[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
DS4_N_HEAD_DIM) != 0;
    const bool raw_batch_attention = zero_prefix && ratio == 0;
    bool batch_attention_done = false;

    if (ok && raw_batch_attention) {
        ok = ds4_gpu_attention_prefill_raw_heads_tensor(g->batch_heads,
                                                          model->map,
                                                          model->size,
                                                          layer->attn_sinks->abs_offset,
                                                          g->batch_q,
                                                          g->batch_kv,
                                                          n_tokens,
                                                          g->raw_window,
                                                          DS4_N_HEAD,
                                                          DS4_N_HEAD_DIM) != 0;
        if (ok) batch_attention_done = true;
    } else if (ok && !zero_prefix && ratio == 0 && n_tokens <= g->raw_cap) {
        /*
         * The ubatch path stores the whole batch in the SWA cache, then runs
         * one batched attention kernel with an absolute-position causal/window
         * mask.  This avoids mixing prefill with the different single-token
         * attention path.
         */
        const uint32_t n_raw = metal_graph_raw_span_for_batch(g, pos0, n_tokens);
        /* Nonzero prompt chunks read the SWA cache as a ring.  FlashAttention
         * receives a linearized window starting at raw_start, not physical row
         * zero; otherwise wrapped chunks silently miss recent raw keys. */
        const uint32_t raw_start = metal_graph_raw_start_for_span(g,
                                                                  pos0 + n_tokens - 1u,
                                                                  n_raw);
        ok = ds4_gpu_store_raw_kv_batch_tensor(g->layer_raw_cache[il],
                                                 g->batch_kv,
                                                 g->raw_cap,
                                                 pos0,
                                                 n_tokens,
                                                 DS4_N_HEAD_DIM) != 0;
        if (ok) {
            metal_graph_debug_dump_tensor("raw_cache",
                                          g->layer_raw_cache[il],
                                          (uint64_t)n_raw * DS4_N_HEAD_DIM,
                                          il,
                                          pos0);
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
DS4_N_HEAD_DIM) != 0;
    const bool raw_batch_attention = zero_prefix && ratio == 0;
    bool batch_attention_done = false;

