[rtl] Flush Zcmp state machine on exception or interrupt

rtl/ibex_compressed_decoder.sv

@@ -25,6 +25,7 @@ module ibex_compressed_decoder #(
   output logic [31:0]          instr_o,
   output logic                 is_compressed_o,
   output ibex_pkg::instr_exp_e gets_expanded_o,
+  input  logic                 flush_expanded_i,
   output logic                 illegal_instr_o
 );
   import ibex_pkg::*;
@@ -799,7 +800,7 @@ module ibex_compressed_decoder #(
     if (!rst_ni) begin
       cm_state_q <= CmIdle;
     end else begin
-      cm_state_q <= cm_state_d;
+      cm_state_q <= flush_expanded_i ? CmIdle : cm_state_d;
     end
   end
 

rtl/ibex_if_stage.sv

@@ -409,6 +409,12 @@ module ibex_if_stage import ibex_pkg::*; #(
   //
   // since it does not matter where we decompress instructions, we do it here
   // to ease timing closure
+
+  // The compressed decoder only has state for the Zcmp expanded instructions. Flush this state if
+  // there is an exception.
+  logic flush_expanded;
+  assign flush_expanded = pc_set_i & (pc_mux_i == ibex_pkg::PC_EXC);
+
   ibex_compressed_decoder #(
     .RV32ZC   (RV32ZC),
     .ResetAll (ResetAll)
@@ -421,6 +427,7 @@ module ibex_if_stage import ibex_pkg::*; #(
     .instr_o        (instr_decompressed),
     .is_compressed_o(instr_is_compressed),
     .gets_expanded_o(instr_gets_expanded),
+    .flush_expanded_i(flush_expanded),
     .illegal_instr_o(illegal_c_insn)
   );