gdb: add make-init-c script

I would like to modify how the init.c file is generated (its content).
But as it is, a shell script with multiple sed invocations in a Makefile
target, it's not very maintainable.  Replace that with a shell script
that does the same, but in a more readable way.

The Makefile rule uses the "-" prefix in front of the for loop, I
presume to ignore any error coming from the fact that xml-builtin.c and
cp-name-parser.c are not found in the srcdir (they are generated source
files).  I prefer not to blindly ignore errors, so filter these files
out of INIT_FILES instead (we already filter out other files).

There are no expected meaningful changes to the generated init.c file.
Just the _initialize_all_file declaration that is moved down and "void"
in parenthesis that is removed.

The new regular expression is a bit tighter than the existing one, it
requires the init function to be followed by exactly ` ()`.  Update
bpf-tdep.c accordingly.

gdb/ChangeLog:

	* Makefile.in (INIT_FILES_FILTER_OUT): New.
	(INIT_FILES): Use INIT_FILES_FILTER_OUT.
	(stamp-init): Use make-init-c.
	* bpf-tdep.c (_initialize_bpf_tdep): Remove "void".
	* silent-rules.mk (ECHO_INIT_C): Change.
	* make-init-c: New file.

Change-Id: I6d6b12cbccf24ab79d1219bff05df01624c684f9

5 files changed, 82 insertions, 27 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index b52d060..1db1264 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,14 @@
 2021-05-27  Simon Marchi  <simon.marchi@polymtl.ca>
 
+	* Makefile.in (INIT_FILES_FILTER_OUT): New.
+	(INIT_FILES): Use INIT_FILES_FILTER_OUT.
+	(stamp-init): Use make-init-c.
+	* bpf-tdep.c (_initialize_bpf_tdep): Remove "void".
+	* silent-rules.mk (ECHO_INIT_C): Change.
+	* make-init-c: New file.
+
+2021-05-27  Simon Marchi  <simon.marchi@polymtl.ca>
+
 	* command.h (add_alias_cmd): Accept target as
 	cmd_list_element.  Update callers.
 
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index a9fade8..bb6c5df 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1837,42 +1837,31 @@ test-cp-name-parser$(EXEEXT): test-cp-name-parser.o $(LIBIBERTY)
 # maybe we could just require every .o file to have an initialization routine
 # of a given name (top.o -> _initialize_top, etc.).
 #
-# Formatting conventions:  The name of the _initialize_* routines must start
-# in column zero, and must not be inside #if.
-#
 # Note that the set of files with init functions might change, or the names
 # of the functions might change, so this files needs to depend on all the
 # source files that will be linked into gdb.  However, due to the way
 # this Makefile has generally been written, we do this indirectly, by
 # computing the list of source files from the list of object files.
 
+INIT_FILES_FILTER_OUT = \
+	cp-name-parser.o \
+	init.o \
+	version.o \
+	xml-builtin.o \
+	%_S.o \
+	%_U.o
+
 INIT_FILES = \
 	$(patsubst %.o,%.c, \
 	  $(patsubst %-exp.o,%-exp.y, \
-	    $(filter-out init.o version.o %_S.o %_U.o,\
-	      $(COMMON_OBS))))
+	    $(filter-out $(INIT_FILES_FILTER_OUT), $(COMMON_OBS))))
 
