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// SPDX-License-Identifier: GPL-3.0-or-later
#include "rcc/Target/RISCV/RISCVTargetConstant.h"
#include "rcc/Target/RISCV/RISCVTargetRelocationKinds.h"
#include <bit>
#include <charconv>
#include <cstddef>
#include <cstdint>
#include <string>
#include <string_view>
#include <system_error>
#include <utility>
#include <vector>
namespace rcc::riscv {
namespace {
[[nodiscard]] std::string_view kindSpelling(RISCVSymbolConstantKind Kind) noexcept {
switch (Kind) {
case RISCVSymbolConstantKind::GlobalValue:
return "global";
case RISCVSymbolConstantKind::ExternalSymbol:
return "external";
}
return {};
}
[[nodiscard]] Expected<RISCVSymbolConstantKind> parseKind(std::string_view Text) {
if (Text == "global")
return RISCVSymbolConstantKind::GlobalValue;
if (Text == "external")
return RISCVSymbolConstantKind::ExternalSymbol;
return makeUnexpected(ErrorCode::ParseError, "unknown RV64GC symbol constant kind");
}
void appendU64(std::vector<std::byte> &Bytes, std::uint64_t Value) {
for (std::uint8_t Shift = 0; Shift < 64; Shift += 8)
Bytes.push_back(static_cast<std::byte>(Value >> Shift));
}
[[nodiscard]] std::uint64_t readU64(std::span<const std::byte> Bytes) noexcept {
std::uint64_t Result = 0;
for (std::uint8_t Shift = 0; Shift < 64; Shift += 8)
Result |= std::to_integer<std::uint64_t>(Bytes[Shift / 8U]) << Shift;
return Result;
}
} // namespace
Expected<void> RISCVSymbolConstant::verify() const {
if (kindSpelling(ConstantKind).empty())
return makeUnexpected(ErrorCode::VerificationError, "RV64GC symbol constant kind is invalid");
if (SymbolName.empty() || SymbolName.find('\0') != std::string::npos) {
return makeUnexpected(ErrorCode::VerificationError,
"RV64GC symbol constant requires a valid symbol name");
}
return {};
}
Expected<RISCVSymbolConstant> RISCVSymbolConstant::clone() const {
return RISCVSymbolConstant(ConstantKind, SymbolName, SymbolAddend);
}
std::uint64_t RISCVSymbolConstant::stableHash() const noexcept {
constexpr std::uint64_t OffsetBasis = 14695981039346656037ULL;
constexpr std::uint64_t Prime = 1099511628211ULL;
std::uint64_t Hash = OffsetBasis;
const auto Mix = [&Hash](std::uint8_t Byte) {
Hash ^= Byte;
Hash *= Prime;
};
Mix(static_cast<std::uint8_t>(ConstantKind));
const std::uint64_t AddendBits = std::bit_cast<std::uint64_t>(SymbolAddend);
for (std::uint8_t Shift = 0; Shift < 64; Shift += 8)
Mix(static_cast<std::uint8_t>(AddendBits >> Shift));
for (const char Character : SymbolName)
Mix(static_cast<unsigned char>(Character));
return Hash;
}
std::string RISCVSymbolConstant::print() const {
return std::string(kindSpelling(ConstantKind)) + "," + std::to_string(SymbolAddend) + "," +
SymbolName;
}
Expected<std::vector<std::byte>> RISCVSymbolConstant::encode() const {
auto Verification = verify();
if (!Verification)
return std::unexpected(Verification.error());
std::vector<std::byte> Payload;
Payload.reserve(9U + SymbolName.size());
Payload.push_back(static_cast<std::byte>(static_cast<std::uint8_t>(ConstantKind)));
appendU64(Payload, std::bit_cast<std::uint64_t>(SymbolAddend));
for (const char Character : SymbolName)
Payload.push_back(static_cast<std::byte>(static_cast<unsigned char>(Character)));
return Payload;
}
Expected<TargetConstantEmission> RISCVSymbolConstant::emit() const {
auto Verification = verify();
if (!Verification)
return std::unexpected(Verification.error());
TargetConstantEmission Emission;
Emission.Bytes.resize(8);
Emission.Fixups.push_back(TargetConstantFixup{
.Offset = 0,
.Kind = targetRelocationKind(RISCVTargetRelocationKind::Absolute64),
.Symbol = SymbolName,
.Addend = SymbolAddend,
});
return Emission;
}
Alignment RISCVSymbolConstant::requiredAlignment() const noexcept {
return *Alignment::create(8);
}
std::optional<TargetRelocationKindID> RISCVSymbolConstant::relocationKind() const noexcept {
return targetRelocationKind(RISCVTargetRelocationKind::Absolute64);
}
Expected<RISCVSymbolConstant> RISCVSymbolConstant::parse(std::string_view Text) {
const std::size_t KindEnd = Text.find(',');
const std::size_t AddendEnd =
KindEnd == std::string_view::npos ? std::string_view::npos : Text.find(',', KindEnd + 1U);
if (KindEnd == std::string_view::npos || AddendEnd == std::string_view::npos) {
return makeUnexpected(ErrorCode::ParseError,
"RV64GC symbol constant must be 'kind,addend,symbol'");
}
auto Kind = parseKind(Text.substr(0, KindEnd));
if (!Kind)
return std::unexpected(Kind.error());
std::int64_t Addend = 0;
const std::string_view AddendText = Text.substr(KindEnd + 1U, AddendEnd - KindEnd - 1U);
const auto [End, Error] =
std::from_chars(AddendText.data(), AddendText.data() + AddendText.size(), Addend);
if (Error != std::errc{} || End != AddendText.data() + AddendText.size())
return makeUnexpected(ErrorCode::ParseError, "RV64GC symbol constant addend is invalid");
RISCVSymbolConstant Result(*Kind, std::string(Text.substr(AddendEnd + 1U)), Addend);
auto Verification = Result.verify();
if (!Verification)
return std::unexpected(Verification.error());
return Result;
}
Expected<RISCVSymbolConstant> RISCVSymbolConstant::decode(std::uint32_t Version,
std::span<const std::byte> Payload) {
if (Version != schemaVersion() || Payload.size() < 10) {
return makeUnexpected(ErrorCode::ParseError,
"encoded RV64GC symbol constant has an invalid version or size");
}
const auto KindValue = std::to_integer<std::uint8_t>(Payload.front());
if (KindValue > static_cast<std::uint8_t>(RISCVSymbolConstantKind::ExternalSymbol))
return makeUnexpected(ErrorCode::ParseError, "encoded RV64GC symbol constant kind is invalid");
std::string Symbol;
Symbol.reserve(Payload.size() - 9U);
for (const std::byte Character : Payload.subspan(9))
Symbol.push_back(static_cast<char>(std::to_integer<unsigned char>(Character)));
RISCVSymbolConstant Result(static_cast<RISCVSymbolConstantKind>(KindValue), std::move(Symbol),
std::bit_cast<std::int64_t>(readU64(Payload.subspan(1, 8))));
auto Verification = Result.verify();
if (!Verification)
return std::unexpected(Verification.error());
return Result;
}
} // namespace rcc::riscv
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