Merge pull request #18219 from hrydgard/get-index-bounds-autovec

Make GetIndexBounds friendlier to autovectorization. Works on x86 at least.

Author: hrydgard

GPU/Common/VertexDecoderCommon.cpp

@@ -108,28 +108,36 @@ void DecVtxFormat::InitializeFromID(uint32_t id) {
 void GetIndexBounds(const void *inds, int count, u32 vertType, u16 *indexLowerBound, u16 *indexUpperBound) {
 	// Find index bounds. Could cache this in display lists.
 	// Also, this could be greatly sped up with SSE2/NEON, although rarely a bottleneck.
-	int lowerBound = 0x7FFFFFFF;
-	int upperBound = 0;
 	u32 idx = vertType & GE_VTYPE_IDX_MASK;
-	if (idx == GE_VTYPE_IDX_8BIT) {
-		const u8 *ind8 = (const u8 *)inds;
+	if (idx == GE_VTYPE_IDX_16BIT) {
+		uint16_t upperBound = 0;
+		uint16_t lowerBound = 0xFFFF;
+		const u16_le *ind16 = (const u16_le *)inds;
 		for (int i = 0; i < count; i++) {
-			u8 value = ind8[i];
+			u16 value = ind16[i];
 			if (value > upperBound)
 				upperBound = value;
 			if (value < lowerBound)
 				lowerBound = value;
 		}
-	} else if (idx == GE_VTYPE_IDX_16BIT) {
-		const u16_le *ind16 = (const u16_le *)inds;
+		*indexLowerBound = lowerBound;
+		*indexUpperBound = upperBound;
+	} else if (idx == GE_VTYPE_IDX_8BIT) {
+		uint8_t upperBound = 0;
+		uint8_t lowerBound = 0xFF;
+		const u8 *ind8 = (const u8 *)inds;
 		for (int i = 0; i < count; i++) {
-			u16 value = ind16[i];
+			u8 value = ind8[i];
 			if (value > upperBound)
 				upperBound = value;
 			if (value < lowerBound)
 				lowerBound = value;
 		}
+		*indexLowerBound = lowerBound;
+		*indexUpperBound = upperBound;
 	} else if (idx == GE_VTYPE_IDX_32BIT) {
+		int lowerBound = 0x7FFFFFFF;
+		int upperBound = 0;
 		WARN_LOG_REPORT_ONCE(indexBounds32, G3D, "GetIndexBounds: Decoding 32-bit indexes");
 		const u32_le *ind32 = (const u32_le *)inds;
 		for (int i = 0; i < count; i++) {
@@ -143,12 +151,12 @@ void GetIndexBounds(const void *inds, int count, u32 vertType, u16 *indexLowerBo
 			if (value < lowerBound)
 				lowerBound = value;
 		}
+		*indexLowerBound = (u16)lowerBound;
+		*indexUpperBound = (u16)upperBound;
 	} else {
-		lowerBound = 0;
-		upperBound = count - 1;
+		*indexLowerBound = 0;
+		*indexUpperBound = count - 1;
 	}
-	*indexLowerBound = (u16)lowerBound;
-	*indexUpperBound = (u16)upperBound;
 }
 
 void PrintDecodedVertex(const VertexReader &vtx) {