    if (ok && raw_batch_attention) {
        ok = ds4_gpu_attention_prefill_raw_heads_tensor(g->batch_heads,
                                                          model->map,
                                                          model->size,
                                                          layer->attn_sinks->abs_offset,
                                                          g->batch_q,
                                                          g->batch_kv,
                                                          n_tokens,
                                                          g->raw_window,
                                                          DS4_N_HEAD,
                                                          DS4_N_HEAD_DIM) != 0;
        if (ok) batch_attention_done = true;
    } else if (ok && !zero_prefix && ratio == 0 && n_tokens <= g->raw_cap) {
        /*
         * The ubatch path stores the whole batch in the SWA cache, then runs
         * one batched attention kernel with an absolute-position causal/window
         * mask.  This avoids mixing prefill with the different single-token
         * attention path.
         */
        const uint32_t n_raw = metal_graph_raw_span_for_batch(g, pos0, n_tokens);
        /* Nonzero prompt chunks read the SWA cache as a ring.  FlashAttention
         * receives a linearized window starting at raw_start, not physical row
         * zero; otherwise wrapped chunks silently miss recent raw keys. */
        const uint32_t raw_start = metal_graph_raw_start_for_span(g,
                                                                  pos0 + n_tokens - 1u,
                                                                  n_raw);
        ok = ds4_gpu_store_raw_kv_batch_tensor(g->layer_raw_cache[il],
                                                 g->batch_kv,
                                                 g->raw_cap,
                                                 pos0,
                                                 n_tokens,
                                                 DS4_N_HEAD_DIM) != 0;
        if (ok) {
            metal_graph_debug_dump_tensor("raw_cache",
                                          g->layer_raw_cache[il],
                                          (uint64_t)n_raw * DS4_N_HEAD_DIM,
                                          il,
                                          pos0);
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
ache[il],
                                          (uint64_t)n_raw * DS4_N_HEAD_DIM,
                                          il,
                                          pos0);
        }
        if (ok) {
            ok = ds4_gpu_attention_decode_raw_batch_heads_tensor(g->batch_heads,
                                                                   model->map,
                                                                   model->size,
                                                                   layer->attn_sinks->abs_offset,
                                                                   g->batch_q,
                                                                   g->layer_raw_cache[il],
                                                                   n_tokens,
                                                                   pos0,
                                                                   n_raw,
                                                                   g->raw_cap,
                                                                   raw_start,
                                                                   g->raw_window,
                                                                   DS4_N_HEAD,
                                                                   DS4_N_HEAD_DIM) != 0;
        }
        if (ok) batch_attention_done = true;
    } else if (ok && ratio != 0) {
        const uint32_t coff = ratio == 4 ? 2u : 1u;
        const uint32_t comp_width = coff * DS4_N_HEAD_DIM;
        const bool have_attn_comp = layer->attn_compressor_kv && layer->attn_compressor_gate &&
                                    layer->attn_compressor_ape && layer->attn_compressor_norm;
        if (!have_attn_comp) {
            fprintf(stderr, "ds4: Metal layer-major prefill needs attention compressor weights\n");
            ok = false;
        }
        if (ok) ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_kv,
                                                 model->map,
                                                 model->size,
                                                 layer->attn_compressor_kv->abs_offset,
                                                 DS4_N_EMBD,
                                                 comp_width,
                                                 g->batch_attn_norm,
                                                 n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_kv_raw",
                                              g->batch_comp_kv,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
ache[il],
                                          (uint64_t)n_raw * DS4_N_HEAD_DIM,
                                          il,
                                          pos0);
        }
        if (ok) {
            ok = ds4_gpu_attention_decode_raw_batch_heads_tensor(g->batch_heads,
                                                                   model->map,
                                                                   model->size,
                                                                   layer->attn_sinks->abs_offset,
                                                                   g->batch_q,
                                                                   g->layer_raw_cache[il],
                                                                   n_tokens,
                                                                   pos0,
                                                                   n_raw,
                                                                   g->raw_cap,
                                                                   raw_start,
                                                                   g->raw_window,
                                                                   DS4_N_HEAD,
                                                                   DS4_N_HEAD_DIM) != 0;
        }
        if (ok) batch_attention_done = true;
    } else if (ok && ratio != 0) {
        const uint32_t coff = ratio == 4 ? 2u : 1u;
        const uint32_t comp_width = coff * DS4_N_HEAD_DIM;
        const bool have_attn_comp = layer->attn_compressor_kv && layer->attn_compressor_gate &&
                                    layer->attn_compressor_ape && layer->attn_compressor_norm;
        if (!have_attn_comp) {
            fprintf(stderr, "ds4: Metal layer-major prefill needs attention compressor weights\n");
            ok = false;
        }
        if (ok) ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_kv,
                                                 model->map,
                                                 model->size,
                                                 layer->attn_compressor_kv->abs_offset,
                                                 DS4_N_EMBD,
                                                 comp_width,
                                                 g->batch_attn_norm,
                                                 n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_kv_raw",
                                              g->batch_comp_kv,
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
ache[il],
                                          (uint64_t)n_raw * DS4_N_HEAD_DIM,
                                          il,
                                          pos0);
        }
        if (ok) {
            ok = ds4_gpu_attention_decode_raw_batch_heads_tensor(g->batch_heads,
                                                                   model->map,
                                                                   model->size,
                                                                   layer->attn_sinks->abs_offset,
                                                                   g->batch_q,
                                                                   g->layer_raw_cache[il],
                                                                   n_tokens,
                                                                   pos0,
                                                                   n_raw,
                                                                   g->raw_cap,
                                                                   raw_start,
                                                                   g->raw_window,
                                                                   DS4_N_HEAD,
                                                                   DS4_N_HEAD_DIM) != 0;
        }
        if (ok) batch_attention_done = true;
    } else if (ok && ratio != 0) {
        const uint32_t coff = ratio == 4 ? 2u : 1u;
        const uint32_t comp_width = coff * DS4_N_HEAD_DIM;
        const bool have_attn_comp = layer->attn_compressor_kv && layer->attn_compressor_gate &&
                                    layer->attn_compressor_ape && layer->attn_compressor_norm;
        if (!have_attn_comp) {
            fprintf(stderr, "ds4: Metal layer-major prefill needs attention compressor weights\n");
            ok = false;
        }
        if (ok) ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_kv,
                                                 model->map,
                                                 model->size,
                                                 layer->attn_compressor_kv->abs_offset,
                                                 DS4_N_EMBD,
                                                 comp_width,
                                                 g->batch_attn_norm,
                                                 n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_kv_raw",
                                              g->batch_comp_kv,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
ache[il],
                                          (uint64_t)n_raw * DS4_N_HEAD_DIM,
                                          il,
                                          pos0);
        }
        if (ok) {
            ok = ds4_gpu_attention_decode_raw_batch_heads_tensor(g->batch_heads,
                                                                   model->map,
                                                                   model->size,
                                                                   layer->attn_sinks->abs_offset,
                                                                   g->batch_q,
                                                                   g->layer_raw_cache[il],
                                                                   n_tokens,
                                                                   pos0,
                                                                   n_raw,
                                                                   g->raw_cap,
                                                                   raw_start,
                                                                   g->raw_window,
                                                                   DS4_N_HEAD,
                                                                   DS4_N_HEAD_DIM) != 0;
        }
        if (ok) batch_attention_done = true;
    } else if (ok && ratio != 0) {
        const uint32_t coff = ratio == 4 ? 2u : 1u;
        const uint32_t comp_width = coff * DS4_N_HEAD_DIM;
        const bool have_attn_comp = layer->attn_compressor_kv && layer->attn_compressor_gate &&
                                    layer->attn_compressor_ape && layer->attn_compressor_norm;
        if (!have_attn_comp) {
            fprintf(stderr, "ds4: Metal layer-major prefill needs attention compressor weights\n");
            ok = false;
        }
        if (ok) ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_kv,
                                                 model->map,
                                                 model->size,
                                                 layer->attn_compressor_kv->abs_offset,
                                                 DS4_N_EMBD,
                                                 comp_width,
                                                 g->batch_attn_norm,
                                                 n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_kv_raw",
                                              g->batch_comp_kv,
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_kv_raw",
                                              g->batch_comp_kv,
                                              (uint64_t)comp_width * n_tokens,
                                              il,
                                              pos0);
        if (ok) ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_sc,
                                                 model->map,
                                                 model->size,
                                                 layer->attn_compressor_gate->abs_offset,
                                                 DS4_N_EMBD,
                                                 comp_width,
                                                 g->batch_attn_norm,
                                                 n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_score_raw",
                                              g->batch_comp_sc,
                                              (uint64_t)comp_width * n_tokens,
                                              il,
                                              pos0);
        uint32_t n_comp = g->layer_n_comp[il];
        if (zero_prefix) {
            n_comp = n_tokens / ratio;
            if (ok && n_comp > g->layer_comp_cap[il]) {
                fprintf(stderr, "ds4: Metal layer-major compressed KV cache capacity exceeded at layer %u\n", il);
                ok = false;
            }
            if (ok) {
                ok = ds4_gpu_compressor_prefill_tensor(g->layer_attn_comp_cache[il],
                                                         g->layer_attn_state_kv[il],
                                                         g->layer_attn_state_score[il],
                                                         g->batch_comp_kv,
                                                         g->batch_comp_sc,
                                                         model->map,
                                                         model->size,
                                                         layer->attn_compressor_ape->abs_offset,
                                                         layer->attn_compressor_ape->type,
                                                         layer->attn_compressor_norm->abs_offset,
                                                         layer->attn_compressor_norm->type,
                                                         DS4_N_HEAD_DIM,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_kv_raw",
                                              g->batch_comp_kv,
                                              (uint64_t)comp_width * n_tokens,
                                              il,
                                              pos0);
        if (ok) ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_sc,
                                                 model->map,
                                                 model->size,
                                                 layer->attn_compressor_gate->abs_offset,
                                                 DS4_N_EMBD,
                                                 comp_width,
                                                 g->batch_attn_norm,
                                                 n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_score_raw",
                                              g->batch_comp_sc,
                                              (uint64_t)comp_width * n_tokens,
                                              il,
                                              pos0);
        uint32_t n_comp = g->layer_n_comp[il];
        if (zero_prefix) {
            n_comp = n_tokens / ratio;
            if (ok && n_comp > g->layer_comp_cap[il]) {
                fprintf(stderr, "ds4: Metal layer-major compressed KV cache capacity exceeded at layer %u\n", il);
                ok = false;
            }
            if (ok) {
                ok = ds4_gpu_compressor_prefill_tensor(g->layer_attn_comp_cache[il],
                                                         g->layer_attn_state_kv[il],
                                                         g->layer_attn_state_score[il],
                                                         g->batch_comp_kv,
                                                         g->batch_comp_sc,
                                                         model->map,
                                                         model->size,
