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Fix not inlining cases with multiple switch expressions in a single line #564

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Fix not inlining cases with multiple switch expressions in a single line #564

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5eed0e4
Fix not inlining cases with multiple switch expressions in a single line
coehlrich Apr 15, 2026
0d3696a
Remove import
coehlrich Apr 15, 2026
c8f2590
rewrite how statements are iterated
coehlrich Apr 16, 2026
99a7771
Fix synchronized inlining
coehlrich Apr 17, 2026
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111 changes: 87 additions & 24 deletions src/org/jetbrains/java/decompiler/modules/decompiler/StackVarsProcessor.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,10 +14,7 @@
import org.jetbrains.java.decompiler.modules.decompiler.flow.FlattenStatementsHelper;
import org.jetbrains.java.decompiler.modules.decompiler.exps.FunctionExprent.FunctionType;
import org.jetbrains.java.decompiler.modules.decompiler.sforms.*;
import org.jetbrains.java.decompiler.modules.decompiler.stats.CatchStatement;
import org.jetbrains.java.decompiler.modules.decompiler.stats.DoStatement;
import org.jetbrains.java.decompiler.modules.decompiler.stats.RootStatement;
import org.jetbrains.java.decompiler.modules.decompiler.stats.Statement;
import org.jetbrains.java.decompiler.modules.decompiler.stats.*;
import org.jetbrains.java.decompiler.modules.decompiler.vars.VarVersionNode;
import org.jetbrains.java.decompiler.modules.decompiler.vars.VarVersionPair;
import org.jetbrains.java.decompiler.modules.decompiler.vars.VarVersionsGraph;
Expand All @@ -34,6 +31,7 @@

import java.util.*;
import java.util.Map.Entry;
import java.util.function.Predicate;
import java.util.stream.Collectors;

public class StackVarsProcessor {
Expand Down Expand Up @@ -123,21 +121,47 @@ private static boolean iterateStatements(RootStatement root, SSAUConstructorSpar
FlattenStatementsHelper flatthelper = new FlattenStatementsHelper();
DirectGraph dgraph = flatthelper.buildDirectGraph(root);

Map<VarVersionPair, LocalVariable> lvts = new HashMap<>();

boolean res = iterateStatementsNested(root, dgraph.first, ssa, options, dgraph, lvts, new HashSet<>(), new LinkedList<>(), new LinkedList<>(), null);

dgraph.iterateExprentsDeep(ex -> {
if (ex instanceof VarExprent var && lvts.containsKey(var.getVarVersionPair())) {
LocalVariable lvt = lvts.get(var.getVarVersionPair());
if (var.getLVT() == null) {
var.setLVT(lvt);
}
}

return 0;
});

return res;
}

private static boolean iterateStatementsNested(Statement root, DirectNode start, SSAUConstructorSparseEx ssa, StackSimplifyOptions options, DirectGraph dgraph, Map<VarVersionPair, LocalVariable> lvts, Set<DirectNode> setVisited, LinkedList<DirectNode> parentStack, LinkedList<Map<VarVersionPair, Exprent>> parentStackMaps, Map<VarVersionPair, Exprent> currentParentStackMap) {

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boolean res = false;

Set<DirectNode> setVisited = new HashSet<>();
LinkedList<DirectNode> stack = new LinkedList<>();
LinkedList<Map<VarVersionPair, Exprent>> stackMaps = new LinkedList<>();

stack.add(dgraph.first);
stack.add(start);
stackMaps.add(new HashMap<>());

Map<VarVersionPair, LocalVariable> lvts = new HashMap<>();

int[] ret = {0, 0};
while (!stack.isEmpty()) {
DirectNode nd = stack.removeFirst();
Map<VarVersionPair, Exprent> mapVarValues = stackMaps.removeFirst();

// Treat phantom switch statements as a sub method
if (nd.statement instanceof SwitchStatement switchSt && switchSt.isPhantom() && root != switchSt) {
res |= iterateStatementsNested(switchSt, nd, ssa, options, dgraph, lvts, setVisited, stack, stackMaps, mapVarValues);
continue;
} else if (!root.containsStatement(nd.statement) && !(root instanceof RootStatement)) {
parentStack.add(nd);
parentStackMaps.add(new HashMap<>(currentParentStackMap));
continue;
}
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@Kroppeb Kroppeb Apr 15, 2026

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I don't understand this case


if (setVisited.contains(nd)) {
continue;
Expand All @@ -156,8 +180,51 @@ private static boolean iterateStatements(RootStatement root, SSAUConstructorSpar
DirectNode ndsucc = succs.get(0).getDestination();

if (ndsucc.type == DirectNodeType.TAIL && !ndsucc.exprents.isEmpty()) {
lstLists.add(succs.get(0).getDestination().exprents);
nd = ndsucc;

// Skip over phantom switch statements
if (ndsucc.statement instanceof SwitchStatement switchSt && switchSt.isPhantom()) {

