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//===--- EnumSizeCheck.cpp - clang-tidy -----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "EnumSizeCheck.h"
#include "../utils/Matchers.h"
#include "../utils/OptionsUtils.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include <algorithm>
#include <cinttypes>
#include <cstdint>
#include <limits>
#include <utility>
using namespace clang::ast_matchers;
namespace clang::tidy::performance {
namespace {
AST_MATCHER(EnumDecl, hasEnumerators) { return !Node.enumerators().empty(); }
const std::uint64_t Min8 =
std::imaxabs(std::numeric_limits<std::int8_t>::min());
const std::uint64_t Max8 = std::numeric_limits<std::int8_t>::max();
const std::uint64_t Min16 =
std::imaxabs(std::numeric_limits<std::int16_t>::min());
const std::uint64_t Max16 = std::numeric_limits<std::int16_t>::max();
const std::uint64_t Min32 =
std::imaxabs(std::numeric_limits<std::int32_t>::min());
const std::uint64_t Max32 = std::numeric_limits<std::int32_t>::max();
std::pair<const char *, std::uint32_t>
getNewType(std::size_t Size, std::uint64_t Min, std::uint64_t Max) noexcept {
if (Min) {
if (Min <= Min8 && Max <= Max8) {
return {"std::int8_t", sizeof(std::int8_t)};
}
if (Min <= Min16 && Max <= Max16 && Size > sizeof(std::int16_t)) {
return {"std::int16_t", sizeof(std::int16_t)};
}
if (Min <= Min32 && Max <= Max32 && Size > sizeof(std::int32_t)) {
return {"std::int32_t", sizeof(std::int32_t)};
}
return {};
}
if (Max) {
if (Max <= std::numeric_limits<std::uint8_t>::max()) {
return {"std::uint8_t", sizeof(std::uint8_t)};
}
if (Max <= std::numeric_limits<std::uint16_t>::max() &&
Size > sizeof(std::uint16_t)) {
return {"std::uint16_t", sizeof(std::uint16_t)};
}
if (Max <= std::numeric_limits<std::uint32_t>::max() &&
Size > sizeof(std::uint32_t)) {
return {"std::uint32_t", sizeof(std::uint32_t)};
}
return {};
}
// Zero case
return {"std::uint8_t", sizeof(std::uint8_t)};
}
} // namespace
EnumSizeCheck::EnumSizeCheck(StringRef Name, ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
EnumIgnoreList(
utils::options::parseStringList(Options.get("EnumIgnoreList", ""))) {}
void EnumSizeCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "EnumIgnoreList",
utils::options::serializeStringList(EnumIgnoreList));
}
bool EnumSizeCheck::isLanguageVersionSupported(
const LangOptions &LangOpts) const {
return LangOpts.CPlusPlus11;
}
void EnumSizeCheck::registerMatchers(MatchFinder *Finder) {
Finder->addMatcher(
enumDecl(unless(isExpansionInSystemHeader()), isDefinition(),
hasEnumerators(),
unless(matchers::matchesAnyListedName(EnumIgnoreList)))
.bind("e"),
this);
}
void EnumSizeCheck::check(const MatchFinder::MatchResult &Result) {
const auto *MatchedDecl = Result.Nodes.getNodeAs<EnumDecl>("e");
const QualType BaseType = MatchedDecl->getIntegerType().getCanonicalType();
if (!BaseType->isIntegerType())
return;
const std::uint32_t Size = Result.Context->getTypeSize(BaseType) / 8U;
if (1U == Size)
return;
std::uint64_t MinV = 0U;
std::uint64_t MaxV = 0U;
for (const auto &It : MatchedDecl->enumerators()) {
const llvm::APSInt &InitVal = It->getInitVal();
if ((InitVal.isUnsigned() || InitVal.isNonNegative())) {
MaxV = std::max<std::uint64_t>(MaxV, InitVal.getZExtValue());
} else {
MinV = std::max<std::uint64_t>(MinV, InitVal.abs().getZExtValue());
}
}
auto NewType = getNewType(Size, MinV, MaxV);
if (!NewType.first || Size <= NewType.second)
return;
diag(MatchedDecl->getLocation(),
"enum %0 uses a larger base type (%1, size: %2 %select{byte|bytes}5) "
"than necessary for its value set, consider using '%3' (%4 "
"%select{byte|bytes}6) as the base type to reduce its size")
<< MatchedDecl << MatchedDecl->getIntegerType() << Size << NewType.first
<< NewType.second << (Size > 1U) << (NewType.second > 1U);
}
} // namespace clang::tidy::performance
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