Use extconf.rb for external GC compilation

This commit adds extconf.rb for both the default GC and and MMTk to build
the external GC. This allows common.mk to not need to contain any
implementation-specific build configuration.

.github/workflows/modgc.yml

@@ -116,24 +116,22 @@ jobs:
           ${arch:+--target=$arch-$OSTYPE --host=$arch-$OSTYPE}
 
       - uses: actions-rust-lang/setup-rust-toolchain@v1
-      - name: Build MMTK Ruby lib
+      - name: Set MMTk environment variables
         run: |
-          cd ../src/gc/mmtk
-          if [[ ${{ matrix.gc.mmtk_build }} == release ]]; then
-            cargo build --release
-          else
-            cargo build
+          if [[ ${{ matrix.gc.mmtk_build }} == debug ]]; then
+            echo 'RUST_LOG=' >> $GITHUB_ENV
             # Debug builds run much slower so we should increase the timeout
             echo 'RUBY_TEST_TIMEOUT_SCALE=10' >> $GITHUB_ENV
             # SYNTAX_SUGGEST_TIMEOUT defaults to 1 second
             echo 'SYNTAX_SUGGEST_TIMEOUT=60' >> $GITHUB_ENV
           fi
-          echo 'RUST_LOG=' >> $GITHUB_ENV
           echo 'MMTK_PLAN=${{ matrix.gc.mmtk_plan }}' >> $GITHUB_ENV
           echo 'EXCLUDES=../src/test/.excludes-mmtk' >> $GITHUB_ENV
           echo 'MSPECOPT=-B../src/spec/mmtk.mspec' >> $GITHUB_ENV
         if: ${{ matrix.gc.name == 'mmtk' }}
 
+      - run: $SETARCH make
+
       - name: Build shared GC
         run: |
           echo "RUBY_GC_LIBRARY=${{ matrix.gc.name }}" >> $GITHUB_ENV
@@ -150,8 +148,6 @@ jobs:
           fi
         if: ${{ matrix.gc.name == 'mmtk' }}
 
-      - run: $SETARCH make
-
       - run: |
           $SETARCH make golf
           case "${{ matrix.configure }}" in

common.mk

@@ -721,7 +721,7 @@ install-prereq: $(CLEAR_INSTALLED_LIST) yes-fake sudo-precheck PHONY
 clear-installed-list: PHONY
 	@> $(INSTALLED_LIST) set MAKE="$(MAKE)"
 
-clean: clean-ext clean-enc clean-golf clean-docs clean-extout clean-local clean-platform clean-spec
+clean: clean-ext clean-enc clean-golf clean-docs clean-extout clean-gc clean-local clean-platform clean-spec
 clean-local:: clean-runnable
 	$(Q)$(RM) $(ALLOBJS) $(LIBRUBY_A) $(LIBRUBY_SO) $(LIBRUBY) $(LIBRUBY_ALIASES)
 	$(Q)$(RM) $(PROGRAM) $(WPROGRAM) miniruby$(EXEEXT) dmyext.$(OBJEXT) dmyenc.$(OBJEXT) $(ARCHFILE) .*.time
@@ -751,11 +751,13 @@ clean-capi: PHONY
 clean-platform: PHONY
 clean-extout: PHONY
 	-$(Q)$(RMDIR) $(EXTOUT)/$(arch) $(RUBYCOMMONDIR) $(EXTOUT) 2> $(NULL) || $(NULLCMD)
+clean-gc: PHONY
+	$(Q) $(RMALL) .gc
 clean-docs: clean-rdoc clean-html clean-capi
 clean-spec: PHONY
 clean-rubyspec: clean-spec
 
-distclean: distclean-ext distclean-enc distclean-golf distclean-docs distclean-extout distclean-local distclean-platform distclean-spec
+distclean: distclean-ext distclean-enc distclean-golf distclean-docs distclean-extout distclean-gc distclean-local distclean-platform distclean-spec
 distclean-local:: clean-local
 	$(Q)$(RM) $(MKFILES) yasmdata.rb *.inc $(PRELUDES) *.rbinc *.rbbin
 	$(Q)$(RM) config.cache config.status config.status.lineno
@@ -768,6 +770,7 @@ distclean-html: clean-html
 distclean-capi: clean-capi
 distclean-docs: clean-docs
 distclean-extout: clean-extout
+distclean-gc: clean-gc
 distclean-platform: clean-platform
 distclean-spec: clean-spec
 distclean-rubyspec: distclean-spec
@@ -1940,30 +1943,19 @@ rewindable:
 
 HELP_EXTRA_TASKS = ""
 