                                                         layer->attn_compressor_ape->abs_offset,
                                                         layer->attn_compressor_ape->type,
                                                         layer->attn_compressor_norm->abs_offset,
                                                         layer->attn_compressor_norm->type,
                                                         DS4_N_HEAD_DIM,
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_kv_raw",
                                              g->batch_comp_kv,
                                              (uint64_t)comp_width * n_tokens,
                                              il,
                                              pos0);
        if (ok) ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_sc,
                                                 model->map,
                                                 model->size,
                                                 layer->attn_compressor_gate->abs_offset,
                                                 DS4_N_EMBD,
                                                 comp_width,
                                                 g->batch_attn_norm,
                                                 n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_score_raw",
                                              g->batch_comp_sc,
                                              (uint64_t)comp_width * n_tokens,
                                              il,
                                              pos0);
        uint32_t n_comp = g->layer_n_comp[il];
        if (zero_prefix) {
            n_comp = n_tokens / ratio;
            if (ok && n_comp > g->layer_comp_cap[il]) {
                fprintf(stderr, "ds4: Metal layer-major compressed KV cache capacity exceeded at layer %u\n", il);
                ok = false;
            }
            if (ok) {
                ok = ds4_gpu_compressor_prefill_tensor(g->layer_attn_comp_cache[il],
                                                         g->layer_attn_state_kv[il],
                                                         g->layer_attn_state_score[il],
                                                         g->batch_comp_kv,
                                                         g->batch_comp_sc,
                                                         model->map,
                                                         model->size,
                                                         layer->attn_compressor_ape->abs_offset,
                                                         layer->attn_compressor_ape->type,
                                                         layer->attn_compressor_norm->abs_offset,
                                                         layer->attn_compressor_norm->type,
                                                         DS4_N_HEAD_DIM,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_kv_raw",
                                              g->batch_comp_kv,
                                              (uint64_t)comp_width * n_tokens,
                                              il,
                                              pos0);
        if (ok) ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_sc,
                                                 model->map,
                                                 model->size,
                                                 layer->attn_compressor_gate->abs_offset,
                                                 DS4_N_EMBD,
                                                 comp_width,
                                                 g->batch_attn_norm,
                                                 n_tokens) != 0;
        if (ok) metal_graph_debug_dump_tensor("attn_comp_score_raw",
                                              g->batch_comp_sc,
                                              (uint64_t)comp_width * n_tokens,
                                              il,
                                              pos0);
        uint32_t n_comp = g->layer_n_comp[il];
        if (zero_prefix) {
            n_comp = n_tokens / ratio;
            if (ok && n_comp > g->layer_comp_cap[il]) {
                fprintf(stderr, "ds4: Metal layer-major compressed KV cache capacity exceeded at layer %u\n", il);
                ok = false;
            }
            if (ok) {
                ok = ds4_gpu_compressor_prefill_tensor(g->layer_attn_comp_cache[il],
                                                         g->layer_attn_state_kv[il],
                                                         g->layer_attn_state_score[il],
                                                         g->batch_comp_kv,
                                                         g->batch_comp_sc,
                                                         model->map,
                                                         model->size,
                                                         layer->attn_compressor_ape->abs_offset,
                                                         layer->attn_compressor_ape->type,
                                                         layer->attn_compressor_norm->abs_offset,
                                                         layer->attn_compressor_norm->type,
                                                         DS4_N_HEAD_DIM,
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
rm->abs_offset,
                                                         layer->attn_compressor_norm->type,
                                                         DS4_N_HEAD_DIM,
                                                         ratio,
                                                         pos0,
                                                         n_tokens,
                                                         DS4_N_ROT,
                                                         compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                                                         true,
                                                         freq_base,
                                                         freq_scale,
                                                         ext_factor,
                                                         attn_factor,
                                                         DS4_ROPE_YARN_BETA_FAST,
                                                         DS4_ROPE_YARN_BETA_SLOW,
                                                         DS4_RMS_EPS) != 0;
                if (ok && ratio == 4) {
                    ok = metal_graph_refresh_ratio4_compressor_state(g,
                                                                     model,
                                                                     g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
                                                                     layer->attn_compressor_kv,
                                                                     layer->attn_compressor_gate,
                                                                     layer->attn_compressor_ape,
                                                                     DS4_N_HEAD_DIM,
                                                                     comp_width,
                                                                     pos0,
                                                                     n_tokens);
                }
            }
            if (ok) {
                g->layer_n_comp[il] = n_comp;
                for (uint32_t t = 0; t < n_tokens; t++) {
                    comp_counts[t] = (pos0 + t + 1u) / ratio;
                }
                if (n_comp != 0) {
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  g->layer_attn_comp_cache[il],
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
rm->abs_offset,
                                                         layer->attn_compressor_norm->type,
                                                         DS4_N_HEAD_DIM,
                                                         ratio,
                                                         pos0,
                                                         n_tokens,
                                                         DS4_N_ROT,
                                                         compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                                                         true,
                                                         freq_base,
                                                         freq_scale,
                                                         ext_factor,
                                                         attn_factor,
                                                         DS4_ROPE_YARN_BETA_FAST,
                                                         DS4_ROPE_YARN_BETA_SLOW,
                                                         DS4_RMS_EPS) != 0;
                if (ok && ratio == 4) {
                    ok = metal_graph_refresh_ratio4_compressor_state(g,
                                                                     model,
                                                                     g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
                                                                     layer->attn_compressor_kv,
                                                                     layer->attn_compressor_gate,
                                                                     layer->attn_compressor_ape,
                                                                     DS4_N_HEAD_DIM,
                                                                     comp_width,
                                                                     pos0,
                                                                     n_tokens);
                }
            }
            if (ok) {
                g->layer_n_comp[il] = n_comp;
                for (uint32_t t = 0; t < n_tokens; t++) {
                    comp_counts[t] = (pos0 + t + 1u) / ratio;
                }
                if (n_comp != 0) {
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  g->layer_attn_comp_cache[il],
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
rm->abs_offset,
                                                         layer->attn_compressor_norm->type,
                                                         DS4_N_HEAD_DIM,
                                                         ratio,
                                                         pos0,
                                                         n_tokens,
                                                         DS4_N_ROT,
                                                         compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                                                         true,
                                                         freq_base,
                                                         freq_scale,
                                                         ext_factor,
                                                         attn_factor,
                                                         DS4_ROPE_YARN_BETA_FAST,
                                                         DS4_ROPE_YARN_BETA_SLOW,
                                                         DS4_RMS_EPS) != 0;
                if (ok && ratio == 4) {
                    ok = metal_graph_refresh_ratio4_compressor_state(g,
                                                                     model,
                                                                     g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
                                                                     layer->attn_compressor_kv,
                                                                     layer->attn_compressor_gate,
                                                                     layer->attn_compressor_ape,
                                                                     DS4_N_HEAD_DIM,
                                                                     comp_width,
                                                                     pos0,
                                                                     n_tokens);
                }
            }
            if (ok) {
                g->layer_n_comp[il] = n_comp;
                for (uint32_t t = 0; t < n_tokens; t++) {
                    comp_counts[t] = (pos0 + t + 1u) / ratio;
                }
                if (n_comp != 0) {
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  g->layer_attn_comp_cache[il],
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
rm->abs_offset,
                                                         layer->attn_compressor_norm->type,
                                                         DS4_N_HEAD_DIM,
                                                         ratio,
                                                         pos0,
                                                         n_tokens,
                                                         DS4_N_ROT,
                                                         compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                                                         true,
                                                         freq_base,
                                                         freq_scale,
                                                         ext_factor,
                                                         attn_factor,
                                                         DS4_ROPE_YARN_BETA_FAST,
                                                         DS4_ROPE_YARN_BETA_SLOW,
                                                         DS4_RMS_EPS) != 0;
                if (ok && ratio == 4) {
                    ok = metal_graph_refresh_ratio4_compressor_state(g,
                                                                     model,
                                                                     g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
                                                                     layer->attn_compressor_kv,
                                                                     layer->attn_compressor_gate,
                                                                     layer->attn_compressor_ape,
                                                                     DS4_N_HEAD_DIM,
                                                                     comp_width,
                                                                     pos0,
                                                                     n_tokens);
                }
            }
            if (ok) {
                g->layer_n_comp[il] = n_comp;
                for (uint32_t t = 0; t < n_tokens; t++) {
                    comp_counts[t] = (pos0 + t + 1u) / ratio;
                }
                if (n_comp != 0) {
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  g->layer_attn_comp_cache[il],
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
}
                if (n_comp != 0) {
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  g->layer_attn_comp_cache[il],
                                                  (uint64_t)n_comp * DS4_N_HEAD_DIM,
                                                  il,
                                                  pos0);
                }
                metal_graph_debug_dump_tensor("attn_state_kv",
                                              g->layer_attn_state_kv[il],
                                              (uint64_t)comp_width * coff * ratio,
                                              il,
                                              pos0);
                metal_graph_debug_dump_tensor("attn_state_score",
                                              g->layer_attn_state_score[il],
                                              (uint64_t)comp_width * coff * ratio,
                                              il,
                                              pos0);
            }
        } else {
            const bool aligned_chunk = (pos0 % ratio) == 0u && (n_tokens % ratio) == 0u;
            if (aligned_chunk) {
                const uint32_t comp_before = g->layer_n_comp[il];
                const uint32_t comp_chunk = n_tokens / ratio;
                if (comp_before + comp_chunk > g->layer_comp_cap[il]) {
                    fprintf(stderr, "ds4: Metal graph compressed KV cache capacity exceeded at layer %u\n", il);
                    ok = false;
                }
                ds4_gpu_tensor *comp_view = NULL;
                if (ok) {
                    comp_view = ds4_gpu_tensor_view(g->layer_attn_comp_cache[il],
                                                      (uint64_t)comp_before * DS4_N_HEAD_DIM * sizeof(float),
                                                      (uint64_t)comp_chunk * DS4_N_HEAD_DIM * sizeof(float));
                    ok = comp_view != NULL;
                }
                if (ok && ratio == 4) {
                    ok = ds4_gpu_compressor_prefill_ratio4_replay_tensor(
