encode: Add alt names for C_EX/C_SEP

The fadec-specific names are non-standard and as the operand size is
included in the encode mnemonic anyways, also support the standard name.

encode-test.inc

@@ -155,6 +155,18 @@ TEST("\x67\x66\x0f\xf7\xc1", SSE_MASKMOVDQUrr, FE_ADDR32, FE_XMM0, FE_XMM1);
 TEST("\x0f\xae\xe8", LFENCE, 0);
 TEST("\x0f\xae\xf0", MFENCE, 0);
 TEST("\x0f\xae\xf8", SFENCE, 0);
+TEST("\x66\x98", C_EX16, 0);
+TEST("\x66\x98", CBW, 0);
+TEST("\x98", C_EX32, 0);
+TEST("\x98", CWDE, 0);
+TEST("\x48\x98", C_EX64, 0);
+TEST("\x48\x98", CDQE, 0);
+TEST("\x66\x99", C_SEP16, 0);
+TEST("\x66\x99", CWD, 0);
+TEST("\x99", C_SEP32, 0);
+TEST("\x99", CDQ, 0);
+TEST("\x48\x99", C_SEP64, 0);
+TEST("\x48\x99", CQO, 0);
 
 // Test FD/TD encodings
 TEST("\xa0\x00\x00\x00\x00\x00\x00\x00\x00", MOV8ra, 0, FE_AX, 0);

parseinstrs.py

@@ -824,6 +824,12 @@ def encode_mnems(entries):
                 if separate_opsize:
                     name += f"{op.abssize(opsize//8, vecsize//8)*8}"
             mnemonics[name, opsize, ots].append((spec_opcode, desc))
+            altname = {
+                "C_EX16": "CBW", "C_EX32": "CWDE", "C_EX64": "CDQE",
+                "C_SEP16": "CWD", "C_SEP32": "CDQ", "C_SEP64": "CQO",
+            }.get(name)
+            if altname:
+                mnemonics[altname, opsize, ots].append((spec_opcode, desc))
 
     for (mnem, opsize, ots), variants in mnemonics.items():
         dedup = OrderedDict()