82acc31fd4
OPC_Decode is a specialized OPC_TryDecode. The difference between them is that OPC_TryDecode performs a "completeness check", while OPC_Decode asserts that the check passes. The check is just a boolean test, which is nothing compared to the complexity of the decoding process, so there is no point in having a special opcode that optimizes the check.
63 lines
2.6 KiB
TableGen
63 lines
2.6 KiB
TableGen
// RUN: llvm-tblgen -gen-disassembler -I %p/../../../include %s | FileCheck %s
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// RUN: llvm-tblgen -gen-disassembler --large-decoder-table -I %p/../../../include %s | FileCheck %s --check-prefix=CHECK-LARGE
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// Check that if decoding of an instruction fails and the instruction does not
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// have a complete decoder method that can determine if the bitpattern is valid
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// or not then the decoder tries to find a more general instruction that
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// matches the bitpattern too.
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include "llvm/Target/Target.td"
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def archInstrInfo : InstrInfo { }
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def arch : Target {
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let InstructionSet = archInstrInfo;
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}
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class TestInstruction : Instruction {
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let Size = 1;
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let OutOperandList = (outs);
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let InOperandList = (ins);
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field bits<8> Inst;
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field bits<8> SoftFail = 0;
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}
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def InstA : TestInstruction {
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let Inst = {0,0,0,0,?,?,?,?};
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let AsmString = "InstA";
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}
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def InstB : TestInstruction {
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let Inst = {0,0,0,0,0,0,?,?};
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let AsmString = "InstB";
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let DecoderMethod = "DecodeInstB";
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let hasCompleteDecoder = 0;
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}
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// CHECK: /* 0 */ OPC_CheckField, 4, 4, 0, // if Inst{7-4} != 0x0
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// CHECK-NEXT: /* 4 */ OPC_Scope, 8, 0, // end scope at 15
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// CHECK-NEXT: /* 7 */ OPC_CheckField, 2, 2, 0, // if Inst{3-2} != 0x0
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// CHECK-NEXT: /* 11 */ OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 0, // Opcode: InstB, DecodeIdx: 0
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// CHECK-NEXT: /* 15 */ OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 1, // Opcode: InstA, DecodeIdx: 1
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// CHECK-NEXT: };
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// CHECK: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
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// CHECK: unsigned NumToSkip = *Ptr++;
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// CHECK-NEXT: NumToSkip |= (*Ptr++) << 8;
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// CHECK-NEXT: return NumToSkip;
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// CHECK-LARGE: /* 0 */ OPC_CheckField, 4, 4, 0, // if Inst{7-4} != 0x0
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// CHECK-LARGE-NEXT: /* 4 */ OPC_Scope, 8, 0, 0, // end scope at 16
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// CHECK-LARGE-NEXT: /* 8 */ OPC_CheckField, 2, 2, 0, // if Inst{3-2} != 0x0
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// CHECK-LARGE-NEXT: /* 12 */ OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 0, // Opcode: InstB, DecodeIdx: 0
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// CHECK-LARGE-NEXT: /* 16 */ OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 1, // Opcode: InstA, DecodeIdx: 1
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// CHECK-LARGE-NEXT: };
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// CHECK-LARGE: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
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// CHECK-LARGE: unsigned NumToSkip = *Ptr++;
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// CHECK-LARGE-NEXT: NumToSkip |= (*Ptr++) << 8;
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// CHECK-LARGE-NEXT: NumToSkip |= (*Ptr++) << 16;
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// CHECK-LARGE-NEXT: return NumToSkip;
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