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//===--- BufferDerefCheck.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 "BufferDerefCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Tooling/FixIt.h"
using namespace clang::ast_matchers;
namespace clang::tidy::mpi {
void BufferDerefCheck::registerMatchers(MatchFinder *Finder) {
Finder->addMatcher(callExpr().bind("CE"), this);
}
void BufferDerefCheck::check(const MatchFinder::MatchResult &Result) {
const auto *CE = Result.Nodes.getNodeAs<CallExpr>("CE");
if (!CE->getDirectCallee())
return;
if (!FuncClassifier)
FuncClassifier.emplace(*Result.Context);
const IdentifierInfo *Identifier = CE->getDirectCallee()->getIdentifier();
if (!Identifier || !FuncClassifier->isMPIType(Identifier))
return;
// These containers are used, to capture the type and expression of a buffer.
SmallVector<const Type *, 1> BufferTypes;
SmallVector<const Expr *, 1> BufferExprs;
// Adds the type and expression of a buffer that is used in the MPI call
// expression to the captured containers.
auto AddBuffer = [&CE, &Result, &BufferTypes,
&BufferExprs](const size_t BufferIdx) {
// Skip null pointer constants and in place 'operators'.
if (CE->getArg(BufferIdx)->isNullPointerConstant(
*Result.Context, Expr::NPC_ValueDependentIsNull) ||
tooling::fixit::getText(*CE->getArg(BufferIdx), *Result.Context) ==
"MPI_IN_PLACE")
return;
const Expr *ArgExpr = CE->getArg(BufferIdx);
if (!ArgExpr)
return;
const Type *ArgType = ArgExpr->IgnoreImpCasts()->getType().getTypePtr();
if (!ArgType)
return;
BufferExprs.push_back(ArgExpr);
BufferTypes.push_back(ArgType);
};
// Collect buffer types and argument expressions for all buffers used in the
// MPI call expression. The number passed to the lambda corresponds to the
// argument index of the currently verified MPI function call.
if (FuncClassifier->isPointToPointType(Identifier)) {
AddBuffer(0);
} else if (FuncClassifier->isCollectiveType(Identifier)) {
if (FuncClassifier->isReduceType(Identifier)) {
AddBuffer(0);
AddBuffer(1);
} else if (FuncClassifier->isScatterType(Identifier) ||
FuncClassifier->isGatherType(Identifier) ||
FuncClassifier->isAlltoallType(Identifier)) {
AddBuffer(0);
AddBuffer(3);
} else if (FuncClassifier->isBcastType(Identifier)) {
AddBuffer(0);
}
}
checkBuffers(BufferTypes, BufferExprs);
}
void BufferDerefCheck::checkBuffers(ArrayRef<const Type *> BufferTypes,
ArrayRef<const Expr *> BufferExprs) {
for (size_t I = 0; I < BufferTypes.size(); ++I) {
unsigned IndirectionCount = 0;
const Type *BufferType = BufferTypes[I];
llvm::SmallVector<IndirectionType, 1> Indirections;
// Capture the depth and types of indirections for the passed buffer.
while (true) {
if (BufferType->isPointerType()) {
BufferType = BufferType->getPointeeType().getTypePtr();
Indirections.push_back(IndirectionType::Pointer);
} else if (BufferType->isArrayType()) {
BufferType = BufferType->getArrayElementTypeNoTypeQual();
Indirections.push_back(IndirectionType::Array);
} else {
break;
}
++IndirectionCount;
}
if (IndirectionCount > 1) {
// Referencing an array with '&' is valid, as this also points to the
// beginning of the array.
if (IndirectionCount == 2 &&
Indirections[0] == IndirectionType::Pointer &&
Indirections[1] == IndirectionType::Array)
return;
// Build the indirection description in reverse order of discovery.
std::string IndirectionDesc;
for (auto It = Indirections.rbegin(); It != Indirections.rend(); ++It) {
if (!IndirectionDesc.empty())
IndirectionDesc += "->";
if (*It == IndirectionType::Pointer) {
IndirectionDesc += "pointer";
} else {
IndirectionDesc += "array";
}
}
const auto Loc = BufferExprs[I]->getSourceRange().getBegin();
diag(Loc, "buffer is insufficiently dereferenced: %0") << IndirectionDesc;
}
}
}
void BufferDerefCheck::onEndOfTranslationUnit() { FuncClassifier.reset(); }
} // namespace clang::tidy::mpi
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