ library
       DerivedConstants.h
       rts/EventLogConstants.h
       rts/EventTypes.h
+      AutoApply.cmm.h
+      AutoApply_V16.cmm.h
+      AutoApply_V32.cmm.h
+      AutoApply_V64.cmm.h
 
     install-includes:
       -- Common headers for non-JS builds
@@ -771,10 +797,8 @@ library nonthreaded-nodebug
       import: rts-base-config, rts-cmm-sources-base, rts-c-sources-base, rts-link-options, rts-global-build-flags
 
     visibility: public
-
     ghc-options: -optc-DRtsWay="v"
 
-
 library threaded-nodebug
     import: rts-base-config, rts-cmm-sources-base, rts-c-sources-base, rts-link-options, rts-global-build-flags, rts-threaded-flags
     visibility: public

From 38af39d1982e6a064fb90929e241ce334578034e Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Tue, 16 Sep 2025 10:05:10 +0900
Subject: [PATCH 11/23] Makefile: symlink dylibs

---
 Makefile | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Makefile b/Makefile
index 454f3e18e11..f06ceb600d8 100644
--- a/Makefile
+++ b/Makefile
@@ -879,6 +879,13 @@ _build/bindist: stage2 driver/ghc-usage.txt driver/ghci-usage.txt
 	$@/bin/ghc-pkg recache
 	# Copy headers
 	@$(call copy_all_stage2_h,$@/bin/ghc-pkg)
+	# Add basename symlinks for nested shared libs (.dylib, .so) in lib/$(HOST_PLATFORM)
+	@if [ -d "$@/lib/$(HOST_PLATFORM)" ]; then \
+	  cd "$@/lib/$(HOST_PLATFORM)" ; \
+	  for lib in $$(find . -mindepth 2 \( -name "*.dylib" -o -name "*.so" \) -type f) ; do \
+	    ln -sf "$$lib" "$$(basename "$$lib")" ; \
+	  done ; \
+	fi
 	@echo "::endgroup::"
 
 _build/bindist/ghc.tar.gz: _build/bindist
@@ -903,6 +910,13 @@ _build/bindist/lib/targets/%: _build/bindist driver/ghc-usage.txt driver/ghci-us
 	# Copy libraries and settings
 	@if [ -e $(CURDIR)/_build/bindist/lib/targets/$(@F)/lib/$(@F) ] ; then find $(CURDIR)/_build/bindist/lib/targets/$(@F)/lib/$(@F)/ -mindepth 1 -type f -name "*.so" -execdir mv '{}' $(CURDIR)/_build/bindist/lib/targets/$(@F)/lib/$(@F)/'{}' \; ; fi
 	$(call copycrosslib,$(@F))
+	# Add basename symlinks for nested shared libs (.dylib, .so) in lib/$(@F)
+	@if [ -d $(CURDIR)/_build/bindist/lib/targets/$(@F)/lib/$(@F) ] ; then \
+	  cd $(CURDIR)/_build/bindist/lib/targets/$(@F)/lib/$(@F) ; \
+	  for lib in $$(find . -mindepth 2 \( -name "*.dylib" -o -name "*.so" \) -type f) ; do \
+	    ln -sf "$$lib" "$$(basename "$$lib")" ; \
+	  done ; \
+	fi
 	# --help
 	@cp -rfp driver/ghc-usage.txt _build/bindist/lib/targets/$(@F)/lib/
 	@cp -rfp driver/ghci-usage.txt _build/bindist/lib/targets/$(@F)/lib/

From aed1df397727d688085122326f8c7ac8ae34cd67 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Tue, 16 Sep 2025 15:07:54 +0900
Subject: [PATCH 12/23] rts.cabal: double all the flags to ensure we definetly
 get them set

