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//===-- ODRHash.cpp - Hashing to diagnose ODR failures ----------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file implements the ODRHash class, which calculates a hash based
/// on AST nodes, which is stable across different runs.
///
//===----------------------------------------------------------------------===//
#include "clang/AST/ODRHash.h"
#include "clang/AST/DeclVisitor.h"
#include "clang/AST/NestedNameSpecifier.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/AST/TypeVisitor.h"
using namespace clang;
void ODRHash::AddStmt(const Stmt *S) {
assert(S && "Expecting non-null pointer.");
S->ProcessODRHash(ID, *this);
}
void ODRHash::AddIdentifierInfo(const IdentifierInfo *II) {
assert(II && "Expecting non-null pointer.");
ID.AddString(II->getName());
}
void ODRHash::AddNestedNameSpecifier(const NestedNameSpecifier *NNS) {}
void ODRHash::AddTemplateName(TemplateName Name) {}
void ODRHash::AddDeclarationName(DeclarationName Name) {}
void ODRHash::AddTemplateArgument(TemplateArgument TA) {}
void ODRHash::AddTemplateParameterList(const TemplateParameterList *TPL) {}
void ODRHash::clear() {
DeclMap.clear();
TypeMap.clear();
Bools.clear();
ID.clear();
}
unsigned ODRHash::CalculateHash() {
// Append the bools to the end of the data segment backwards. This allows
// for the bools data to be compressed 32 times smaller compared to using
// ID.AddBoolean
const unsigned unsigned_bits = sizeof(unsigned) * CHAR_BIT;
const unsigned size = Bools.size();
const unsigned remainder = size % unsigned_bits;
const unsigned loops = size / unsigned_bits;
auto I = Bools.rbegin();
unsigned value = 0;
for (unsigned i = 0; i < remainder; ++i) {
value <<= 1;
value |= *I;
++I;
}
ID.AddInteger(value);
for (unsigned i = 0; i < loops; ++i) {
value = 0;
for (unsigned j = 0; j < unsigned_bits; ++j) {
value <<= 1;
value |= *I;
++I;
}
ID.AddInteger(value);
}
assert(I == Bools.rend());
Bools.clear();
return ID.ComputeHash();
}
// Process a Decl pointer. Add* methods call back into ODRHash while Visit*
// methods process the relevant parts of the Decl.
class ODRDeclVisitor : public ConstDeclVisitor<ODRDeclVisitor> {
typedef ConstDeclVisitor<ODRDeclVisitor> Inherited;
llvm::FoldingSetNodeID &ID;
ODRHash &Hash;
public:
ODRDeclVisitor(llvm::FoldingSetNodeID &ID, ODRHash &Hash)
: ID(ID), Hash(Hash) {}
void AddStmt(const Stmt *S) {
Hash.AddBoolean(S);
if (S) {
Hash.AddStmt(S);
}
}
void AddIdentifierInfo(const IdentifierInfo *II) {
Hash.AddBoolean(II);
if (II) {
Hash.AddIdentifierInfo(II);
}
}
void Visit(const Decl *D) {
ID.AddInteger(D->getKind());
Inherited::Visit(D);
}
void VisitNamedDecl(const NamedDecl *D) {
AddIdentifierInfo(D->getIdentifier());
Inherited::VisitNamedDecl(D);
}
void VisitAccessSpecDecl(const AccessSpecDecl *D) {
ID.AddInteger(D->getAccess());
Inherited::VisitAccessSpecDecl(D);
}
void VisitStaticAssertDecl(const StaticAssertDecl *D) {
AddStmt(D->getAssertExpr());
AddStmt(D->getMessage());
Inherited::VisitStaticAssertDecl(D);
}
void VisitFieldDecl(const FieldDecl *D) {
Inherited::VisitFieldDecl(D);
}
};
// Only allow a small portion of Decl's to be processed. Remove this once
// all Decl's can be handled.
bool ODRHash::isWhitelistedDecl(const Decl *D, const CXXRecordDecl *Parent) {
if (D->isImplicit()) return false;
if (D->getDeclContext() != Parent) return false;
switch (D->getKind()) {
default:
return false;
case Decl::AccessSpec:
case Decl::Field:
case Decl::StaticAssert:
return true;
}
}
void ODRHash::AddSubDecl(const Decl *D) {
assert(D && "Expecting non-null pointer.");
AddDecl(D);
ODRDeclVisitor(ID, *this).Visit(D);
}
void ODRHash::AddCXXRecordDecl(const CXXRecordDecl *Record) {
assert(Record && Record->hasDefinition() &&
"Expected non-null record to be a definition.");
AddDecl(Record);
// Filter out sub-Decls which will not be processed in order to get an
// accurate count of Decl's.
llvm::SmallVector<const Decl *, 16> Decls;
for (const Decl *SubDecl : Record->decls()) {
if (isWhitelistedDecl(SubDecl, Record)) {
Decls.push_back(SubDecl);
}
}
ID.AddInteger(Decls.size());
for (auto SubDecl : Decls) {
AddSubDecl(SubDecl);
}
}
void ODRHash::AddDecl(const Decl *D) {
assert(D && "Expecting non-null pointer.");
auto Result = DeclMap.insert(std::make_pair(D, DeclMap.size()));
ID.AddInteger(Result.first->second);
// On first encounter of a Decl pointer, process it. Every time afterwards,
// only the index value is needed.
if (!Result.second) {
return;
}
ID.AddInteger(D->getKind());
}
void ODRHash::AddType(const Type *T) {}
void ODRHash::AddQualType(QualType T) {}
void ODRHash::AddBoolean(bool Value) {
Bools.push_back(Value);
}
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