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@Kroppeb Kroppeb Apr 15, 2026

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I don't understand what is going on here :[

Set<DirectNode> visited = new HashSet<>();
List<DirectNode> nodes = new ArrayList<>();
nodes.add(ndsucc);
boolean changed = false;
do {
changed = false;
List<DirectNode> newNodes = new ArrayList<>();
for (DirectNode node : nodes) {
if (switchSt.containsStatement(node.statement)) {
for (DirectEdge next : node.getSuccessors(DirectEdgeType.REGULAR)) {
if (!(next.getDestination().statement instanceof DummyExitStatement) && visited.add(next.getDestination())) {
newNodes.add(next.getDestination());
changed = true;
}
}
} else {
newNodes.add(node);
}
}
nodes = newNodes;
} while (changed);

if (nodes.size() == 1) {
ndsucc = nodes.get(0);
} else {
ndsucc = null;
}

while (ndsucc != null && ndsucc.exprents.isEmpty()) {

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List<DirectEdge> next = ndsucc.getSuccessors(DirectEdgeType.REGULAR);
if (next.size() == 1) {
ndsucc = next.get(0).getDestination();
} else {
ndsucc = null;
}
}
}

if (ndsucc != null) {
lstLists.add(ndsucc.exprents);
nd = ndsucc;
}
}
}

Expand Down Expand Up @@ -235,18 +302,6 @@ private static boolean iterateStatements(RootStatement root, SSAUConstructorSpar
}
}
}

dgraph.iterateExprentsDeep(ex -> {
if (ex instanceof VarExprent var && lvts.containsKey(var.getVarVersionPair())) {
LocalVariable lvt = lvts.get(var.getVarVersionPair());
if (var.getLVT() == null) {
var.setLVT(lvt);
}
}

return 0;
});

return res;
}

Expand Down Expand Up @@ -316,7 +371,11 @@ private static void iterateExprent(List<Exprent> lstExprents,
int changed = 0;

Object[] arr = {null, false, false};
for (Exprent expr : exprent.getAllExprents()) {
List<Exprent> containing = exprent.getAllExprents();
if (exprent instanceof SwitchExprent switchExp) {
containing = switchExp.getBacking().getHeadexprentList();
}
for (Exprent expr : containing) {
while (true) {
iterateChildExprent(expr, exprent, next, mapVarValues, ssau, arr, options);
Exprent retexpr = (Exprent)arr[0];
Expand Down Expand Up @@ -758,7 +817,11 @@ private static void iterateChildExprent(Exprent exprent,
boolean changed = false;

Object[] arr = {null, false, false};
for (Exprent expr : exprent.getAllExprents()) {
List<Exprent> containing = exprent.getAllExprents();
if (exprent instanceof SwitchExprent switchExp) {
containing = switchExp.getBacking().getHeadexprentList();
}
for (Exprent expr : containing) {
while (true) {
iterateChildExprent(expr, parent, next, mapVarValues, ssau, arr, options);
Exprent retexpr = (Exprent)arr[0];
Expand Down
2 changes: 2 additions & 0 deletions test/org/jetbrains/java/decompiler/SingleClassesTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -831,6 +831,8 @@ private void registerDefault() {
register(JAVA_17, "TestStringSwitchTypes");

register(JAVA_16, "TestSwitchExpressionIfBlocks");

register(JAVA_16, "TestSwitchExpressionMultiple");
}

private void registerEntireClassPath() {
Expand Down
171 changes: 171 additions & 0 deletions testData/results/pkg/TestSwitchExpressionMultiple.dec
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Original file line number Diff line number Diff line change
@@ -0,0 +1,171 @@
package pkg;

public class TestSwitchExpressionMultiple {
public int test(int i1, int i2) {
return switch (switch (i2) {// 5
case 0 -> 1;// 6
case 1 -> 0;// 7
default -> 0;// 8
}) {
case 0 -> 1;// 10
case 1 -> 0;// 11
default -> 0;// 12
} + switch (i1) {
case 0 -> {
switch (i2) {// 14
case 0:
yield 1;// 15
case 1:
yield 0;// 16
default:
yield 0;// 17
}
}
case 1 -> 0;// 19
default -> 0;// 20
};
}
}

class 'pkg/TestSwitchExpressionMultiple' {
method 'test (II)I' {
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}
}

Lines mapping:
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23 changes: 23 additions & 0 deletions testData/src/java16/pkg/TestSwitchExpressionMultiple.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
package pkg;

public class TestSwitchExpressionMultiple {

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public int test(int i1, int i2) {
return switch (switch (i2) {
case 0 -> 1;
case 1 -> 0;
default -> 0;
}) {
case 0 -> 1;
case 1 -> 0;
default -> 0;
} + switch (i1) {
case 0 -> switch (i2) {
case 0 -> 1;
case 1 -> 0;
default -> 0;
};
case 1 -> 0;
default -> 0;
};
}
}
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