This is kidna stupid. Julian hit something similar with the THREADED one :-/
---
 rts/rts.cabal | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/rts/rts.cabal b/rts/rts.cabal
index 46acc0ba0b4..aa2760dc4ae 100644
--- a/rts/rts.cabal
+++ b/rts/rts.cabal
@@ -615,25 +615,35 @@ common rts-link-options
          ld-options: -read_only_relocs warning
 
 common rts-global-build-flags
-    ghc-options: -DCOMPILING_RTS
+    ghc-options: -DCOMPILING_RTS -optc-DCOMPILING_RTS
     cpp-options: -DCOMPILING_RTS
+    cmm-options: -DCOMPILING_RTS
+    cc-options:  -DCOMPILING_RTS
     if !flag(smp)
-       ghc-options: -DNOSMP
+       ghc-options: -DNOSMP -optc-DNOSMP
        cpp-options: -DNOSMP
+       cmm-options: -DNOSMP
+       cc-options:  -DNOSMP
     if flag(dynamic)
-       ghc-options: -DDYNAMIC
+       ghc-options: -DDYNAMIC -optc-DDYNAMIC
        cpp-options: -DDYNAMIC
+       cmm-options: -DDYNAMIC
+       cc-options:  -DDYNAMIC
     if flag(thread-sanitizer)
       cc-options: -fsanitize=thread
       ld-options: -fsanitize=thread
 
 common rts-debug-flags
-    ghc-options: -optc-DDEBUG
+    ghc-options: -DDEBUG -optc-DDEBUG
     cpp-options: -DDEBUG -fno-omit-frame-pointer -g3 -O0
+    cmm-options: -DDEBUG -fno-omit-frame-pointer -g3 -O0
+    cc-options:  -DDEBUG -fno-omit-frame-pointer -g3 -O0
 
 common rts-threaded-flags
-    ghc-options: -DTHREADED_RTS
+    ghc-options: -DTHREADED_RTS -optc-DTHREADED_RTS
     cpp-options: -DTHREADED_RTS
+    cmm-options: -DTHREADED_RTS
+    cc-options:  -DTHREADED_RTS
 
 -- the _main_ library needs to deal with all the _configure_ time stuff.
 library

From f270d6eb8e78ab64e5851d481e68fbe35774af73 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Tue, 16 Sep 2025 17:58:08 +0900
Subject: [PATCH 13/23] testsuite: Make sure we prefix the ghcconfig with a
 hash

Ideally, ghc should just be able to produce this data outright, without having to resort to a separate tool. This seems highly
questionable.  It would be much better if ghc should emitted
this information in a structured way.
---
 testsuite/.gitignore        |  4 ++++
 testsuite/mk/boilerplate.mk | 13 ++++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/testsuite/.gitignore b/testsuite/.gitignore
index 2c699cf0462..65095f05566 100644
--- a/testsuite/.gitignore
+++ b/testsuite/.gitignore
@@ -60,6 +60,10 @@ tmp.d
 *.so
 *bindisttest_install___dir_bin_ghc.mk
 *bindisttest_install___dir_bin_ghc.exe.mk
+mk/*_ghcconfig*_bin_ghc*.mk
+mk/*_ghcconfig*_bin_ghc*.exe.mk
+mk/*_ghcconfig*_test___spaces_ghc*.mk
+mk/*_ghcconfig*_test___spaces_ghc*.exe.mk
 mk/ghcconfig*_bin_ghc*.mk
 mk/ghcconfig*_bin_ghc*.exe.mk
 mk/ghcconfig*_test___spaces_ghc*.mk
diff --git a/testsuite/mk/boilerplate.mk b/testsuite/mk/boilerplate.mk
index 9ad8b3308e3..333285d2bc3 100644
--- a/testsuite/mk/boilerplate.mk
+++ b/testsuite/mk/boilerplate.mk
@@ -260,7 +260,18 @@ $(TOP)/ghc-config/ghc-config : $(TOP)/ghc-config/ghc-config.hs
 empty=
 space=$(empty) $(empty)
 ifeq "$(ghc_config_mk)" ""
-ghc_config_mk = $(TOP)/mk/ghcconfig$(subst $(space),_,$(subst :,_,$(subst /,_,$(subst \,_,$(TEST_HC))))).mk
+sanitized_hc := $(subst $(space),_,$(subst :,_,$(subst /,_,$(subst \,_,$(TEST_HC)))))
+test_hc_hash := $(shell \
+  if command -v openssl >/dev/null 2>&1; then \
+    openssl dgst -sha256 $(TEST_HC) | awk '{print substr($$2, 1, 8)}'; \
+  elif command -v sha256sum >/dev/null 2>&1; then \
+    sha256sum $(TEST_HC) | awk '{print substr($$1, 1, 8)}'; \
+  elif command -v shasum >/dev/null 2>&1; then \
+    shasum -a 256 $(TEST_HC) | awk '{print substr($$1, 1, 8)}'; \
+  else \
+    echo "no_hash"; \
+  fi)
+ghc_config_mk = $(TOP)/mk/$(test_hc_hash)_ghcconfig$(sanitized_hc).mk
 