                            comp_view,
                            g->layer_attn_state_kv[il],
                            g->layer_attn_state_score[il],
                            g->batch_comp_kv,
                            g->batch_comp_sc,
                            model->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
}
                if (n_comp != 0) {
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  g->layer_attn_comp_cache[il],
                                                  (uint64_t)n_comp * DS4_N_HEAD_DIM,
                                                  il,
                                                  pos0);
                }
                metal_graph_debug_dump_tensor("attn_state_kv",
                                              g->layer_attn_state_kv[il],
                                              (uint64_t)comp_width * coff * ratio,
                                              il,
                                              pos0);
                metal_graph_debug_dump_tensor("attn_state_score",
                                              g->layer_attn_state_score[il],
                                              (uint64_t)comp_width * coff * ratio,
                                              il,
                                              pos0);
            }
        } else {
            const bool aligned_chunk = (pos0 % ratio) == 0u && (n_tokens % ratio) == 0u;
            if (aligned_chunk) {
                const uint32_t comp_before = g->layer_n_comp[il];
                const uint32_t comp_chunk = n_tokens / ratio;
                if (comp_before + comp_chunk > g->layer_comp_cap[il]) {
                    fprintf(stderr, "ds4: Metal graph compressed KV cache capacity exceeded at layer %u\n", il);
                    ok = false;
                }
                ds4_gpu_tensor *comp_view = NULL;
                if (ok) {
                    comp_view = ds4_gpu_tensor_view(g->layer_attn_comp_cache[il],
                                                      (uint64_t)comp_before * DS4_N_HEAD_DIM * sizeof(float),
                                                      (uint64_t)comp_chunk * DS4_N_HEAD_DIM * sizeof(float));
                    ok = comp_view != NULL;
                }
                if (ok && ratio == 4) {
                    ok = ds4_gpu_compressor_prefill_ratio4_replay_tensor(
                            comp_view,
                            g->layer_attn_state_kv[il],
                            g->layer_attn_state_score[il],
                            g->batch_comp_kv,
                            g->batch_comp_sc,
                            model->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
}
                if (n_comp != 0) {
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  g->layer_attn_comp_cache[il],
                                                  (uint64_t)n_comp * DS4_N_HEAD_DIM,
                                                  il,
                                                  pos0);
                }
                metal_graph_debug_dump_tensor("attn_state_kv",
                                              g->layer_attn_state_kv[il],
                                              (uint64_t)comp_width * coff * ratio,
                                              il,
                                              pos0);
                metal_graph_debug_dump_tensor("attn_state_score",
                                              g->layer_attn_state_score[il],
                                              (uint64_t)comp_width * coff * ratio,
                                              il,
                                              pos0);
            }
        } else {
            const bool aligned_chunk = (pos0 % ratio) == 0u && (n_tokens % ratio) == 0u;
            if (aligned_chunk) {
                const uint32_t comp_before = g->layer_n_comp[il];
                const uint32_t comp_chunk = n_tokens / ratio;
                if (comp_before + comp_chunk > g->layer_comp_cap[il]) {
                    fprintf(stderr, "ds4: Metal graph compressed KV cache capacity exceeded at layer %u\n", il);
                    ok = false;
                }
                ds4_gpu_tensor *comp_view = NULL;
                if (ok) {
                    comp_view = ds4_gpu_tensor_view(g->layer_attn_comp_cache[il],
                                                      (uint64_t)comp_before * DS4_N_HEAD_DIM * sizeof(float),
                                                      (uint64_t)comp_chunk * DS4_N_HEAD_DIM * sizeof(float));
                    ok = comp_view != NULL;
                }
                if (ok && ratio == 4) {
                    ok = ds4_gpu_compressor_prefill_ratio4_replay_tensor(
                            comp_view,
                            g->layer_attn_state_kv[il],
                            g->layer_attn_state_score[il],
                            g->batch_comp_kv,
                            g->batch_comp_sc,
                            model->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
}
                if (n_comp != 0) {
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  g->layer_attn_comp_cache[il],
                                                  (uint64_t)n_comp * DS4_N_HEAD_DIM,
                                                  il,
                                                  pos0);
                }
                metal_graph_debug_dump_tensor("attn_state_kv",
                                              g->layer_attn_state_kv[il],
                                              (uint64_t)comp_width * coff * ratio,
                                              il,
                                              pos0);
                metal_graph_debug_dump_tensor("attn_state_score",
                                              g->layer_attn_state_score[il],
                                              (uint64_t)comp_width * coff * ratio,
                                              il,
                                              pos0);
            }
        } else {
            const bool aligned_chunk = (pos0 % ratio) == 0u && (n_tokens % ratio) == 0u;
            if (aligned_chunk) {
                const uint32_t comp_before = g->layer_n_comp[il];
                const uint32_t comp_chunk = n_tokens / ratio;
                if (comp_before + comp_chunk > g->layer_comp_cap[il]) {
                    fprintf(stderr, "ds4: Metal graph compressed KV cache capacity exceeded at layer %u\n", il);
                    ok = false;
                }
                ds4_gpu_tensor *comp_view = NULL;
                if (ok) {
                    comp_view = ds4_gpu_tensor_view(g->layer_attn_comp_cache[il],
                                                      (uint64_t)comp_before * DS4_N_HEAD_DIM * sizeof(float),
                                                      (uint64_t)comp_chunk * DS4_N_HEAD_DIM * sizeof(float));
                    ok = comp_view != NULL;
                }
                if (ok && ratio == 4) {
                    ok = ds4_gpu_compressor_prefill_ratio4_replay_tensor(
                            comp_view,
                            g->layer_attn_state_kv[il],
                            g->layer_attn_state_score[il],
                            g->batch_comp_kv,
                            g->batch_comp_sc,
                            model->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
del->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
                            layer->attn_compressor_norm->abs_offset,
                            layer->attn_compressor_norm->type,
                            DS4_N_HEAD_DIM,
                            pos0,
                            n_tokens,
                            DS4_N_ROT,
                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                            true,
                            freq_base,
                            freq_scale,
                            ext_factor,
                            attn_factor,
                            DS4_ROPE_YARN_BETA_FAST,
                            DS4_ROPE_YARN_BETA_SLOW,
                            DS4_RMS_EPS) != 0;
                } else if (ok) {
                    ok = ds4_gpu_compressor_prefill_tensor(
                            comp_view,
                            g->layer_attn_state_kv[il],
                            g->layer_attn_state_score[il],
                            g->batch_comp_kv,
                            g->batch_comp_sc,
                            model->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
                            layer->attn_compressor_norm->abs_offset,
                            layer->attn_compressor_norm->type,
                            DS4_N_HEAD_DIM,
                            ratio,
                            pos0,
                            n_tokens,
                            DS4_N_ROT,
                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                            true,
                            freq_base,
                            freq_scale,
                            ext_factor,
                            attn_factor,
                            DS4_ROPE_YARN_BETA_FAST,
                            DS4_ROPE_YARN_BETA_SLOW,
                            DS4_RMS_EPS) != 0;
                }
                if (ok && ratio == 4) {
                    ok = metal_graph_refresh_ratio4_compressor_state(g,
                                                                     model,
                                                                     g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
del->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
                            layer->attn_compressor_norm->abs_offset,
                            layer->attn_compressor_norm->type,
                            DS4_N_HEAD_DIM,
                            pos0,
                            n_tokens,
                            DS4_N_ROT,
                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                            true,
                            freq_base,
                            freq_scale,
                            ext_factor,
                            attn_factor,
                            DS4_ROPE_YARN_BETA_FAST,
                            DS4_ROPE_YARN_BETA_SLOW,
                            DS4_RMS_EPS) != 0;
                } else if (ok) {
                    ok = ds4_gpu_compressor_prefill_tensor(
                            comp_view,
                            g->layer_attn_state_kv[il],
                            g->layer_attn_state_score[il],
                            g->batch_comp_kv,
                            g->batch_comp_sc,
                            model->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
                            layer->attn_compressor_norm->abs_offset,
                            layer->attn_compressor_norm->type,
                            DS4_N_HEAD_DIM,
                            ratio,
                            pos0,
                            n_tokens,
                            DS4_N_ROT,
                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                            true,
                            freq_base,
                            freq_scale,
                            ext_factor,
                            attn_factor,
                            DS4_ROPE_YARN_BETA_FAST,
                            DS4_ROPE_YARN_BETA_SLOW,
                            DS4_RMS_EPS) != 0;
                }
                if (ok && ratio == 4) {
                    ok = metal_graph_refresh_ratio4_compressor_state(g,
                                                                     model,
                                                                     g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
del->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
                            layer->attn_compressor_norm->abs_offset,
                            layer->attn_compressor_norm->type,
                            DS4_N_HEAD_DIM,
                            pos0,
                            n_tokens,
                            DS4_N_ROT,
                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                            true,
                            freq_base,
                            freq_scale,
                            ext_factor,
                            attn_factor,
                            DS4_ROPE_YARN_BETA_FAST,
                            DS4_ROPE_YARN_BETA_SLOW,
                            DS4_RMS_EPS) != 0;
                } else if (ok) {
                    ok = ds4_gpu_compressor_prefill_tensor(
                            comp_view,
                            g->layer_attn_state_kv[il],
                            g->layer_attn_state_score[il],
                            g->batch_comp_kv,
                            g->batch_comp_sc,
                            model->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
                            layer->attn_compressor_norm->abs_offset,
                            layer->attn_compressor_norm->type,
                            DS4_N_HEAD_DIM,
                            ratio,
                            pos0,
                            n_tokens,
                            DS4_N_ROT,
                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                            true,
                            freq_base,
                            freq_scale,
                            ext_factor,
                            attn_factor,
                            DS4_ROPE_YARN_BETA_FAST,
                            DS4_ROPE_YARN_BETA_SLOW,
                            DS4_RMS_EPS) != 0;
                }
                if (ok && ratio == 4) {
                    ok = metal_graph_refresh_ratio4_compressor_state(g,
                                                                     model,
                                                                     g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
del->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
                            layer->attn_compressor_norm->abs_offset,
                            layer->attn_compressor_norm->type,
                            DS4_N_HEAD_DIM,
                            pos0,
                            n_tokens,
                            DS4_N_ROT,
                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                            true,
                            freq_base,
                            freq_scale,
                            ext_factor,
                            attn_factor,
                            DS4_ROPE_YARN_BETA_FAST,
                            DS4_ROPE_YARN_BETA_SLOW,
                            DS4_RMS_EPS) != 0;
                } else if (ok) {
                    ok = ds4_gpu_compressor_prefill_tensor(
                            comp_view,
                            g->layer_attn_state_kv[il],
                            g->layer_attn_state_score[il],
                            g->batch_comp_kv,
                            g->batch_comp_sc,
                            model->map,
                            model->size,
                            layer->attn_compressor_ape->abs_offset,
                            layer->attn_compressor_ape->type,
                            layer->attn_compressor_norm->abs_offset,
                            layer->attn_compressor_norm->type,
                            DS4_N_HEAD_DIM,
                            ratio,
                            pos0,
                            n_tokens,
                            DS4_N_ROT,
                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                            true,
                            freq_base,
                            freq_scale,
                            ext_factor,
                            attn_factor,
                            DS4_ROPE_YARN_BETA_FAST,
                            DS4_ROPE_YARN_BETA_SLOW,
                            DS4_RMS_EPS) != 0;
                }
                if (ok && ratio == 4) {
                    ok = metal_graph_refresh_ratio4_compressor_state(g,
                                                                     model,
                                                                     g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
ange(m->map, m->size, t->abs_offset, t->bytes, t->dim[0], t->dim[1], label) == 0) {
                fprintf(stderr, "ds4: accelerator failed to cache dequantized Q8 tensor %.*s\n",
                        (int)t->name.len, t->name.ptr);
                return false;
            }
        }
    }
    if (cached != 0) {
        const double t1 = now_sec();
        if (ds4_log_is_tty(stderr)) fputc('\n', stderr);
        fprintf(stderr,
                "ds4: CUDA startup model cache prepared %.2f GiB of tensor spans in %.3fs\n",
                (double)cached / 1073741824.0,
                t1 - t0);
    }
    return true;
}
#else
static bool accelerator_cache_model_tensors(ds4_backend backend, const ds4_model *m) {
    (void)backend;
    (void)m;
    return true;
}
#endif
#endif

