Lift artificial limit of 191 extensions

Add new accessors that accept the isa_extension_t enum.

Retain the original ones that accept unsigned char to avoid churn.

riscv/isa_parser.cc

@@ -28,7 +28,7 @@ static void bad_priv_string(const char* priv)
 }
 
 isa_parser_t::isa_parser_t(const char* str, const char *priv)
-  : extension_table(256, false)
+  : extension_table(NUM_ISA_EXTENSIONS, false)
 {
   isa_string = strtolower(str);
   const char* all_subsets = "mafdqchpv";

riscv/isa_parser.h

@@ -62,6 +62,7 @@ typedef enum {
   EXT_XZBR,
   EXT_XZBT,
   EXT_SSTC,
+  NUM_ISA_EXTENSIONS
 } isa_extension_t;
 
 typedef enum {
@@ -83,6 +84,9 @@ public:
   reg_t get_max_isa() const { return max_isa; }
   std::string get_isa_string() const { return isa_string; }
   bool extension_enabled(unsigned char ext) const {
+    return extension_enabled(isa_extension_t(ext));
+  }
+  bool extension_enabled(isa_extension_t ext) const {
     if (ext >= 'A' && ext <= 'Z')
       return (max_isa >> (ext - 'A')) & 1;
     else

riscv/processor.h

@@ -217,6 +217,9 @@ public:
     return !custom_extensions.empty();
   }
   bool extension_enabled(unsigned char ext) const {
+    return extension_enabled(isa_extension_t(ext));
+  }
+  bool extension_enabled(isa_extension_t ext) const {
     if (ext >= 'A' && ext <= 'Z')
       return state.misa->extension_enabled(ext);
     else
@@ -226,6 +229,9 @@ public:
   // possibly be disabled dynamically. Useful for documenting
   // assumptions about writable misa bits.
   bool extension_enabled_const(unsigned char ext) const {
+    return extension_enabled_const(isa_extension_t(ext));
+  }
+  bool extension_enabled_const(isa_extension_t ext) const {
     if (ext >= 'A' && ext <= 'Z')
       return state.misa->extension_enabled_const(ext);
     else