some opt

midend/llvm/instr/PhiInstr.java

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+package midend.llvm.instr;
+
+import java.util.ArrayList;
+import java.util.StringJoiner;
+
+import midend.llvm.type.IrType;
+import midend.llvm.value.IrBasicBlock;
+import midend.llvm.value.IrValue;
+
+public class PhiInstr extends IrInstr {
+    private ArrayList<IrBasicBlock> predBBs;
+
+    public PhiInstr(IrType type, IrBasicBlock bblock, String name) {
+        super(type, name, IrInstrType.PHI);
+        this.setBBlock(bblock);
+        this.predBBs = new ArrayList<>(bblock.getPreds());
+        for (IrBasicBlock bb : predBBs) {
+            this.addUse(null);
+        }
+    }
+
+    public ArrayList<IrBasicBlock> getPredBBs() {
+        return predBBs;
+    }
+
+    public void setValueForPred(IrBasicBlock pred, IrValue value) {
+        int index = predBBs.indexOf(pred);
+        this.setUse(index, value);
+    }
+
+    public void deletePred(IrBasicBlock pred) {
+        int index = predBBs.indexOf(pred);
+        if (index != -1) {
+            predBBs.remove(index);
+            this.deleteUse(index);
+        }
+    }
+
+    public void replacePred(IrBasicBlock oldPred, IrBasicBlock newPred) {
+        //TODO: whether the function is needed    
+    }
+
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append(getName());
+        sb.append(" = phi ");
+        sb.append(getType().toString());
+        for (int i = 0; i < this.predBBs.size(); i++) {
+            sb.append("[ ");
+            sb.append(getUse(i).getName());
+            sb.append(", %");
+            sb.append(this.predBBs.get(i).getName());
+            sb.append(" ]");
+        }
+        return sb.toString();
+    }
+}