Predecode: fix ebreak predecoded as jalr (#2186)

src/main/scala/xiangshan/backend/decode/isa/predecode/predecode.scala

@@ -22,7 +22,8 @@ import xiangshan.frontend.BrType
 object PreDecodeInst {
   // def C_JAL     = BitPat("b????????????????_?01_?_??_???_??_???_01") // RV32C
   def C_J       = BitPat("b????????????????_101_?_??_???_??_???_01")
-  def C_JALR    = BitPat("b????????????????_100_?_??_???_00_000_10")  //c.jalr & c.jr
+  def C_EBREAK  = BitPat("b????????????????_100_?_00_000_00_000_10")
+  def C_JALR    = BitPat("b????????????????_100_?_??_???_00_000_10")  // c.jalr & c.jr
   def C_BRANCH  = BitPat("b????????????????_11?_?_??_???_??_???_01")
   def JAL       = BitPat("b????????????????_???_?????_1101111")
   def JALR      = BitPat("b????????????????_000_?????_1100111")
@@ -32,6 +33,7 @@ object PreDecodeInst {
 
   val brTable = Array(
     // C_JAL     -> List(BrType.jal),
+    C_EBREAK  -> List(BrType.notCFI), // c.ebreak should not be decoded as jalr, higher priority than c.jalr
     C_J       -> List(BrType.jal),
     C_JALR    -> List(BrType.jalr),
     C_BRANCH  -> List(BrType.branch),