fix: don't rerun SSA transform in ConstructorVisitor (#2236)

jadx-core/src/main/java/jadx/core/dex/attributes/AFlag.java

@@ -90,7 +90,6 @@ public enum AFlag {
 
 	REQUEST_IF_REGION_OPTIMIZE, // run if region visitor again
 	REQUEST_CODE_SHRINK,
-	RERUN_SSA_TRANSFORM,
 
 	METHOD_CANDIDATE_FOR_INLINE,
 	USE_LINES_HINTS, // source lines info in methods can be trusted

jadx-core/src/main/java/jadx/core/dex/instructions/PhiInsn.java

@@ -43,6 +43,9 @@ public void bindArg(RegisterArg arg, BlockNode pred) {
 		if (blockBinds.contains(pred)) {
 			throw new JadxRuntimeException("Duplicate predecessors in PHI insn: " + pred + ", " + this);
 		}
+		if (pred == null) {
+			throw new JadxRuntimeException("Null bind block in PHI insn: " + this);
+		}
 		super.addArg(arg);
 		blockBinds.add(pred);
 	}

jadx-core/src/main/java/jadx/core/dex/visitors/ConstructorVisitor.java

@@ -6,6 +6,7 @@
 import jadx.core.dex.attributes.AFlag;
 import jadx.core.dex.instructions.InsnType;
 import jadx.core.dex.instructions.InvokeNode;
+import jadx.core.dex.instructions.PhiInsn;
 import jadx.core.dex.instructions.args.InsnArg;
 import jadx.core.dex.instructions.args.LiteralArg;
 import jadx.core.dex.instructions.args.RegisterArg;
@@ -18,6 +19,7 @@
 import jadx.core.dex.visitors.typeinference.TypeInferenceVisitor;
 import jadx.core.utils.BlockUtils;
 import jadx.core.utils.InsnRemover;
+import jadx.core.utils.exceptions.JadxRuntimeException;
 
 @JadxVisitor(
 		name = "ConstructorVisitor",
@@ -34,9 +36,6 @@ public void visit(MethodNode mth) {
 		if (replaceInvoke(mth)) {
 			MoveInlineVisitor.moveInline(mth);
 		}
-		if (mth.contains(AFlag.RERUN_SSA_TRANSFORM)) {
-			SSATransform.rerun(mth);
-		}
 	}
 
 	private static boolean replaceInvoke(MethodNode mth) {
@@ -75,7 +74,8 @@ private static boolean processInvoke(MethodNode mth, BlockNode block, int indexI
 			if (assignInsn != null) {
 				if (assignInsn.getType() == InsnType.CONSTRUCTOR) {
 					// arg already used in another constructor instruction
-					mth.add(AFlag.RERUN_SSA_TRANSFORM);
+					// insert new PHI insn to merge these branched constructors results
+					instanceArg = insertPhiInsn(mth, block, instanceArg, ((ConstructorInsn) assignInsn));
 				} else {
 					InsnNode newInstInsn = removeAssignChain(mth, assignInsn, remover, InsnType.NEW_INSTANCE);
 					if (newInstInsn != null) {
@@ -99,6 +99,31 @@ private static boolean processInvoke(MethodNode mth, BlockNode block, int indexI
 		return true;
 	}
 
