[Arch64AsmParser] better diagnostic for isb

[SjoerdMeijer]

Summary

Instruction isb takes as an operand either 'sy' or an immediate value. This improves the diagnostic when the string is not 'sy' and adds a test case for this which was missing.

[john.brawn]

This breaks non-isb barrier instructions, e.g. "dsb foo" ends up getting a segfault.

[SjoerdMeijer]

Oops, thanks for reviewing/checking! This shows we also need more tests for dsb and dmb; currently regression tests check only for incorrect immediate values and not the option.

[SjoerdMeijer]

Fixed segfault and added tests for dsb and dmb.

[john.brawn]

LGTM.

llvm/trunk/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

if (parseOptionalToken(AsmToken::Hash) ||
     return MatchOperand_Success;
   }
 
   if (Tok.isNot(AsmToken::Identifier)) {
     TokError("invalid operand for instruction");
     return MatchOperand_ParseFail;
   }
 
-  auto DB = AArch64DB::lookupDBByName(Tok.getString());
-  if (!DB) {
-    TokError("invalid barrier option name");
-    return MatchOperand_ParseFail;
-  }
-
   // The only valid named option for ISB is 'sy'
-  if (Mnemonic == "isb" && DB->Encoding != AArch64DB::sy) {
+  auto DB = AArch64DB::lookupDBByName(Tok.getString());
+  if (Mnemonic == "isb" && (!DB || DB->Encoding != AArch64DB::sy)) {
     TokError("'sy' or #imm operand expected");
     return MatchOperand_ParseFail;
+  } else if (!DB) {
+    TokError("invalid barrier option name");
+    return MatchOperand_ParseFail;
   }
 
   Operands.push_back(AArch64Operand::CreateBarrier(
       DB->Encoding, Tok.getString(), getLoc(), getContext()));
   Parser.Lex(); // Consume the option
 
   return MatchOperand_Success;
 }

llvm/trunk/test/MC/AArch64/basic-a64-diagnostics.s

 // CHECK-ERROR-NEXT:         clrex #-1
 // CHECK-ERROR-NEXT:               ^
 // CHECK-ERROR-NEXT: error: {{expected|immediate must be an}} integer in range [0, 15]
 // CHECK-ERROR-NEXT:         clrex #16
 // CHECK-ERROR-NEXT:               ^
 
         dsb #-1
         dsb #16
+        dsb foo
         dmb #-1
         dmb #16
+        dmb foo
 // CHECK-ERROR-NEXT: error: {{Invalid immediate for instruction|barrier operand out of range}}
 // CHECK-ERROR-NEXT:         dsb #-1
 // CHECK-ERROR-NEXT:             ^
 // CHECK-ERROR-NEXT: error: {{Invalid immediate for instruction|barrier operand out of range}}
 // CHECK-ERROR-NEXT:         dsb #16
 // CHECK-ERROR-NEXT:             ^
+// CHECK-ERROR-NEXT: error: invalid barrier option name
+// CHECK-ERROR-NEXT:         dsb foo
+// CHECK-ERROR-NEXT:             ^
 // CHECK-ERROR-NEXT: error: {{Invalid immediate for instruction|barrier operand out of range}}
 // CHECK-ERROR-NEXT:         dmb #-1
 // CHECK-ERROR-NEXT:             ^
 // CHECK-ERROR-NEXT: error: {{Invalid immediate for instruction|barrier operand out of range}}
 // CHECK-ERROR-NEXT:         dmb #16
 // CHECK-ERROR-NEXT:             ^
+// CHECK-ERROR-NEXT: error: invalid barrier option name
+// CHECK-ERROR-NEXT:         dmb foo
+// CHECK-ERROR-NEXT:             ^
 
         isb #-1
         isb #16
+        isb foo
 // CHECK-ERROR-NEXT: error: {{Invalid immediate for instruction|barrier operand out of range}}
 // CHECK-ERROR-NEXT:         isb #-1
 // CHECK-ERROR-NEXT:             ^
 // CHECK-ERROR-NEXT: error: {{Invalid immediate for instruction|barrier operand out of range}}
 // CHECK-ERROR-NEXT:         isb #16
 // CHECK-ERROR-NEXT:             ^
+// CHECK-ERROR-NEXT: error: 'sy' or #imm operand expected
+// CHECK-ERROR-NEXT:        isb foo
+// CHECK-ERROR-NEXT:            ^
 
         msr daifset, x4
         msr spsel, #-1
         msr spsel #-1
         msr daifclr, #16
 // CHECK-ERROR: [[@LINE-4]]:22: error: {{expected|immediate must be an}} integer in range [0, 15]
 // CHECK-ERROR: [[@LINE-4]]:20: error: {{expected|immediate must be an}} integer in range [0, 15]
 // CHECK-ERROR: [[@LINE-4]]:{{9|19}}: error: {{too few operands for instruction|expected comma before next operand|unexpected token in argument list}}