Revert the commented out section in iqk_mul_mat.cpp

It does have some benefit at long contexts.

Author: Iwan Kawrakow

ggml/src/iqk/iqk_mul_mat.cpp

@@ -17103,25 +17103,23 @@ template <int Dk, int Dv, int k_step, typename KHelper, typename VHelper>
 inline void iqk_flash_helper(KHelper& kh, VHelper& vh, int nq1, int nk1, int stride_q, int stride_m, int stride_qkv,
                         const float * q, const char * mask, float scale, float softcap, float * qkv, float * M, float * S) {
 
-    // Not sure if this actually helps.
-    // So, let's reduce compilation time by commenting it out for now.
-    //if (nk1 >= 256) { //4096) {
-    //    if (nq1 >= 64) {
-    //        FlashAttn<Dk, Dv, 64, k_step> fa(scale, softcap);
-    //        fa.compute(kh, vh, nq1, nk1, stride_q, stride_m, stride_qkv, q, (const char *)mask, qkv, M, S);
-    //        return;
-    //    }
-    //    if (nq1 >= 32) {
-    //        FlashAttn<Dk, Dv, 32, k_step> fa(scale, softcap);
-    //        fa.compute(kh, vh, nq1, nk1, stride_q, stride_m, stride_qkv, q, (const char *)mask, qkv, M, S);
-    //        return;
-    //    }
-    //    if (nq1 >= 16) {
-    //        FlashAttn<Dk, Dv, 16, k_step> fa(scale, softcap);
-    //        fa.compute(kh, vh, nq1, nk1, stride_q, stride_m, stride_qkv, q, (const char *)mask, qkv, M, S);
-    //        return;
-    //    }
-    //}
+    if (nk1 >= 256) { //4096) {
+        if (nq1 >= 64) {
+            FlashAttn<Dk, Dv, 64, k_step> fa(scale, softcap);
+            fa.compute(kh, vh, nq1, nk1, stride_q, stride_m, stride_qkv, q, (const char *)mask, qkv, M, S);
+            return;
+        }
+        if (nq1 >= 32) {
+            FlashAttn<Dk, Dv, 32, k_step> fa(scale, softcap);
+            fa.compute(kh, vh, nq1, nk1, stride_q, stride_m, stride_qkv, q, (const char *)mask, qkv, M, S);
+            return;
+        }
+        if (nq1 >= 16) {
+            FlashAttn<Dk, Dv, 16, k_step> fa(scale, softcap);
+            fa.compute(kh, vh, nq1, nk1, stride_q, stride_m, stride_qkv, q, (const char *)mask, qkv, M, S);
+            return;
+        }
+    }
     if (nq1 >= 8) {
         FlashAttn<Dk, Dv, 8, k_step> fa(scale, softcap);
         fa.compute(kh, vh, nq1, nk1, stride_q, stride_m, stride_qkv, q, (const char *)mask, qkv, M, S);