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Give the encode table an explicit operand index for control flow target
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@ZehMatt
ZehMatt committed Jun 18, 2024
1 parent 0892476 commit 73069b8
Showing 1 changed file with 36 additions and 28 deletions.
64 changes: 36 additions & 28 deletions zasm/src/zasm/src/encoder/encoder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -33,11 +33,19 @@ namespace zasm

static constexpr std::int32_t kHintRequiresSize = -1;

static constexpr auto kAllowedEncodingX86 = static_cast<ZydisEncodableEncoding>(
ZYDIS_ENCODABLE_ENCODING_LEGACY | ZYDIS_ENCODABLE_ENCODING_3DNOW);

static constexpr auto kAllowedEncodingX64 = static_cast<ZydisEncodableEncoding>(
ZYDIS_ENCODABLE_ENCODING_LEGACY | ZYDIS_ENCODABLE_ENCODING_3DNOW | ZYDIS_ENCODABLE_ENCODING_XOP
| ZYDIS_ENCODABLE_ENCODING_VEX | ZYDIS_ENCODABLE_ENCODING_EVEX);

struct EncodeVariantsInfo
{
bool isControlFlow{};
std::int8_t encodeSizeRel8{ -1 };
std::int8_t encodeSizeRel32{ -1 };
std::int8_t cfOperandIndex{ -1 };

constexpr bool canEncodeRel8() const noexcept
{
Expand All @@ -55,32 +63,30 @@ namespace zasm
std::array<EncodeVariantsInfo, ZydisMnemonic::ZYDIS_MNEMONIC_MAX_VALUE> data{};

// NOLINTBEGIN(cppcoreguidelines-avoid-magic-numbers, readability-magic-numbers)
data[ZYDIS_MNEMONIC_JMP] = EncodeVariantsInfo{ true, 2, 5 };
data[ZYDIS_MNEMONIC_JB] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JBE] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JCXZ] = EncodeVariantsInfo{ true, 2, -1 };
data[ZYDIS_MNEMONIC_JECXZ] = EncodeVariantsInfo{ true, 2, -1 };
data[ZYDIS_MNEMONIC_JKNZD] = EncodeVariantsInfo{ true, 2, 5 };
data[ZYDIS_MNEMONIC_JKZD] = EncodeVariantsInfo{ true, 2, 5 };
data[ZYDIS_MNEMONIC_JRCXZ] = EncodeVariantsInfo{ true, 2, -1 };
data[ZYDIS_MNEMONIC_JL] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JLE] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JNB] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JNBE] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JNL] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JNLE] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JNO] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JNP] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JNS] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JNZ] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JO] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JP] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JS] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_JZ] = EncodeVariantsInfo{ true, 2, 6 };
data[ZYDIS_MNEMONIC_LOOP] = EncodeVariantsInfo{ true, 2, -1 };
data[ZYDIS_MNEMONIC_LOOPE] = EncodeVariantsInfo{ true, 2, -1 };
data[ZYDIS_MNEMONIC_LOOPNE] = EncodeVariantsInfo{ true, 2, -1 };
data[ZYDIS_MNEMONIC_CALL] = EncodeVariantsInfo{ true, -1, 5 };
data[ZYDIS_MNEMONIC_JMP] = EncodeVariantsInfo{ true, 2, 5, 0 };
data[ZYDIS_MNEMONIC_JB] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JBE] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JCXZ] = EncodeVariantsInfo{ true, 2, -1, 0 };
data[ZYDIS_MNEMONIC_JECXZ] = EncodeVariantsInfo{ true, 2, -1, 0 };
data[ZYDIS_MNEMONIC_JRCXZ] = EncodeVariantsInfo{ true, 2, -1, 0 };
data[ZYDIS_MNEMONIC_JL] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JLE] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JNB] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JNBE] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JNL] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JNLE] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JNO] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JNP] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JNS] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JNZ] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JO] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JP] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JS] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_JZ] = EncodeVariantsInfo{ true, 2, 6, 0 };
data[ZYDIS_MNEMONIC_LOOP] = EncodeVariantsInfo{ true, 2, -1, 0 };
data[ZYDIS_MNEMONIC_LOOPE] = EncodeVariantsInfo{ true, 2, -1, 0 };
data[ZYDIS_MNEMONIC_LOOPNE] = EncodeVariantsInfo{ true, 2, -1, 0 };
data[ZYDIS_MNEMONIC_CALL] = EncodeVariantsInfo{ true, -1, 5, 0 };
// NOLINTEND(cppcoreguidelines-avoid-magic-numbers, readability-magic-numbers)

return data;
Expand Down Expand Up @@ -234,7 +240,7 @@ namespace zasm
}

// Check if this operand is used as the control flow target.
if (state.operandIndex == 0 && encodeInfo.isControlFlow)
if (encodeInfo.isControlFlow && state.operandIndex == encodeInfo.cfOperandIndex)
{
const auto targetAddress = labelVA.has_value() ? *labelVA : immValue;

Expand Down Expand Up @@ -289,7 +295,7 @@ namespace zasm

// Check if this operand is used as the control flow target.
const auto& encodeInfo = getEncodeVariantInfo(state.req.mnemonic);
if (state.operandIndex == 0 && encodeInfo.isControlFlow)
if (encodeInfo.isControlFlow && state.operandIndex == encodeInfo.cfOperandIndex)
{
const auto targetAddress = immValue;
const auto [addrRel, branchType] = processRelAddress(encodeInfo, ctx, targetAddress);
Expand Down Expand Up @@ -533,10 +539,12 @@ namespace zasm
if (mode == MachineMode::AMD64)
{
req.machine_mode = ZYDIS_MACHINE_MODE_LONG_64;
req.allowed_encodings = kAllowedEncodingX64;
}
else if (mode == MachineMode::I386)
{
req.machine_mode = ZYDIS_MACHINE_MODE_LONG_COMPAT_32;
req.allowed_encodings = kAllowedEncodingX86;
}
req.mnemonic = static_cast<ZydisMnemonic>(mnemonic.value());
req.prefixes = getAttribs(attribs);
Expand Down

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