shader_recompiler: Improvements to buffer addressing implementation. (#2123)

src/video_core/amdgpu/resource.h

@@ -76,6 +76,16 @@ struct Buffer {
     u32 GetSize() const noexcept {
         return stride == 0 ? num_records : (stride * num_records);
     }
+
+    u32 GetIndexStride() const noexcept {
+        // Index stride is 2 bits, meaning 8, 16, 32, or 64.
+        return 8 << index_stride;
+    }
+
+    u32 GetElementSize() const noexcept {
+        // Element size is 2 bits, meaning 2, 4, 8, or 16.
+        return 2 << element_size;
+    }
 };
 static_assert(sizeof(Buffer) == 16); // 128bits