[AMX] Error out when AMX DP instructions use same registers (#97686)

Fixes #97522

Author: phoebewang

llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp

@@ -3849,6 +3849,14 @@ bool X86AsmParser::validateInstruction(MCInst &Inst, const OperandVector &Ops) {
         return Warning(Ops[0]->getStartLoc(), "mask, index, and destination "
                                               "registers should be distinct");
     }
+  } else if (isTCMMIMFP16PS(Opcode) || isTCMMRLFP16PS(Opcode) ||
+             isTDPBF16PS(Opcode) || isTDPFP16PS(Opcode) || isTDPBSSD(Opcode) ||
+             isTDPBSUD(Opcode) || isTDPBUSD(Opcode) || isTDPBUUD(Opcode)) {
+    unsigned SrcDest = Inst.getOperand(0).getReg();
+    unsigned Src1 = Inst.getOperand(2).getReg();
+    unsigned Src2 = Inst.getOperand(3).getReg();
+    if (SrcDest == Src1 || SrcDest == Src2 || Src1 == Src2)
+      return Error(Ops[0]->getStartLoc(), "all tmm registers must be distinct");
   }
 
   // Check that we aren't mixing AH/BH/CH/DH with REX prefix. We only need to

llvm/test/MC/X86/AMX/amx-error.s

@@ -0,0 +1,25 @@
+// RUN: not llvm-mc -triple x86_64 %s 2>&1 | FileCheck %s
+
+// CHECK: error: all tmm registers must be distinct
+tcmmimfp16ps %tmm0, %tmm0, %tmm0
+
+// CHECK: error: all tmm registers must be distinct
+tcmmrlfp16ps %tmm1, %tmm0, %tmm1
+
+// CHECK: error: all tmm registers must be distinct
+tdpbf16ps %tmm2, %tmm2, %tmm0
+
+// CHECK: error: all tmm registers must be distinct
+tdpfp16ps %tmm3, %tmm0, %tmm0
+
+// CHECK: error: all tmm registers must be distinct
+tdpbssd %tmm0, %tmm0, %tmm0
+
+// CHECK: error: all tmm registers must be distinct
+tdpbsud %tmm1, %tmm0, %tmm1
+
+// CHECK: error: all tmm registers must be distinct
+tdpbusd %tmm2, %tmm2, %tmm0
+
+// CHECK: error: all tmm registers must be distinct
+tdpbuud %tmm3, %tmm0, %tmm0