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//===--- DurationFactoryScaleCheck.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 "DurationFactoryScaleCheck.h"
#include "DurationRewriter.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Tooling/FixIt.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace abseil {
// Given the name of a duration factory function, return the appropriate
// `DurationScale` for that factory. If no factory can be found for
// `FactoryName`, return `None`.
static llvm::Optional<DurationScale>
getScaleForFactory(llvm::StringRef FactoryName) {
static const std::unordered_map<std::string, DurationScale> ScaleMap(
{{"Nanoseconds", DurationScale::Nanoseconds},
{"Microseconds", DurationScale::Microseconds},
{"Milliseconds", DurationScale::Milliseconds},
{"Seconds", DurationScale::Seconds},
{"Minutes", DurationScale::Minutes},
{"Hours", DurationScale::Hours}});
auto ScaleIter = ScaleMap.find(FactoryName);
if (ScaleIter == ScaleMap.end())
return llvm::None;
return ScaleIter->second;
}
// Given either an integer or float literal, return its value.
// One and only one of `IntLit` and `FloatLit` should be provided.
static double GetValue(const IntegerLiteral *IntLit,
const FloatingLiteral *FloatLit) {
if (IntLit)
return IntLit->getValue().getLimitedValue();
assert(FloatLit != nullptr && "Neither IntLit nor FloatLit set");
return FloatLit->getValueAsApproximateDouble();
}
// Given the scale of a duration and a `Multiplier`, determine if `Multiplier`
// would produce a new scale. If so, return a tuple containing the new scale
// and a suitable Multipler for that scale, otherwise `None`.
static llvm::Optional<std::tuple<DurationScale, double>>
GetNewScaleSingleStep(DurationScale OldScale, double Multiplier) {
switch (OldScale) {
case DurationScale::Hours:
if (Multiplier <= 1.0 / 60.0)
return std::make_tuple(DurationScale::Minutes, Multiplier * 60.0);
break;
case DurationScale::Minutes:
if (Multiplier >= 60.0)
return std::make_tuple(DurationScale::Hours, Multiplier / 60.0);
if (Multiplier <= 1.0 / 60.0)
return std::make_tuple(DurationScale::Seconds, Multiplier * 60.0);
break;
case DurationScale::Seconds:
if (Multiplier >= 60.0)
return std::make_tuple(DurationScale::Minutes, Multiplier / 60.0);
if (Multiplier <= 1e-3)
return std::make_tuple(DurationScale::Milliseconds, Multiplier * 1e3);
break;
case DurationScale::Milliseconds:
if (Multiplier >= 1e3)
return std::make_tuple(DurationScale::Seconds, Multiplier / 1e3);
if (Multiplier <= 1e-3)
return std::make_tuple(DurationScale::Microseconds, Multiplier * 1e3);
break;
case DurationScale::Microseconds:
if (Multiplier >= 1e3)
return std::make_tuple(DurationScale::Milliseconds, Multiplier / 1e3);
if (Multiplier <= 1e-3)
return std::make_tuple(DurationScale::Nanoseconds, Multiplier * 1e-3);
break;
case DurationScale::Nanoseconds:
if (Multiplier >= 1e3)
return std::make_tuple(DurationScale::Microseconds, Multiplier / 1e3);
break;
}
return llvm::None;
}
// Given the scale of a duration and a `Multiplier`, determine if `Multiplier`
// would produce a new scale. If so, return it, otherwise `None`.
static llvm::Optional<DurationScale> GetNewScale(DurationScale OldScale,
double Multiplier) {
while (Multiplier != 1.0) {
llvm::Optional<std::tuple<DurationScale, double>> result =
GetNewScaleSingleStep(OldScale, Multiplier);
if (!result)
break;
if (std::get<1>(*result) == 1.0)
return std::get<0>(*result);
Multiplier = std::get<1>(*result);
OldScale = std::get<0>(*result);
}
return llvm::None;
}
void DurationFactoryScaleCheck::registerMatchers(MatchFinder *Finder) {
Finder->addMatcher(
callExpr(
callee(functionDecl(DurationFactoryFunction()).bind("call_decl")),
hasArgument(
0,
ignoringImpCasts(anyOf(
cxxFunctionalCastExpr(
hasDestinationType(
anyOf(isInteger(), realFloatingPointType())),
hasSourceExpression(initListExpr())),
integerLiteral(equals(0)), floatLiteral(equals(0.0)),
binaryOperator(hasOperatorName("*"),
hasEitherOperand(ignoringImpCasts(
anyOf(integerLiteral(), floatLiteral()))))
.bind("mult_binop"),
binaryOperator(hasOperatorName("/"), hasRHS(floatLiteral()))
.bind("div_binop")))))
.bind("call"),
this);
}
void DurationFactoryScaleCheck::check(const MatchFinder::MatchResult &Result) {
const auto *Call = Result.Nodes.getNodeAs<CallExpr>("call");
// Don't try to replace things inside of macro definitions.
