GabrielTofvesson/Beethoven
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Implement removal of extraneous (injected) GOTO instructions

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Gabriel Tofvesson 2021-02-05 15:11:46 +01:00
parent a13c241f47
commit a1bda63564
1 changed files with 36 additions and 6 deletions
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42
src/dev/w1zzrd/asm/Combine.java
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@ -379,8 +379,13 @@ public class Combine {
}
private void storeAndGotoFromReturn(MethodNode source, InsnList nodes, int storeIndex, MethodSignature sig) {
// The last (injected) GOTO can always be removed
AbstractInsnNode lastGoto = null;
int jumpCount = 0;
// If we already have a final frame, there's no need to add one
LabelNode endLabel = hasEndJumpFrame(nodes) ? findOrMakeEndLabel(nodes) : makeEndJumpFrame(nodes, sig, source);
boolean hadEJF = hasEndJumpFrame(nodes);
LabelNode endLabel = hadEJF ? findOrMakeEndLabel(nodes) : makeEndJumpFrame(nodes, sig, source);
INSTRUCTION_LOOP:
for (AbstractInsnNode current = nodes.getFirst(); current != null; current = current.getNext()) {
@ -406,19 +411,33 @@ public class Combine {
break;
case Opcodes.RETURN:
nodes.set(current, current = new JumpInsnNode(Opcodes.GOTO, endLabel));
nodes.set(current, lastGoto = current = new JumpInsnNode(Opcodes.GOTO, endLabel));
++jumpCount;
// Fallthrough
default:
continue INSTRUCTION_LOOP;
}
nodes.insert(current, current = new JumpInsnNode(Opcodes.GOTO, endLabel));
nodes.insert(current, lastGoto = current = new JumpInsnNode(Opcodes.GOTO, endLabel));
++jumpCount;
}
if (lastGoto != null) {
nodes.remove(lastGoto);
// The final jump frame and label can be removed
if (jumpCount == 1 && !hadEJF)
nodes.remove(endLabel.getNext());
}
}
private void popAndGotoFromReturn(MethodNode source, InsnList nodes, MethodSignature sig) {
AbstractInsnNode lastGoto = null;
int jumpCount = 0;
// If we already have a final frame, there's no need to add one
LabelNode endLabel = hasEndJumpFrame(nodes) ? findOrMakeEndLabel(nodes) : makeEndJumpFrame(nodes, sig, source);
boolean hadEJF = hasEndJumpFrame(nodes);
LabelNode endLabel = hadEJF ? findOrMakeEndLabel(nodes) : makeEndJumpFrame(nodes, sig, source);
INSTRUCTION_LOOP:
for (AbstractInsnNode current = nodes.getFirst(); current != null; current = current.getNext()) {
@ -435,14 +454,25 @@ public class Combine {
break;
case Opcodes.RETURN:
nodes.set(current, current = new JumpInsnNode(Opcodes.GOTO, endLabel));
nodes.set(current, lastGoto = current = new JumpInsnNode(Opcodes.GOTO, endLabel));
++jumpCount;
// Fallthrough
default:
continue INSTRUCTION_LOOP;
}
nodes.insert(current, current = new JumpInsnNode(Opcodes.GOTO, endLabel));
nodes.insert(current, lastGoto = current = new JumpInsnNode(Opcodes.GOTO, endLabel));
++jumpCount;
}
if (lastGoto != null) {
nodes.remove(lastGoto);
// The final jump frame and label can be removed
if (jumpCount == 1 && !hadEJF)
nodes.remove(endLabel.getNext());
}
}