--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/llvm/test/TableGen/trydecode-emission.td	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,43 @@
+// RUN: llvm-tblgen -gen-disassembler -I %p/../../include %s | FileCheck %s
+
+// Check that if decoding of an instruction fails and the instruction does not
+// have a complete decoder method that can determine if the bitpattern is valid
+// or not then the decoder tries to find a more general instruction that
+// matches the bitpattern too.
+
+include "llvm/Target/Target.td"
+
+def archInstrInfo : InstrInfo { }
+
+def arch : Target {
+  let InstructionSet = archInstrInfo;
+}
+
+class TestInstruction : Instruction {
+  let Size = 1;
+  let OutOperandList = (outs);
+  let InOperandList = (ins);
+  field bits<8> Inst;
+  field bits<8> SoftFail = 0;
+}
+
+def InstA : TestInstruction {
+  let Inst = {0,0,0,0,?,?,?,?};
+  let AsmString = "InstA";
+}
+
+def InstB : TestInstruction {
+  let Inst = {0,0,0,0,0,0,?,?};
+  let AsmString = "InstB";
+  let DecoderMethod = "DecodeInstB";
+  let hasCompleteDecoder = 0;
+}
+
+// CHECK:      /* 0 */       MCD::OPC_ExtractField, 4, 4,  // Inst{7-4} ...
+// CHECK-NEXT: /* 3 */       MCD::OPC_FilterValue, 0, 18, 0, 0, // Skip to: 26
+// CHECK-NEXT: /* 8 */       MCD::OPC_CheckField, 2, 2, 0, 7, 0, 0, // Skip to: 22
+// CHECK-NEXT: /* 15 */      MCD::OPC_TryDecode, {{[0-9]+}}, 1, 0, 0, 0, 0, // Opcode: InstB, skip to: 22
+// CHECK-NEXT: /* 22 */      MCD::OPC_Decode, {{[0-9]+}}, 1, 1, // Opcode: InstA
+// CHECK-NEXT: /* 26 */      MCD::OPC_Fail,
+
+// CHECK: if (DecodeInstB(MI, insn, Address, Decoder) == MCDisassembler::Fail) { DecodeComplete = false; return MCDisassembler::Fail; }