if (Call->getExprLoc().isMacroID())
return;
const Expr *Arg = Call->getArg(0)->IgnoreParenImpCasts();
// Arguments which are macros are ignored.
if (Arg->getBeginLoc().isMacroID())
return;
// We first handle the cases of literal zero (both float and integer).
if (IsLiteralZero(Result, *Arg)) {
diag(Call->getBeginLoc(),
"use ZeroDuration() for zero-length time intervals")
<< FixItHint::CreateReplacement(Call->getSourceRange(),
"absl::ZeroDuration()");
return;
}
const auto *CallDecl = Result.Nodes.getNodeAs<FunctionDecl>("call_decl");
llvm::Optional<DurationScale> MaybeScale =
getScaleForFactory(CallDecl->getName());
if (!MaybeScale)
return;
DurationScale Scale = *MaybeScale;
const Expr *Remainder;
llvm::Optional<DurationScale> NewScale;
// We next handle the cases of multiplication and division.
if (const auto *MultBinOp =
Result.Nodes.getNodeAs<BinaryOperator>("mult_binop")) {
// For multiplication, we need to look at both operands, and consider the
// cases where a user is multiplying by something such as 1e-3.
// First check the LHS
const auto *IntLit = llvm::dyn_cast<IntegerLiteral>(MultBinOp->getLHS());
const auto *FloatLit = llvm::dyn_cast<FloatingLiteral>(MultBinOp->getLHS());
if (IntLit || FloatLit) {
NewScale = GetNewScale(Scale, GetValue(IntLit, FloatLit));
if (NewScale)
Remainder = MultBinOp->getRHS();
}
// If we weren't able to scale based on the LHS, check the RHS
if (!NewScale) {
IntLit = llvm::dyn_cast<IntegerLiteral>(MultBinOp->getRHS());
FloatLit = llvm::dyn_cast<FloatingLiteral>(MultBinOp->getRHS());
if (IntLit || FloatLit) {
NewScale = GetNewScale(Scale, GetValue(IntLit, FloatLit));
if (NewScale)
Remainder = MultBinOp->getLHS();
}
}
} else if (const auto *DivBinOp =
Result.Nodes.getNodeAs<BinaryOperator>("div_binop")) {
// We next handle division.
// For division, we only check the RHS.
const auto *FloatLit = llvm::dyn_cast<FloatingLiteral>(DivBinOp->getRHS());
llvm::Optional<DurationScale> NewScale =
GetNewScale(Scale, 1.0 / FloatLit->getValueAsApproximateDouble());
if (NewScale) {
const Expr *Remainder = DivBinOp->getLHS();
// We've found an appropriate scaling factor and the new scale, so output
// the relevant fix.
diag(Call->getBeginLoc(), "internal duration scaling can be removed")
<< FixItHint::CreateReplacement(
Call->getSourceRange(),
(llvm::Twine(getDurationFactoryForScale(*NewScale)) + "(" +
tooling::fixit::getText(*Remainder, *Result.Context) + ")")
.str());
}
}
if (NewScale) {
assert(Remainder && "No remainder found");
// We've found an appropriate scaling factor and the new scale, so output
// the relevant fix.
diag(Call->getBeginLoc(), "internal duration scaling can be removed")
<< FixItHint::CreateReplacement(
Call->getSourceRange(),
(llvm::Twine(getDurationFactoryForScale(*NewScale)) + "(" +
tooling::fixit::getText(*Remainder, *Result.Context) + ")")
.str());
}
return;
}
} // namespace abseil
} // namespace tidy
} // namespace clang
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