bpo-46541: Generate the global objects initializer. (gh-30941)

This change is a prerequisite for generating code for other global objects (like strings in gh-30928).

(We borrowed some code from Tools/scripts/deepfreeze.py.)

https://bugs.python.org/issue46541

Author: ericsnowcurrently

Include/internal/pycore_runtime_init.h

@@ -94,6 +94,8 @@ extern "C" {
         _PyBytes_SIMPLE_INIT(CH, 1) \
     }
 
+
+/* The following is auto-generated by Tools/scripts/generate_global_objects.py. */
 #define _Py_global_objects_INIT { \
     .singletons = { \
         .small_ints = { \
@@ -622,6 +624,7 @@ extern "C" {
         }, \
     }, \
 }
+/* End auto-generated code */
 
 
 #ifdef __cplusplus

Makefile.pre.in

@@ -1172,6 +1172,13 @@ Python/deepfreeze/deepfreeze.c: $(DEEPFREEZE_DEPS)
 .PHONY: regen-importlib
 regen-importlib: regen-frozen
 
+############################################################################
+# Global objects
+
+.PHONY: regen-global-objects
+regen-global-objects: $(srcdir)/Tools/scripts/generate_global_objects.py $(FREEZE_MODULE_DEPS)
+	$(PYTHON_FOR_FREEZE) $(srcdir)/Tools/scripts/generate_global_objects.py
+
 ############################################################################
 # ABI
 
@@ -1183,7 +1190,8 @@ regen-limited-abi: all
 
 regen-all: regen-opcode regen-opcode-targets regen-typeslots \
 	regen-token regen-ast regen-keyword regen-frozen clinic \
-	regen-pegen-metaparser regen-pegen regen-test-frozenmain
+	regen-pegen-metaparser regen-pegen regen-test-frozenmain \
+	regen-global-objects
 	@echo
 	@echo "Note: make regen-stdlib-module-names and make autoconf should be run manually"
 

Tools/scripts/generate_global_objects.py

@@ -0,0 +1,124 @@
+import argparse
+import ast
+import builtins
+import collections
+import contextlib
+import os.path
+import sys
+
+
+assert os.path.isabs(__file__), __file__
+ROOT = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
+INTERNAL = os.path.join(ROOT, 'Include', 'internal')
+
+
+#######################################
+# helpers
+
+def iter_to_marker(lines, marker):
+    for line in lines:
+        if line.rstrip() == marker:
+            break
+        yield line
+
+
+class Printer:
+
+    def __init__(self, file):
+        self.level = 0
+        self.file = file
+        self.continuation = [False]
+
+    @contextlib.contextmanager
+    def indent(self):
+        save_level = self.level
+        try:
+            self.level += 1
+            yield
+        finally:
+            self.level = save_level
+
+    def write(self, arg):
+        eol = '\n'
+        if self.continuation[-1]:
+            eol = f' \\{eol}' if arg else f'\\{eol}'
+        self.file.writelines(("    "*self.level, arg, eol))
+
+    @contextlib.contextmanager
+    def block(self, prefix, suffix="", *, continuation=None):
+        if continuation is None:
+            continuation = self.continuation[-1]
+        self.continuation.append(continuation)
+
+        self.write(prefix + " {")
+        with self.indent():
+            yield
+        self.continuation.pop()
+        self.write("}" + suffix)
+
+
+#######################################
+# the global objects
+
+START = '/* The following is auto-generated by Tools/scripts/generate_global_objects.py. */'
+END = '/* End auto-generated code */'
+
+
+def generate_runtime_init():
+    # First get some info from the declarations.
+    nsmallposints = None
+    nsmallnegints = None
+    with open(os.path.join(INTERNAL, 'pycore_global_objects.h')) as infile:
+        for line in infile:
+            if line.startswith('#define _PY_NSMALLPOSINTS'):
+                nsmallposints = int(line.split()[-1])
+            elif line.startswith('#define _PY_NSMALLNEGINTS'):
+                nsmallnegints = int(line.split()[-1])
+                break
+        else:
+            raise NotImplementedError
+    assert nsmallposints and nsmallnegints
+
+    # Then target the runtime initializer.
+    filename = os.path.join(INTERNAL, 'pycore_runtime_init.h')
+
+    # Read the non-generated part of the file.
+    with open(filename) as infile:
+        before = ''.join(iter_to_marker(infile, START))[:-1]
+        for _ in iter_to_marker(infile, END):
+            pass
+        after = infile.read()[:-1]
+
+    # Generate the file.
+    with open(filename, 'w', encoding='utf-8') as outfile:
+        printer = Printer(outfile)
+        printer.write(before)
+        printer.write(START)
+        with printer.block('#define _Py_global_objects_INIT', continuation=True):
+            with printer.block('.singletons =', ','):
+                # Global int objects.
+                with printer.block('.small_ints =', ','):
+                    for i in range(-nsmallnegints, nsmallposints):
+                        printer.write(f'_PyLong_DIGIT_INIT({i}),')
+                printer.write('')
+                # Global bytes objects.
+                printer.write('.bytes_empty = _PyBytes_SIMPLE_INIT(0, 0),')
+                with printer.block('.bytes_characters =', ','):
+                    for i in range(256):
+                        printer.write(f'_PyBytes_CHAR_INIT({i}),')
+        printer.write(END)
+        printer.write(after)
+
+
+#######################################
+# the script
+
+def main() -> None:
+    generate_runtime_init()
+
+
+if __name__ == '__main__':
+    argv = sys.argv[1:]
+    if argv:
+        sys.exit(f'ERROR: got unexpected args {argv}')
+    main()