 $(ghc_config_mk) : $(TOP)/ghc-config/ghc-config
 	$(TOP)/ghc-config/ghc-config "$(TEST_HC)" >"$@"; if [ "$$?" != "0" ]; then $(RM) "$@"; exit 1; fi

From 1967f0806c272a318fa45adb27720e0ff1a88b7f Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Tue, 16 Sep 2025 18:26:14 +0900
Subject: [PATCH 14/23] testsuite: Add explicit flushs [WRONG!]

This seems conceptually wrong. I don't fully understand why we need this?
---
 testsuite/tests/annotations/should_compile/th/annth.hs | 1 +
 testsuite/tests/simplStg/should_compile/T22840.hs      | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/testsuite/tests/annotations/should_compile/th/annth.hs b/testsuite/tests/annotations/should_compile/th/annth.hs
index 8cc3a242ff9..87768e1a4ba 100644
--- a/testsuite/tests/annotations/should_compile/th/annth.hs
+++ b/testsuite/tests/annotations/should_compile/th/annth.hs
@@ -24,5 +24,6 @@ main = do
     runIO $ print (anns :: [String])
     anns <- reifyAnnotations (AnnLookupName 'TestTypeTH)
     runIO $ print (anns :: [String])
+    runIO $ hFlush stdout
     [| return () |] )
   hFlush stdout
diff --git a/testsuite/tests/simplStg/should_compile/T22840.hs b/testsuite/tests/simplStg/should_compile/T22840.hs
index f7e4e59bc07..86ffbf9c310 100644
--- a/testsuite/tests/simplStg/should_compile/T22840.hs
+++ b/testsuite/tests/simplStg/should_compile/T22840.hs
@@ -6,9 +6,11 @@ module C where
 import T22840A
 import T22840B
 import Control.Monad.IO.Class
+import System.IO (hFlush, stdout)
 
 $(liftIO $ do
     putStrLn "start"
     putStrLn (disp theT)
     putStrLn "end"
+    hFlush stdout
     return [])

From 41b298d273080b38f7a73914d82aef5cf80e45d9 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Wed, 17 Sep 2025 13:18:22 +0900
Subject: [PATCH 15/23] fixup! rts.cabal: double all the flags to ensure we
 definetly get them set

---
 rts/rts.cabal | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rts/rts.cabal b/rts/rts.cabal
index aa2760dc4ae..bb58a1614e5 100644
--- a/rts/rts.cabal
+++ b/rts/rts.cabal
@@ -636,7 +636,7 @@ common rts-global-build-flags
 common rts-debug-flags
     ghc-options: -DDEBUG -optc-DDEBUG
     cpp-options: -DDEBUG -fno-omit-frame-pointer -g3 -O0
-    cmm-options: -DDEBUG -fno-omit-frame-pointer -g3 -O0
+    cmm-options: -DDEBUG
     cc-options:  -DDEBUG -fno-omit-frame-pointer -g3 -O0
 
 common rts-threaded-flags

From 49ce37f5f4ad2cfdfa492103dc764596b456e743 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Wed, 17 Sep 2025 13:18:49 +0900
Subject: [PATCH 16/23] makefile: symlink ghc-iserv-dyn <- ghc-iserv

this is stupid, but it will have to do for now for dyanmic.
---
 Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Makefile b/Makefile
index f06ceb600d8..ab31f45a622 100644
--- a/Makefile
+++ b/Makefile
@@ -886,6 +886,9 @@ _build/bindist: stage2 driver/ghc-usage.txt driver/ghci-usage.txt
 	    ln -sf "$$lib" "$$(basename "$$lib")" ; \
 	  done ; \
 	fi
+	# Create -dyn iserv executable. #FIXME: THIS IS IDIOTIC!
+	@cd "$@/bin"
+	@ln -sf ghc-iserv-dyn ghc-iserv
 	@echo "::endgroup::"
 
