[AMDGPU][MC][GFX11] Improve diagnostic messages for invalid VOPD syntax

[Joe_Nash]

LGTM

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

if (isSupportedMnemo(Mnemo, FeatureBitset().set())) {
     return Error(IDLoc, "instruction not supported on this GPU");
   }
 
   // Instruction not supported on any GPU. Probably a typo.
   std::string Suggestion = AMDGPUMnemonicSpellCheck(Mnemo, FBS);
   return Error(IDLoc, "invalid instruction" + Suggestion);
 }
 
+static bool isInvalidVOPDY(const OperandVector &Operands,
+                           uint64_t InvalidOprIdx) {
+  assert(InvalidOprIdx < Operands.size());
+  const auto &Op = ((AMDGPUOperand &)*Operands[InvalidOprIdx]);
+  if (Op.isToken() && InvalidOprIdx > 1) {
+    const auto &PrevOp = ((AMDGPUOperand &)*Operands[InvalidOprIdx - 1]);
+    return PrevOp.isToken() && PrevOp.getToken() == "::";
+  }
+  return false;
+}
+
 bool AMDGPUAsmParser::MatchAndEmitInstruction(SMLoc IDLoc, unsigned &Opcode,
                                               OperandVector &Operands,
                                               MCStreamer &Out,
                                               uint64_t &ErrorInfo,
                                               bool MatchingInlineAsm) {
   MCInst Inst;
   unsigned Result = Match_Success;
   for (auto Variant : getMatchedVariants()) {
case Match_InvalidOperand: {
     SMLoc ErrorLoc = IDLoc;
     if (ErrorInfo != ~0ULL) {
       if (ErrorInfo >= Operands.size()) {
         return Error(IDLoc, "too few operands for instruction");
       }
       ErrorLoc = ((AMDGPUOperand &)*Operands[ErrorInfo]).getStartLoc();
       if (ErrorLoc == SMLoc())
         ErrorLoc = IDLoc;
+
+      if (isInvalidVOPDY(Operands, ErrorInfo))
+        return Error(ErrorLoc, "invalid VOPDY instruction");
     }
     return Error(ErrorLoc, "invalid operand for instruction");
   }
 
   case Match_PreferE32:
     return Error(IDLoc, "internal error: instruction without _e64 suffix "
                         "should be encoded as e32");
   case Match_MnemonicFail:
OperandMatchResultTy AMDGPUAsmParser::parseVOPD(OperandVector &Operands) {
   if (!hasVOPD(getSTI()))
     return MatchOperand_NoMatch;
 
   if (isToken(AsmToken::Colon) && peekToken(false).is(AsmToken::Colon)) {
     SMLoc S = getLoc();
     lex();
     lex();
     Operands.push_back(AMDGPUOperand::CreateToken(this, "::", S));
+    SMLoc OpYLoc = getLoc();
     StringRef OpYName;
     if (isToken(AsmToken::Identifier) && !Parser.parseIdentifier(OpYName)) {
-      Operands.push_back(AMDGPUOperand::CreateToken(this, OpYName, S));
+      Operands.push_back(AMDGPUOperand::CreateToken(this, OpYName, OpYLoc));
       return MatchOperand_Success;
     }
-    Error(S, "invalid VOPD :: usage");
+    Error(OpYLoc, "expected a VOPDY instruction after ::");
     return MatchOperand_ParseFail;
   }
   return MatchOperand_NoMatch;
 }
 
 // Create VOPD MCInst operands using parsed assembler operands.
 void AMDGPUAsmParser::cvtVOPD(MCInst &Inst, const OperandVector &Operands) {
   auto addOp = [&](uint16_t i) { // NOLINT:function pointer

llvm/test/MC/AMDGPU/gfx11_asm_vopd_err.s

 // GFX11: error: src2 operands must use different VGPR banks
 // GFX11-NEXT:{{^}}v_dual_fmac_f32     v7, v1, v2                   :: v_dual_fmamk_f32      v6, v2, 0xaf123456, v3
 // GFX11-NEXT:{{^}}                                                                                              ^
 
 v_dual_fmamk_f32    v6, v1, 0xaf123456, v3       :: v_dual_fmac_f32       v5, v2, v3
 // GFX11: error: src2 operands must use different VGPR banks
 // GFX11-NEXT:{{^}}v_dual_fmamk_f32    v6, v1, 0xaf123456, v3       :: v_dual_fmac_f32       v5, v2, v3
 // GFX11-NEXT:{{^}}                                                                          ^
+
+//===----------------------------------------------------------------------===//
+// Check invalid VOPD syntax.
+//===----------------------------------------------------------------------===//
+
+v_dual_fmamk_f32    v6, v1, 0xaf123456, v2       : : v_dual_fmac_f32       v5, v2, v3
+// GFX11: error: unknown token in expression
+// GFX11-NEXT:{{^}}v_dual_fmamk_f32    v6, v1, 0xaf123456, v2       : : v_dual_fmac_f32       v5, v2, v3
+// GFX11-NEXT:{{^}}                                                 ^
+
+v_dual_fmamk_f32    v6, v1, 0xaf123456, v3
+// GFX11: error: too few operands for instruction
+// GFX11-NEXT:{{^}}v_dual_fmamk_f32    v6, v1, 0xaf123456, v3
+// GFX11-NEXT:{{^}}^
+
+v_dual_fmamk_f32    v6, v1, 0xaf123456, v2       :: v_dual_fmac_f32
+// GFX11: error: too few operands for instruction
+// GFX11-NEXT:{{^}}v_dual_fmamk_f32    v6, v1, 0xaf123456, v2       :: v_dual_fmac_f32
+// GFX11-NEXT:{{^}}^
+
+v_dual_add_f32      v255, v4 :: v_add_f32 v6, v1, v3
+// GFX11: error: invalid operand for instruction
+// GFX11-NEXT:{{^}}v_dual_add_f32      v255, v4 :: v_add_f32 v6, v1, v3
+// GFX11-NEXT:{{^}}                             ^
+
+v_dual_fmamk_f32    v6, v1, 0xaf123456, v3 ::
+// GFX11: error: expected a VOPDY instruction after ::
+// GFX11-NEXT:{{^}}v_dual_fmamk_f32    v6, v1, 0xaf123456, v3 ::
+// GFX11-NEXT:{{^}}                                             ^
+
+v_add_f32           v6, v1, v3 ::
+// GFX11: error: expected a VOPDY instruction after ::
+// GFX11-NEXT:{{^}}v_add_f32           v6, v1, v3 ::
+// GFX11-NEXT:{{^}}                                 ^
+
+v_dual_add_f32      v255::
+// GFX11: error: expected a VOPDY instruction after ::
+// GFX11-NEXT:{{^}}v_dual_add_f32      v255::
+// GFX11-NEXT:{{^}}                          ^
+
+v_dual_add_f32      v255, v4, v2 :: v_add_f32 v6, v1, v3
+// GFX11: error: invalid VOPDY instruction
+// GFX11-NEXT:{{^}}v_dual_add_f32      v255, v4, v2 :: v_add_f32 v6, v1, v3
+// GFX11-NEXT:{{^}}                                    ^