build: add missing GCC condition for pragma

diff --git a/modules/features2d/src/sift.simd.hpp b/modules/features2d/src/sift.simd.hpp
index dfe113b9b311dc992d027787be367b6fed97b594..8a038612c452a3ae84da7a2bca05a5f519a13e86 100644 (file)
--- a/modules/features2d/src/sift.simd.hpp
+++ b/modules/features2d/src/sift.simd.hpp
@@ -829,14 +829,19 @@ else // CV_8U
         v_pack_store(dst + k, __pack01);
     }
 #endif
+
+#if defined(__GNUC__) && __GNUC__ >= 9
 // avoid warning "iteration 7 invokes undefined behavior" on Linux ARM64
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Waggressive-loop-optimizations"
+#endif
     for( ; k < len; k++ )
     {
         dst[k] = saturate_cast<uchar>(rawDst[k]*nrm2);
     }
+#if defined(__GNUC__) && __GNUC__ >= 9
 #pragma GCC diagnostic pop
+#endif
 }
 #else
     float* dst = dstMat.ptr<float>(row);