diff --git a/aom_dsp/x86/synonyms.h b/aom_dsp/x86/synonyms.h
--- a/aom_dsp/x86/synonyms.h
+++ b/aom_dsp/x86/synonyms.h
@@ -41,22 +41,33 @@ static INLINE __m128i xx_loadl_64(const 
 static INLINE __m128i xx_load_128(const void *a) {
   return _mm_load_si128((const __m128i *)a);
 }
 
 static INLINE __m128i xx_loadu_128(const void *a) {
   return _mm_loadu_si128((const __m128i *)a);
 }
 
+// _mm_loadu_si64 has been introduced in GCC 9, reimplement the function
+// manually on older compilers.
+#if !defined(__clang__) && __GNUC_MAJOR__ < 9
+static INLINE __m128i xx_loadu_2x64(const void *hi, const void *lo) {
+  __m64 hi_, lo_;
+  memcpy(&hi_, hi, sizeof(hi_));
+  memcpy(&lo_, lo, sizeof(lo_));
+  return _mm_set_epi64(hi_, lo_);
+}
+#else
 // Load 64 bits from each of hi and low, and pack into an SSE register
 // Since directly loading as `int64_t`s and using _mm_set_epi64 may violate
 // the strict aliasing rule, this takes a different approach
 static INLINE __m128i xx_loadu_2x64(const void *hi, const void *lo) {
   return _mm_unpacklo_epi64(_mm_loadu_si64(lo), _mm_loadu_si64(hi));
 }
+#endif
 
 static INLINE void xx_storel_32(void *const a, const __m128i v) {
   const int val = _mm_cvtsi128_si32(v);
   memcpy(a, &val, sizeof(val));
 }
 
 static INLINE void xx_storel_64(void *const a, const __m128i v) {
   _mm_storel_epi64((__m128i *)a, v);
diff --git a/aom_dsp/x86/synonyms_avx2.h b/aom_dsp/x86/synonyms_avx2.h
--- a/aom_dsp/x86/synonyms_avx2.h
+++ b/aom_dsp/x86/synonyms_avx2.h
@@ -66,21 +66,36 @@ static INLINE __m256i yy_set1_64_from_32
 
 // Some compilers don't have _mm256_set_m128i defined in immintrin.h. We
 // therefore define an equivalent function using a different intrinsic.
 // ([ hi ], [ lo ]) -> [ hi ][ lo ]
 static INLINE __m256i yy_set_m128i(__m128i hi, __m128i lo) {
   return _mm256_insertf128_si256(_mm256_castsi128_si256(lo), hi, 1);
 }
 
+#define GCC_VERSION (__GNUC__ * 10000 \
+                     + __GNUC_MINOR__ * 100 \
+                     + __GNUC_PATCHLEVEL__)
+
+// _mm256_loadu2_m128i has been introduced in GCC 10.1
+#if !defined(__clang__) && GCC_VERSION < 101000
+static INLINE __m256i yy_loadu2_128(const void *hi, const void *lo) {
+  __m128i mhi = _mm_loadu_si128((const __m128i *)(hi));
+  __m128i mlo = _mm_loadu_si128((const __m128i *)(lo));
+  return _mm256_set_m128i(mhi, mlo);
+}
+#else
 static INLINE __m256i yy_loadu2_128(const void *hi, const void *lo) {
   __m128i mhi = _mm_loadu_si128((const __m128i *)(hi));
   __m128i mlo = _mm_loadu_si128((const __m128i *)(lo));
   return yy_set_m128i(mhi, mlo);
 }
+#endif
+
+#undef GCC_VERSION
 
 static INLINE void yy_storeu2_128(void *hi, void *lo, const __m256i a) {
   _mm_storeu_si128((__m128i *)hi, _mm256_extracti128_si256(a, 1));
   _mm_storeu_si128((__m128i *)lo, _mm256_castsi256_si128(a));
 }
 
 static INLINE __m256i yy_roundn_epu16(__m256i v_val_w, int bits) {
   const __m256i v_s_w = _mm256_srli_epi16(v_val_w, bits - 1);