/* Return the in-place tensor payload inside the mapped GGUF. */
static const void *tensor_data(const ds4_model *m, const ds4_tensor *t) {
    return m->map + t->abs_offset;
}

/* Optional startup pass that touches tensor pages before timing generation. */
static void model_warm_weights(const ds4_model *m) {
    const uint64_t start = m->tensor_data_pos;
    const uint64_t end = m->size;
    if (start >= end) return;

    const uint64_t page = (uint64_t)sysconf(_SC_PAGESIZE);
    const uint8_t *p = m->map;
    volatile uint64_t checksum = 0;
    const double t0 = now_sec();

    fprintf(stderr, "ds4: warming mapped tensor pages: %.2f GiB\n",
            (double)(end - start) / (1024.0 * 1024.0 * 1024.0));

#if defined(POSIX_MADV_WILLNEED)
    (void)posix_madvise((void *)(p + start), (size_t)(end - start), POSIX_MADV_WILLNEED);
#endif

    for (uint64_t off = start; off < end; off += page) {
        checksum += p[off];
    }
    checksum += p[end - 1];

    const double t1 = now_sec();
    fprintf(stderr, "ds4: warmed tensor pages in %.3fs (checksum=%llu)\n",
            t1 - t0, (unsigned long long)checksum);
}

