NX2navi/tests/excl_mt.py

"""Multithreaded test of the exclusive monitor helpers in cpu.h (ldxN/stxN, ldxp128/stxp128).

- A changed value: thread A loads X exclusively, thread B changes X to Y with its own exclusive pair, then A's store
  exclusive must fail. Checked for the 32-bit, 64-bit and 128-bit pair forms, plus a control where B touches nothing.
- A value changed and changed back (ABA): B changes X to Y and back to X, and A's store exclusive succeeds. The monitor
  is a compare-and-swap of the value loaded (runtime/cpu.h, "exclusive monitor"), so it does not see this case, where
  the console's monitor would fail the store; the check holds the helpers to what they are.
- Contention: N threads increment one counter with load/store-exclusive retry loops; the total must be exact.

Needs no game files. Usage: excl_mt.py [--runtime DIR] [--threads N] [--iters K]
"""
import argparse
import os
import subprocess
import sys
import tempfile
from pathlib import Path

sys.path.insert(0, str(Path(__file__).resolve().parent / 'diff'))
from common import MSYS_BIN, ROOT, compiler  # noqa: E402

SRC = r'''
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include "cpu.h"

static volatile int step;
static uint64_t cell[4] __attribute__((aligned(64)));
static int nthreads, iters;
static int fails;

static void wait_step(int s) { while (__atomic_load_n(&step, __ATOMIC_ACQUIRE) != s) {} }
static void set_step(int s) { __atomic_store_n(&step, s, __ATOMIC_RELEASE); }

// Thread B: aba_changes exclusive stores of the given width (0 = do nothing, the control): one changes X to Y, two
// change it to Y and back to X.
static int aba_width, aba_changes;
static void *aba_b(void *arg) {
    (void)arg;
    Cpu c = {0};
    uint64_t a = (uint64_t)(uintptr_t)cell;
    wait_step(1);
    for (int k = 0; aba_width && k < aba_changes; k++) {
        for (;;) {
            if (aba_width == 32) { uint32_t v = (uint32_t)ldx32(&c, a); if (!stx32(&c, a, v ^ 0x5a5a5a5au)) break; }
            else if (aba_width == 64) { uint64_t v = ldx64(&c, a); if (!stx64(&c, a, v ^ 0x5a5a5a5a5a5a5a5aull)) break; }
            else { __uint128_t v = ldxp128(&c, a); if (!stxp128(&c, a, (uint64_t)v ^ 1, (uint64_t)(v >> 64) ^ 2)) break; }
        }
    }
    set_step(2);
    return 0;
}

static void aba_case(int width, int changes, int expect_fail) {
    pthread_t t;
    Cpu c = {0};
    uint64_t a = (uint64_t)(uintptr_t)cell;
    cell[0] = 0x1111222233334444ull;
    cell[1] = 0x5555666677778888ull;
    aba_width = width;
    aba_changes = changes;
    set_step(0);
    pthread_create(&t, 0, aba_b, 0);
    uint32_t st;
    if (width == 128) {
        __uint128_t v = ldxp128(&c, a);
        set_step(1);
        wait_step(2);
        st = stxp128(&c, a, (uint64_t)v + 7, (uint64_t)(v >> 64));
    } else if (width == 32) {
        uint32_t v = (uint32_t)ldx32(&c, a);
        set_step(1);
        wait_step(2);
        st = stx32(&c, a, v + 7);
    } else {
        uint64_t v = ldx64(&c, a);
        set_step(1);
        wait_step(2);
        st = stx64(&c, a, v + 7);
    }
    pthread_join(t, 0);
    int want = expect_fail != 0;
    printf("aba width %3d, %d change%s: stx status %u, want %d %s\n", width, changes, changes == 1 ? "" : "s", st, want,
           st == (uint32_t)want ? "ok" : "FAIL");
    if (st != (uint32_t)want) fails++;
}

static int inc_width;
static void *inc(void *arg) {
    (void)arg;
    Cpu c = {0};
    uint64_t a = (uint64_t)(uintptr_t)cell;
    for (int i = 0; i < iters; i++) {
        for (;;) {
            if (inc_width == 32) { uint32_t v = (uint32_t)ldx32(&c, a); if (!stx32(&c, a, v + 1)) break; }
            else if (inc_width == 64) { uint64_t v = ldx64(&c, a); if (!stx64(&c, a, v + 1)) break; }
            else { __uint128_t v = ldxp128(&c, a); if (!stxp128(&c, a, (uint64_t)v + 1, (uint64_t)(v >> 64) + 3)) break; }
        }
    }
    return 0;
}

static void inc_case(int width) {
    pthread_t t[64];
    cell[0] = cell[1] = 0;
    inc_width = width;
    for (int i = 0; i < nthreads; i++) pthread_create(&t[i], 0, inc, 0);
    for (int i = 0; i < nthreads; i++) pthread_join(t[i], 0);
    uint64_t want = (uint64_t)nthreads * iters;
    uint64_t got = width == 32 ? (uint32_t)cell[0] : cell[0];
    int ok = got == (width == 32 ? (uint32_t)want : want) && (width != 128 || cell[1] == 3 * want);
    printf("contention width %3d: %d threads x %d, counter %llu (hi %llu), want %llu %s\n", width, nthreads, iters,
           (unsigned long long)got, (unsigned long long)cell[1], (unsigned long long)want, ok ? "ok" : "FAIL");
    if (!ok) fails++;
}

int main(int argc, char **argv) {
    nthreads = atoi(argv[1]);
    iters = atoi(argv[2]);
    aba_case(0, 0, 0);
    aba_case(32, 1, 1);
    aba_case(64, 1, 1);
    aba_case(128, 1, 1);
    // The monitor is a compare-and-swap of the value loaded (runtime/cpu.h, "exclusive monitor"): a value changed and
    // changed back is not seen, and the store exclusive succeeds where the console's monitor would fail it.
    aba_case(32, 2, 0);
    aba_case(64, 2, 0);
    aba_case(128, 2, 0);
    inc_case(32);
    inc_case(64);
    inc_case(128);
    printf("%s\n", fails ? "FAILED" : "PASSED");
    return fails != 0;
}
'''


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument('--runtime', type=Path, default=ROOT / 'runtime', help='directory holding cpu.h')
    ap.add_argument('--threads', type=int, default=8)
    ap.add_argument('--iters', type=int, default=200000)
    args = ap.parse_args()
    env = dict(os.environ)
    if os.name == 'nt' and MSYS_BIN.exists():
        env['PATH'] = str(MSYS_BIN) + os.pathsep + env.get('PATH', '')
    with tempfile.TemporaryDirectory() as tmp:
        src = Path(tmp) / 'excl_mt.c'
        exe = Path(tmp) / ('excl_mt.exe' if os.name == 'nt' else 'excl_mt')
        src.write_text(SRC)
        subprocess.check_call([compiler(), '-O2', '-march=x86-64-v3', '-fno-strict-aliasing', '-I', str(args.runtime),
                               str(src), '-o', str(exe), '-lpthread'], env=env)
        return subprocess.run([str(exe), str(args.threads), str(args.iters)], env=env).returncode


if __name__ == '__main__':
    sys.exit(main())