feat(ittage): when using old_entry, the strong bias of jalr should re…

…main unchanged.
OpenXiangShan · Oct 16, 2024 · 1d1cc1b · 1d1cc1b
1 parent d2137e7
commit 1d1cc1b
Showing 1 changed file with 8 additions and 2 deletions.
diff --git a/src/main/scala/xiangshan/frontend/NewFtq.scala b/src/main/scala/xiangshan/frontend/NewFtq.scala
@@ -379,8 +379,14 @@ class FTBEntryGen(implicit p: Parameters) extends XSModule with HasBackendRedire
   val old_entry_always_taken = WireInit(oe)
   val always_taken_modified_vec = Wire(Vec(numBr, Bool())) // whether modified or not
   for (i <- 0 until numBr) {
-    old_entry_always_taken.strong_bias(i) :=
-      oe.strong_bias(i) && io.cfiIndex.valid && oe.brValids(i) && io.cfiIndex.bits === oe.brOffset(i)
+    if (i == numBr - 1){
+      //strong bias of jalr should remain unchanged
+      old_entry_always_taken.strong_bias(i) :=
+        oe.strong_bias(i) && io.cfiIndex.valid && io.cfiIndex.bits === oe.brOffset(i) && oe.tailSlot.valid
+    }else{
+      old_entry_always_taken.strong_bias(i) :=
+        oe.strong_bias(i) && io.cfiIndex.valid && oe.brValids(i) && io.cfiIndex.bits === oe.brOffset(i)
+    }
     always_taken_modified_vec(i) := oe.strong_bias(i) && oe.brValids(i) && !old_entry_always_taken.strong_bias(i)
   }
   val always_taken_modified = always_taken_modified_vec.reduce(_||_)