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// SPDX-License-Identifier: GPL-3.0-or-later
#include "rcc/MC/MCExpr.h"
#include <cstddef>
#include <cstdint>
#include <limits>
#include <memory>
#include <optional>
#include <utility>
namespace rcc::mc {
namespace {
[[nodiscard]] std::optional<std::int64_t> checkedUnary(MCUnaryOperator Operator,
std::int64_t Value) noexcept {
switch (Operator) {
case MCUnaryOperator::Plus:
return Value;
case MCUnaryOperator::Minus:
if (Value == std::numeric_limits<std::int64_t>::min())
return std::nullopt;
return -Value;
case MCUnaryOperator::BitwiseNot:
return ~Value;
case MCUnaryOperator::LogicalNot:
return Value == 0 ? 1 : 0;
}
return std::nullopt;
}
[[nodiscard]] std::optional<std::int64_t>
checkedBinary(MCBinaryOperator Operator, std::int64_t Left, std::int64_t Right) noexcept {
std::int64_t Result = 0;
switch (Operator) {
case MCBinaryOperator::Add:
return __builtin_add_overflow(Left, Right, &Result) ? std::nullopt : std::optional(Result);
case MCBinaryOperator::Subtract:
return __builtin_sub_overflow(Left, Right, &Result) ? std::nullopt : std::optional(Result);
case MCBinaryOperator::Multiply:
return __builtin_mul_overflow(Left, Right, &Result) ? std::nullopt : std::optional(Result);
case MCBinaryOperator::Divide:
if (Right == 0 || (Left == std::numeric_limits<std::int64_t>::min() && Right == -1))
return std::nullopt;
return Left / Right;
case MCBinaryOperator::Modulo:
if (Right == 0 || (Left == std::numeric_limits<std::int64_t>::min() && Right == -1))
return std::nullopt;
return Left % Right;
case MCBinaryOperator::ShiftLeft:
if (Right < 0 || Right >= 64)
return std::nullopt;
if (Right == 63) {
if (Left == 0)
return 0;
return Left == -1 ? std::optional(std::numeric_limits<std::int64_t>::min()) : std::nullopt;
}
if (__builtin_mul_overflow(Left, std::int64_t{1} << Right, &Result))
return std::nullopt;
return Result;
case MCBinaryOperator::ShiftRight:
if (Right < 0 || Right >= 64)
return std::nullopt;
return Left >> Right;
case MCBinaryOperator::BitwiseAnd:
return Left & Right;
case MCBinaryOperator::BitwiseOr:
return Left | Right;
case MCBinaryOperator::BitwiseXor:
return Left ^ Right;
case MCBinaryOperator::LogicalAnd:
return Left != 0 && Right != 0 ? 1 : 0;
case MCBinaryOperator::LogicalOr:
return Left != 0 || Right != 0 ? 1 : 0;
case MCBinaryOperator::Equal:
return Left == Right ? 1 : 0;
case MCBinaryOperator::NotEqual:
return Left != Right ? 1 : 0;
case MCBinaryOperator::Less:
return Left < Right ? 1 : 0;
case MCBinaryOperator::LessEqual:
return Left <= Right ? 1 : 0;
case MCBinaryOperator::Greater:
return Left > Right ? 1 : 0;
case MCBinaryOperator::GreaterEqual:
return Left >= Right ? 1 : 0;
}
return std::nullopt;
}
[[nodiscard]] Expected<void> verifyExpression(const MCExpr &Expression, std::size_t Depth,
std::size_t MaximumDepth) {
if (Depth > MaximumDepth)
return makeUnexpected(ErrorCode::InvalidArgument, "MC expression exceeds its depth limit");
switch (Expression.kind()) {
case MCExpr::Kind::Constant:
if (Expression.getIf<std::int64_t>() == nullptr)
return makeUnexpected(ErrorCode::InternalError, "MC constant expression storage is invalid");
return {};
case MCExpr::Kind::SymbolRef: {
const auto *Reference = Expression.getIf<MCSymbolRefExpr>();
if (Reference == nullptr || !Reference->Symbol || Reference->Symbol->name().empty()) {
return makeUnexpected(ErrorCode::InvalidArgument,
"MC symbol expression requires a valid symbol");
}
return {};
}
case MCExpr::Kind::Unary: {
const auto *Unary = Expression.getIf<MCUnaryExpr>();
if (Unary == nullptr || !Unary->Operand)
