[llvm] [X86][MC] Support encoding/decoding for JMPABS (PR #72835)

[Shengchen Kan via llvm-commits]

================
@@ -966,9 +966,12 @@ namespace X86II {
     NoTrackShift = EVEX_RCShift + 1,
     NOTRACK = 1ULL << NoTrackShift,
 
-    // Force VEX encoding
-    ExplicitVEXShift = NoTrackShift + 1,
-    ExplicitVEXPrefix = 1ULL << ExplicitVEXShift
+    // Force REX2/VEX/EVEX encoding
+    ExplicitOpPrefixShift = NoTrackShift + 1,
+    ExplicitREX2Prefix = 1ULL << ExplicitOpPrefixShift,
+    ExplicitVEXPrefix = 2ULL << ExplicitOpPrefixShift,
+    ExplicitEVEXPrefix = 3ULL << ExplicitOpPrefixShift,
----------------
KanRobert wrote:

Sure, let me add it in the code.

https://github.com/llvm/llvm-project/pull/72835