GS: Fix looping over pages of textures with massive strides

pcsx2/GS/GSLocalMemory.cpp

@@ -1819,6 +1819,8 @@ GSOffset::PageLooper GSOffset::pageLooperForRect(const GSVector4i& rect) const
 	out.yCnt = botPg - topPg;
 	out.firstRowPgXStart = out.midRowPgXStart = out.lastRowPgXStart = rect.left >> m_pageShiftX;
 	out.firstRowPgXEnd = out.midRowPgXEnd = out.lastRowPgXEnd = ((rect.right + m_pageMask.x) >> m_pageShiftX) + !aligned;
+	out.slowPath = static_cast<u32>(out.yCnt * out.yInc + out.midRowPgXEnd - out.midRowPgXStart) > MAX_PAGES;
+
 	// Page-aligned bp is easy, all tiles touch their lower page but not the upper
 	if (aligned)
 		return out;

pcsx2/GS/GSLocalMemory.h

@@ -310,6 +310,7 @@ public:
 		int bp;   ///< Page offset of y=top x=0
 		int yInc; ///< Amount to add to bp when increasing y by one page
 		int yCnt; ///< Number of pages the rect covers in the y direction
+		bool slowPath; ///< True if the texture is big enough to wrap around GS memory and overlap itself
 
 		friend class GSOffset;
 
@@ -320,30 +321,66 @@ public:
 		void loopPagesWithBreak(Fn&& fn) const
 		{
 			int lineBP = bp;
-			int nextMin = 0;
-
 			int startOff = firstRowPgXStart;
 			int endOff   = firstRowPgXEnd;
 			int yCnt = this->yCnt;
-			for (int y = 0; y < yCnt; y++)
-			{
-				int start = std::max(nextMin, lineBP + startOff);
-				int end = lineBP + endOff;
-				nextMin = end;
-				lineBP += yInc;
-				for (int pos = start; pos < end; pos++)
-					if (!fn(pos % MAX_PAGES))
-						return;
 
-				if (y < yCnt - 1)
+			if (unlikely(slowPath))
+			{
+				u32 touched[MAX_PAGES / 32] = {};
+				for (int y = 0; y < yCnt; y++)
 				{
-					startOff = midRowPgXStart;
-					endOff   = midRowPgXEnd;
+					u32 start = lineBP + startOff;
+					u32 end   = lineBP + endOff;
+					lineBP += yInc;
+					for (u32 pos = start; pos < end; pos++)
+					{
+						u32 page = pos % MAX_PAGES;
+						u32 idx = page / 32;
+						u32 mask = 1 << (page % 32);
+						if (touched[idx] & mask)
+							continue;
+						if (!fn(page))
+							return;
+						touched[idx] |= mask;
+					}
+
+					if (y < yCnt - 1)
+					{
+						startOff = midRowPgXStart;
+						endOff   = midRowPgXEnd;
+					}
+					else
+					{
+						startOff = lastRowPgXStart;
+						endOff   = lastRowPgXEnd;
+					}
 				}
-				else
+			}
+			else
+			{
+				u32 nextMin = 0;
+
+				for (int y = 0; y < yCnt; y++)
 				{
-					startOff = lastRowPgXStart;
-					endOff   = lastRowPgXEnd;
+					u32 start = std::max<u32>(nextMin, lineBP + startOff);
+					u32 end   = lineBP + endOff;
+					nextMin = end;
+					lineBP += yInc;
+					for (u32 pos = start; pos < end; pos++)
+						if (!fn(pos % MAX_PAGES))
+							return;
+
+					if (y < yCnt - 1)
+					{
+						startOff = midRowPgXStart;
+						endOff   = midRowPgXEnd;
+					}
+					else
+					{
+						startOff = lastRowPgXStart;
+						endOff   = lastRowPgXEnd;
+					}
 				}
 			}
 		}