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Issue janino-compiler#113: Grow the code for relocatables, and do fix…
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…up, and relocate

Also add a reproducer for janino-compiler#113
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@HeartSaVioR
HeartSaVioR committed Mar 6, 2020
1 parent 354abed commit e63c23e
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Showing 2 changed files with 90 additions and 29 deletions.
69 changes: 40 additions & 29 deletions janino/src/main/java/org/codehaus/janino/CodeContext.java
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Original file line number Diff line number Diff line change
Expand Up @@ -385,14 +385,19 @@ class LocalScope {
*/
public void
fixUpAndRelocate() {
maybeGrow();
fixUp();
relocate();
}

// We do this in a loop to allow relocatables to adjust the size
// of things in the byte stream. It is extremely unlikely, but possible
// that a late relocatable will grow the size of the bytecode, and require
// an earlier relocatable to switch from 32K mode to 64K mode branching
do {
this.fixUp();
} while (!this.relocate());
/**
* Grow the code if relocatables are required to.
*/
private void
maybeGrow() {
for (Relocatable relocatable : this.relocatables) {
relocatable.grow();
}
}

/**
Expand All @@ -407,20 +412,13 @@ class LocalScope {
}

/**
* Relocates all relocatables and aggregate their response into a single one.
*
* @return {@code true} if all of them relocated successfully, {@code false} if any of them needed to change size
* Relocates all relocatables.
*/
private boolean
private void
relocate() {
boolean finished = true;
for (Relocatable relocatable : this.relocatables) {

// Do not terminate earlier so that everything gets a chance to grow in the first pass changes the common
// case for this to be O(n) instead of O(n**2).
finished &= relocatable.relocate();
relocatable.relocate();
}
return finished;
}

/**
Expand Down Expand Up @@ -622,8 +620,8 @@ class Branch extends Relocatable {
}
}

@Override public boolean
relocate() {
@Override public void
grow() {
if (this.destination.offset == Offset.UNSET) {
throw new InternalCompilerException("Cannot relocate branch to unset destination offset");
}
Expand All @@ -643,9 +641,17 @@ class Branch extends Relocatable {
CodeContext.this.popInserter();
this.source.offset = pos;
this.expanded = true;
return false;
}
}

@Override public void
relocate() {
if (this.destination.offset == Offset.UNSET) {
throw new InternalCompilerException("Cannot relocate branch to unset destination offset");
}
int offset = this.destination.offset - this.source.offset;

@SuppressWarnings("deprecation") final int opcodeJsr = Opcode.JSR;
final byte[] ba;
if (!this.expanded) {
//we fit in a 16-bit jump
Expand Down Expand Up @@ -683,7 +689,6 @@ class Branch extends Relocatable {
}
}
System.arraycopy(ba, 0, CodeContext.this.code, this.source.offset, ba.length);
return true;
}

private boolean expanded; //marks whether this has been expanded to account for a wide branch
Expand Down Expand Up @@ -748,7 +753,10 @@ class OffsetBranch extends Relocatable {
this.destination = destination;
}

@Override public boolean
@Override public void
grow() {}

@Override public void
relocate() {
if (this.source.offset == Offset.UNSET || this.destination.offset == Offset.UNSET) {
throw new InternalCompilerException("Cannot relocate offset branch to unset destination offset");
Expand All @@ -761,7 +769,6 @@ class OffsetBranch extends Relocatable {
(byte) offset
};
System.arraycopy(ba, 0, CodeContext.this.code, this.where.offset, 4);
return true;
}
private final Offset where, source, destination;
}
Expand Down Expand Up @@ -1026,13 +1033,15 @@ class LineNumberOffset extends Offset {
private abstract
class Relocatable {

/**
* Grow the code if the relocation cannot be done without growing code.
*/
public abstract void grow();

/**
* Relocates this object.
*
* @return {@code true} if the relocation succeeded in place; {@code false} if the relocation grew the number
* of bytes required
*/
public abstract boolean relocate();
public abstract void relocate();
}

/**
Expand Down Expand Up @@ -1213,10 +1222,12 @@ interface FixUp {

this.relocatables.add(new Relocatable() {

@Override public boolean
@Override public void
grow() {}

@Override public void
relocate() {
uvi.offset = (short) o.offset;
return true;
}
});

Expand Down
50 changes: 50 additions & 0 deletions janino/src/test/java/org/codehaus/janino/tests/GithubIssuesTest.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -266,6 +266,56 @@ class GithubIssuesTest {
);
}

@Test public void
testIssue113() throws Exception {
CompileUnit unit1 = new CompileUnit("demo.pkg3", "A$$1", (
""
+ "package demo.pkg3;\n"
+ "public class A$$1 {\n"
+ " public static String main() {\n"
+ " StringBuilder sb = new StringBuilder();\n"
+ " short b = 1;\n"
+ " for (int i = 0; i < 4; i++) {\n"
+ " ;\n"
+ " switch (i) {\n"
+ " case 0:\n"
+ " sb.append(\"A\");\n"
+ " break;\n"
+ " case 1:\n"
+ " sb.append(\"B\");\n"
+ " break;\n"
+ " case 2:\n"
+ " sb.append(\"C\");\n"
+ " break;\n"
+ " case 3:\n"
+ " sb.append(\"D\");\n"
+ " break;\n"
+ " }\n"
+ injectDummyLargeCodeExceedingShort()
+ " }\n"
+ " return sb.toString();\n"
+ " }\n"
+ "}\n"
));

ClassLoader
classLoader = this.compile(Thread.currentThread().getContextClassLoader(), unit1);

Assert.assertEquals(
"ABCD",
classLoader.loadClass("demo.pkg3.A$$1").getMethod("main").invoke(null)
);
}

private String injectDummyLargeCodeExceedingShort() {
StringBuilder sb = new StringBuilder();
sb.append("int a = -1;\n");
for (int i = 0 ; i < Short.MAX_VALUE / 3 ; i++) {
sb.append("a = " + i + ";\n");
}
return sb.toString();
}

public ClassLoader
compile(ClassLoader parentClassLoader, CompileUnit... compileUnits) {

Expand Down

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