[RFC v2 03/38] add make-target-delegates

[Tom Tromey <tromey at redhat dot com>]

This patch adds a new script, call make-target-delegates, which
auto-generates some target delegation code based on annotations in
target.h.  This adds the new delegation macros, the new generated
file, and adds the necessary calls to the new generated functions to
target.c.  It doesn't, however, add any actual annotations to the
target methods, leaving these for separate patches.

2014-02-06  Tom Tromey  <tromey@redhat.com>

	PR build/7701:
	* target-delegates.c: New file.
	* target.c: Include target-delegates.c.
	(init_dummy_target): Call install_dummy_methods.
	(complete_target_initialization): Call install_delegators.
	* target.h (TARGET_DEFAULT_IGNORE, TARGET_DEFAULT_NORETURN)
	(TARGET_DEFAULT_RETURN, TARGET_DEFAULT_FUNC): New defines.
	* make-target-delegates: New file.
---
 gdb/ChangeLog             |  11 ++
 gdb/make-target-delegates | 253 ++++++++++++++++++++++++++++++++++++++++++++++
 gdb/target-delegates.c    |  14 +++
 gdb/target.c              |   9 ++
 gdb/target.h              |  24 +++++
 5 files changed, 311 insertions(+)
 create mode 100755 gdb/make-target-delegates
 create mode 100644 gdb/target-delegates.c

