build: Makefile splits Scheme compilation in four steps.

Fixes <https://bugs.gnu.org/48963>.
Reported by Julien Lepiller <julien@lepiller.eu>.

This reduces peak memory consumption to something less unreasonable.

* Makefile.am (make-go): Depend on 'make-*-go' targets; remove body.
(guile-compilation-rule): New function.
(MODULES_CORE, MODULES_PACKAGES, MODULES_SYSTEM, MODULES_CLI): New
variables.
<top level>: Call 'guile-compilation-rule' 4 times.
* build-aux/compile-all.scm <top level>: Expect "--total" and
"--processed".  Take them into account when displaying progress
reports.

Makefile.am

@@ -663,7 +663,12 @@ CLEANFILES =					\
 # the whole thing.  Likewise, set 'XDG_CACHE_HOME' to avoid loading possibly
 # stale files from ~/.cache/guile/ccache.
 %.go: make-go ; @:
-make-go: $(MODULES) guix/config.scm $(dist_noinst_DATA)
+make-go: make-core-go make-packages-go make-system-go make-cli-go
+
+# Define a rule to build a subset of the .go files.
+define guile-compilation-rule
+
+$(1): $(2)
 	$(AM_V_at)echo "Compiling Scheme modules..." ;		\
 	unset GUILE_LOAD_COMPILED_PATH ;			\
 	XDG_CACHE_HOME=/nowhere					\
@@ -671,7 +676,40 @@ make-go: $(MODULES) guix/config.scm $(dist_noinst_DATA)
 	$(top_builddir)/pre-inst-env				\
 	$(GUILE) -L "$(top_builddir)" -L "$(top_srcdir)"	\
 	  --no-auto-compile					\
-	  -s "$(top_srcdir)"/build-aux/compile-all.scm $^
+	  -s "$(top_srcdir)"/build-aux/compile-all.scm		\
+	  --total $(words $(MODULES))				\
+	  --completed $(3)					\
+	  $$(filter %.scm,$$^)
+
+.PHONY: $(1)
+
+endef
+
+# Split compilation in several steps, each of which building a subset of
+# $(MODULES).  The main goal is to reduce peak memory consumption, as reported
+# in <https://issues.guix.gnu.org/48963>.  Each 'eval' call below creates a
+# 'make-*-go' phony target that builds the corresponding subset.
+
+MODULES_CORE     = $(filter-out guix/scripts/%,$(filter guix/%,$(MODULES)))
+MODULES_PACKAGES = $(filter gnu/packages/%,$(MODULES))
+MODULES_SYSTEM   = $(filter-out gnu/packages/%,$(filter gnu/%,$(MODULES)))
+MODULES_CLI      = $(filter guix/scripts/%,$(MODULES))
+
+$(eval $(call guile-compilation-rule,make-core-go,	\
+  $(MODULES_CORE) guix/config.scm $(dist_noinst_DATA),	\
+  0))
+
+$(eval $(call guile-compilation-rule,make-packages-go,	\
+  $(MODULES_PACKAGES) make-core-go,			\
+  $(words $(MODULES_CORE))))
+
+$(eval $(call guile-compilation-rule,make-system-go,	\
+  $(MODULES_SYSTEM) make-packages-go make-core-go,	\
+  $(words $(MODULES_CORE) $(MODULES_PACKAGES))))
+
+$(eval $(call guile-compilation-rule,make-cli-go,			\
+  $(MODULES_CLI) make-system-go make-packages-go make-core-go,		\
+  $(words $(MODULES_CORE) $(MODULES_PACKAGES) $(MODULES_SYSTEM))))
 
 SUFFIXES = .go
 

build-aux/compile-all.scm

@@ -98,26 +98,36 @@ (define (% completed total)
     (exit 1)))
 
 (match (command-line)
-  ((_ . files)
+  ((_ "--total" (= string->number grand-total)
+      "--completed" (= string->number processed)
+      . files)
+   ;; GRAND-TOTAL is the total number of .scm files in the project; PROCESSED
+   ;; is the total number of .scm files already compiled in previous
+   ;; invocations of this script.
    (catch #t
      (lambda ()
-       (compile-files srcdir (getcwd)
+       (let* ((to-build  (filter file-needs-compilation? files))
-                      (filter file-needs-compilation? files)
+              (processed (+ processed
+                            (- (length files) (length to-build)))))
+         (compile-files srcdir (getcwd) to-build
                         #:workers (parallel-job-count*)
                         #:host host
                         #:report-load (lambda (file total completed)
                                         (when file
                                           (format #t "[~3d%] LOAD     ~a~%"
-                                                (% (+ 1 completed) (* 2 total))
+                                                  (% (+ 1 completed
+                                                          (* 2 processed))
+                                                     (* 2 grand-total))
                                                   file)
                                           (force-output)))
                         #:report-compilation (lambda (file total completed)
                                                (when file
                                                  (format #t "[~3d%] GUILEC   ~a~%"
-                                                       (% (+ total completed 1)
+                                                         (% (+ total completed 1
-                                                          (* 2 total))
+                                                                     (* 2 processed))
+                                                            (* 2 grand-total))
                                                          (scm->go file))
-                                               (force-output)))))
+                                                 (force-output))))))
      (lambda _
        (primitive-exit 1))
      (lambda args