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perf: fix deferred divide precision, threadlocal TLS, MSVC target

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Removed deferred divide from both ray-tri functions -- the det-scaled
epsilon comparisons lose precision for near-parallel rays, potentially
accepting triangles the original rejects. Downstream SetupBoxFrustum
then writes to wrong globals near 0xCE6738 (SGroupPtr), causing
ERROR #124 on exit.

inflate_hook: replaced manual FS:0x24 thread ID pool with Zig native
threadlocal. Fixes potential crash on Wine where FS segment layout
may differ.

Build: switched from GNU to MSVC ABI (4-5K smaller per DLL, no
.eh_frame unwind tables). Added setjmp.h stub for libdeflate MSVC
build. Added noperf build variant (zig build noperf).
This commit is contained in:
MarcelineVQ
2026-03-26 11:38:33 -07:00
parent bf5a7aa624
commit 14ba112b0d
7 changed files with 128 additions and 123 deletions
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src/performance/inflate_hook.zig
+12 -40
View File
@@ -4,10 +4,9 @@
//! uses libdeflate (~2.2x faster than stock zlib). Falls back to original on failure.
//!
//! Thread-safety: the decompressor struct contains mutable decode tables rebuilt
//! per block, so each thread gets its own cached decompressor via a thread-local
//! pool keyed by Windows thread ID (FS:[0x24]). This avoids both the race condition
//! (shared decompressor → wild writes) and the per-call alloc overhead (~8-9% gain
//! over alloc/free each call).
//! per block, so each thread gets its own cached decompressor via Zig's native
//! threadlocal (OS-managed TLS). This avoids both the race condition
//! (shared decompressor -> wild writes) and the per-call alloc overhead.
//!
//! Benchmark results (84k calls, heavy load):
//! stock=2681ms | per-call-alloc=1304ms (2.05x) | tls-cached=1194ms (2.2x)
@@ -24,43 +23,17 @@ extern fn libdeflate_zlib_decompress(?*anyopaque, [*]const u8, usize, [*]u8, usi
var lib_available: bool = false;
var log: logging.Logger = .{};
// --- Thread-local decompressor pool ---
// Keyed by Windows thread ID. WoW has ~5-10 threads; only 2-3 call decompress.
const TLS_SLOTS = 8;
const TlsSlot = struct {
thread_id: u32 = 0,
decomp: ?*anyopaque = null,
};
var tls_pool: [TLS_SLOTS]TlsSlot = [_]TlsSlot{.{}} ** TLS_SLOTS;
fn getCurrentThreadId() u32 {
return asm volatile ("movl %%fs:0x24, %[ret]"
: [ret] "=r" (-> u32),
);
}
// --- Thread-local decompressor ---
// Each thread lazily allocates its own decompressor on first use.
// OS-managed TLS via Zig's threadlocal -- works correctly on both
// native Windows and Wine without manual FS segment access.
threadlocal var tls_decomp: ?*anyopaque = null;
fn getTlsDecompressor() ?*anyopaque {
const tid = getCurrentThreadId();
for (&tls_pool) |*slot| {
if (slot.thread_id == tid) return slot.decomp;
}
const decomp = libdeflate_alloc_decompressor() orelse return null;
for (&tls_pool) |*slot| {
if (slot.thread_id == 0) {
slot.thread_id = tid;
slot.decomp = decomp;
return decomp;
}
}
libdeflate_free_decompressor(decomp);
return null;
}
fn freeTlsPool() void {
for (&tls_pool) |*slot| {
if (slot.decomp) |d| libdeflate_free_decompressor(d);
slot.* = .{};
}
if (tls_decomp) |d| return d;
const d = libdeflate_alloc_decompressor() orelse return null;
tls_decomp = d;
return d;
}
// --- Timing ---
@@ -142,5 +115,4 @@ pub fn install() bool {
pub fn remove() void {
decompress_hook.detach();
lib_available = false;
freeTlsPool();
}