diff --git a/gdb/make-target-delegates b/gdb/make-target-delegates
new file mode 100755
index 0000000..f09f89d
--- /dev/null
+++ b/gdb/make-target-delegates
@@ -0,0 +1,253 @@
+#!/usr/bin/perl
+
+# Copyright (C) 2013-2014 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/>.
+
+
+# Usage:
+#    make-target-delegates target.h > target-delegates.c
+
+# The line we search for in target.h that marks where we should start
+# looking for methods.
+$TRIGGER = qr,^struct target_ops$,;
+# The end of the methods part.
+$ENDER = qr,^\s*};$,;
+
+# Match a C symbol.
+$SYMBOL = qr,[a-zA-Z_][a-zA-Z0-9_]*,;
+# Match the name part of a method in struct target_ops.
+$NAME_PART = qr,\(\*(?<name>${SYMBOL}+)\)\s,;
+# Match the start of arguments to a method.
+$ARGS_PART = qr,(?<args>\(.*)$,;
+# Match indentation.
+$INTRO_PART = qr,^\s*,;
+
+# Match the return type when it is "ordinary".
+$SIMPLE_RETURN_PART = qr,[^\(]+,;
+# Match the return type when it is a VEC.
+$VEC_RETURN_PART = qr,VEC\s*\([^\)]+\)[^\(]*,;
+
+# Match the TARGET_DEFAULT_* attribute for a method.
+$TARGET_DEFAULT_PART = qr,TARGET_DEFAULT_(?<style>[A-Z_]+)\s*\((?<default_arg>.*)\),;
+
+# Match the introductory line to a method definition.
+$METHOD = ($INTRO_PART . "(?<return_type>" . $SIMPLE_RETURN_PART
+	   . "|" . $VEC_RETURN_PART . ")"
+	   . $NAME_PART . $ARGS_PART);
+
+# Match the arguments and trailing attribute of a method definition.
+$METHOD_TRAILER = qr,(?<args>\(.+\))\s*${TARGET_DEFAULT_PART};$,;
+
+sub trim($) {
+    my ($result) = @_;
+    $result =~ s,^\s*(\S*)\s*$,\1,;
+    return $result;
+}
+
+# Read from the input files until we find the trigger line.
+# Die if not found.
+sub find_trigger() {
+    while (<>) {
+	chomp;
+	return if m/$TRIGGER/;
+    }
+
+    die "could not find trigger line\n";
+}
+
+# Parse arguments into a list.
+sub parse_argtypes($) {
+    my ($typestr) = @_;
+
+    $typestr =~ s/^\((.*)\)$/\1/;
+
+    my (@typelist) = split (/,\s*/, $typestr);
+    my (@result, $iter, $onetype);
+
+    foreach $iter (@typelist) {
+	if ($iter =~ m/^(enum\s+${SYMBOL}\s*)(${SYMBOL})?$/) {
+	    $onetype = $1;
+	} elsif ($iter =~ m/^(.*(enum\s+)?${SYMBOL}.*(\s|\*))${SYMBOL}+$/) {
+	    $onetype = $1;
+	} elsif ($iter eq 'void') {
+	    next;
+	} else {
+	    $onetype = $iter;
+	}
+	push @result, trim ($onetype);
+    }
+
+    return @result;
+}
+
+sub dname($) {
+    my ($name) = @_;
+    $name =~ s/to_/delegate_/;
+    return $name;
+}
+
+# Write function header given name, return type, and argtypes.
+# Returns a list of actual argument names.
+sub write_function_header($$@) {
+    my ($name, $return_type, @argtypes) = @_;
+
+    print "static " . $return_type . "\n";
+    print $name . ' (';
+
+    my $iter;
+    my @argdecls;
+    my @actuals;
+    my $i = 0;
+    foreach $iter (@argtypes) {
+	my $val = $iter;
+
+	if ($iter !~ m,\*$,) {
+	    $val .= ' ';
+	}
+
+	my $vname;
+	if ($i == 0) {
+	    # Just a random nicety.
+	    $vname = 'self';
+	} else {
+	    $vname .= "arg$i";
+	}
+	$val .= $vname;
+
+	push @argdecls, $val;
+	push @actuals, $vname;
+	++$i;
+    }
+
+    print join (', ', @argdecls) . ")\n";
+    print "{\n";
+
+    return @actuals;
+}
+
+# Write out a delegation function.
+sub write_delegator($$@) {
+    my ($name, $return_type, @argtypes) = @_;
+
+    my (@names) = write_function_header (dname ($name), $return_type,
+					 @argtypes);
+
+    print "  $names[0] = $names[0]->beneath;\n";
+    print "  ";
+    if ($return_type ne 'void') {
+	print "return ";
+    }
+    print "$names[0]->" . $name . " (";
+    print join (', ', @names);
+    print ");\n";
+    print "}\n\n";
+}
+
+sub tdname ($) {
+    my ($name) = @_;
+    $name =~ s/to_/tdefault_/;
+    return $name;
+}
+
+# Write out a default function.
+sub write_tdefault($$$$@) {
+    my ($content, $style, $name, $return_type, @argtypes) = @_;
+
+    if ($style eq 'FUNC') {
+	return $content;
+    }
+
+    write_function_header (tdname ($name), $return_type, @argtypes);
+
+    if ($style eq 'RETURN') {
+	print "  return $content;\n";
+    } elsif ($style eq 'NORETURN') {
+	print "  $content;\n";
+    } elsif ($style eq 'IGNORE') {
+	# Nothing.
+    } else {
+	die "unrecognized style: $style\n";
+    }
+
+    print "}\n\n";
+
+    return tdname ($name);
+}
+
+print "/* THIS FILE IS GENERATED -*- buffer-read-only: t -*- */\n";
+print "/* vi:set ro: */\n\n";
+print "/* To regenerate this file, run:*/\n";
+print "/*      make-target-delegates target.h > target-delegates.c */\n";
+
+find_trigger();
+
+%tdefault_names = ();
+@delegators = ();
+$current_line = '';
+while (<>) {
+    chomp;
+    last if m/$ENDER/;
+
+    if ($current_line ne '') {
+	s/^\s*//;
+	$current_line .= $_;
+    } elsif (m/$METHOD/) {
+	$name = $+{name};
+	$current_line = $+{args};
+	$return_type = trim ($+{return_type});
+    }
+
+    if ($current_line =~ /\);\s*$/) {
+	if ($current_line =~ m,$METHOD_TRAILER,) {
+	    $current_args = $+{args};
+	    $tdefault = $+{default_arg};
+	    $style = $+{style};
+
+	    @argtypes = parse_argtypes ($current_args);
+
+	    # The first argument must be "this" to be delegatable.
+	    if ($argtypes[0] =~ /\s*struct\s+target_ops\s*\*\s*/) {
+		write_delegator ($name, $return_type, @argtypes);
+
+		push @delegators, $name;
+
+		$tdefault_names{$name} = write_tdefault ($tdefault, $style,
+							 $name, $return_type,
+							 @argtypes);
+	    }
+	}
+
+	$current_line = '';
+    }
+}
+
+# Now the delegation code.
+print "static void\ninstall_delegators (struct target_ops *ops)\n{\n";
+
+for $iter (@delegators) {
+    print "  if (ops->" . $iter . " == NULL)\n";
+    print "    ops->" . $iter . " = " . dname ($iter) . ";\n";
+}
+print "}\n\n";
+
+# Now the default method code.
+print "static void\ninstall_dummy_methods (struct target_ops *ops)\n{\n";
+
+for $iter (@delegators) {
+    print "  ops->" . $iter . " = " . $tdefault_names{$iter} . ";\n";
+}
+print "}\n";
diff --git a/gdb/target-delegates.c b/gdb/target-delegates.c
new file mode 100644
index 0000000..cf6364d
--- /dev/null
+++ b/gdb/target-delegates.c
@@ -0,0 +1,14 @@
+/* THIS FILE IS GENERATED -*- buffer-read-only: t -*- */
+/* vi:set ro: */
+
+/* To regenerate this file, run:*/
+/*      make-target-delegates target.h > target-delegates.c */
+static void
+install_delegators (struct target_ops *ops)
+{
+}
+
+static void
+install_dummy_methods (struct target_ops *ops)
+{
+}
diff --git a/gdb/target.c b/gdb/target.c
index c9f004a..3109559 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -79,6 +79,8 @@ static target_xfer_partial_ftype current_xfer_partial;
 static struct gdbarch *default_thread_architecture (struct target_ops *ops,
 						    ptid_t ptid);
 
