1 files changed, 19 insertions, 0 deletions
diff --git a/third_party/aom/aom_dsp/x86/synonyms.h b/third_party/aom/aom_dsp/x86/synonyms.h
index 6744ec51d0..74318de2e5 100644
--- a/third_party/aom/aom_dsp/x86/synonyms.h
+++ b/third_party/aom/aom_dsp/x86/synonyms.h
@@ -46,6 +46,25 @@ 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));