/* =========================================================================
 * Scalar Conversion and Quantized Tensor Kernels.
 * =========================================================================
 *
 * These functions are the CPU reference math used by the C backend and by
 * Metal diagnostics.  They implement only the tensor formats present in the
 * DeepSeek V4 Flash GGUF: F16, F32, Q8_0, Q2_K, IQ2_XXS, and Q8_K activation
 * blocks used for expert dot products.
 */

static inline float f16_to_f32(uint16_t h) {
#if defined(__ARM_NEON)
    const float16x4_t hv = vreinterpret_f16_u16(vdup_n_u16(h));
    return vgetq_lane_f32(vcvt_f32_f16(hv), 0);
#else
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
ange(m->map, m->size, t->abs_offset, t->bytes, t->dim[0], t->dim[1], label) == 0) {
                fprintf(stderr, "ds4: accelerator failed to cache dequantized Q8 tensor %.*s\n",
                        (int)t->name.len, t->name.ptr);
                return false;
            }
        }
    }
    if (cached != 0) {
        const double t1 = now_sec();
        if (ds4_log_is_tty(stderr)) fputc('\n', stderr);
        fprintf(stderr,
                "ds4: CUDA startup model cache prepared %.2f GiB of tensor spans in %.3fs\n",
                (double)cached / 1073741824.0,
                t1 - t0);
    }
    return true;
}
#else
static bool accelerator_cache_model_tensors(ds4_backend backend, const ds4_model *m) {
    (void)backend;
    (void)m;
    return true;
}
#endif
#endif

/* Return the in-place tensor payload inside the mapped GGUF. */
static const void *tensor_data(const ds4_model *m, const ds4_tensor *t) {
    return m->map + t->abs_offset;
}

/* Optional startup pass that touches tensor pages before timing generation. */
static void model_warm_weights(const ds4_model *m) {
    const uint64_t start = m->tensor_data_pos;
    const uint64_t end = m->size;
    if (start >= end) return;

    const uint64_t page = (uint64_t)sysconf(_SC_PAGESIZE);
    const uint8_t *p = m->map;
    volatile uint64_t checksum = 0;
    const double t0 = now_sec();

    fprintf(stderr, "ds4: warming mapped tensor pages: %.2f GiB\n",
            (double)(end - start) / (1024.0 * 1024.0 * 1024.0));

#if defined(POSIX_MADV_WILLNEED)
    (void)posix_madvise((void *)(p + start), (size_t)(end - start), POSIX_MADV_WILLNEED);
#endif

    for (uint64_t off = start; off < end; off += page) {
        checksum += p[off];
    }
    checksum += p[end - 1];

    const double t1 = now_sec();
    fprintf(stderr, "ds4: warmed tensor pages in %.3fs (checksum=%llu)\n",
            t1 - t0, (unsigned long long)checksum);
}

/* =========================================================================
 * Scalar Conversion and Quantized Tensor Kernels.
 * =========================================================================
 *
 * These functions are the CPU reference math used by the C backend and by
 * Metal diagnostics.  They implement only the tensor formats present in the
 * DeepSeek V4 Flash GGUF: F16, F32, Q8_0, Q2_K, IQ2_XXS, and Q8_K activation
 * blocks used for expert dot products.
 */

static inline float f16_to_f32(uint16_t h) {
#if defined(__ARM_NEON)
    const float16x4_t hv = vreinterpret_f16_u16(vdup_n_u16(h));
    return vgetq_lane_f32(vcvt_f32_f16(hv), 0);
#else
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
ange(m->map, m->size, t->abs_offset, t->bytes, t->dim[0], t->dim[1], label) == 0) {
                fprintf(stderr, "ds4: accelerator failed to cache dequantized Q8 tensor %.*s\n",
                        (int)t->name.len, t->name.ptr);
                return false;
            }
        }
    }
    if (cached != 0) {
        const double t1 = now_sec();
        if (ds4_log_is_tty(stderr)) fputc('\n', stderr);
        fprintf(stderr,
                "ds4: CUDA startup model cache prepared %.2f GiB of tensor spans in %.3fs\n",
                (double)cached / 1073741824.0,
                t1 - t0);
    }
    return true;
}
#else
static bool accelerator_cache_model_tensors(ds4_backend backend, const ds4_model *m) {
    (void)backend;
    (void)m;
    return true;
}
#endif
#endif

/* Return the in-place tensor payload inside the mapped GGUF. */
static const void *tensor_data(const ds4_model *m, const ds4_tensor *t) {
    return m->map + t->abs_offset;
}

/* Optional startup pass that touches tensor pages before timing generation. */
static void model_warm_weights(const ds4_model *m) {
    const uint64_t start = m->tensor_data_pos;
    const uint64_t end = m->size;
    if (start >= end) return;

    const uint64_t page = (uint64_t)sysconf(_SC_PAGESIZE);
    const uint8_t *p = m->map;
    volatile uint64_t checksum = 0;
    const double t0 = now_sec();

    fprintf(stderr, "ds4: warming mapped tensor pages: %.2f GiB\n",
            (double)(end - start) / (1024.0 * 1024.0 * 1024.0));

#if defined(POSIX_MADV_WILLNEED)
    (void)posix_madvise((void *)(p + start), (size_t)(end - start), POSIX_MADV_WILLNEED);
#endif

    for (uint64_t off = start; off < end; off += page) {
        checksum += p[off];
    }
    checksum += p[end - 1];

    const double t1 = now_sec();
    fprintf(stderr, "ds4: warmed tensor pages in %.3fs (checksum=%llu)\n",
            t1 - t0, (unsigned long long)checksum);
}

/* =========================================================================
 * Scalar Conversion and Quantized Tensor Kernels.
 * =========================================================================
 *
 * These functions are the CPU reference math used by the C backend and by
 * Metal diagnostics.  They implement only the tensor formats present in the
 * DeepSeek V4 Flash GGUF: F16, F32, Q8_0, Q2_K, IQ2_XXS, and Q8_K activation
 * blocks used for expert dot products.
 */

static inline float f16_to_f32(uint16_t h) {
#if defined(__ARM_NEON)
    const float16x4_t hv = vreinterpret_f16_u16(vdup_n_u16(h));
    return vgetq_lane_f32(vcvt_f32_f16(hv), 0);
#else
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
ange(m->map, m->size, t->abs_offset, t->bytes, t->dim[0], t->dim[1], label) == 0) {
                fprintf(stderr, "ds4: accelerator failed to cache dequantized Q8 tensor %.*s\n",
                        (int)t->name.len, t->name.ptr);
                return false;
            }
        }
    }
    if (cached != 0) {
        const double t1 = now_sec();
        if (ds4_log_is_tty(stderr)) fputc('\n', stderr);
        fprintf(stderr,
                "ds4: CUDA startup model cache prepared %.2f GiB of tensor spans in %.3fs\n",
                (double)cached / 1073741824.0,
                t1 - t0);
    }
    return true;
}
#else
static bool accelerator_cache_model_tensors(ds4_backend backend, const ds4_model *m) {
    (void)backend;
    (void)m;
    return true;
}
#endif
#endif

