Merge remote-tracking branch 'origin/opt-ibuf' into ifu-timing

src/main/scala/xiangshan/frontend/Ibuffer.scala

@@ -52,24 +52,33 @@ class Ibuffer extends XSModule with HasCircularQueuePtrHelper {
   }
 
   // Ibuffer define
-  val ibuf = Mem(IBufSize, new IBufEntry)
+  val ibuf = Reg(Vec(IBufSize, new IBufEntry))
   val head_ptr = RegInit(IbufPtr(false.B, 0.U))
-  val tail_ptr = RegInit(IbufPtr(false.B, 0.U))
+  val tail_vec = RegInit(VecInit((0 until PredictWidth).map(_.U.asTypeOf(new IbufPtr))))
+  val tail_ptr = tail_vec(0)
 
-  val validEntries = distanceBetween(tail_ptr, head_ptr) // valid entries
+  // val validEntries = distanceBetween(tail_ptr, head_ptr) // valid entries
+  val validEntries = RegInit(0.U((log2Up(IBufSize)+1).W))// valid entries
+  val allowEnq = RegInit(true.B)
 
-  val enqValid = IBufSize.U - PredictWidth.U >= validEntries
+  // val enqValid = (IBufSize.U - PredictWidth.U) >= validEntries
   val deqValid = validEntries > 0.U
 
+  val numEnq = Mux(io.in.fire, PopCount(io.in.bits.mask), 0.U)
+  val numDeq = Mux(deqValid, PopCount(io.out.map(_.fire)), 0.U)
+
+  validEntries := validEntries + numEnq - numDeq
+  allowEnq := (IBufSize.U - PredictWidth.U) >= (validEntries + numEnq)
+
   // Enque
-  io.in.ready := enqValid
+  io.in.ready := allowEnq
 
-  val enq_vec = Wire(Vec(PredictWidth, UInt(log2Up(IBufSize).W)))
+  val offset = Wire(Vec(PredictWidth, UInt(log2Up(PredictWidth).W)))
   for(i <- 0 until PredictWidth) {
     if (i == 0) {
-      enq_vec(i) := tail_ptr.value
+      offset(i) := 0.U
     } else {
-      enq_vec(i) := tail_ptr.value + PopCount(io.in.bits.pdmask(i-1, 0))
+      offset(i) := PopCount(io.in.bits.pdmask(i-1, 0))
     }
   }
 
@@ -87,11 +96,11 @@ class Ibuffer extends XSModule with HasCircularQueuePtrHelper {
         inWire.ipf := io.in.bits.ipf
         inWire.acf := io.in.bits.acf
         inWire.crossPageIPFFix := io.in.bits.crossPageIPFFix
-        ibuf(enq_vec(i)) := inWire
+        ibuf(tail_vec(offset(i)).value) := inWire
       }
     }
 
-    tail_ptr := tail_ptr + PopCount(io.in.bits.mask)
+    tail_vec := VecInit(tail_vec.map(_ + PopCount(io.in.bits.mask)))
   }
 
   // Deque
@@ -125,10 +134,11 @@ class Ibuffer extends XSModule with HasCircularQueuePtrHelper {
 
   // Flush
   when(io.flush) {
+    validEntries := 0.U
+    allowEnq := true.B
     head_ptr.value := 0.U
     head_ptr.flag := false.B
-    tail_ptr.value := 0.U
-    tail_ptr.flag := false.B
+    tail_vec := VecInit((0 until PredictWidth).map(_.U.asTypeOf(new IbufPtr)))
   }
 
   // Debug info
@@ -164,7 +174,7 @@ class Ibuffer extends XSModule with HasCircularQueuePtrHelper {
   //   )
   // }
 
-  XSDebug(p"last_head_ptr=$head_ptr  last_tail_ptr=$tail_ptr\n")
+  XSDebug(p"validEntries=$validEntries, last_head_ptr=$head_ptr  last_tail_ptr=$tail_ptr\n")
   for(i <- 0 until IBufSize/8) {
     XSDebug("%x | %x | %x | %x | %x | %x | %x | %x\n",
       ibuf(i*8+0).inst,