TODO: Check that the part removing the dependency from stamp-gnatlib1
to stamp-gnatlib2 is not necessary anymore with gcc-9.

* Link tools dynamically.
* Prevent direct embedding of libada objects:
  Mark ALI files as read-only, remove objects after the build.
  A solution keeping the objects would be more intrusive.
* Rebuild gnatbind/make/link with themselves.
  This removes unneeded objects inherited from the hardcoded bootstrap list.
  The same thing would be useful for gnat1drv, but is less easy.
* TOOLS_ALREADY_COMPILED lists LIBGNAT objects that
  gcc/ada/gcc-interface/Makefile should not rebuild.
* Link libgnat/gnarl with LDFLAGS.
* Link libgnarl with an explicit path to a shared object.
  This prevents undefined symbols or unwanted usage of host libgnat.
* Compile with -gnatn for efficiency.
  Double-check the link since Debian moves some symbols.
* set LD_LIBRARY_PATH so that rebuilt tools can be executed.

--- a/src/gcc/ada/Makefile.rtl
+++ b/src/gcc/ada/Makefile.rtl
@@ -1836,6 +1836,11 @@ ifeq ($(strip $(filter-out s390% linux%,
   LIBRARY_VERSION := $(LIB_VERSION)
 endif
 
+ifeq ($(strip $(filter-out hppa% unknown linux gnu,$(targ))),)
+  GNATLIB_SHARED = gnatlib-shared-dual
+  LIBRARY_VERSION := $(LIB_VERSION)
+endif
+
 # HP/PA HP-UX 10
 ifeq ($(strip $(filter-out hppa% hp hpux10%,$(target_cpu) $(target_vendor) $(target_os))),)
   LIBGNAT_TARGET_PAIRS = \
--- a/src/gcc/ada/gcc-interface/Makefile.in
+++ b/src/gcc/ada/gcc-interface/Makefile.in
@@ -498,6 +498,20 @@ gnatlink-re: ../stamp-tools gnatmake-re
 	  --GCC="$(CC) $(ADA_INCLUDES)" --LINK="$(GCC_LINK)" $(TOOLS_LIBS)
 	$(MV)  ../../gnatlinknew$(exeext)  ../../gnatlink$(exeext)
 
+gnatbind-re: ../stamp-tools gnatmake-re gnatlink-re
+	$(GNATMAKE) -j0 -c $(ADA_INCLUDES) gnatbind --GCC="$(CC) $(ALL_ADAFLAGS)"
+	$(GNATBIND) $(ADA_INCLUDES) $(GNATBIND_FLAGS) gnatbind
+	$(GNATLINK) -v gnatbind -o ../../gnatbind$(exeext) \
+	  --GCC="$(CC) $(ADA_INCLUDES)" --LINK="$(GCC_LINK)" $(TOOLS_LIBS)
+
+# When driven by gnattools/Makefile for a native build,
+# TOOLS_ALREADY_COMPILED will list objects in the target standard Ada
+# libraries, that Make should avoid rebuilding.
+# We cannot use recursive variables to avoid an infinite loop,
+# so we must put this after definition of EXTRA_GNATMAKE_OBJS.
+GNATLINK_OBJS := $(filter-out $(TOOLS_ALREADY_COMPILED),$(GNATLINK_OBJS))
+GNATMAKE_OBJS := $(filter-out $(TOOLS_ALREADY_COMPILED),$(GNATMAKE_OBJS))
+
 # Needs to be built with CC=gcc
 # Since the RTL should be built with the latest compiler, remove the
 #  stamp target in the parent directory whenever gnat1 is rebuilt
@@ -625,7 +639,7 @@ $(RTSDIR)/s-oscons.ads: ../stamp-gnatlib
 	    $(OSCONS_EXTRACT) ; \
 	    ../bldtools/oscons/xoscons s-oscons)
 
