diff --git a/src/main/java/cn/edu/nju/software/backend/RiscInstrGenerator.java b/src/main/java/cn/edu/nju/software/backend/RiscInstrGenerator.java
index 9fe363668d33733910be4bb788cd37a38ecbbdd9..86aa8c4be154635c4d794aadea01909d69133bdf 100644
--- a/src/main/java/cn/edu/nju/software/backend/RiscInstrGenerator.java
+++ b/src/main/java/cn/edu/nju/software/backend/RiscInstrGenerator.java
@@ -496,6 +496,7 @@ public class RiscInstrGenerator implements InstructionVisitor {
         String funcName = call.getFunction().getName();
         if (funcName.equals("starttime") || funcName.equals("stoptime")) {
             funcName = "_sysy_" + funcName;
+            riscInstructions.add(new RiscLi(new Register("a0"), new ImmediateValue(call.getLineNo())));
         }
         riscInstructions.add(new RiscComment("call " + funcName));
         riscInstructions.add(new RiscCall(funcName));
diff --git a/src/main/java/cn/edu/nju/software/pass/MemToReg.java b/src/main/java/cn/edu/nju/software/pass/MemToReg.java
index 3d2c5d06fbbeca1c4cadf6afeedacd2d859fe91a..6b90d89fafdf1086dba2582bbe38a1e2e5b67995 100644
--- a/src/main/java/cn/edu/nju/software/pass/MemToReg.java
+++ b/src/main/java/cn/edu/nju/software/pass/MemToReg.java
@@ -240,7 +240,7 @@ public class MemToReg implements ModulePass {
             changed |= eliminateConstExp.runOnModule(this.module);
         }
         // reduce phi and drop phi's dead pred
-        runPhiModifyPass();
+//        runPhiModifyPass();
         modifyPhiOnModule();
         return false;
     }