pointer masking: Support _ssnpm to --isa

Author: YenHaoChen

disasm/isa_parser.cc

@@ -322,6 +322,8 @@ isa_parser_t::isa_parser_t(const char* str, const char *priv)
       extension_table[EXT_SMMPM] = true;
     } else if (ext_str == "smnpm") {
       extension_table[EXT_SMNPM] = true;
+    } else if (ext_str == "ssnpm") {
+      extension_table[EXT_SSNPM] = true;
     } else if (ext_str.substr(0, 3) == "zvl") {
       reg_t new_vlen;
       try {

riscv/isa_parser.h

@@ -84,6 +84,7 @@ typedef enum {
   EXT_SSDBLTRP,
   EXT_SMMPM,
   EXT_SMNPM,
+  EXT_SSNPM,
   NUM_ISA_EXTENSIONS
 } isa_extension_t;