 _build/bindist/ghc.tar.gz: _build/bindist

From 9e4cf800b95b8b40f67b34f58081f89d35ccf44f Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Wed, 17 Sep 2025 14:03:58 +0900
Subject: [PATCH 17/23] fixup! makefile: symlink ghc-iserv-dyn <- ghc-iserv

---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index ab31f45a622..4fa39da95af 100644
--- a/Makefile
+++ b/Makefile
@@ -888,7 +888,7 @@ _build/bindist: stage2 driver/ghc-usage.txt driver/ghci-usage.txt
 	fi
 	# Create -dyn iserv executable. #FIXME: THIS IS IDIOTIC!
 	@cd "$@/bin"
-	@ln -sf ghc-iserv-dyn ghc-iserv
+	@ln -sf ghc-iserv ghc-iserv-dyn
 	@echo "::endgroup::"
 
 _build/bindist/ghc.tar.gz: _build/bindist

From 0c7e99d0427538d4b1ea05b721d13882c1738ad5 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Wed, 17 Sep 2025 14:42:48 +0900
Subject: [PATCH 18/23] testsuite: improve logging; also check non-inplace
 libraries.

---
 testsuite/driver/testlib.py | 69 ++++++++++++++++++++++++++-----------
 1 file changed, 49 insertions(+), 20 deletions(-)

diff --git a/testsuite/driver/testlib.py b/testsuite/driver/testlib.py
index 609561ceac6..579b2f602b7 100644
--- a/testsuite/driver/testlib.py
+++ b/testsuite/driver/testlib.py
@@ -661,7 +661,19 @@ def collect_size ( deviation, path ):
     return collect_size_func(deviation, lambda: path)
 
 def collect_size_func ( deviation, path_func ):
-    return collect_generic_stat ( 'size', deviation, lambda way: os.path.getsize(in_testdir(path_func())) )
+    # Wrap path resolution to avoid passing None/invalid paths to Path APIs.
+    def current(_way):
+        p = path_func()
+        if p is None:
+            raise StatsException("No path returned for size collection")
+        # If p looks absolute, use it directly; else resolve relative to testdir
+        pth = Path(p)
+        if not pth.is_absolute():
+            pth = in_testdir(p)
+        if not pth.exists():
+            raise StatsException(f"Path not found for size collection: {pth}")
+        return os.path.getsize(pth)
+    return collect_generic_stat ( 'size', deviation, current )
 
 def get_dir_size(path):
     total = 0
@@ -674,7 +686,7 @@ def get_dir_size(path):
                     total += get_dir_size(entry.path)
         return total
     except FileNotFoundError:
-        print("Exception: Could not find: " + path)
+        raise StatsException(f"Directory not found for size collection: {path}")
 
 def collect_size_dir ( deviation, path ):
     return collect_size_dir_func ( deviation, lambda: path )
@@ -706,7 +718,12 @@ def collect_size_ghc_pkg (deviation, library):
 # same for collect_size and find_so
 def collect_object_size (deviation, library, use_non_inplace=False):
     if use_non_inplace:
-        return collect_size_func(deviation, lambda: find_non_inplace_so(library))
+        try:
+            return collect_size_func(deviation, lambda: find_non_inplace_so(library))
+        except Exception as _:
+            # should we fail to find inplace, let's try to find non-inplace.
+            # FIXME: remove the whole inplace nonsense outright.
+            return collect_size_func(deviation, lambda: find_so(library))
     else:
         return collect_size_func(deviation, lambda: find_so(library))
 