 init.c: stamp-init; @true
-stamp-init: $(INIT_FILES) config.status
-	@$(ECHO_INIT_C) echo "Making init.c"
-	@rm -f init.c-tmp init.l-tmp
-	@touch init.c-tmp
-	@-for f in $(INIT_FILES); do \
-	    sed -n -e 's/^_initialize_\([a-z_0-9A-Z]*\).*/\1/p' \
-	        $(srcdir)/$$f 2>/dev/null; \
-	done > init.l-tmp
-	@echo '/* Do not modify this file.  */' >>init.c-tmp
-	@echo '/* It is created automatically by the Makefile.  */'>>init.c-tmp
-	@echo '#include "defs.h"      /* For initialize_file_ftype.  */' >>init.c-tmp
-	@echo 'extern void initialize_all_files(void);' >>init.c-tmp
-	@sed -e 's/\(.*\)/extern initialize_file_ftype _initialize_\1;/' <init.l-tmp >>init.c-tmp
-	@echo 'void' >>init.c-tmp
-	@echo 'initialize_all_files (void)' >>init.c-tmp
-	@echo '{' >>init.c-tmp
-	@sed -e 's/\(.*\)/  _initialize_\1 ();/' <init.l-tmp >>init.c-tmp
-	@echo '}' >>init.c-tmp
-	@$(SHELL) $(srcdir)/../move-if-change init.c-tmp init.c
-	@echo stamp > stamp-init
+stamp-init: $(INIT_FILES) config.status $(srcdir)/make-init-c
+	$(ECHO_INIT_C)
+	$(SILENCE) $(srcdir)/make-init-c $(addprefix $(srcdir)/,$(INIT_FILES)) > init.c-tmp
+	$(SILENCE) $(SHELL) $(srcdir)/../move-if-change init.c-tmp init.c
+	$(SILENCE) echo stamp > stamp-init
 
 .PRECIOUS: init.c
 
diff --git a/gdb/bpf-tdep.c b/gdb/bpf-tdep.c
index 352a221..a29cd90 100644
--- a/gdb/bpf-tdep.c
+++ b/gdb/bpf-tdep.c
@@ -370,7 +370,7 @@ bpf_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 
 void _initialize_bpf_tdep ();
 void
-_initialize_bpf_tdep (void)
+_initialize_bpf_tdep ()
 {
   register_gdbarch_init (bfd_arch_bpf, bpf_gdbarch_init);
 
diff --git a/gdb/make-init-c b/gdb/make-init-c
new file mode 100755
index 0000000..1588760
--- /dev/null
+++ b/gdb/make-init-c
@@ -0,0 +1,57 @@
+#!/usr/bin/env sh
+
+# Copyright (C) 2013-2021 Free Software Foundation, Inc.
+#
+# This file is part of GDB.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Generate the init.c source file.
+#
+# Usage:
+#
+#    ./make-init-c source-files > init.c-tmp
+#
+# Where SOURCE-FILES is the list of source files to extract init functions from.
+#
+# Formatting conventions:  The name of the initialization routines must begin
+# with `_initialize_`, must start in column zero, and be followed with exactly
+# ` ()`.  For example:
+#
+# void
+# _initialize_foo ()
+# {
+#   ...
+# }
+#
+
+# Abort on command error.
+set -e
+
+echo "/* Do not modify this file.  */"
+echo "/* It is created automatically by the Makefile.  */"
+echo "#include \"defs.h\"      /* For initialize_file_ftype.  */"
+echo ""
+sed -n -e 's/^\(_initialize_[a-zA-Z0-9_]*\) ()$/\1/p' "$@" | while read -r name; do
+  echo "extern initialize_file_ftype $name;"
+done
+echo ""
+echo "void initialize_all_files ();"
+echo "void"
+echo "initialize_all_files ()"
+echo "{"
+sed -n -e 's/^\(_initialize_[a-zA-Z0-9_]*\) ()$/\1/p' "$@" | while read -r name; do
+  echo "  $name ();"
+done
+echo "}"
diff --git a/gdb/silent-rules.mk b/gdb/silent-rules.mk
index 7ed73a7..f7b959f 100644
--- a/gdb/silent-rules.mk
+++ b/gdb/silent-rules.mk
@@ -9,7 +9,7 @@ ECHO_GEN_XML_BUILTIN = \
               @echo "  GEN    xml-builtin.c";
 ECHO_GEN_XML_BUILTIN_GENERATED = \
               @echo "  GEN    xml-builtin-generated.c";
-ECHO_INIT_C =  echo "  GEN    init.c" ||
+ECHO_INIT_C = @echo "  GEN    init.c"
 ECHO_SIGN =   @echo "  SIGN   gdb";
 ECHO_YACC =   @echo "  YACC   $@";
 ECHO_LEX  =   @echo "  LEX    $@";