Rewrite make-target-delegates in Python

I think gdb is probably better off having fewer languages involved
when generating code.  'sh' is unavoidable for build-time generation,
but for other things, let's use Python.

This rewrites make-target-delegates in Python.  I've stuck pretty
closely to the original code in this rewrite, so it may look slightly
weird from a Python perspective.

The only output difference is that a copyright header is now
generated, using the code introduced in the previous patch.

make-target-delegates.py is simpler to invoke, as it knows the correct
input file to scan and it creates the output file itself.

1 files changed, 340 insertions, 0 deletions

diff --git a/gdb/make-target-delegates.py b/gdb/make-target-delegates.py
new file mode 100755
index 0000000..9717807
--- /dev/null
+++ b/gdb/make-target-delegates.py
@@ -0,0 +1,340 @@
+#!/usr/bin/env python3
+
+# Copyright (C) 2013-2022 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.py
+
+import re
+import gdbcopyright
+
+
+# The line we search for in target.h that marks where we should start
+# looking for methods.
+TRIGGER = re.compile(r"^struct target_ops$")
+# The end of the methods part.
+ENDER = re.compile(r"^\s*};$")
+
+# Match a C symbol.
+SYMBOL = "[a-zA-Z_][a-zA-Z0-9_]*"
+# Match the name part of a method in struct target_ops.
+NAME_PART = r"(?P<name>" + SYMBOL + ")\s"
+# Match the arguments to a method.
+ARGS_PART = r"(?P<args>\(.*\))"
+# We strip the indentation so here we only need the caret.
+INTRO_PART = r"^"
+
+POINTER_PART = r"\s*(\*)?\s*"
+
+# Match a C++ symbol, including scope operators and template
+# parameters.  E.g., 'std::vector<something>'.
+CP_SYMBOL = r"[a-zA-Z_][a-zA-Z0-9_<>:]*"
+# Match the return type when it is "ordinary".
+SIMPLE_RETURN_PART = r"((struct|class|enum|union)\s+)?" + CP_SYMBOL
+
+# Match a return type.
+RETURN_PART = r"((const|volatile)\s+)?(" + SIMPLE_RETURN_PART + ")" + POINTER_PART
+
+# Match "virtual".
+VIRTUAL_PART = r"virtual\s"
+
+# Match the TARGET_DEFAULT_* attribute for a method.
+TARGET_DEFAULT_PART = r"TARGET_DEFAULT_(?P<style>[A-Z_]+)\s*\((?P<default_arg>.*)\)"
+
+# Match the arguments and trailing attribute of a method definition.
+# Note we don't match the trailing ";".
+METHOD_TRAILER = r"\s*" + TARGET_DEFAULT_PART + "$"
+
+# Match an entire method definition.
+METHOD = re.compile(
+    INTRO_PART
+    + VIRTUAL_PART
+    + "(?P<return_type>"
+    + RETURN_PART
+    + ")"
+    + NAME_PART
+    + ARGS_PART
+    + METHOD_TRAILER
+)
+
+# Regular expression used to dissect argument types.
+ARGTYPES = re.compile(
+    "^("
+    + r"(?P<E>enum\s+"
+    + SYMBOL
+    + r"\s*)("
+    + SYMBOL
+    + ")?"
+    + r"|(?P<T>.*(enum\s+)?"
+    + SYMBOL
+    + r".*(\s|\*|&))"
+    + SYMBOL
+    + ")$"
+)
+
+# Match TARGET_DEBUG_PRINTER in an argument type.
+# This must match the whole "sub-expression" including the parens.
+TARGET_DEBUG_PRINTER = r"\s*TARGET_DEBUG_PRINTER\s*\((?P<arg>[^)]*)\)\s*"
+
+
+def scan_target_h():
+    found_trigger = False
+    all_the_text = ""
+    with open("target.h", "r") as target_h:
+        for line in target_h:
+            line = line.strip()
+            if not found_trigger:
+                if TRIGGER.match(line):
+                    found_trigger = True
+            elif "{" in line:
+                # Skip the open brace.
+                pass
+            elif ENDER.match(line):
+                break
+            else:
+                # Strip // comments.
+                line = re.split("//", line)[0]
+                all_the_text = all_the_text + " " + line
+    if not found_trigger:
+        raise "Could not find trigger line"
+    # Now strip out the C comments.
+    all_the_text = re.sub(r"/\*(.*?)\*/", "", all_the_text)
