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fix: Drop var name usage when var is used before range begins
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misc: Move labelPrefix config to PrintContext
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@Col-E
Col-E committed Jan 10, 2025
1 parent cf415d8 commit 77dfe0c
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Showing 4 changed files with 118 additions and 56 deletions.
2 changes: 1 addition & 1 deletion build.gradle
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
allprojects {
group 'me.darknet'
version '2.7.0'
version '2.7.1'
}

subprojects {
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9 changes: 4 additions & 5 deletions jasm-composition-jvm/src/main/java/me/darknet/assembler/printer/JvmMemberPrinter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -7,15 +7,14 @@
import dev.xdark.blw.classfile.Annotated;
import dev.xdark.blw.classfile.Member;
import dev.xdark.blw.classfile.Signed;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.List;

public record JvmMemberPrinter(
@Nullable Annotated annotated, @Nullable Signed signed, @Nullable Accessible accessible, Type type
) {
public record JvmMemberPrinter(@Nullable Annotated annotated, @Nullable Signed signed, @Nullable Accessible accessible, @NotNull Type type) {

public JvmMemberPrinter(Member member, Type type) {
public JvmMemberPrinter(@Nullable Member<?> member, @NotNull Type type) {
this(member, member, member, type);
}

Expand Down Expand Up @@ -109,7 +108,7 @@ public PrintContext<?> printDeclaration(PrintContext<?> ctx) {
return null;
}

enum Type {
public enum Type {
CLASS,
FIELD,
METHOD
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148 changes: 98 additions & 50 deletions jasm-composition-jvm/src/main/java/me/darknet/assembler/printer/JvmMethodPrinter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
import dev.xdark.blw.annotation.Element;
import dev.xdark.blw.code.Code;
import dev.xdark.blw.code.generic.GenericLabel;
import dev.xdark.blw.code.instruction.VarInstruction;
import dev.xdark.blw.type.PrimitiveType;
import dev.xdark.blw.type.Type;
import dev.xdark.blw.type.Types;
Expand All @@ -26,31 +27,18 @@ public class JvmMethodPrinter implements MethodPrinter {

protected final Method method;
protected final JvmMemberPrinter memberPrinter;
protected String labelPrefix;

public JvmMethodPrinter(Method method) {
this.method = method;
this.memberPrinter = new JvmMemberPrinter(method, JvmMemberPrinter.Type.METHOD);
}

static String escapeName(String name, int index, boolean isStatic) {
if (name.equals("this") && !(index == 0 && !isStatic))
return "p" + index;
else
return EscapeUtil.escapeLiteral(name);
}

@SuppressWarnings("unused")
public void setLabelPrefix(String labelPrefix) {
this.labelPrefix = labelPrefix;
}

public @NotNull Variables buildVariables() {
public @NotNull Variables buildVariables(PrintContext<?> ctx) {
Map<String, Type> nameToType = new HashMap<>();
List<Variables.Local> locals = new ArrayList<>();
boolean isStatic = (method.accessFlags() & AccessFlag.ACC_STATIC) != 0;
Code code = method.code();
if (code != null) {
if (code != null && !ctx.ignoreExistingVariableNames) {
for (Local local : code.localVariables()) {
// Transform local name to be legal
int index = local.index();
Expand All @@ -66,10 +54,7 @@ public void setLabelPrefix(String labelPrefix) {
// String foo = "" ---> foo2
// byte[] foo = ... ---> foo3
Type existingVarType = nameToType.get(name);
if (existingVarType != null &&
(varType.getClass() != existingVarType.getClass() || (varType instanceof PrimitiveType varPrim
&& existingVarType instanceof PrimitiveType existingPrim
&& varPrim.kind() != existingPrim.kind()))) {
if (requiresDeconfliction(varType, existingVarType)) {
// If we have an escaped name like "\\u0000" we cannot just append a number to it and call it a day.
// In these cases we will revert the name back to an auto-generated value based on its index.
if (escaped)
Expand All @@ -81,7 +66,25 @@ public void setLabelPrefix(String labelPrefix) {
name = prefix + (i++);
}

locals.add(new Variables.Local(index, local.start().getIndex(), local.end().getIndex(), name, descriptor));
int start = local.start().getIndex();
int end = local.end().getIndex();

if (ctx.aggressivelyDropVars) {
// Validate that the variable scope isn't busted.
//
// Kotlin is stupid for example, because it will say the variable begins at an offset beyond
// where the variable is first assigned (by several instructions). So the code assigning the value
// is outside the variable scope, and usage of the then assigned variable is in-scope.
//
// We'll just do a blunt check if the variable is assigned between the last label and the supposed start.
// If so we'll say that this cope is not valid. This result in some valid label ranges being discarded,
// but it is safer to more aggressively discard than to fall into the trap mentioned above.
int priorLabelOffset = findPriorLabelOffset(code, start);
if (isVarUsedInRange(code, index, priorLabelOffset, start))
continue;
}

locals.add(new Variables.Local(index, start, end, name, descriptor));
nameToType.put(name, varType);
}
}
Expand All @@ -102,43 +105,32 @@ public void setLabelPrefix(String labelPrefix) {
if (Types.category(type) > 1)
offset++;
}
return new Variables(parameterNames, locals);
return new Variables(parameterNames, locals);
}