@@ -723,21 +740,20 @@ def path_from_ghcPkg (library, field):
 
     try:
         result = subprocess.run(ghcPkgCmd, capture_output=True, shell=True)
-
         # check_returncode throws an exception if the return code is not 0.
         result.check_returncode()
-
-        # if we get here then the call worked and we have the path we split by
-        # whitespace and then return the path which becomes the second element
-        # in the array
-        return re.split(r'\s+', result.stdout.decode("utf-8"))[1]
+        out = result.stdout.decode("utf-8").strip()
+        # Expected format: "<field>: <value>" possibly spanning lines; grab text after first colon.
+        m = re.split(r"^\s*[^:]+:\s*", out, maxsplit=1, flags=re.MULTILINE)
+        if len(m) == 2:
+            val = m[1].strip().splitlines()[0].strip()
+            if val:
+                return val
+        raise StatsException(f"ghc-pkg returned no {field} for {library}. Output: {out}")
+    except subprocess.CalledProcessError as e:
+        raise StatsException(f"ghc-pkg failed for {library} {field}: {e}")
     except Exception as e:
-        message = f"""
-        Attempt to find {field} of {library} using ghc-pkg failed.
-        ghc-pkg path: {config.ghc_pkg}
-        error" {e}
-        """
-        print(message)
+        raise StatsException(f"Error parsing ghc-pkg output for {library} {field}: {e}")
 
 
 def _find_so(lib, directory, in_place):
@@ -772,21 +788,34 @@ def _find_so(lib, directory, in_place):
         to_match = r'libHS{}-\d+(\.\d+)+-ghc\S+\.' + suffix
 
     matches = []
-    # wrap this in some exception handling, hadrian test will error out because
-    # these files don't exist yet, so we pass when this occurs
+    # Robust error handling: raise a stats exception for missing directory or no match
+    if directory is None:
+        raise StatsException(f"No directory provided to find shared object for {lib}")
     try:
+        dsos = []
         for f in os.listdir(directory):
             if f.endswith(suffix):
+                dsos.append(f)
                 pattern = re.compile(to_match.format(re.escape(lib)))
                 match   = re.match(pattern, f)
                 if match:
                     matches.append(match.group())
+        if not matches:
+            raise StatsException(f"Could not find shared object file for {lib} in {directory}")
         return os.path.join(directory, matches[0])
-    except:
-        failBecause('Could not find shared object file: ' + lib)
+    except FileNotFoundError:
+        raise StatsException(f"Directory not found while searching shared object for {lib}: {directory}")
+    except Exception as e:
+        raise StatsException(f"Error while searching shared object for {lib} in {directory}: {e}")
 
 def find_so(lib):
-    return _find_so(lib,path_from_ghcPkg(lib, "dynamic-library-dirs"),True)
+    try:
+        return _find_so(lib,path_from_ghcPkg(lib, "dynamic-library-dirs"),True)
+    except Exception as _:
+        # if we fail to find the inplace so, fallback to trying to find the
+        # non-inplace so indead;
+        # FIXME: This whole inplace logic needs to be ripped out!
+        return _find_so(lib,path_from_ghcPkg(lib, "dynamic-library-dirs"),False)
 
 def find_non_inplace_so(lib):
     return _find_so(lib,path_from_ghcPkg(lib, "dynamic-library-dirs"),False)

From 6a9fa8a312031a678948946cbd27d1fce684cda6 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Wed, 17 Sep 2025 17:33:59 +0900
Subject: [PATCH 19/23] fixup! testsuite: improve logging; also check
 non-inplace libraries.

---
 testsuite/driver/testlib.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/testsuite/driver/testlib.py b/testsuite/driver/testlib.py
index 579b2f602b7..3356d4d2f85 100644
--- a/testsuite/driver/testlib.py
+++ b/testsuite/driver/testlib.py
@@ -792,10 +792,8 @@ def _find_so(lib, directory, in_place):
     if directory is None:
         raise StatsException(f"No directory provided to find shared object for {lib}")
     try:
-        dsos = []
         for f in os.listdir(directory):
             if f.endswith(suffix):
-                dsos.append(f)
                 pattern = re.compile(to_match.format(re.escape(lib)))
                 match   = re.match(pattern, f)
                 if match:

From b54cf122aeacbdba2f08ca665226baae22c205c6 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Fri, 19 Sep 2025 11:18:30 +0900
Subject: [PATCH 20/23] testsuite: disable rts test, which is invalid since the
 rts split.