+    # Replace sequences whitespace with a single space character.
+    # We need the space because the method may have been split
+    # between multiple lines, like e.g.:
+    #
+    #  virtual std::vector<long_type_name>
+    #    my_long_method_name ()
+    #    TARGET_DEFAULT_IGNORE ();
+    #
+    # If we didn't preserve the space, then we'd end up with:
+    #
+    #  virtual std::vector<long_type_name>my_long_method_name ()TARGET_DEFAULT_IGNORE ()
+    #
+    # ... which wouldn't later be parsed correctly.
+    all_the_text = re.sub(r"\s+", " ", all_the_text)
+    return all_the_text.split(";")
+
+
+# Parse arguments into a list.
+def parse_argtypes(typestr):
+    # Remove the outer parens.
+    typestr = re.sub(r"^\((.*)\)$", r"\1", typestr)
+    result = []
+    for item in re.split(r",\s*", typestr):
+        if item == "void" or item == "":
+            continue
+        m = ARGTYPES.match(item)
+        if m:
+            if m.group("E"):
+                onetype = m.group("E")
+            else:
+                onetype = m.group("T")
+        else:
+            onetype = item
+        result.append(onetype.strip())
+    return result
+
+
+# Write function header given name, return type, and argtypes.
+# Returns a list of actual argument names.
+def write_function_header(f, decl, name, return_type, argtypes):
+    print(return_type, file=f, end="")
+    if decl:
+        if not return_type.endswith("*"):
+            print(" ", file=f, end="")
+    else:
+        print("", file=f)
+    print(name + " (", file=f, end="")
+    argdecls = []
+    actuals = []
+    for i in range(len(argtypes)):
+        val = re.sub(TARGET_DEBUG_PRINTER, "", argtypes[i])
+        if not val.endswith("*") and not val.endswith("&"):
+            val = val + " "
+        vname = "arg" + str(i)
+        val = val + vname
+        argdecls.append(val)
+        actuals.append(vname)
+    print(", ".join(argdecls) + ")", file=f, end="")
+    if decl:
+        print(" override;", file=f)
+    else:
+        print("\n{", file=f)
+    return actuals
+
+
+# Write out a declaration.
+def write_declaration(f, name, return_type, argtypes):
+    write_function_header(f, True, name, return_type, argtypes)
+
+
+# Write out a delegation function.
+def write_delegator(f, name, return_type, argtypes):
+    names = write_function_header(
+        f, False, "target_ops::" + name, return_type, argtypes
+    )
+    print("  ", file=f, end="")
+    if return_type != "void":
+        print("return ", file=f, end="")
+    print("this->beneath ()->" + name + " (", file=f, end="")
+    print(", ".join(names), file=f, end="")
+    print(");", file=f)
+    print("}\n", file=f)
+
+
+# Write out a default function.
+def write_tdefault(f, content, style, name, return_type, argtypes):
+    name = "dummy_target::" + name
+    names = write_function_header(f, False, name, return_type, argtypes)
+    if style == "FUNC":
+        print("  ", file=f, end="")
+        if return_type != "void":
+            print("return ", file=f, end="")
+        print(content + " (", file=f, end="")
+        names.insert(0, "this")
+        print(", ".join(names) + ");", file=f)
+    elif style == "RETURN":
+        print("  return " + content + ";", file=f)
+    elif style == "NORETURN":
+        print("  " + content + ";", file=f)
+    elif style == "IGNORE":
+        # Nothing.
+        pass
+    else:
+        raise "unrecognized style: " + style
+    print("}\n", file=f)
+
+
+def munge_type(typename):
+    m = re.search(TARGET_DEBUG_PRINTER, typename)
+    if m:
+        return m.group("arg")
+    typename = typename.rstrip()
+    typename = re.sub("[ ()<>:]", "_", typename)
+    typename = re.sub("[*]", "p", typename)
+    typename = re.sub("&", "r", typename)
+    # Identifers with double underscores are reserved to the C++