-gnatlib: ../stamp-gnatlib1-$(RTSDIR) ../stamp-gnatlib2-$(RTSDIR) $(RTSDIR)/s-oscons.ads
+gnatlib: ../stamp-gnatlib1-$(RTSDIR) $(RTSDIR)/s-oscons.ads
 	test -f $(RTSDIR)/s-oscons.ads || exit 1
 # C files
 	$(MAKE) -C $(RTSDIR) \
@@ -657,18 +671,30 @@ gnatlib: ../stamp-gnatlib1-$(RTSDIR) ../
 		$(RANLIB_FOR_TARGET) $(RTSDIR)/libgmem$(arext)
         endif
 	$(CHMOD) a-wx $(RTSDIR)/*.ali
+# Provide .ads .adb (read-only).ali .so .a, but prevent direct use of .o.
+	$(RM) $(RTSDIR)/*.o
 	touch ../stamp-gnatlib-$(RTSDIR)
 
 # Warning: this target assumes that LIBRARY_VERSION has been set correctly.
 gnatlib-shared-default:
-	$(MAKE) $(FLAGS_TO_PASS) \
-             GNATLIBFLAGS="$(GNATLIBFLAGS)" \
-	     GNATLIBCFLAGS="$(GNATLIBCFLAGS) $(PICFLAG_FOR_TARGET) -fno-lto" \
-	     GNATLIBCFLAGS_FOR_C="$(GNATLIBCFLAGS_FOR_C) $(PICFLAG_FOR_TARGET) -fno-lto" \
-	     MULTISUBDIR="$(MULTISUBDIR)" \
-	     THREAD_KIND="$(THREAD_KIND)" \
-	     LN_S="$(LN_S)" \
-             gnatlib
+	$(MAKE) -C $(RTSDIR) \
+		CC="`echo \"$(GCC_FOR_TARGET)\" \
+		| sed -e 's,\./xgcc,../../xgcc,' -e 's,-B\./,-B../../,'`" \
+	        INCLUDES="$(INCLUDES_FOR_SUBDIR) -I./../.." \
+                CFLAGS="$(GNATLIBCFLAGS_FOR_C) $(PICFLAG_FOR_TARGET) -fno-lto" \
+	        FORCE_DEBUG_ADAFLAGS="$(FORCE_DEBUG_ADAFLAGS)" \
+		srcdir=$(fsrcdir) \
+	        -f ../Makefile $(LIBGNAT_OBJS)
+	$(MAKE) -C $(RTSDIR) \
+		CC="`echo \"$(GCC_FOR_TARGET)\" \
+		| sed -e 's,\./xgcc,../../xgcc,' -e 's,-B\./,-B../../,'`" \
+	        ADA_INCLUDES="" \
+                CFLAGS="$(GNATLIBCFLAGS) $(PICFLAG_FOR_TARGET) -fno-lto" \
+	        ADAFLAGS="$(GNATLIBFLAGS) $(PICFLAG_FOR_TARGET) -fno-lto" \
+	        FORCE_DEBUG_ADAFLAGS="$(FORCE_DEBUG_ADAFLAGS)" \
+		srcdir=$(fsrcdir) \
+	        -f ../Makefile \
+	        $(GNATRTL_OBJS)
 	$(RM) $(RTSDIR)/libgna*$(soext)
 	cd $(RTSDIR); $(GCC_FOR_ADA_RTS) -shared $(GNATLIBCFLAGS) \
 		$(PICFLAG_FOR_TARGET) \
@@ -679,8 +705,10 @@ gnatlib-shared-default:
 	cd $(RTSDIR); $(GCC_FOR_ADA_RTS) -shared $(GNATLIBCFLAGS) \
 		$(PICFLAG_FOR_TARGET) \
 		-o libgnarl$(hyphen)$(LIBRARY_VERSION)$(soext) \
+		$(LDFLAGS) \
 		$(GNATRTL_TASKING_OBJS) \
 		$(SO_OPTS)libgnarl$(hyphen)$(LIBRARY_VERSION)$(soext) \
+		libgnat$(hyphen)$(LIBRARY_VERSION).so \
 		$(THREADSLIB)
 	cd $(RTSDIR); $(LN_S) libgnat$(hyphen)$(LIBRARY_VERSION)$(soext) \
 		libgnat$(soext)
@@ -696,6 +724,10 @@ gnatlib-shared-default:
 	   $(addprefix $(RTSDIR)/,$(GNATRTL_TASKING_OBJS))
 	$(RANLIB_FOR_TARGET) $(RTSDIR)/libgnarl_pic$(arext)
 
