fix data_swa uninitialized

Author: ngxson

src/llama.cpp

@@ -12687,12 +12687,14 @@ static void llama_set_inputs(llama_context & lctx, const llama_batch & batch) {
 
             float * data = (float *) lctx.inp_KQ_mask->data;
             float * data_swa = nullptr;
+            const llama_pos n_keep_swa = hparams.n_ctx_swa - batch.n_tokens;
 
             if (lctx.model.arch == LLM_ARCH_GEMMA2) {
                 GGML_ASSERT(!lctx.inp_KQ_mask_l.empty() && "gemma 2 requires different KQ mask per layer");
                 GGML_ASSERT(hparams.n_ctx_swa > 0);
                 data_swa = (float *) lctx.inp_KQ_mask_l[0]->data;
                 data     = (float *) lctx.inp_KQ_mask_l[1]->data;
+                // because layer masks are alternate for gemma 2, we only need to take first 2 layers
             }
 
             // For causal attention, use only the previous KV cells
@@ -12717,9 +12719,8 @@ static void llama_set_inputs(llama_context & lctx, const llama_batch & batch) {
                         data[h*(n_kv*n_tokens) + j*n_kv + i] = f;
 
                         // may need to cut off old tokens for sliding window
-                        if (data_swa && f != -INFINITY) {
-                            const llama_pos n_keep = hparams.n_ctx_swa - batch.n_tokens;
-                            if (pos - lctx.kv_self.cells[i].pos > n_keep) {
+                        if (data_swa) {
+                            if (pos - lctx.kv_self.cells[i].pos > n_keep_swa) {
                                 f = -INFINITY;
                             }
                             data_swa[h*(n_kv*n_tokens) + j*n_kv + i] = f;