修改bru，去除分支预测

chisel/playground/src/pipeline/execute/fu/Bru.scala

@@ -0,0 +1,44 @@
+package cpu.pipeline.execute
+
+import chisel3._
+import chisel3.util._
+import cpu.defines._
+import cpu.defines.Const._
+
+class Bru extends Module {
+  val io = IO(new Bundle {
+    val in = new Bundle {
+      val pc       = Input(UInt(XLEN.W))
+      val info     = Input(new Info())
+      val src_info = Input(new SrcInfo())
+    }
+    val out = new Bundle {
+      val branch = Output(Bool())
+      val target = Output(UInt(XLEN.W))
+    }
+  })
+  val valid =
+    io.in.info.fusel === FuType.bru && io.in.info.valid
+  val src1   = io.in.src_info.src1_data
+  val src2   = io.in.src_info.src2_data
+  val op     = io.in.info.op
+  val is_sub = !BRUOpType.isAdd(op)
+  val adder  = (src1 +& (src2 ^ Fill(XLEN, is_sub))) + is_sub
+  val xor    = src1 ^ src2
+  val sltu   = !adder(XLEN)
+  val slt    = xor(XLEN - 1) ^ sltu
+  val table = List(
+    BRUOpType.getBranchType(BRUOpType.beq)  -> !xor.orR,
+    BRUOpType.getBranchType(BRUOpType.blt)  -> slt,
+    BRUOpType.getBranchType(BRUOpType.bltu) -> sltu
+  )
+  io.out.branch := valid &
+    (LookupTree(BRUOpType.getBranchType(op), table) ^ BRUOpType.isBranchInvert(op) |
+      BRUOpType.isJump(op))
+  io.out.target := Mux1H(
+    Seq(
+      (io.out.branch)         -> (io.in.pc + io.in.info.imm),
+      (op === BRUOpType.jalr) -> ((src1 + src2) & ~1.U(XLEN.W))
+    )
+  )
+}