---
 testsuite/tests/perf/size/all.T | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/testsuite/tests/perf/size/all.T b/testsuite/tests/perf/size/all.T
index 4c45cb4d11f..e5fd683fce7 100644
--- a/testsuite/tests/perf/size/all.T
+++ b/testsuite/tests/perf/size/all.T
@@ -84,7 +84,9 @@ test('mtl_so'             ,[req_dynamic_ghc, js_skip, windows_skip, collect_obje
 test('os_string_so'       ,[req_dynamic_ghc, js_skip, windows_skip, collect_object_size(size_acceptance_threshold, "os-string")]        , static_stats, [] )
 test('parsec_so'          ,[req_dynamic_ghc, js_skip, windows_skip, collect_object_size(size_acceptance_threshold, "parsec")]           , static_stats, [] )
 test('process_so'         ,[req_dynamic_ghc, js_skip, windows_skip, collect_object_size(size_acceptance_threshold, "process")]          , static_stats, [] )
-test('rts_so'             ,[req_dynamic_ghc, js_skip, windows_skip, collect_object_size(size_acceptance_threshold, "rts", True)]              , static_stats, [] )
+# after the rts-split, there is not signle rts anymore. The single rts package is just headers, and thus empty. We now have one rts per threaded/debug combination.
+# they are also sublibs, which means the regex in the test-driver doesn't work for this. Thus for now we disable this test.
+# test('rts_so'             ,[req_dynamic_ghc, js_skip, windows_skip, collect_object_size(size_acceptance_threshold, "rts", True)]              , static_stats, [] )
 test('template_haskell_so',[req_dynamic_ghc, js_skip, windows_skip, collect_object_size(size_acceptance_threshold, "template-haskell")] , static_stats, [] )
 # terminfo is not built in cross ghc so skip it
 test('terminfo_so'        ,[req_dynamic_ghc, when(config.cross, skip), windows_skip, collect_object_size(size_acceptance_threshold, "terminfo")], static_stats, [] )

From cf05f6e33856b20290a53f9956f40da0b78612d6 Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Fri, 19 Sep 2025 11:19:05 +0900
Subject: [PATCH 21/23] testsuite: T2228 does not appear broken.

---
 testsuite/tests/ghc-e/should_run/all.T | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/testsuite/tests/ghc-e/should_run/all.T b/testsuite/tests/ghc-e/should_run/all.T
index 03ee37cb9ff..7362b190741 100644
--- a/testsuite/tests/ghc-e/should_run/all.T
+++ b/testsuite/tests/ghc-e/should_run/all.T
@@ -6,9 +6,7 @@ test('ghc-e004', req_interp, makefile_test, ['ghc-e004'])
 test('ghc-e005', req_interp, makefile_test, ['ghc-e005'])
 test('ghc-e006', req_interp, makefile_test, ['ghc-e006'])
 
-test('T2228',
-     [req_interp, when(ghc_dynamic(), expect_broken(7298))],
-     makefile_test, ['T2228'])
+test('T2228', req_interp, makefile_test, ['T2228'])
 test('T2636', req_interp, makefile_test, ['T2636'])
 test('T3890', req_interp, makefile_test, ['T3890'])
 test('T7299', req_interp, makefile_test, ['T7299'])

From a03584d8770522ab40606dddb77585226c21b5aa Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Fri, 19 Sep 2025 19:32:37 +0900
Subject: [PATCH 22/23] compiler: inject rpath for the rts as needed.

