From 7806cceb3345d09a12843461785a173027aad9b4 Mon Sep 17 00:00:00 2001
From: Kawe Mazidjatari <48657826+Mauler125@users.noreply.github.com>
Date: Sat, 23 Sep 2023 16:34:37 +0200
Subject: [PATCH] Swap SSE4.1 instruction with an SSE2 instruction

The min spec is SSSE3, using SSE4.1 instructions (_mm_extract_epi64) will break compatibility. The code containing the defect is debug only, and %90+ of the user base uses an SSE4.1 capable processor.
---
 src/game/shared/ai_utility_shared.cpp | 9 ++++++---
 src/game/shared/ai_utility_shared.h   | 2 +-
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/game/shared/ai_utility_shared.cpp b/src/game/shared/ai_utility_shared.cpp
index de9d5aa2..f2e76f6e 100644
--- a/src/game/shared/ai_utility_shared.cpp
+++ b/src/game/shared/ai_utility_shared.cpp
@@ -138,7 +138,10 @@ void CAI_Utility::DrawAIScriptNetwork(
             int nNearest = GetNearestNodeToPos(pNetwork, &pScriptNode->m_vOrigin);
             if (nNearest != NO_NODE) // NO_NODE = -1
             {
-                auto p = uLinkSet.insert(_mm_extract_epi64(PackNodeLink(i, nNearest), 1));
+                shortx8 packedLinks = PackNodeLink(i, nNearest);
+                packedLinks = _mm_srli_si128(packedLinks, 8); // Only the upper 64bits are used.
+
+                auto p = uLinkSet.insert(reinterpret_cast<int64_t&>(packedLinks));
                 if (p.second) // Only render if link hasn't already been rendered.
                 {
                     const CAI_ScriptNode* pNearestNode = &pNetwork->m_ScriptNode[nNearest];
@@ -536,9 +539,9 @@ void CAI_Utility::DrawNavMeshPolyBoundaries(const dtNavMesh* pMesh,
 //          d - 
 // Output : packed node set as i64x2
 //------------------------------------------------------------------------------
-__m128i CAI_Utility::PackNodeLink(int32_t a, int32_t b, int32_t c, int32_t d) const
+shortx8 CAI_Utility::PackNodeLink(int32_t a, int32_t b, int32_t c, int32_t d) const
 {
-    __m128i xResult = _mm_set_epi32(a, b, c, d);
+    shortx8 xResult = _mm_set_epi32(a, b, c, d);
 
     // We shuffle a b and c d if following condition is met, this is to 
     // ensure we always end up with one possible combination of indices.
diff --git a/src/game/shared/ai_utility_shared.h b/src/game/shared/ai_utility_shared.h
index 071a534f..d8e32b81 100644
--- a/src/game/shared/ai_utility_shared.h
+++ b/src/game/shared/ai_utility_shared.h
@@ -57,7 +57,7 @@ public:
 		const int nTileRange,
 		const bool bDepthBuffer) const;
 
-	__m128i PackNodeLink(int32_t a, int32_t b, int32_t c = 0, int32_t d = 0) const;
+	shortx8 PackNodeLink(int32_t a, int32_t b, int32_t c = 0, int32_t d = 0) const;
 	int GetNearestNodeToPos(const CAI_Network* pAINetwork, const Vector3D* vec) const;
 	bool IsTileWithinRange(const dtMeshTile* pTile, const VPlane& vPlane, const Vector3D& vCamera, const float flCameraRadius) const;