/* Return the in-place tensor payload inside the mapped GGUF. */
static const void *tensor_data(const ds4_model *m, const ds4_tensor *t) {
    return m->map + t->abs_offset;
}

/* Optional startup pass that touches tensor pages before timing generation. */
static void model_warm_weights(const ds4_model *m) {
    const uint64_t start = m->tensor_data_pos;
    const uint64_t end = m->size;
    if (start >= end) return;

    const uint64_t page = (uint64_t)sysconf(_SC_PAGESIZE);
    const uint8_t *p = m->map;
    volatile uint64_t checksum = 0;
    const double t0 = now_sec();

    fprintf(stderr, "ds4: warming mapped tensor pages: %.2f GiB\n",
            (double)(end - start) / (1024.0 * 1024.0 * 1024.0));

#if defined(POSIX_MADV_WILLNEED)
    (void)posix_madvise((void *)(p + start), (size_t)(end - start), POSIX_MADV_WILLNEED);
#endif

    for (uint64_t off = start; off < end; off += page) {
        checksum += p[off];
    }
    checksum += p[end - 1];

    const double t1 = now_sec();
    fprintf(stderr, "ds4: warmed tensor pages in %.3fs (checksum=%llu)\n",
            t1 - t0, (unsigned long long)checksum);
}

/* =========================================================================
 * Scalar Conversion and Quantized Tensor Kernels.
 * =========================================================================
 *
 * These functions are the CPU reference math used by the C backend and by
 * Metal diagnostics.  They implement only the tensor formats present in the
 * DeepSeek V4 Flash GGUF: F16, F32, Q8_0, Q2_K, IQ2_XXS, and Q8_K activation
 * blocks used for expert dot products.
 */

