Update user's guide and release noteswip/t21766

Add mention of IPE data compression to user's guide and the release
notes for 9.8.1. Also note the impact compression has on binary size in
both places.

See ticket #21766

4 files changed, 38 insertions, 17 deletions

diff --git a/.gitlab/gen_ci.hs b/.gitlab/gen_ci.hs
index fb306a3adf..3b1280189c 100755
--- a/.gitlab/gen_ci.hs
+++ b/.gitlab/gen_ci.hs
@@ -233,10 +233,6 @@ debug = vanilla { buildFlavour = SlowValidate
                 , withAssertions = True
                 -- WithNuma so at least one job tests Numa
                 , withNuma = True
-
-                -- Build with IPE in debug so at least one job tests
-                -- uncompressed IPE data
-                , withIpe = True
                 }
 
 ipe :: BuildConfig
diff --git a/.gitlab/jobs.yaml b/.gitlab/jobs.yaml
index a51cd695a4..791f9e5001 100644
--- a/.gitlab/jobs.yaml
+++ b/.gitlab/jobs.yaml
@@ -1029,7 +1029,7 @@
       "XZ_OPT": "-9"
     }
   },
-  "nightly-x86_64-linux-deb10-numa-slow-validate+ipe": {
+  "nightly-x86_64-linux-deb10-numa-slow-validate": {
     "after_script": [
       ".gitlab/ci.sh save_cache",
       ".gitlab/ci.sh clean",
@@ -1039,7 +1039,7 @@
     "artifacts": {
       "expire_in": "8 weeks",
       "paths": [
-        "ghc-x86_64-linux-deb10-numa-slow-validate+ipe.tar.xz",
+        "ghc-x86_64-linux-deb10-numa-slow-validate.tar.xz",
         "junit.xml"
       ],
       "reports": {
@@ -1081,11 +1081,11 @@
     ],
     "variables": {
       "BIGNUM_BACKEND": "gmp",
-      "BIN_DIST_NAME": "ghc-x86_64-linux-deb10-numa-slow-validate+ipe",
-      "BUILD_FLAVOUR": "slow-validate+ipe",
+      "BIN_DIST_NAME": "ghc-x86_64-linux-deb10-numa-slow-validate",
+      "BUILD_FLAVOUR": "slow-validate",
       "CONFIGURE_ARGS": "",
       "ENABLE_NUMA": "1",
-      "TEST_ENV": "x86_64-linux-deb10-numa-slow-validate+ipe",
+      "TEST_ENV": "x86_64-linux-deb10-numa-slow-validate",
       "XZ_OPT": "-9"
     }
   },
@@ -3814,7 +3814,7 @@
       "TEST_ENV": "x86_64-linux-deb10-no_tntc-validate"
     }
   },
-  "x86_64-linux-deb10-numa-slow-validate+ipe": {
+  "x86_64-linux-deb10-numa-slow-validate": {
     "after_script": [
       ".gitlab/ci.sh save_cache",
       ".gitlab/ci.sh clean",
@@ -3824,7 +3824,7 @@
     "artifacts": {
       "expire_in": "2 weeks",
       "paths": [
-        "ghc-x86_64-linux-deb10-numa-slow-validate+ipe.tar.xz",
+        "ghc-x86_64-linux-deb10-numa-slow-validate.tar.xz",
         "junit.xml"
       ],
       "reports": {
@@ -3866,11 +3866,11 @@
     ],
     "variables": {
       "BIGNUM_BACKEND": "gmp",
-      "BIN_DIST_NAME": "ghc-x86_64-linux-deb10-numa-slow-validate+ipe",
-      "BUILD_FLAVOUR": "slow-validate+ipe",
+      "BIN_DIST_NAME": "ghc-x86_64-linux-deb10-numa-slow-validate",
+      "BUILD_FLAVOUR": "slow-validate",
       "CONFIGURE_ARGS": "",
       "ENABLE_NUMA": "1",
-      "TEST_ENV": "x86_64-linux-deb10-numa-slow-validate+ipe"
+      "TEST_ENV": "x86_64-linux-deb10-numa-slow-validate"
     }
   },
   "x86_64-linux-deb10-unreg-validate": {
diff --git a/docs/users_guide/9.8.1-notes.rst b/docs/users_guide/9.8.1-notes.rst
index a624eb2705..8619447cdf 100644
--- a/docs/users_guide/9.8.1-notes.rst
+++ b/docs/users_guide/9.8.1-notes.rst
@@ -87,6 +87,17 @@ Compiler
 
       deriving instance TypeError (Text "Boo") => Bar Baz
 
+- The compiler may now be configured to compress the debugging information
+  included in :ghc-flag:`-finfo-table-map` enabled binaries. To do so, one must
+  build GHC from source (see
+  `here<https://gitlab.haskell.org/ghc/ghc/-/wikis/building>` for directions)
+  and supply the ``--enable-ipe-data-compression`` flag to the ``configure``
+  script. **Note**: This feature requires that the machine building GHC has
+  `libzstd <https://github.com/facebook/zstd/>`_ installed.
+
+  In a test compiling GHC itself, the size of the :ghc-flag:`-finfo-table-map`
+  enabled build results was reduced by over 20% when compression was enabled.
+
 GHCi
 ~~~~
 
diff --git a/docs/users_guide/debug-info.rst b/docs/users_guide/debug-info.rst
index 8679bd84e3..c820257988 100644
--- a/docs/users_guide/debug-info.rst
+++ b/docs/users_guide/debug-info.rst
@@ -370,9 +370,23 @@ to a source location. This lookup table is generated by using the ``-finfo-table
     also want more precise information about constructor info tables then you
     should also use :ghc-flag:`-fdistinct-constructor-tables`.
 
-    This flag will increase the binary size by quite a lot, depending on how
-    big your project is. For compiling a project the size of GHC the overhead was
-    about 200 megabytes.
+    The :ghc-flag:`-finfo-table-map` flag will increase the binary size by quite
+    a lot, depending on how big your project is. For compiling a project the
+    size of GHC the overhead was about 200 megabytes.
+
+    :since: 9.8
+
+    If you wish to reduce the size of :ghc-flag:`-finfo-table-map` enabled
+    binaries, consider building GHC from source and supplying the
+    ``--enable-ipe-data-compression`` flag to the ``configure`` script. This
+    will cause GHC to compress the :ghc-flag:`-finfo-table-map` related
+    debugging information included in binaries using the `libzstd
+    <https://github.com/facebook/zstd/>`_ compression library. **Note**: This
+    feature requires that the machine building GHC has
+    `libzstd <https://github.com/facebook/zstd/>`_ installed.
+
+    In a test compiling GHC itself, the size of the :ghc-flag:`-finfo-table-map`
+    enabled build results was reduced by over 20% when compression was enabled.
 
 .. ghc-flag:: -fdistinct-constructor-tables
     :shortdesc: Generate a fresh info table for each usage