metal : slight speed-up for add and mul kernels (#2917)

Author: ggerganov

ggml-metal.m

@@ -680,6 +680,12 @@ void ggml_metal_graph_compute(
                         } break;
                     case GGML_OP_ADD:
                         {
+                            GGML_ASSERT(ggml_is_contiguous(src0));
+
+                            // utilize float4
+                            GGML_ASSERT(ne00 % 4 == 0);
+                            const int64_t nb = ne00/4;
+
                             if (ggml_nelements(src1) == ne10) {
                                 // src1 is a row
                                 [encoder setComputePipelineState:ctx->pipeline_add_row];
@@ -689,14 +695,20 @@ void ggml_metal_graph_compute(
                             [encoder setBuffer:id_src0 offset:offs_src0 atIndex:0];
                             [encoder setBuffer:id_src1 offset:offs_src1 atIndex:1];
                             [encoder setBuffer:id_dst  offset:offs_dst  atIndex:2];
-                            [encoder setBytes:&ne00 length:sizeof(ne00) atIndex:3];
+                            [encoder setBytes:&nb     length:sizeof(nb) atIndex:3];
 
-                            const int64_t n = ggml_nelements(dst);
+                            const int64_t n = ggml_nelements(dst)/4;
 
                             [encoder dispatchThreadgroups:MTLSizeMake(n, 1, 1) threadsPerThreadgroup:MTLSizeMake(1, 1, 1)];
                         } break;
                     case GGML_OP_MUL:
                         {
+                            GGML_ASSERT(ggml_is_contiguous(src0));
+
+                            // utilize float4
+                            GGML_ASSERT(ne00 % 4 == 0);
+                            const int64_t nb = ne00/4;
+
                             if (ggml_nelements(src1) == ne10) {
                                 // src1 is a row
                                 [encoder setComputePipelineState:ctx->pipeline_mul_row];
@@ -706,9 +718,9 @@ void ggml_metal_graph_compute(
                             [encoder setBuffer:id_src0 offset:offs_src0 atIndex:0];
                             [encoder setBuffer:id_src1 offset:offs_src1 atIndex:1];
                             [encoder setBuffer:id_dst  offset:offs_dst  atIndex:2];
-                            [encoder setBytes:&ne00 length:sizeof(ne00) atIndex:3];
+                            [encoder setBytes:&nb     length:sizeof(nb) atIndex:3];
 
-                            const int64_t n = ggml_nelements(dst);
+                            const int64_t n = ggml_nelements(dst)/4;
 
                             [encoder dispatchThreadgroups:MTLSizeMake(n, 1, 1) threadsPerThreadgroup:MTLSizeMake(1, 1, 1)];
                         } break;

ggml-metal.metal

@@ -25,41 +25,41 @@ typedef struct {
 } block_q8_0;
 
 kernel void kernel_add(
-        device const float * src0,
-        device const float * src1,
-        device       float * dst,
+        device const float4 * src0,
+        device const float4 * src1,
+        device       float4 * dst,
         uint tpig[[thread_position_in_grid]]) {
     dst[tpig] = src0[tpig] + src1[tpig];
 }
 
 // assumption: src1 is a row
 // broadcast src1 into src0
 kernel void kernel_add_row(
-        device const float * src0,
-        device const float * src1,
-        device       float * dst,
-        constant   int64_t & ne00,
+        device const float4 * src0,
+        device const float4 * src1,
+        device       float4 * dst,
+        constant   int64_t & nb,
         uint tpig[[thread_position_in_grid]]) {
-    dst[tpig] = src0[tpig] + src1[tpig % ne00];
+    dst[tpig] = src0[tpig] + src1[tpig % nb];
 }
 
 kernel void kernel_mul(
-        device const float * src0,
-        device const float * src1,
-        device       float * dst,
+        device const float4 * src0,
+        device const float4 * src1,
+        device       float4 * dst,
         uint tpig[[thread_position_in_grid]]) {
     dst[tpig] = src0[tpig] * src1[tpig];
 }
 
 // assumption: src1 is a row
 // broadcast src1 into src0
 kernel void kernel_mul_row(
-        device const float * src0,
-        device const float * src1,
-        device       float * dst,
-        constant   int64_t & ne00,
+        device const float4 * src0,
+        device const float4 * src1,
+        device       float4 * dst,
+        constant    int64_t & nb,
         uint tpig[[thread_position_in_grid]]) {
-    dst[tpig] = src0[tpig] * src1[tpig % ne00];
+    dst[tpig] = src0[tpig] * src1[tpig % nb];
 }
 
 kernel void kernel_scale(