+# Provide .ads .adb (read-only).ali .so .a, but prevent direct use of .o.
+	$(CHMOD) a-wx $(RTSDIR)/*.ali
+	$(RM) $(RTSDIR)/*.o
+
 gnatlib-shared-dual:
 	$(MAKE) $(FLAGS_TO_PASS) \
              GNATLIBFLAGS="$(GNATLIBFLAGS)" \
@@ -705,11 +737,8 @@ gnatlib-shared-dual:
 	     MULTISUBDIR="$(MULTISUBDIR)" \
 	     THREAD_KIND="$(THREAD_KIND)" \
 	     LN_S="$(LN_S)" \
-             gnatlib-shared-default
-	$(MV) $(RTSDIR)/libgna*$(soext) .
-	$(MV) $(RTSDIR)/libgnat_pic$(arext) .
-	$(MV) $(RTSDIR)/libgnarl_pic$(arext) .
-	$(RM) ../stamp-gnatlib2-$(RTSDIR)
+	     gnatlib
+	$(RM) $(RTSDIR)/*.o $(RTSDIR)/*.ali
 	$(MAKE) $(FLAGS_TO_PASS) \
              GNATLIBFLAGS="$(GNATLIBFLAGS)" \
 	     GNATLIBCFLAGS="$(GNATLIBCFLAGS)" \
@@ -717,10 +746,7 @@ gnatlib-shared-dual:
 	     MULTISUBDIR="$(MULTISUBDIR)" \
 	     THREAD_KIND="$(THREAD_KIND)" \
 	     LN_S="$(LN_S)" \
-	     gnatlib
-	$(MV) libgna*$(soext) $(RTSDIR)
-	$(MV) libgnat_pic$(arext) $(RTSDIR)
-	$(MV) libgnarl_pic$(arext) $(RTSDIR)
+	     gnatlib-shared-default
 
 gnatlib-shared-dual-win32:
 	$(MAKE) $(FLAGS_TO_PASS) \
@@ -731,9 +757,8 @@ gnatlib-shared-dual-win32:
 	     MULTISUBDIR="$(MULTISUBDIR)" \
 	     THREAD_KIND="$(THREAD_KIND)" \
 	     LN_S="$(LN_S)" \
-	     gnatlib-shared-win32
-	$(MV) $(RTSDIR)/libgna*$(soext) .
-	$(RM) ../stamp-gnatlib2-$(RTSDIR)
+             gnatlib
+	$(RM) $(RTSDIR)/*.o $(RTSDIR)/*.ali
 	$(MAKE) $(FLAGS_TO_PASS) \
              GNATLIBFLAGS="$(GNATLIBFLAGS)" \
 	     GNATLIBCFLAGS="$(GNATLIBCFLAGS)" \
@@ -741,8 +766,7 @@ gnatlib-shared-dual-win32:
 	     MULTISUBDIR="$(MULTISUBDIR)" \
 	     THREAD_KIND="$(THREAD_KIND)" \
 	     LN_S="$(LN_S)" \
-	     gnatlib
-	$(MV) libgna*$(soext) $(RTSDIR)
+	     gnatlib-shared-win32
 
