[AMDGPU][MC] Corrected error position for invalid operands

[dp]

Summary

Generic parser may report an incorrect error position when an offending operand is followed by a comma.

See bug 48884 for details.

llvm/lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp

bool AMDGPUAsmParser::ParseInstruction(ParseInstructionInfo &Info,
   bool IsMIMG = Name.startswith("image_");
 
   while (!trySkipToken(AsmToken::EndOfStatement)) {
     OperandMode Mode = OperandMode_Default;
     if (IsMIMG && isGFX10Plus() && Operands.size() == 2)
       Mode = OperandMode_NSA;
     OperandMatchResultTy Res = parseOperand(Operands, Name, Mode);
 
-    // Eat the comma or space if there is one.
-    trySkipToken(AsmToken::Comma);
-
     if (Res != MatchOperand_Success) {
       checkUnsupportedInstruction(Name, NameLoc);
       if (!Parser.hasPendingError()) {
         // FIXME: use real operand location rather than the current location.
         StringRef Msg =
           (Res == MatchOperand_ParseFail) ? "failed parsing operand." :
                                             "not a valid operand.";
         Error(getLoc(), Msg);
       }
       while (!trySkipToken(AsmToken::EndOfStatement)) {
         lex();
       }
       return true;
     }
+
+    // Eat the comma or space if there is one.
+    trySkipToken(AsmToken::Comma);
   }
 
   return false;
 }
 
 //===----------------------------------------------------------------------===//
 // Utility functions
 //===----------------------------------------------------------------------===//

llvm/test/MC/AMDGPU/gfx10_err_pos.s

 // CHECK-NEXT:{{^}}image_load v[0:1], v0, s[0:7] dmask:0x9 dim:1 D
 // CHECK-NEXT:{{^}}                                              ^
 
 v_ceil_f16 v0, abs(neg(1))
 // CHECK: error: failed parsing operand.
 // CHECK-NEXT:{{^}}v_ceil_f16 v0, abs(neg(1))
 // CHECK-NEXT:{{^}}                   ^
 
+image_atomic_xor v4, v32, s[96:103] dmask:0x1 dim:, glc
+// CHECK: error: failed parsing operand.
+// CHECK-NEXT:{{^}}image_atomic_xor v4, v32, s[96:103] dmask:0x1 dim:, glc
+// CHECK-NEXT:{{^}}                                                  ^
+
 //==============================================================================
 // first register index should not exceed second index
 
 s_mov_b64 s[10:11], s[1:0]
 // CHECK: error: first register index should not exceed second index
 // CHECK-NEXT:{{^}}s_mov_b64 s[10:11], s[1:0]
 // CHECK-NEXT:{{^}}                      ^