+#include "target-delegates.c"
+
 static void init_dummy_target (void);
 
 static struct target_ops debug_target;
@@ -353,6 +355,8 @@ complete_target_initialization (struct target_ops *t)
 
   if (t->to_has_execution == NULL)
     t->to_has_execution = (int (*) (struct target_ops *, ptid_t)) return_zero;
+
+  install_delegators (t);
 }
 
 /* Add possible target architecture T to the list and add a new
@@ -560,6 +564,9 @@ update_current_target (void)
   /* First, reset current's contents.  */
   memset (&current_target, 0, sizeof (current_target));
 
+  /* Install the delegators.  */
+  install_delegators (&current_target);
+
 #define INHERIT(FIELD, TARGET) \
       if (!current_target.FIELD) \
 	current_target.FIELD = (TARGET)->FIELD
@@ -3820,6 +3827,8 @@ init_dummy_target (void)
   dummy_target.to_stopped_data_address =
     (int (*) (struct target_ops *, CORE_ADDR *)) return_zero;
   dummy_target.to_magic = OPS_MAGIC;
+
+  install_dummy_methods (&dummy_target);
 }
 
 static void
diff --git a/gdb/target.h b/gdb/target.h
index 07d0afd..19db907 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -350,6 +350,30 @@ struct thread_info;		/* fwd decl for parameter list below: */
 typedef void async_callback_ftype (enum inferior_event_type event_type,
 				   void *context);
 
+/* These defines are used to mark target_ops methods.  The script
+   make-target-delegates scans these and auto-generates the base
+   method implementations.  There are four macros that can be used:
+   
+   1. TARGET_DEFAULT_IGNORE.  There is no argument.  The base method
+   does nothing.  This is only valid if the method return type is
+   'void'.
+   
+   2. TARGET_DEFAULT_NORETURN.  The argument is a function call, like
+   'tcomplain ()'.  The base method simply makes this call, which is
+   assumed not to return.
+   
+   3. TARGET_DEFAULT_RETURN.  The argument is a C expression.  The
+   base method returns this expression's value.
+   
+   4. TARGET_DEFAULT_FUNC.  The argument is the name of a function.
+   make-target-delegates does not generate a base method in this case,
+   but instead uses the argument function as the base method.  */
+
+#define TARGET_DEFAULT_IGNORE()
+#define TARGET_DEFAULT_NORETURN(ARG)
+#define TARGET_DEFAULT_RETURN(ARG)
+#define TARGET_DEFAULT_FUNC(ARG)
+
 struct target_ops
   {
     struct target_ops *beneath;	/* To the target under this one.  */
-- 
1.8.1.4