return makeUnexpected(ErrorCode::InvalidArgument, "MC unary expression has no operand");
return verifyExpression(*Unary->Operand, Depth + 1, MaximumDepth);
}
case MCExpr::Kind::Binary: {
const auto *Binary = Expression.getIf<MCBinaryExpr>();
if (Binary == nullptr || !Binary->Left || !Binary->Right)
return makeUnexpected(ErrorCode::InvalidArgument, "MC binary expression has a null operand");
auto Left = verifyExpression(*Binary->Left, Depth + 1, MaximumDepth);
if (!Left)
return std::unexpected(Left.error());
return verifyExpression(*Binary->Right, Depth + 1, MaximumDepth);
}
case MCExpr::Kind::Target: {
const auto *Target = Expression.getIf<MCTargetExpr>();
if (Target == nullptr || Target->Kind == 0 || !Target->Operand) {
return makeUnexpected(ErrorCode::InvalidArgument,
"target MC expression requires a nonzero kind and an operand");
}
return verifyExpression(*Target->Operand, Depth + 1, MaximumDepth);
}
}
return makeUnexpected(ErrorCode::InternalError, "MC expression kind is invalid");
}
} // namespace
MCExprRef MCExpr::constant(std::int64_t Value) {
return std::shared_ptr<const MCExpr>(new MCExpr(Kind::Constant, Value));
}
Expected<MCExprRef> MCExpr::symbol(MCSymbolRef Symbol) {
if (!Symbol || Symbol->name().empty())
return makeUnexpected(ErrorCode::InvalidArgument, "MC symbol expression requires a symbol");
return std::shared_ptr<const MCExpr>(
new MCExpr(Kind::SymbolRef, MCSymbolRefExpr{.Symbol = std::move(Symbol)}));
}
Expected<MCExprRef> MCExpr::unary(MCUnaryOperator Operator, MCExprRef Operand) {
if (!Operand)
return makeUnexpected(ErrorCode::InvalidArgument, "MC unary expression requires an operand");
return std::shared_ptr<const MCExpr>(
new MCExpr(Kind::Unary, MCUnaryExpr{.Operator = Operator, .Operand = std::move(Operand)}));
}
Expected<MCExprRef> MCExpr::binary(MCBinaryOperator Operator, MCExprRef Left, MCExprRef Right) {
if (!Left || !Right)
return makeUnexpected(ErrorCode::InvalidArgument, "MC binary expression requires two operands");
return std::shared_ptr<const MCExpr>(new MCExpr(
Kind::Binary,
MCBinaryExpr{.Operator = Operator, .Left = std::move(Left), .Right = std::move(Right)}));
}
Expected<MCExprRef> MCExpr::target(std::uint32_t Kind, MCExprRef Operand) {
if (Kind == 0 || !Operand) {
return makeUnexpected(ErrorCode::InvalidArgument,
"target MC expression requires a nonzero kind and an operand");
}
return std::shared_ptr<const MCExpr>(
new MCExpr(MCExpr::Kind::Target, MCTargetExpr{.Kind = Kind, .Operand = std::move(Operand)}));
}
Expected<void> MCExpr::verify(std::size_t MaximumDepth) const {
if (MaximumDepth == 0)
return makeUnexpected(ErrorCode::InvalidArgument, "MC expression depth limit cannot be zero");
return verifyExpression(*this, 1, MaximumDepth);
}
std::optional<std::int64_t> MCExpr::evaluateAbsolute() const noexcept {
switch (ExpressionKind) {
case Kind::Constant:
return *getIf<std::int64_t>();
case Kind::SymbolRef:
case Kind::Target:
return std::nullopt;
case Kind::Unary: {
const auto *Unary = getIf<MCUnaryExpr>();
if (Unary == nullptr || !Unary->Operand)
return std::nullopt;
const auto Value = Unary->Operand->evaluateAbsolute();
return Value ? checkedUnary(Unary->Operator, *Value) : std::nullopt;
}
case Kind::Binary: {
const auto *Binary = getIf<MCBinaryExpr>();
if (Binary == nullptr || !Binary->Left || !Binary->Right)
return std::nullopt;
const auto Left = Binary->Left->evaluateAbsolute();
const auto Right = Binary->Right->evaluateAbsolute();
return Left && Right ? checkedBinary(Binary->Operator, *Left, *Right) : std::nullopt;
}
}
return std::nullopt;
}
} // namespace rcc::mc
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