-MMTK_BUILD=debug
-MMTK_SRC_PATH=$(srcdir)/gc/mmtk
-MMTK_LIB_PATH=$(srcdir)/gc/mmtk/target/$(MMTK_BUILD)/libmmtk_ruby.$(LIBEXT)
-
 shared-gc: probes.h
 	$(Q) if test -z $(shared_gc_dir); then \
 		echo "You must configure with --with-shared-gc to use shared GC"; \
 		exit 1; \
 	elif test -z $(SHARED_GC); then \
 		echo "You must specify SHARED_GC with the GC to build"; \
 		exit 1; \
-	else \
-		$(MAKEDIRS) $(shared_gc_dir); \
-		echo generating $(shared_gc_dir)librubygc.$(SHARED_GC).$(SOEXT); \
-		if [ "$(SHARED_GC)" = "mmtk" ]; then \
-			if test ! -f $(MMTK_LIB_PATH); then \
-				echo "libmmtk_ruby.$(LIBEXT) not found. Please run 'cargo build' inside $(MMTK_SRC_PATH)"; \
-				exit 1; \
-			fi; \
-			$(LDSHARED) -I$(srcdir)/include -I$(srcdir) -I$(arch_hdrdir) $(XDLDFLAGS) $(cflags) -DBUILDING_SHARED_GC -fPIC -o $(shared_gc_dir)librubygc.$(SHARED_GC).$(SOEXT) $(srcdir)/gc/$(SHARED_GC).c $(MMTK_LIB_PATH); \
-		else \
-			$(LDSHARED) -I$(srcdir)/include -I$(srcdir) -I$(arch_hdrdir) $(XDLDFLAGS) $(cflags) -DBUILDING_SHARED_GC -fPIC -o $(shared_gc_dir)librubygc.$(SHARED_GC).$(SOEXT) $(srcdir)/gc/$(SHARED_GC).c; \
-		fi; \
 	fi
+	$(Q) $(MAKEDIRS) $(shared_gc_dir) .gc/$(arch)/$(SHARED_GC)
+	$(Q) $(RUNRUBY) -C .gc/$(arch)/$(SHARED_GC) $(CURDIR)/$(srcdir)/gc/$(SHARED_GC)/$(EXTCONF)
+	$(Q) $(CHDIR) .gc/$(arch)/$(SHARED_GC) && \
+		$(MAKE) extout=../../../$(EXTOUT) BUILTRUBY=../../../miniruby$(EXEEXT) && \
+		$(CP) librubygc.$(SHARED_GC).$(DLEXT) $(shared_gc_dir)
 
 help: PHONY
 	$(MESSAGE_BEGIN) \
@@ -7285,7 +7277,7 @@ gc.$(OBJEXT): $(CCAN_DIR)/str/str.h
 gc.$(OBJEXT): $(hdrdir)/ruby.h
 gc.$(OBJEXT): $(hdrdir)/ruby/ruby.h
 gc.$(OBJEXT): $(hdrdir)/ruby/version.h
-gc.$(OBJEXT): $(top_srcdir)/gc/default.c
+gc.$(OBJEXT): $(top_srcdir)/gc/default/default.c
 gc.$(OBJEXT): $(top_srcdir)/gc/gc.h
 gc.$(OBJEXT): $(top_srcdir)/gc/gc_impl.h
 gc.$(OBJEXT): $(top_srcdir)/internal/array.h

gc.c

@@ -622,7 +622,7 @@ rb_gc_guarded_ptr_val(volatile VALUE *ptr, VALUE val)
 
 static const char *obj_type_name(VALUE obj);
 #define RB_AMALGAMATED_DEFAULT_GC
-#include "gc/default.c"
+#include "gc/default/default.c"
 static int external_gc_loaded = FALSE;
 
 
@@ -742,7 +742,7 @@ ruby_external_gc_init(void)
             }
         }
 
-        size_t gc_so_path_size = strlen(SHARED_GC_DIR "librubygc." SOEXT) + strlen(gc_so_file) + 1;
+        size_t gc_so_path_size = strlen(SHARED_GC_DIR "librubygc." DLEXT) + strlen(gc_so_file) + 1;
         gc_so_path = alloca(gc_so_path_size);
         {
             size_t gc_so_path_idx = 0;
@@ -752,7 +752,7 @@ ruby_external_gc_init(void)
             GC_SO_PATH_APPEND(SHARED_GC_DIR);
             GC_SO_PATH_APPEND("librubygc.");
             GC_SO_PATH_APPEND(gc_so_file);
-            GC_SO_PATH_APPEND(SOEXT);
+            GC_SO_PATH_APPEND(DLEXT);
             GC_ASSERT(gc_so_path_idx == gc_so_path_size - 1);
 #undef GC_SO_PATH_APPEND
         }

gc/default/extconf.rb

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+require_relative "../extconf_base"
+
+create_gc_makefile("default")

gc/extconf_base.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require "mkmf"
+
+srcdir = File.join(__dir__, "..")
+$CFLAGS << " -I#{srcdir}"
+
+$CFLAGS << " -DBUILDING_SHARED_GC"
+$CFLAGS << " -fPIC"
+
+def create_gc_makefile(name)
+  create_makefile("librubygc.#{name}")
+end

gc/mmtk/extconf.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+require_relative "../extconf_base"
+
+# Statically link `libmmtk_ruby.a`
+$LIBS << " $(MMTK_BUILD)/libmmtk_ruby.#{RbConfig::CONFIG["LIBEXT"]}"
+
+create_gc_makefile("mmtk")
+
+makefile = File.read("Makefile")
+
+# Modify the `all` target to run the `mmtk` target first
+makefile.gsub!(/^all:\s+(.*)$/, 'all: mmtk \1')
+
+# Add the `mmtk` target to run `cargo build`
+makefile << <<~'MAKEFILE'
+  $(srcdir)/mmtk.c: mmtk
+
+  MMTK_BUILD=debug
+
+  .PHONY: mmtk
+  mmtk:
+  	$(Q) case $(MMTK_BUILD) in \
+  		release) \
+  			CARGO_TARGET_DIR="." cargo build --manifest-path=$(srcdir)/Cargo.toml --release \
+  			;; \
+  		debug) \
+  			CARGO_TARGET_DIR="." cargo build --manifest-path=$(srcdir)/Cargo.toml \
+  			;; \
+  		*) \
+  			$(ECHO) Unknown MMTK_BUILD=$(MMTK_BUILD) \
+  			exit 1 \
+  			;; \
+  	esac
+MAKEFILE
+
+File.open("Makefile", "w") { |file| file.puts(makefile) }

gc/mmtk.c → gc/mmtk/mmtk.c

@@ -7,7 +7,7 @@
 
 #include "gc/gc.h"
 #include "gc/gc_impl.h"
-#include "gc/mmtk.h"
+#include "gc/mmtk/mmtk.h"
 
 #include "ccan/list/list.h"
 #include "darray.h"