d93f850c6f
Both OPC_ExtractField and OPC_CheckField are currently defined to take an unsigned 8-bit start value. On some architectures with long instruction words, this value can silently overflow, resulting in a bad decoder table. This patch changes each to take a ULE128B-encoded start value instead. Additionally, a range assertion is added for the 8-bit length to prominently notify a user in case that field ever overflows. This problem isn't currently exposed upstream since all in-tree targets use small instruction words (i.e., bitwidth <= 64 bits). It does show up in at least one downstream target with instructions > 64 bits long. Co-authored-by: Jason Eckhardt <jeckhardt@nvidia.com>
45 lines
1.4 KiB
TableGen
45 lines
1.4 KiB
TableGen
// RUN: llvm-tblgen -gen-disassembler -I %p/../../include %s | FileCheck %s
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// Test for OPC_ExtractField/OPC_CheckField with start bit > 255.
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// These large start values may arise for architectures with long instruction
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// words.
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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 = 64;
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let OutOperandList = (outs);
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let InOperandList = (ins);
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field bits<512> Inst;
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field bits<512> SoftFail = 0;
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}
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def InstA : TestInstruction {
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let Inst{509-502} = {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{509-502} = {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 */ MCD::OPC_ExtractField, 250, 3, 4, // Inst{509-506} ...
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// CHECK-NEXT: /* 4 */ MCD::OPC_FilterValue, 0, 19, 0, 0, // Skip to: 28
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// CHECK-NEXT: /* 9 */ MCD::OPC_CheckField, 248, 3, 2, 0, 7, 0, 0, // Skip to: 24
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// CHECK-NEXT: /* 17 */ MCD::OPC_TryDecode, {{[0-9]+}}, {{[0-9]+}}, 0, 0, 0, 0, // Opcode: InstB, skip to: 24
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// CHECK-NEXT: /* 24 */ MCD::OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 1, // Opcode: InstA
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// CHECK-NEXT: /* 28 */ MCD::OPC_Fail,
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// CHECK: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
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