+    # implementation.
+    typename = re.sub("_+", "_", typename)
+    # Avoid ending the function name with underscore, for
+    # cosmetics.  Trailing underscores appear after munging types
+    # with template parameters, like e.g. "foo<int>".
+    typename = re.sub("_+$", "", typename)
+    return "target_debug_print_" + typename
+
+
+# Write out a debug method.
+def write_debugmethod(f, content, name, return_type, argtypes):
+    debugname = "debug_target::" + name
+    names = write_function_header(f, False, debugname, return_type, argtypes)
+    if return_type != "void":
+        print("  " + return_type + " result;", file=f)
+    print(
+        '  fprintf_unfiltered (gdb_stdlog, "-> %s->'
+        + name
+        + ' (...)\\n", this->beneath ()->shortname ());',
+        file=f,
+    )
+
+    # Delegate to the beneath target.
+    print("  ", file=f, end="")
+    if return_type != "void":
+        print("result = ", file=f, end="")
+    print("this->beneath ()->" + name + " (", file=f, end="")
+    print(", ".join(names), file=f, end="")
+    print(");", file=f)
+
+    # Now print the arguments.
+    print(
+        '  fprintf_unfiltered (gdb_stdlog, "<- %s->'
+        + name
+        + ' (", this->beneath ()->shortname ());',
+        file=f,
+    )
+    for i in range(len(argtypes)):
+        if i > 0:
+            print('  fputs_unfiltered (", ", gdb_stdlog);', file=f)
+        printer = munge_type(argtypes[i])
+        print("  " + printer + " (" + names[i] + ");", file=f)
+    if return_type != "void":
+        print('  fputs_unfiltered (") = ", gdb_stdlog);', file=f)
+        printer = munge_type(return_type)
+        print("  " + printer + " (result);", file=f)
+        print('  fputs_unfiltered ("\\n", gdb_stdlog);', file=f)
+    else:
+        print('  fputs_unfiltered (")\\n", gdb_stdlog);', file=f)
+
+    if return_type != "void":
+        print("  return result;", file=f)
+
+    print("}\n", file=f)
+
+
+def print_class(f, class_name, delegators, entries):
+    print("struct " + class_name + " : public target_ops", file=f)
+    print("{", file=f)
+    print("  const target_info &info () const override;", file=f)
+    print("", file=f)
+    print("  strata stratum () const override;", file=f)
+    print("", file=f)
+
+    for name in delegators:
+        return_type = entries[name]["return_type"]
+        argtypes = entries[name]["argtypes"]
+        print("  ", file=f, end="")
+        write_declaration(f, name, return_type, argtypes)
+
+    print("};\n", file=f)
+
+
+delegators = []
+entries = {}
+for current_line in scan_target_h():
+    # See comments in scan_target_h.  Here we strip away the leading
+    # and trailing whitespace.
+    current_line = current_line.strip()
+    m = METHOD.match(current_line)
+    if not m:
+        continue
+    data = m.groupdict()
+    data["argtypes"] = parse_argtypes(data["args"])
+    data["return_type"] = data["return_type"].strip()
+    entries[data["name"]] = data
+
+    delegators.append(data["name"])
+
+with open("target-delegates.c", "w") as f:
+    print(
+        gdbcopyright.copyright(
+            "make-target-delegates.py", "Boilerplate target methods for GDB"
+        ),
+        file=f,
+    )
+    print_class(f, "dummy_target", delegators, entries)
+    print_class(f, "debug_target", delegators, entries)
+
+    for name in delegators:
+        tdefault = entries[name]["default_arg"]
+        return_type = entries[name]["return_type"]
+        style = entries[name]["style"]
+        argtypes = entries[name]["argtypes"]
+
+        write_delegator(f, name, return_type, argtypes)
+        write_tdefault(f, tdefault, style, name, return_type, argtypes)
+        write_debugmethod(f, tdefault, name, return_type, argtypes)