try hack in missing hmax2 functions (+1 squashed commits)

Squashed commits:

[c98d0ab] try hack in missing hmax2 functions (+1 squashed commits)

Squashed commits:

[9ba8599] try hack in missing hmax2 functions (+2 squashed commit)

Squashed commit:

[be49749] try hack in missing hmax2 functions

[159ee4c] bypass missing hmax functions on old cuda

Author: LostRuins

ggml-cuda/fattn.cu

@@ -11,6 +11,29 @@
 #define HALF_MAX_HALF         __float2half(65504.0f/2) // Use neg. of this instead of -INFINITY to initialize KQ max vals to avoid NaN upon subtraction.
 #define SOFTMAX_FTZ_THRESHOLD -20.0f                   // Softmax exp. of values smaller than this are flushed to zero to avoid NaNs.
 
+//hack: polyfill hmax and hmax2 for older cuda version
+#if CUDART_VERSION < CUDART_HMAX
+__device__ __inline__ __half hmax(const __half a, const __half b) {
+    const float fa = __half2float(a);
+    const float fb = __half2float(b);
+    return __float2half(fa > fb ? fa : fb);
+}
+__device__ __inline__ __half2 hmax2(const __half2 a, const __half2 b) {
+    __half2 result;
+    result.x = hmax(a.x, b.x);
+    result.y = hmax(a.y, b.y);
+    return result;
+}
+#else
+__device__ __inline__ __half hmax(const __half a, const __half b) {
+    return __hmax(a,b);
+}
+__device__ __inline__ __half2 hmax2(const __half2 a, const __half2 b) {
+    return __hmax2(a,b);
+}
+#endif
+
+
 template<int D, int parallel_blocks> // D == head size
 __launch_bounds__(((D + WARP_SIZE - 1) / WARP_SIZE)*WARP_SIZE, 1)
 static __global__ void flash_attn_vec_ext_f16(
@@ -116,7 +139,7 @@ static __global__ void flash_attn_vec_ext_f16(
             sum2 = warp_reduce_sum(sum2);
             half sum = __low2half(sum2) + __high2half(sum2);
             sum += mask ? maskh[k_VKQ_0 + i_KQ] : __float2half(0.0f);
-            kqmax_new = __hmax(kqmax_new, sum);
+            kqmax_new = hmax(kqmax_new, sum);
             if (threadIdx.x == 0) {
                 KQ[i_KQ] = sum;
             }
@@ -416,9 +439,9 @@ static __global__ void flash_attn_ext_f16(
                     const int k = k0 + threadIdx.x;
 
                     KQ2_tmp[k0/WARP_SIZE] += mask ? mask2[(j*ne11 + k_VKQ_0)/2 + k] : make_half2(0.0f, 0.0f);
-                    KQ_max_new = __hmax2(KQ_max_new, KQ2_tmp[k0/WARP_SIZE]);
+                    KQ_max_new = hmax2(KQ_max_new, KQ2_tmp[k0/WARP_SIZE]);
                 }
-                KQ_max_new = __half2half2(warp_reduce_max(__hmax(__low2half(KQ_max_new), __high2half(KQ_max_new))));
+                KQ_max_new = __half2half2(warp_reduce_max(hmax(__low2half(KQ_max_new), __high2half(KQ_max_new))));
                 const half2 diff = KQ_max_h2[j0/nwarps] - KQ_max_new;
                 KQ_max_scale_h2[j0/nwarps] = h2exp(diff);
                 const uint32_t ftz_mask = __hgt2_mask(diff, make_half2(SOFTMAX_FTZ_THRESHOLD, SOFTMAX_FTZ_THRESHOLD));