+	private static RegisterArg insertPhiInsn(MethodNode mth, BlockNode curBlock,
+			RegisterArg instArg, ConstructorInsn otherCtr) {
+		BlockNode otherBlock = BlockUtils.getBlockByInsn(mth, otherCtr);
+		if (otherBlock == null) {
+			throw new JadxRuntimeException("Block not found by insn: " + otherCtr);
+		}
+		BlockNode crossBlock = BlockUtils.getPathCross(mth, curBlock, otherBlock);
+		if (crossBlock == null) {
+			throw new JadxRuntimeException("Path cross not found for blocks: " + curBlock + " and " + otherBlock);
+		}
+		RegisterArg newResArg = instArg.duplicateWithNewSSAVar(mth);
+		RegisterArg useArg = otherCtr.getResult();
+		RegisterArg otherResArg = useArg.duplicateWithNewSSAVar(mth);
+
+		PhiInsn phiInsn = SSATransform.addPhi(mth, crossBlock, useArg.getRegNum());
+		phiInsn.setResult(useArg.duplicate());
+		phiInsn.bindArg(newResArg.duplicate(), BlockUtils.getPrevBlockOnPath(crossBlock, curBlock));
+		phiInsn.bindArg(otherResArg.duplicate(), BlockUtils.getPrevBlockOnPath(crossBlock, otherBlock));
+		phiInsn.rebindArgs();
+
+		otherCtr.setResult(otherResArg.duplicate());
+		otherCtr.rebindArgs();
+		return newResArg;
+	}
+
 	private static boolean canRemoveConstructor(MethodNode mth, ConstructorInsn co) {
 		ClassNode parentClass = mth.getParentClass();
 		if (co.isSuper() && (co.getArgsCount() == 0 || parentClass.isEnum())) {

jadx-core/src/main/java/jadx/core/dex/visitors/ssa/SSATransform.java

@@ -44,12 +44,6 @@ public void visit(MethodNode mth) throws JadxException {
 		process(mth);
 	}
 
-	public static void rerun(MethodNode mth) {
-		mth.remove(AFlag.RERUN_SSA_TRANSFORM);
-		resetSSAVars(mth);
-		process(mth);
-	}
-
 	private static void process(MethodNode mth) {
 		if (!mth.getSVars().isEmpty()) {
 			return;
@@ -87,7 +81,8 @@ private static void placePhi(MethodNode mth, int regNum, LiveVarAnalysis la) {
 			for (int id = domFrontier.nextSetBit(0); id >= 0; id = domFrontier.nextSetBit(id + 1)) {
 				if (!hasPhi.get(id) && la.isLive(id, regNum)) {
 					BlockNode df = blocks.get(id);
-					addPhi(mth, df, regNum);
+					PhiInsn phiInsn = addPhi(mth, df, regNum);
+					df.getInstructions().add(0, phiInsn);
 					hasPhi.set(id);
 					if (!processed.get(id)) {
 						processed.set(id);
@@ -121,7 +116,6 @@ public static PhiInsn addPhi(MethodNode mth, BlockNode block, int regNum) {
 		PhiInsn phiInsn = new PhiInsn(regNum, size);
 		phiList.getList().add(phiInsn);
 		phiInsn.setOffset(block.getStartOffset());
-		block.getInstructions().add(0, phiInsn);
 		return phiInsn;
 	}
 
@@ -457,17 +451,6 @@ private static void hidePhiInsns(MethodNode mth) {
 		}
 	}
 
-	private static void resetSSAVars(MethodNode mth) {
-		for (SSAVar ssaVar : mth.getSVars()) {
-			ssaVar.getAssign().resetSSAVar();
-			ssaVar.getUseList().forEach(RegisterArg::resetSSAVar);
-		}
-		for (BlockNode block : mth.getBasicBlocks()) {
-			block.remove(AType.PHI_LIST);
-		}
-		mth.getSVars().clear();
-	}
-
 	private static void removeUnusedInvokeResults(MethodNode mth) {
 		Iterator<SSAVar> it = mth.getSVars().iterator();
 		while (it.hasNext()) {

jadx-core/src/main/java/jadx/core/utils/BlockUtils.java

@@ -434,6 +434,23 @@ public static BlockNode getNextBlockToPath(BlockNode block, BlockNode pathEnd) {
 		return null;
 	}
 
+	/**
+	 * Return predecessor on path from 'pathStart' block
+	 */
+	public static @Nullable BlockNode getPrevBlockOnPath(BlockNode block, BlockNode pathStart) {
+		List<BlockNode> preds = block.getPredecessors();
+		if (preds.contains(pathStart)) {
+			return pathStart;
+		}
+		Set<BlockNode> path = getAllPathsBlocks(pathStart, block);
+		for (BlockNode p : preds) {
+			if (path.contains(p)) {
+				return p;
+			}
+		}
+		return null;
+	}
+
 	/**
 	 * Visit blocks on any path from start to end.
 	 * Only one path will be visited!