vk: cache sampler_for's samplers until a sampler registration changes

gpu/vk/vk_bank.cpp

@@ -37,6 +37,7 @@ std::vector<TexReg> tex_regs;
 std::vector<SampReg> samp_regs;
 std::unordered_map<uint64_t, std::vector<int>> regs_by_serial;
 std::atomic<uint64_t> reg_gen{1};   // (bumped by every texture registration: resolved handles go stale)
+std::atomic<uint64_t> samp_gen{1};  // (bumped when a sampler registration's contents change: sampler_for's cache, vk_draw.cpp)
 // (and a version a slot: caches of what a slot resolves to check theirs, not every registration's)
 constexpr int kSlotVersions = 1 << 20;
 std::unique_ptr<std::atomic<uint32_t>[]> slot_versions{new std::atomic<uint32_t>[kSlotVersions]()};
@@ -179,8 +180,14 @@ void register_sampler_copy(int id, const nvn_samp_par& par) {
     const nvn_samp_par* p = &par;
     std::lock_guard lk(reg_mu);
     if ((size_t)id >= samp_regs.size()) samp_regs.resize((size_t)id + 256);
+    // (sampler_for's cache goes stale only when a registration's contents change, not at each rewrite of the same)
+    const bool same = samp_regs[id].ok && !std::memcmp(&samp_regs[id].p, p, sizeof *p);
     samp_regs[id].p = *p;
     samp_regs[id].ok = true;
+    if (!same) samp_gen.fetch_add(1, std::memory_order_acq_rel);
+}
+uint64_t sampler_registrations_generation() {
+    return samp_gen.load(std::memory_order_acquire);
 }
 void texture_released(uint64_t serial) {
     std::lock_guard lk(reg_mu);

gpu/vk/vk_draw.cpp

@@ -48,6 +48,7 @@ namespace mkwvk {
 struct PointerEntry { uint64_t addr, size; };
 const PointerEntry* pointer_table(const NvnState& s, int stage);
 uint32_t stage_cbuf_word(const NvnState& s, const Stage& st, uint32_t index, uint32_t offset);   // (vk_shader.cpp)
+uint64_t sampler_registrations_generation();   // (vk_bank.cpp: sampler_for's cache)
 namespace {
 
 // ---- (hookshot) RX_VK_PROF_FINE=1: where a draw's time goes, finer than the frame line's phases, and what each draw does ----
@@ -1272,7 +1273,23 @@ uint32_t aniso_override() {
     return n;
 }
 /// compare: the shader reads depth with a reference (a sampler without one cannot compare)
+VkSampler sampler_make(int id, bool compare);
+// (each texture of each draw found its sampler through reg_mu, a copy of the registration, a hash of it and a map lookup:
+// ~48000 times a frame at 3000 draws. Now a thread's table by id and compare, good while no sampler registration's contents
+// changed (sampler_registrations_generation). RX_VK_SAMPLER_CACHE=0: off)
 VkSampler sampler_for(int id, bool compare) {
+    static const bool on = !getenv("RX_VK_SAMPLER_CACHE") || atoi(getenv("RX_VK_SAMPLER_CACHE")) != 0;
+    if (!on || id < 0 || id >= 4096) return sampler_make(id, compare);
+    struct Entry { uint64_t gen; VkSampler s; };
+    static thread_local Entry table[2][4096];   // (gen 0: never filled; the generation starts at 1)
+    const uint64_t gen = sampler_registrations_generation();   // (read first: a registration after it makes the next call miss)
+    Entry& e = table[compare ? 1 : 0][id];
+    if (e.gen == gen) return e.s;
+    const VkSampler made = sampler_make(id, compare);
+    e = {gen, made};
+    return made;
+}
+VkSampler sampler_make(int id, bool compare) {
     nvn_samp_par p{};
     if (!sampler_of(id, &p)) p.minf = NVN_MIN_FILTER_LINEAR, p.magf = NVN_MAG_FILTER_LINEAR, p.lod_max = 1000.0f;
     uint64_t key = mix(compare ? 0xC0 : 0xAB, aniso_override());