 # ??? we need to add the option to support auto-import of arrays/records to
 # the GNATLIBFLAGS when this will be supported by GNAT. At this point we will
--- a/src/gnattools/Makefile.in
+++ b/src/gnattools/Makefile.in
@@ -75,16 +75,23 @@ CXX_LFLAGS = \
  -L../../../$(target_noncanonical)/libstdc++-v3/src/.libs \
  -L../../../$(target_noncanonical)/libstdc++-v3/libsupc++/.libs
 
+rtsdir := $(abspath ../gcc/ada/rts)
+
 # Variables for gnattools, native
 TOOLS_FLAGS_TO_PASS_NATIVE= \
 	"CC=../../xgcc -B../../" \
 	"CXX=../../xg++ -B../../ $(CXX_LFLAGS)" \
 	"CFLAGS=$(CFLAGS) $(WARN_CFLAGS)" \
-	"LDFLAGS=$(LDFLAGS)" \
-	"ADAFLAGS=$(ADAFLAGS)" \
+	"LDFLAGS=$(LDFLAGS) -Wl,--no-allow-shlib-undefined \
+	  -Wl,--no-copy-dt-needed-entries -Wl,--no-undefined" \
+	"ADAFLAGS=$(ADAFLAGS) -gnatn" \
 	"ADA_CFLAGS=$(ADA_CFLAGS)" \
 	"INCLUDES=$(INCLUDES_FOR_SUBDIR)" \
-	"ADA_INCLUDES=-I- -I../rts $(ADA_INCLUDES_FOR_SUBDIR)"\
+	"ADA_INCLUDES=-I- -nostdinc -I$(rtsdir) $(ADA_INCLUDES_FOR_SUBDIR)" \
+	"TOOLS_ALREADY_COMPILED=$(foreach d, $(rtsdir), \
+	  $(patsubst $(d)/%.ali,%.o, $(wildcard $(d)/*.ali)))" \
+	'LIBGNAT=$(rtsdir)/libgnat-$$(LIB_VERSION).so' \
+	"GNATBIND_FLAGS=-nostdlib -x" \
 	"exeext=$(exeext)" \
 	"fsrcdir=$(fsrcdir)" \
 	"srcdir=$(fsrcdir)" \
@@ -194,6 +201,10 @@ $(GCC_DIR)/stamp-tools:
 # to be able to build gnatmake without a version of gnatmake around. Once 
 # everything has been compiled once, gnatmake can be recompiled with itself 
 # (see target regnattools) 
+gnattools-native: export LD_LIBRARY_PATH := \
+  $(if $(LD_LIBRARY_PATH),$(LD_LIBRARY_PATH):)$(rtsdir)
+# Useful even for 1st pass, as ../../gnatmake may already be
+# dynamically linked in case this target has already been invoked.
 gnattools-native: $(GCC_DIR)/stamp-tools $(GCC_DIR)/stamp-gnatlib-rts
 	# gnattools1
 	$(MAKE) -C $(GCC_DIR)/ada/tools -f ../Makefile \
@@ -202,6 +213,13 @@ gnattools-native: $(GCC_DIR)/stamp-tools
 	# gnattools2
 	$(MAKE) -C $(GCC_DIR)/ada/tools -f ../Makefile \
 	  $(TOOLS_FLAGS_TO_PASS_NATIVE) common-tools
+# The hard-coded object lists for gnatbind/make/link contain unneeded
+# objects. Use the fresh tools to recompute dependencies.
+# A separate Make run avoids race conditions between gnatmakes
+# building the same object for common-tools and gnat*-re.
+# (parallelism is already forbidden between gnat*-re targets)
+	$(MAKE) -C $(GCC_DIR)/ada/tools -f ../Makefile \
+	  $(TOOLS_FLAGS_TO_PASS_NATIVE) gnatbind-re gnatmake-re gnatlink-re
 
 # gnatmake/link can be built with recent gnatmake/link if they are available.
 # This is especially convenient for building cross tools or for rebuilding