Vendored packtab for Unicode index tables

Vendor harfbuzz/packtab under Tools/unicode/packtab and use it in
Tools/unicode/makeunicodedata.py to generate packed lookup helpers for
the main codepoint->record/type maps.

Switch unicodedata and unicodectype runtime lookups to those generated
helpers.

Measured on macOS arm64 builds:
- python.exe: 6163528 -> 6092632 bytes (-70896, -1.15%)
- unicodedata.so: 772352 -> 722912 bytes (-49440, -6.40%)
- combined shipped: 6935880 -> 6815544 bytes (-120336, -1.73%)

Author: behdad

Modules/unicodedata.c

@@ -89,8 +89,7 @@ _getrecord_ex(Py_UCS4 code)
     if (code >= 0x110000)
         index = 0;
     else {
-        index = index1[(code>>SHIFT)];
-        index = index2[(index<<SHIFT)+(code&((1<<SHIFT)-1))];
+        index = unicodedata_get_record_index(code);
     }
 
     return &_PyUnicode_Database_Records[index];

Modules/unicodedata_db.h

@@ -48,10 +48,8 @@ gettyperecord(Py_UCS4 code)
 
     if (code >= 0x110000)
         index = 0;
-    else
-    {
-        index = index1[(code>>SHIFT)];
-        index = index2[(index<<SHIFT)+(code&((1<<SHIFT)-1))];
+    else {
+        index = unicodetype_get_type_index(code);
     }
 
     return &_PyUnicode_TypeRecords[index];
@@ -285,4 +283,3 @@ int _PyUnicode_IsAlpha(Py_UCS4 ch)
 
     return (ctype->flags & ALPHA_MASK) != 0;
 }
-

Objects/unicodectype.c

@@ -27,6 +27,7 @@
 #
 
 import dataclasses
+import io
 import os
 import sys
 import re
@@ -36,6 +37,12 @@
 from textwrap import dedent
 from typing import Iterator, List, Optional, Set, Tuple
 
+PACKTAB_DIR = os.path.join(os.path.dirname(__file__), "packtab")
+if PACKTAB_DIR not in sys.path:
+    sys.path.insert(0, PACKTAB_DIR)
+
+from packTab import Code, pack_table
+
 SCRIPT = os.path.normpath(sys.argv[0])
 VERSION = "3.3"
 
@@ -427,13 +434,15 @@ def makeunicodedata(unicode, trace):
         fprint("    NULL")
         fprint("};")
 
-        # split record index table
-        index1, index2, shift = splitbins(index, trace)
-
-        fprint("/* index tables for the database records */")
-        fprint("#define SHIFT", shift)
-        Array("index1", index1).dump(fp, trace)
-        Array("index2", index2).dump(fp, trace)
+        fprint("/* lookup helper for the database records */")
+        dump_packtab_lookup(
+            fp,
+            "unicodedata",
+            "get_record_index",
+            index,
+            default=0,
+            trace=trace,
+        )
 
         # split decomposition index table
         index1, index2, shift = splitbins(decomp_index, trace)
@@ -638,13 +647,15 @@ def makeunicodetype(unicode, trace):
         fprint("};")
         fprint()
 
-        # split decomposition index table
-        index1, index2, shift = splitbins(index, trace)
-
-        fprint("/* type indexes */")
-        fprint("#define SHIFT", shift)
-        Array("index1", index1).dump(fp, trace)
-        Array("index2", index2).dump(fp, trace)
+        fprint("/* lookup helper for type indexes */")
+        dump_packtab_lookup(
+            fp,
+            "unicodetype",
+            "get_type_index",
+            index,
+            default=0,
+            trace=trace,
+        )
 
         # Generate code for _PyUnicode_ToNumeric()
         numeric_items = sorted(numeric.items())
@@ -1283,6 +1294,26 @@ def dump(self, file, trace=0):
         file.write("};\n\n")
 
 
+def dump_packtab_lookup(file, namespace, func_name, data, default=0, trace=0, compression=1):
+    solution = pack_table(data, default=default, compression=compression)
+    if trace:
+        print(
+            f"{func_name}: packtab {solution.cost} bytes,"
+            f" {solution.nLookups} lookups, {solution.nExtraOps} extra ops",
+            file=sys.stderr,
+        )
+    code = Code(namespace)
+    solution.genCode(code, func_name, language="c", private=True)
+    buf = io.StringIO()
+    code.print_code(file=buf, language="c")
+    generated = buf.getvalue()
+    if generated.startswith("#include <stdint.h>\n\n"):
+        generated = generated[len("#include <stdint.h>\n\n"):]
+    file.write(generated)
+    if not generated.endswith("\n\n"):
+        file.write("\n")
+
+
 def getsize(data):
     # return smallest possible integer size for the given array
     maxdata = max(data)

Objects/unicodetype_db.h

@@ -0,0 +1,201 @@
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