@NotNull
private static String getName(List<Variables.Local> locals, int i) {
String name = null;
// search for parameter name in local variables, first reference of the index which matches the type
for (Variables.Local local : locals) {
if (local.index() == i) {
name = local.name();
break;
}
}
if (name == null)
name = "p" + i;
return name;
}
private static boolean isVarUsedInRange(Code code, int variableIndex, int start, int end) {
List<CodeElement> elements = code.elements();
for (int i = start; i < end; i++)
if (elements.get(i) instanceof VarInstruction varInsn && varInsn.variableIndex() == variableIndex)
return true;
return false;
}

public Map<Integer, String> getLabelNames(List<CodeElement> elements) {
Map<Integer, String> labelNames = new HashMap<>();
int labelIndex = 0;
for (CodeElement element : elements) {
if (element instanceof Label label) {
String labelName = LabelUtil.getLabelName(labelIndex++);
if (labelPrefix != null) labelName = labelPrefix + labelName;
labelNames.put(label.getIndex(), labelName);
}
}
return labelNames;
}
private static int findPriorLabelOffset(Code code, int start) {
List<CodeElement> elements = code.elements();
for (int i = start - 1; i >= 0; i--) {
if (elements.get(i) instanceof Label)
return i;
}
return 0;
}

@Override
@Override
public void print(PrintContext<?> ctx) {
memberPrinter.printAttributes(ctx);
var obj = memberPrinter.printDeclaration(ctx).literal(method.name()).print(" ")
.literal(method.type().descriptor()).print(" ").object();
Variables variables = buildVariables();
Variables variables = buildVariables(ctx);
boolean hasPrior = !variables.parameters().isEmpty();
if (hasPrior) {
var arr = obj.value("parameters").array();
Expand All @@ -165,7 +157,7 @@ public void print(PrintContext<?> ctx) {
if (hasPrior) obj.next();

// Populate label names
Map<Integer, String> labelNames = getLabelNames(elements);
Map<Integer, String> labelNames = getLabelNames(ctx, elements);

// Print exception ranges
if (!methodCode.tryCatchBlocks().isEmpty()) {
Expand Down Expand Up @@ -215,4 +207,60 @@ public void print(PrintContext<?> ctx) {
public @Nullable AnnotationPrinter invisibleAnnotation(int index) {
return memberPrinter.printInvisibleAnnotation(index);
}

private static @NotNull String getName(List<Variables.Local> locals, int i) {
String name = null;

// search for parameter name in local variables, first reference of the index which matches the type
for (Variables.Local local : locals) {
if (local.index() == i) {
name = local.name();
break;
}
}

if (name == null)
name = "p" + i;
return name;
}

private static Map<Integer, String> getLabelNames(PrintContext<?> ctx, List<CodeElement> elements) {
Map<Integer, String> labelNames = new HashMap<>();
int labelIndex = 0;
for (CodeElement element : elements) {
if (element instanceof Label label) {
String labelName = LabelUtil.getLabelName(labelIndex++);
if (ctx.labelPrefix != null) labelName = ctx.labelPrefix + labelName;
labelNames.put(label.getIndex(), labelName);
}
}
return labelNames;
}

private static boolean requiresDeconfliction(@NotNull Type varType, @Nullable Type existingVarType) {
// If there is no existing type, no conflicts are possible.
if (existingVarType == null)
return false;

// If the var types are different (primitive vs class type) then we MUST deconflict.
if (varType.getClass() != existingVarType.getClass())
return true;

// If the class types do not match we MUST deconflict.
if (varType instanceof ClassType varClass
&& existingVarType instanceof ClassType existingClass
&& !varClass.descriptor().equals(existingClass.descriptor()))
return true;

// If the primitive types do not match we MUST deconflict.
return varType instanceof PrimitiveType varPrim
&& existingVarType instanceof PrimitiveType existingPrim
&& varPrim.kind() != existingPrim.kind();
}

private static @NotNull String escapeName(@NotNull String name, int index, boolean isStatic) {
if (name.equals("this") && !(index == 0 && !isStatic))
return "p" + index;
return EscapeUtil.escapeLiteral(name);
}
}
15 changes: 15 additions & 0 deletions jasm-core/src/main/java/me/darknet/assembler/printer/PrintContext.java
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,10 @@ public class PrintContext<T extends PrintContext<?>> {
protected String indent = "";
protected String indentStep;
protected Writer writer;
protected String labelPrefix;
protected boolean debugTryCatchRanges;
protected boolean aggressivelyDropVars;
protected boolean ignoreExistingVariableNames;

public PrintContext(String indentStep, Writer writer) {
this.indentStep = indentStep;
Expand All @@ -41,10 +44,22 @@ public void setIndentStep(String indent) {
this.indentStep = indent;
}

public void setAggressivelyDropVars(boolean aggressivelyDropVars) {
this.aggressivelyDropVars = aggressivelyDropVars;
}

public void setDebugTryCatchRanges(boolean debugTryCatchRanges) {
this.debugTryCatchRanges = debugTryCatchRanges;
}

public void setLabelPrefix(String labelPrefix) {
this.labelPrefix = labelPrefix;
}

public void setIgnoreExistingVariableNames(boolean ignoreExistingVariableNames) {
this.ignoreExistingVariableNames = ignoreExistingVariableNames;
}

T append(String s) {
try {
writer.append(s);
Expand Down

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