From 11b599f8f98639f38dd59aebf764fc2700abae5e Mon Sep 17 00:00:00 2001
From: Ken Cooke <ken@highfidelity.io>
Date: Tue, 18 Jun 2019 09:34:55 -0700
Subject: [PATCH] Update SIMD resampler to avoid benign UBSan warnings due to
 unaligned load/store

---
 libraries/audio/src/AudioSRC.cpp | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/libraries/audio/src/AudioSRC.cpp b/libraries/audio/src/AudioSRC.cpp
index d488eccb6a..625f45e9ae 100644
--- a/libraries/audio/src/AudioSRC.cpp
+++ b/libraries/audio/src/AudioSRC.cpp
@@ -793,6 +793,18 @@ int AudioSRC::multirateFilter4(const float* input0, const float* input1, const f
 
 #include <emmintrin.h>  // SSE2
 
+// unaligned load/store without undefined behavior
+static inline __m128i mm_loadu_si32(void const* mem_addr) {
+    int32_t temp;
+    memcpy(&temp, mem_addr, sizeof(int32_t));
+    return _mm_cvtsi32_si128(temp);
+}
+
+static inline void mm_storeu_si32(void* mem_addr, __m128i a) {
+   int32_t temp = _mm_cvtsi128_si32(a);
+   memcpy(mem_addr, &temp, sizeof(int32_t));
+}
+
 // convert int16_t to float, deinterleave stereo
 void AudioSRC::convertInput(const int16_t* input, float** outputs, int numFrames) {
     __m128 scale = _mm_set1_ps(1/32768.0f);
@@ -839,7 +851,7 @@ void AudioSRC::convertInput(const int16_t* input, float** outputs, int numFrames
             _mm_storeu_ps(&outputs[1][i], f1);
         }
         for (; i < numFrames; i++) {
-            __m128i a0 = _mm_cvtsi32_si128(*(int32_t*)&input[2*i]);
+            __m128i a0 = mm_loadu_si32((__m128i*)&input[2*i]);
             __m128i a1 = a0;
 
             // deinterleave and sign-extend
@@ -878,9 +890,9 @@ void AudioSRC::convertInput(const int16_t* input, float** outputs, int numFrames
             _mm_storeu_ps(&outputs[3][i], _mm_shuffle_ps(f1, f3, _MM_SHUFFLE(3,1,3,1)));
         }
         for (; i < numFrames; i++) {
-            __m128i a0 = _mm_cvtsi32_si128(*(int32_t*)&input[4*i+0]);
+            __m128i a0 = mm_loadu_si32((__m128i*)&input[4*i+0]);
             __m128i a1 = a0;
-            __m128i a2 = _mm_cvtsi32_si128(*(int32_t*)&input[4*i+2]);
+            __m128i a2 = mm_loadu_si32((__m128i*)&input[4*i+2]);
             __m128i a3 = a2;
 
             // deinterleave and sign-extend
@@ -986,7 +998,7 @@ void AudioSRC::convertOutput(float** inputs, int16_t* output, int numFrames) {
 
             // interleave
             a0 = _mm_unpacklo_epi16(a0, a1);
-            *(int32_t*)&output[2*i] = _mm_cvtsi128_si32(a0);
+            mm_storeu_si32((__m128i*)&output[2*i], a0);
         }
 
     } else if (_numChannels == 4) {