This is needed until https://github.com/haskell/cabal/issues/11221 is properly addressed to ensure that a linked dynamic binary will have the appropriate path for the rts (sublib).
---
 compiler/GHC/Linker/Static.hs | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/compiler/GHC/Linker/Static.hs b/compiler/GHC/Linker/Static.hs
index 8a634258e7f..2d25c46ce56 100644
--- a/compiler/GHC/Linker/Static.hs
+++ b/compiler/GHC/Linker/Static.hs
@@ -100,11 +100,22 @@ linkBinary' staticLink logger tmpfs dflags unit_env o_files dep_units = do
     -- explicit packages with the auto packages and all of their
     -- dependencies, and eliminating duplicates.
     pkgs <- mayThrowUnitErr (preloadUnitsInfo' unit_env dep_units)
+
+    -- Collect per-package library dirs (deduplicated, non-empty)
     let pkg_lib_paths     = collectLibraryDirs ways_ pkgs
-    let pkg_lib_path_opts = concatMap get_pkg_lib_path_opts pkg_lib_paths
-        get_pkg_lib_path_opts l
+    -- Until: https://github.com/haskell/cabal/issues/11221 is in cabal,
+    --        we have to deal with cabal passing -dyload deploy, and manually
+    --        inject rpaths for the rts.
+    -- Build linker options per (pkg, libdir)
+    let pkg_lib_path_opts =
+          concat
+          [ get_pkg_lib_path_opts pkg l
+          | pkg <- pkgs
+          , l <- collectLibraryDirs ways_ [pkg]
+          ]
+        get_pkg_lib_path_opts pkg l
          | osElfTarget (platformOS platform) &&
-           dynLibLoader dflags == SystemDependent &&
+           (dynLibLoader dflags == SystemDependent || unitPackageNameString pkg == rts) &&
            ways_ `hasWay` WayDyn
             = let libpath = if gopt Opt_RelativeDynlibPaths dflags
                             then "$ORIGIN" </>
@@ -125,7 +136,7 @@ linkBinary' staticLink logger tmpfs dflags unit_env o_files dep_units = do
                               else ["-Xlinker", "-rpath-link", "-Xlinker", l]
               in ["-L" ++ l] ++ rpathlink ++ rpath
          | osMachOTarget (platformOS platform) &&
-           dynLibLoader dflags == SystemDependent &&
+           (dynLibLoader dflags == SystemDependent || unitPackageNameString pkg == rts) &&
            ways_ `hasWay` WayDyn &&
            useXLinkerRPath dflags (platformOS platform)
             = let libpath = if gopt Opt_RelativeDynlibPaths dflags

From 8c7a84cafb319e96ef0e698c31d574a20a5ccb9d Mon Sep 17 00:00:00 2001
From: Moritz Angermann <moritz@stable-haskell.org>
Date: Fri, 19 Sep 2025 20:26:08 +0900
Subject: [PATCH 23/23] fixup! compiler: inject rpath for the rts as needed.

---
 compiler/GHC/Linker/Static.hs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/compiler/GHC/Linker/Static.hs b/compiler/GHC/Linker/Static.hs
index 2d25c46ce56..c60e4cc594c 100644
--- a/compiler/GHC/Linker/Static.hs
+++ b/compiler/GHC/Linker/Static.hs
@@ -115,7 +115,7 @@ linkBinary' staticLink logger tmpfs dflags unit_env o_files dep_units = do
           ]
         get_pkg_lib_path_opts pkg l
          | osElfTarget (platformOS platform) &&
-           (dynLibLoader dflags == SystemDependent || unitPackageNameString pkg == rts) &&
+           (dynLibLoader dflags == SystemDependent || unitPackageNameString pkg == "rts") &&
            ways_ `hasWay` WayDyn
             = let libpath = if gopt Opt_RelativeDynlibPaths dflags
                             then "$ORIGIN" </>
@@ -136,7 +136,7 @@ linkBinary' staticLink logger tmpfs dflags unit_env o_files dep_units = do
                               else ["-Xlinker", "-rpath-link", "-Xlinker", l]
               in ["-L" ++ l] ++ rpathlink ++ rpath
          | osMachOTarget (platformOS platform) &&
-           (dynLibLoader dflags == SystemDependent || unitPackageNameString pkg == rts) &&
+           (dynLibLoader dflags == SystemDependent || unitPackageNameString pkg == "rts") &&
            ways_ `hasWay` WayDyn &&
            useXLinkerRPath dflags (platformOS platform)
             = let libpath = if gopt Opt_RelativeDynlibPaths dflags