static inline float f16_to_f32(uint16_t h) {
#if defined(__ARM_NEON)
    const float16x4_t hv = vreinterpret_f16_u16(vdup_n_u16(h));
    return vgetq_lane_f32(vcvt_f32_f16(hv), 0);
#else
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
                                                                     layer->attn_compressor_kv,
                                                                     layer->attn_compressor_gate,
                                                                     layer->attn_compressor_ape,
                                                                     DS4_N_HEAD_DIM,
                                                                     comp_width,
                                                                     pos0,
                                                                     n_tokens);
                }
                if (ok) {
                    g->layer_n_comp[il] = comp_before + comp_chunk;
                    if (comp_counts) {
                        for (uint32_t t = 0; t < n_tokens; t++) {
                            comp_counts[t] = (pos0 + t + 1u) / ratio;
                        }
                    }
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  comp_view,
                                                  (uint64_t)comp_chunk * DS4_N_HEAD_DIM,
                                                  il,
                                                  pos0);
                    metal_graph_debug_dump_tensor("attn_state_kv",
                                                  g->layer_attn_state_kv[il],
                                                  (uint64_t)comp_width * coff * ratio,
                                                  il,
                                                  pos0);
                    metal_graph_debug_dump_tensor("attn_state_score",
                                                  g->layer_attn_state_score[il],
                                                  (uint64_t)comp_width * coff * ratio,
                                                  il,
                                                  pos0);
                }
                ds4_gpu_tensor_free(comp_view);
            } else {
                for (uint32_t t = 0; ok && t < n_tokens; t++) {
                    const uint32_t pos = pos0 + t;
                    const bool emit = ((pos + 1u) % ratio) == 0u;
                    if (emit && g->layer_n_comp[il] >= g->layer_comp_cap[il]) {
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
                                                                     layer->attn_compressor_kv,
                                                                     layer->attn_compressor_gate,
                                                                     layer->attn_compressor_ape,
                                                                     DS4_N_HEAD_DIM,
                                                                     comp_width,
                                                                     pos0,
                                                                     n_tokens);
                }
                if (ok) {
                    g->layer_n_comp[il] = comp_before + comp_chunk;
                    if (comp_counts) {
                        for (uint32_t t = 0; t < n_tokens; t++) {
                            comp_counts[t] = (pos0 + t + 1u) / ratio;
                        }
                    }
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  comp_view,
                                                  (uint64_t)comp_chunk * DS4_N_HEAD_DIM,
                                                  il,
                                                  pos0);
                    metal_graph_debug_dump_tensor("attn_state_kv",
                                                  g->layer_attn_state_kv[il],
                                                  (uint64_t)comp_width * coff * ratio,
                                                  il,
                                                  pos0);
                    metal_graph_debug_dump_tensor("attn_state_score",
                                                  g->layer_attn_state_score[il],
                                                  (uint64_t)comp_width * coff * ratio,
                                                  il,
                                                  pos0);
                }
                ds4_gpu_tensor_free(comp_view);
            } else {
                for (uint32_t t = 0; ok && t < n_tokens; t++) {
                    const uint32_t pos = pos0 + t;
                    const bool emit = ((pos + 1u) % ratio) == 0u;
                    if (emit && g->layer_n_comp[il] >= g->layer_comp_cap[il]) {
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
                                                                     layer->attn_compressor_kv,
                                                                     layer->attn_compressor_gate,
                                                                     layer->attn_compressor_ape,
                                                                     DS4_N_HEAD_DIM,
                                                                     comp_width,
                                                                     pos0,
                                                                     n_tokens);
                }
                if (ok) {
                    g->layer_n_comp[il] = comp_before + comp_chunk;
                    if (comp_counts) {
                        for (uint32_t t = 0; t < n_tokens; t++) {
                            comp_counts[t] = (pos0 + t + 1u) / ratio;
                        }
                    }
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  comp_view,
                                                  (uint64_t)comp_chunk * DS4_N_HEAD_DIM,
                                                  il,
                                                  pos0);
                    metal_graph_debug_dump_tensor("attn_state_kv",
                                                  g->layer_attn_state_kv[il],
                                                  (uint64_t)comp_width * coff * ratio,
                                                  il,
                                                  pos0);
                    metal_graph_debug_dump_tensor("attn_state_score",
                                                  g->layer_attn_state_score[il],
                                                  (uint64_t)comp_width * coff * ratio,
                                                  il,
                                                  pos0);
                }
                ds4_gpu_tensor_free(comp_view);
            } else {
                for (uint32_t t = 0; ok && t < n_tokens; t++) {
                    const uint32_t pos = pos0 + t;
                    const bool emit = ((pos + 1u) % ratio) == 0u;
                    if (emit && g->layer_n_comp[il] >= g->layer_comp_cap[il]) {
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
g->layer_attn_state_kv[il],
                                                                     g->layer_attn_state_score[il],
                                                                     layer->attn_compressor_kv,
                                                                     layer->attn_compressor_gate,
                                                                     layer->attn_compressor_ape,
                                                                     DS4_N_HEAD_DIM,
                                                                     comp_width,
                                                                     pos0,
                                                                     n_tokens);
                }
                if (ok) {
                    g->layer_n_comp[il] = comp_before + comp_chunk;
                    if (comp_counts) {
                        for (uint32_t t = 0; t < n_tokens; t++) {
                            comp_counts[t] = (pos0 + t + 1u) / ratio;
                        }
                    }
                    metal_graph_debug_dump_tensor("KVcompress",
                                                  comp_view,
                                                  (uint64_t)comp_chunk * DS4_N_HEAD_DIM,
                                                  il,
                                                  pos0);
                    metal_graph_debug_dump_tensor("attn_state_kv",
                                                  g->layer_attn_state_kv[il],
                                                  (uint64_t)comp_width * coff * ratio,
                                                  il,
                                                  pos0);
                    metal_graph_debug_dump_tensor("attn_state_score",
                                                  g->layer_attn_state_score[il],
                                                  (uint64_t)comp_width * coff * ratio,
                                                  il,
                                                  pos0);
                }
                ds4_gpu_tensor_free(comp_view);
            } else {
                for (uint32_t t = 0; ok && t < n_tokens; t++) {
                    const uint32_t pos = pos0 + t;
                    const bool emit = ((pos + 1u) % ratio) == 0u;
                    if (emit && g->layer_n_comp[il] >= g->layer_comp_cap[il]) {
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
const uint32_t pos = pos0 + t;
                    const bool emit = ((pos + 1u) % ratio) == 0u;
                    if (emit && g->layer_n_comp[il] >= g->layer_comp_cap[il]) {
                        fprintf(stderr, "ds4: Metal graph compressed KV cache capacity exceeded at layer %u\n", il);
                        ok = false;
                        break;
                    }
                    ds4_gpu_tensor *kv_view = metal_graph_tensor_row_view(g->batch_comp_kv, t, comp_width);
                    ds4_gpu_tensor *sc_view = metal_graph_tensor_row_view(g->batch_comp_sc, t, comp_width);
                    const uint32_t comp_row = g->layer_n_comp[il];
                    ok = kv_view && sc_view &&
                         ds4_gpu_compressor_update_tensor(kv_view,
                                                            sc_view,
                                                            g->layer_attn_state_kv[il],
                                                            g->layer_attn_state_score[il],
                                                            g->layer_attn_comp_cache[il],
                                                            model->map,
                                                            model->size,
                                                            layer->attn_compressor_ape->abs_offset,
                                                            layer->attn_compressor_ape->type,
                                                            layer->attn_compressor_norm->abs_offset,
                                                            layer->attn_compressor_norm->type,
                                                            DS4_N_HEAD_DIM,
                                                            ratio,
                                                            pos,
                                                            comp_row,
                                                            DS4_N_ROT,
                                                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                                                            freq_base,
                                                            freq_scale,
                                                            ext_factor,
                                                            attn_factor,
                                                            DS4_ROPE_YARN_BETA_FAST,
                                                            DS4_ROPE_YARN_BETA_SLOW,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
const uint32_t pos = pos0 + t;
                    const bool emit = ((pos + 1u) % ratio) == 0u;
                    if (emit && g->layer_n_comp[il] >= g->layer_comp_cap[il]) {
                        fprintf(stderr, "ds4: Metal graph compressed KV cache capacity exceeded at layer %u\n", il);
                        ok = false;
                        break;
                    }
                    ds4_gpu_tensor *kv_view = metal_graph_tensor_row_view(g->batch_comp_kv, t, comp_width);
                    ds4_gpu_tensor *sc_view = metal_graph_tensor_row_view(g->batch_comp_sc, t, comp_width);
                    const uint32_t comp_row = g->layer_n_comp[il];
                    ok = kv_view && sc_view &&
                         ds4_gpu_compressor_update_tensor(kv_view,
                                                            sc_view,
                                                            g->layer_attn_state_kv[il],
                                                            g->layer_attn_state_score[il],
                                                            g->layer_attn_comp_cache[il],
                                                            model->map,
                                                            model->size,
                                                            layer->attn_compressor_ape->abs_offset,
                                                            layer->attn_compressor_ape->type,
                                                            layer->attn_compressor_norm->abs_offset,
                                                            layer->attn_compressor_norm->type,
                                                            DS4_N_HEAD_DIM,
                                                            ratio,
                                                            pos,
                                                            comp_row,
                                                            DS4_N_ROT,
                                                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                                                            freq_base,
                                                            freq_scale,
                                                            ext_factor,
                                                            attn_factor,
                                                            DS4_ROPE_YARN_BETA_FAST,
                                                            DS4_ROPE_YARN_BETA_SLOW,
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
const uint32_t pos = pos0 + t;
                    const bool emit = ((pos + 1u) % ratio) == 0u;
                    if (emit && g->layer_n_comp[il] >= g->layer_comp_cap[il]) {
                        fprintf(stderr, "ds4: Metal graph compressed KV cache capacity exceeded at layer %u\n", il);
                        ok = false;
                        break;
                    }
                    ds4_gpu_tensor *kv_view = metal_graph_tensor_row_view(g->batch_comp_kv, t, comp_width);
                    ds4_gpu_tensor *sc_view = metal_graph_tensor_row_view(g->batch_comp_sc, t, comp_width);
                    const uint32_t comp_row = g->layer_n_comp[il];
                    ok = kv_view && sc_view &&
                         ds4_gpu_compressor_update_tensor(kv_view,
                                                            sc_view,
                                                            g->layer_attn_state_kv[il],
                                                            g->layer_attn_state_score[il],
                                                            g->layer_attn_comp_cache[il],
                                                            model->map,
                                                            model->size,
                                                            layer->attn_compressor_ape->abs_offset,
                                                            layer->attn_compressor_ape->type,
                                                            layer->attn_compressor_norm->abs_offset,
                                                            layer->attn_compressor_norm->type,
                                                            DS4_N_HEAD_DIM,
                                                            ratio,
                                                            pos,
                                                            comp_row,
                                                            DS4_N_ROT,
                                                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                                                            freq_base,
                                                            freq_scale,
                                                            ext_factor,
                                                            attn_factor,
                                                            DS4_ROPE_YARN_BETA_FAST,
                                                            DS4_ROPE_YARN_BETA_SLOW,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
const uint32_t pos = pos0 + t;
                    const bool emit = ((pos + 1u) % ratio) == 0u;
                    if (emit && g->layer_n_comp[il] >= g->layer_comp_cap[il]) {
                        fprintf(stderr, "ds4: Metal graph compressed KV cache capacity exceeded at layer %u\n", il);
                        ok = false;
                        break;
                    }
                    ds4_gpu_tensor *kv_view = metal_graph_tensor_row_view(g->batch_comp_kv, t, comp_width);
                    ds4_gpu_tensor *sc_view = metal_graph_tensor_row_view(g->batch_comp_sc, t, comp_width);
                    const uint32_t comp_row = g->layer_n_comp[il];
                    ok = kv_view && sc_view &&
                         ds4_gpu_compressor_update_tensor(kv_view,
                                                            sc_view,
                                                            g->layer_attn_state_kv[il],
                                                            g->layer_attn_state_score[il],
                                                            g->layer_attn_comp_cache[il],
                                                            model->map,
                                                            model->size,
                                                            layer->attn_compressor_ape->abs_offset,
                                                            layer->attn_compressor_ape->type,
                                                            layer->attn_compressor_norm->abs_offset,
                                                            layer->attn_compressor_norm->type,
                                                            DS4_N_HEAD_DIM,
                                                            ratio,
                                                            pos,
                                                            comp_row,
                                                            DS4_N_ROT,
                                                            compressed ? (uint32_t)DS4_ROPE_ORIG_CTX : 0,
                                                            freq_base,
                                                            freq_scale,
                                                            ext_factor,
                                                            attn_factor,
                                                            DS4_ROPE_YARN_BETA_FAST,
                                                            DS4_ROPE_YARN_BETA_SLOW,
```<｜Assistant｜><think>