Fix a problem in previous commit. For GFX940 keep the original

behavior, i.e., op_sel should be 0 for all DOT instructions,
not just the VOP3P DOTs.

Author: jwanggit86

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

@@ -4626,9 +4626,10 @@ bool AMDGPUAsmParser::validateOpSel(const MCInst &Inst) {
 
   uint64_t TSFlags = MII.get(Opc).TSFlags;
 
-  // For VOP3P DOT instructions, op_sel must be 0 if present, and op_sel_hi
-  // cannot be present.
-  if ((TSFlags & SIInstrFlags::IsDOT) && (TSFlags & SIInstrFlags::VOP3P)) {
+  // For DOT instructions on GFX940, or VOP3P DOT instructions on all targets,
+  // op_sel must be 0 if present, and op_sel_hi cannot be present.
+  if ((TSFlags & SIInstrFlags::IsDOT) &&
+      (isGFX940() || (TSFlags & SIInstrFlags::VOP3P))) {
     int OpSelIdx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::op_sel);
     if (OpSelIdx != -1) {
       if (Inst.getOperand(OpSelIdx).getImm() != 0)