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author zaaarf <me@zaaarf.foo>2024-01-24 17:16:50 +0100
committer zaaarf <me@zaaarf.foo>2024-01-24 17:16:50 +0100
commitd06b6211bc0815c36d44c65312c097058901b1c5 (patch)
tree1a942f8d9dfd08ff8f06c576f63ba0663ce051b0 /src/main/java/ftbsc/lll/utils/StackUtils.java
parent660730086dc6b8895eb871a3df98956041453983 (diff)
chore: internal reorganisation (breaking)0.5.0
Diffstat (limited to 'src/main/java/ftbsc/lll/utils/StackUtils.java')
-rw-r--r--src/main/java/ftbsc/lll/utils/StackUtils.java86
1 files changed, 86 insertions, 0 deletions
diff --git a/src/main/java/ftbsc/lll/utils/StackUtils.java b/src/main/java/ftbsc/lll/utils/StackUtils.java
new file mode 100644
index 0000000..225b1ee
--- /dev/null
+++ b/src/main/java/ftbsc/lll/utils/StackUtils.java
@@ -0,0 +1,86 @@
+package ftbsc.lll.utils;
+
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.tree.*;
+
+import java.util.Comparator;
+
+/**
+ * Various methods for manipulating the stack.
+ * Includes anything from instantiation to variable manipulation - just about
+ * anything that loads stuff on or from the stack.
+ */
+public class StackUtils implements Opcodes {
+ /**
+ * Creates a new instance of an object, given its internal name, constructor descriptor and instructions to load
+ * the parameters.
+ * The created object is loaded on the stack.
+ * @param name the internal name of the object to initialize, where
+ * the internal name of a class is its fully qualified name, where '.' are replaced by '/'
+ * @param desc the descriptor of the constructor to call
+ * @param args nodes containing instructions to load the constructor arguments, in the right order
+ * @return an instruction list containing the opcodes needed to create the new object and load it on the stack.
+ */
+ public static InsnList instantiate(String name, String desc, AbstractInsnNode... args) {
+ InsnSequence is = new InsnSequence();
+ is.add(args);
+ return instantiate(name, desc, is);
+ }
+
+ /**
+ * Creates a new instance of an object, given its internal name, constructor descriptor and instructions to load
+ * the parameters.
+ * The created object is loaded on the stack.
+ * @param name the internal name of the object to initialize, where
+ * the internal name of a class is its fully qualified name, where '.' are replaced by '/'
+ * @param desc the descriptor of the constructor to call
+ * @param args a list of instructions loading the constructor arguments onto the stack in the correct order
+ * @return an instruction list containing the opcodes needed to create the new object and load it on the stack.
+ */
+ public static InsnList instantiate(String name, String desc, InsnList args) {
+ InsnSequence list = new InsnSequence();
+ list.add(new TypeInsnNode(NEW, name), new InsnNode(DUP));
+ if(args != null) list.add(args);
+ list.add(new MethodInsnNode(INVOKESPECIAL, name, "<init>", desc, false));
+ return list;
+ }
+
+
+ /**
+ * Creates a new local variable, lasting in scope from the first to the last label of the given method.
+ * @param method the method for which to declare the local variable
+ * @param name the variable's name
+ * @param desc the type descriptor for the new variable
+ * @return the index value of the new local variable
+ */
+ public static int addLocalVariable(MethodNode method, String name, String desc) {
+ return addLocalVariable(
+ method, name, desc,
+ (LabelNode) PatternMatcher.builder().label().build().find(method).getFirst(),
+ (LabelNode) PatternMatcher.builder().label().reverse().build().find(method).getFirst()
+ );
+ }
+
+ /**
+ * Creates a new local variable, lasting in scope between two given {@link LabelNode}s.
+ * @param method the method for which to declare the local variable
+ * @param name the variable's name
+ * @param desc the type descriptor for the new variable
+ * @param start the label at which the variable should enter scope
+ * @param end the label at which the variable should go out of scope
+ * @return the index value of the new local variable
+ */
+ public static int addLocalVariable(MethodNode method, String name, String desc, LabelNode start, LabelNode end) {
+ final int targetIndex =
+ method.localVariables
+ .stream()
+ .max(Comparator.comparingInt(v -> v.index))
+ .map(var -> var.desc.equals("J") || var.desc.equals("D")
+ ? var.index + 2 //skip two if long or double - major java moment
+ : var.index + 1)
+ .orElse(0);
+ LocalVariableNode variable = new LocalVariableNode(name, desc, null, start, end, targetIndex);
+ method.localVariables.add(variable);
+ return targetIndex;
+ }
+}