Bug 1961719 - Add a script for tallying allocation requests r=glandium DONTBUILD

Differential Revision: https://phabricator.services.mozilla.com/D246166

memory/replace/logalloc/README

@@ -93,3 +93,8 @@ through a different allocator. For example:
 
 Will replay the log against jemalloc4 (which is, as of writing, what
 libreplace_jemalloc.so contains).
+
+The log files can also be used for other analysis.  The logalloc_stats.py
+script will tally the allocation requests for small, large and huge
+allocations (as configured on a system with 4KiB pages).
+

memory/replace/logalloc/replay/logalloc_stats.py

@@ -0,0 +1,60 @@
+#!/usr/bin/python3
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+
+import sys
+
+from logalloc_munge import split_log_line
+
+
+def get_size(line):
+    try:
+        pid, tid, func, args, result = split_log_line(line)
+        if func == "malloc":
+            return int(args[0])
+        elif func == "calloc":
+            return int(args[0]) * int(args[1])
+        elif func == "memalign":
+            return int(args[1])
+        elif func == "realloc":
+            return int(args[1])
+        else:
+            return None
+    except Exception:
+        return None
+
+
+def main():
+    small = 0
+    large = 0
+    huge = 0
+
+    for line in sys.stdin:
+        size = get_size(line.strip())
+        if not size:
+            continue
+
+        # Assumes a 4KiB page size, which is not true on Apple Silicon and
+        # some other platforms.
+        if size < 4096:
+            small += 1
+        elif size < 1024 * 1024:
+            large += 1
+        else:
+            huge += 1
+
+    total = small + large + huge
+
+    def print_percent(name, value):
+        pct = 100 * value / total
+        print(f"{name:<5}: {value:>12,} {pct:6.2f}%")
+
+    print_percent("Small", small)
+    print_percent("Large", large)
+    print_percent("Huge", huge)
+
+
+if __name__ == "__main__":
+    main()