core: use NotNull and Nullable annotations

jadx-core/build.gradle

@@ -5,6 +5,7 @@ dependencies {
 
     compile files('lib/dx-1.8.jar')
     compile 'org.ow2.asm:asm:5.0.3'
+    compile 'com.intellij:annotations:12.0'
 
     testCompile 'org.smali:smali:2.0.3'
 }

jadx-core/src/main/java/jadx/core/dex/instructions/args/RegisterArg.java

@@ -19,7 +19,8 @@ public class RegisterArg extends InsnArg implements Named {
 	private static final Logger LOG = LoggerFactory.getLogger(RegisterArg.class);
 
 	protected final int regNum;
-	protected SSAVar sVar;
+	// not null after SSATransform pass
+	private SSAVar sVar;
 
 	public RegisterArg(int rn) {
 		this.regNum = rn;
@@ -139,11 +140,7 @@ public class RegisterArg extends InsnArg implements Named {
 		if (sVar == null) {
 			return null;
 		}
-		RegisterArg assign = sVar.getAssign();
-		if (assign != null) {
-			return assign.getParentInsn();
-		}
-		return null;
+		return sVar.getAssign().getParentInsn();
 	}
 
 	public InsnNode getPhiAssignInsn() {
@@ -151,12 +148,9 @@ public class RegisterArg extends InsnArg implements Named {
 		if (usePhi != null) {
 			return usePhi;
 		}
-		RegisterArg assign = sVar.getAssign();
-		if (assign != null) {
-			InsnNode parent = assign.getParentInsn();
-			if (parent != null && parent.getType() == InsnType.PHI) {
-				return parent;
-			}
+		InsnNode parent = sVar.getAssign().getParentInsn();
+		if (parent != null && parent.getType() == InsnType.PHI) {
+			return parent;
 		}
 		return null;
 	}

jadx-core/src/main/java/jadx/core/dex/instructions/args/SSAVar.java

@@ -5,6 +5,9 @@ import jadx.core.dex.instructions.PhiInsn;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
 public class SSAVar {
 
 	private final int regNum;
@@ -14,21 +17,21 @@ public class SSAVar {
 	private int startUseAddr;
 	private int endUseAddr;
 
+	@NotNull
 	private RegisterArg assign;
 	private final List<RegisterArg> useList = new ArrayList<RegisterArg>(2);
+	@Nullable
 	private PhiInsn usedInPhi;
 
 	private ArgType type;
 	private boolean typeImmutable;
 
-	public SSAVar(int regNum, int v, RegisterArg assign) {
+	public SSAVar(int regNum, int v, @NotNull RegisterArg assign) {
 		this.regNum = regNum;
 		this.version = v;
 		this.assign = assign;
 
-		if (assign != null) {
-			assign.setSVar(this);
-		}
+		assign.setSVar(this);
 		startUseAddr = -1;
 		endUseAddr = -1;
 	}
@@ -51,7 +54,7 @@ public class SSAVar {
 		int start = Integer.MAX_VALUE;
 		int end = Integer.MIN_VALUE;
 
-		if (assign != null && assign.getParentInsn() != null) {
+		if (assign.getParentInsn() != null) {
 			int insnAddr = assign.getParentInsn().getOffset();
 			if (insnAddr >= 0) {
 				start = Math.min(insnAddr, start);
@@ -81,11 +84,12 @@ public class SSAVar {
 		return version;
 	}
 
+	@NotNull
 	public RegisterArg getAssign() {
 		return assign;
 	}
 
-	public void setAssign(RegisterArg assign) {
+	public void setAssign(@NotNull RegisterArg assign) {
 		this.assign = assign;
 	}
 
@@ -114,10 +118,11 @@ public class SSAVar {
 		}
 	}
 
-	public void setUsedInPhi(PhiInsn usedInPhi) {
+	public void setUsedInPhi(@Nullable PhiInsn usedInPhi) {
 		this.usedInPhi = usedInPhi;
 	}
 
+	@Nullable
 	public PhiInsn getUsedInPhi() {
 		return usedInPhi;
 	}
@@ -127,7 +132,7 @@ public class SSAVar {
 	}
 
 	public int getVariableUseCount() {
-		if (!isUsedInPhi()) {
+		if (usedInPhi == null) {
 			return useList.size();
 		}
 		return useList.size() + usedInPhi.getResult().getSVar().getUseCount();
@@ -142,9 +147,7 @@ public class SSAVar {
 			acceptedType = type;
 			this.type = acceptedType;
 		}
-		if (assign != null) {
-			assign.type = acceptedType;
-		}
+		assign.type = acceptedType;
 		for (int i = 0, useListSize = useList.size(); i < useListSize; i++) {
 			useList.get(i).type = acceptedType;
 		}

jadx-core/src/main/java/jadx/core/dex/visitors/regions/TernaryMod.java

@@ -60,8 +60,8 @@ public class TernaryMod {
 		}
 
 		if (t.getResult() != null && e.getResult() != null) {
-			if (!t.getResult().equalRegisterAndType(e.getResult())
-					|| !t.getResult().getSVar().isUsedInPhi()) {
+			PhiInsn phi = t.getResult().getSVar().getUsedInPhi();
+			if (phi == null || !t.getResult().equalRegisterAndType(e.getResult())) {
 				return false;
 			}
 			if (!ifRegion.getParent().replaceSubBlock(ifRegion, header)) {
@@ -71,7 +71,6 @@ public class TernaryMod {
 			InsnList.remove(eb, e);
 
 			RegisterArg resArg;
-			PhiInsn phi = t.getResult().getSVar().getUsedInPhi();
 			if (phi.getArgsCount() == 2) {
 				resArg = phi.getResult();
 			} else {

jadx-core/src/main/java/jadx/core/dex/visitors/typeinference/TypeInference.java

@@ -28,15 +28,14 @@ public class TypeInference extends AbstractVisitor {
 
 			// search variable name
 			String name = processVarName(var);
-			if (name != null) {
-				var.setName(name);
-			}
+			var.setName(name);
 		}
 
 		// fix type for vars used only in Phi nodes
 		for (SSAVar sVar : mth.getSVars()) {
-			if (sVar.isUsedInPhi()) {
-				processPhiNode(sVar.getUsedInPhi());
+			PhiInsn phi = sVar.getUsedInPhi();
+			if (phi != null) {
+				processPhiNode(phi);
 			}
 		}
 	}
@@ -44,10 +43,10 @@ public class TypeInference extends AbstractVisitor {
 	private static ArgType processType(SSAVar var) {
 		RegisterArg assign = var.getAssign();
 		List<RegisterArg> useList = var.getUseList();
-		if (assign != null && (useList.isEmpty() || var.isTypeImmutable())) {
+		if (useList.isEmpty() || var.isTypeImmutable()) {
 			return assign.getType();
 		}
-		ArgType type = assign != null ? assign.getType() : ArgType.UNKNOWN;
+		ArgType type = assign.getType();
 		for (RegisterArg arg : useList) {
 			ArgType useType = arg.getType();
 			ArgType newType = ArgType.merge(type, useType);
@@ -77,19 +76,16 @@ public class TypeInference extends AbstractVisitor {
 	}
 
 	private static String processVarName(SSAVar var) {
-		String name = null;
-		if (var.getAssign() != null) {
-			name = var.getAssign().getName();
-		}
+		String name = var.getAssign().getName();
 		if (name != null) {
 			return name;
 		}
 		for (RegisterArg arg : var.getUseList()) {
 			String vName = arg.getName();
 			if (vName != null) {
-				name = vName;
+				return vName;
 			}
 		}
-		return name;
+		return null;
 	}
 }