Host sampler: accessors in every build; tools/host_profile.py names hot functions

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
(cherry picked from commit a51504fd3b)

runtime/src/host_sampler.c

@@ -12,9 +12,8 @@
  * Windows: SuspendThread / GetThreadContext / ResumeThread from a sampler
  * thread. POSIX: the process CPU-time timer (SIGPROF) delivered to the
  * emulation thread, which reads its own interrupted PC from the ucontext.
- * Other hosts report the sampler as unsupported. */
-#ifndef PSX_NO_DEBUG_TOOLS
-
+ * Other hosts, and builds without debug tools, report the sampler as
+ * unsupported. */
 #if defined(__linux__) && !defined(_GNU_SOURCE)
 #define _GNU_SOURCE 1   /* REG_RIP, dladdr */
 #endif
@@ -31,6 +30,7 @@ static volatile uint64_t s_seq;
 static uintptr_t s_image_base;
 static int s_supported;
 
+#ifndef PSX_NO_DEBUG_TOOLS
 static void record(uintptr_t pc) {
     const uint64_t n = s_seq;
     HostSample *e = &s_ring[n % HOST_SAMPLER_CAP];
@@ -39,8 +39,13 @@ static void record(uintptr_t pc) {
     e->in_pass = g_psx_render_pass_active ? 1u : 0u;
     s_seq = n + 1;
 }
+#endif
 
-#if defined(_WIN32)
+#if defined(PSX_NO_DEBUG_TOOLS)
+/* Production builds carry no sampler: it reports unsupported. */
+void host_sampler_start(void) {}
+
+#elif defined(_WIN32)
 #include <windows.h>
 
 static HANDLE s_target;
@@ -161,5 +166,3 @@ int host_sampler_get(uint64_t seq, HostSample *out) {
     *out = s_ring[seq % HOST_SAMPLER_CAP];
     return 1;
 }
-
-#endif /* !PSX_NO_DEBUG_TOOLS */

tools/host_profile.py

@@ -0,0 +1,125 @@
+#!/usr/bin/env python3
+"""Name the hot host functions of a running psxrecomp game.
+
+Reads the always-on host CPU sampler (TCP host_profile, runtime/src/
+host_sampler.c) over a window of the ring and maps each executable-relative
+address to the function containing it, using the image's own symbol table
+(nm), so a Release build without debug info profiles too.
+
+  host_profile.py --port 4531 --exe game.exe --frames 300 [--pass 1] [--top 40]
+
+--frames N: the last N guest frames. --pass 1 / 0: only samples inside /
+outside render passes. Prints per-function sample counts and shares.
+"""
+import argparse
+import bisect
+import json
+import os
+import shutil
+import socket
+import subprocess
+import sys
+
+
+def query(port, **kw):
+    with socket.create_connection(("127.0.0.1", port), 5) as s:
+        s.settimeout(30)
+        s.sendall((json.dumps(dict(id=1, cmd="host_profile", **kw)) + "\n").encode())
+        with s.makefile("rb") as f:
+            return json.loads(f.readline())
+
+
+def find_nm(explicit):
+    if explicit:
+        return explicit
+    for name in ("llvm-nm", "nm"):
+        p = shutil.which(name)
+        if p:
+            return p
+    sys.exit("no nm on PATH; pass --nm")
+
+
+def preferred_base(exe, out):
+    """The address nm's symbol values are relative to: a PE image's
+    ImageBase (optional header), a Mach-O executable's __mh_execute_header,
+    0 for a position-independent ELF."""
+    with open(exe, "rb") as f:
+        head = f.read(4096)
+    if head[:2] == b"MZ":
+        pe = int.from_bytes(head[0x3C:0x40], "little")
+        magic = int.from_bytes(head[pe + 24:pe + 26], "little")
+        if magic == 0x20B:   # PE32+
+            return int.from_bytes(head[pe + 24 + 24:pe + 24 + 32], "little")
+        return int.from_bytes(head[pe + 24 + 28:pe + 24 + 32], "little")
+    for line in out.splitlines():
+        parts = line.split(None, 2)
+        if len(parts) == 3 and parts[2] in ("__mh_execute_header", "_mh_execute_header"):
+            return int(parts[0], 16)
+    return 0
+
+
+def image_size(exe):
+    """SizeOfImage of a PE executable, or None."""
+    with open(exe, "rb") as f:
+        head = f.read(4096)
+    if head[:2] != b"MZ":
+        return None
+    pe = int.from_bytes(head[0x3C:0x40], "little")
+    return int.from_bytes(head[pe + 24 + 56:pe + 24 + 60], "little")
+
+
+def symbols(nm, exe):
+    """(rva, name) sorted, from the image's text symbols."""
+    out = subprocess.run([nm, "--defined-only", exe], capture_output=True,
+                         text=True, check=True).stdout
+    base = preferred_base(exe, out)
+    table = []
+    for line in out.splitlines():
+        parts = line.split(None, 2)
+        if len(parts) == 3 and parts[1] in ("T", "t"):
+            table.append((int(parts[0], 16) - base, parts[2]))
+    table.sort()
+    return table
+
+
+def main():
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--port", type=int, required=True)
+    ap.add_argument("--exe", required=True)
+    ap.add_argument("--frames", type=int, default=0)
+    ap.add_argument("--since", type=int, default=-1)
+    ap.add_argument("--pass", dest="in_pass", type=int, default=-1)
+    ap.add_argument("--top", type=int, default=40)
+    ap.add_argument("--nm")
+    a = ap.parse_args()
+    kw = {"top": 400}
+    if a.frames > 0:
+        kw["frames"] = a.frames
+    if a.since >= 0:
+        kw["since"] = a.since
+    if a.in_pass >= 0:
+        kw["pass"] = a.in_pass
+    r = query(a.port, **kw)
+    if not r.get("ok") or not r.get("supported"):
+        sys.exit("sampler unavailable: %s" % r)
+    table = symbols(find_nm(a.nm), a.exe)
+    keys = [t[0] for t in table]
+    size = image_size(a.exe)
+    per = {}
+    for rva_s, n in r["top"]:
+        rva = int(rva_s, 16)
+        i = bisect.bisect_right(keys, rva) - 1
+        if (size is not None and rva >= size) or i < 0:
+            name = "(outside the executable: system code, waits)"
+        else:
+            name = table[i][1]
+        per[name] = per.get(name, 0) + n
+    total = r["samples"] or 1
+    print("samples %d (binned top 400 addresses; %d not binned) seq %d" %
+          (r["samples"], r["unbinned"], r["seq"]))
+    for name, n in sorted(per.items(), key=lambda kv: -kv[1])[:a.top]:
+        print("%6d %5.1f%%  %s" % (n, 100.0 * n / total, name))
+
+
+if __name__ == "__main__":
+    main()