[M68k][AsmParser] Fix invalid register name parsing logics

Adjust sanity check in register parsing function to allow register
name with more than 2 characters (e.g. ccr).

Differential Revision: https://reviews.llvm.org/D101733

Author: mshockwave

llvm/lib/Target/M68k/AsmParser/M68kAsmParser.cpp

@@ -479,6 +479,12 @@ bool M68kAsmParser::parseRegisterName(unsigned &RegNo, SMLoc Loc,
                                       StringRef RegisterName) {
   auto RegisterNameLower = RegisterName.lower();
 
+  // CCR register
+  if (RegisterNameLower == "ccr") {
+    RegNo = M68k::CCR;
+    return true;
+  }
+
   // Parse simple general-purpose registers.
   if (RegisterNameLower.size() == 2) {
     static unsigned RegistersByIndex[] = {
@@ -501,13 +507,6 @@ bool M68kAsmParser::parseRegisterName(unsigned &RegNo, SMLoc Loc,
       break;
     }
 
-    case 'c':
-      if (RegisterNameLower[1] == 'c' && RegisterNameLower[2] == 'r') {
-        RegNo = M68k::CCR;
-        return true;
-      }
-      break;
-
     case 's':
       if (RegisterNameLower[1] == 'p') {
         RegNo = M68k::SP;

llvm/test/CodeGen/M68k/Encoding/Data/Classes/MxMoveCCR.mir

@@ -0,0 +1,16 @@
+; RUN: llvm-mc -triple=m68k -show-encoding %s | FileCheck %s
+	.text
+	.globl	MxMoveToCCR
+; CHECK-LABEL: MxMoveToCCR:
+MxMoveToCCR:
+	; CHECK:      move.w  %d1, %ccr
+	; CHECK-SAME: encoding: [0x44,0xc1]
+	move.w	%d1, %ccr
+
+	.globl	MxMoveFromCCR
+; CHECK-LABEL: MxMoveFromCCR:
+MxMoveFromCCR:
+	; CHECK:      move.w  %ccr, %d1
+	; CHECK-SAME: encoding: [0x42,0xc1]
+	move.w	%ccr, %d1
+