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//===-- TransEmptyStatementsAndDealloc.cpp - Transformations to ARC mode --===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// removeEmptyStatementsAndDealloc:
//
// Removes empty statements that are leftovers from previous transformations.
// e.g for
//
// [x retain];
//
// removeRetainReleaseDealloc will leave an empty ";" that removeEmptyStatements
// will remove.
//
//===----------------------------------------------------------------------===//
#include "Transforms.h"
#include "Internals.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/Basic/SourceManager.h"
using namespace clang;
using namespace arcmt;
using namespace trans;
static bool isEmptyARCMTMacroStatement(NullStmt *S,
std::vector<SourceLocation> &MacroLocs,
ASTContext &Ctx) {
if (!S->hasLeadingEmptyMacro())
return false;
SourceLocation SemiLoc = S->getSemiLoc();
if (SemiLoc.isInvalid() || SemiLoc.isMacroID())
return false;
if (MacroLocs.empty())
return false;
SourceManager &SM = Ctx.getSourceManager();
std::vector<SourceLocation>::iterator I = llvm::upper_bound(
MacroLocs, SemiLoc, BeforeThanCompare<SourceLocation>(SM));
--I;
SourceLocation
AfterMacroLoc = I->getLocWithOffset(getARCMTMacroName().size());
assert(AfterMacroLoc.isFileID());
if (AfterMacroLoc == SemiLoc)
return true;
int RelOffs = 0;
if (!SM.isInSameSLocAddrSpace(AfterMacroLoc, SemiLoc, &RelOffs))
return false;
if (RelOffs < 0)
return false;
// We make the reasonable assumption that a semicolon after 100 characters
// means that it is not the next token after our macro. If this assumption
// fails it is not critical, we will just fail to clear out, e.g., an empty
// 'if'.
if (RelOffs - getARCMTMacroName().size() > 100)
return false;
SourceLocation AfterMacroSemiLoc = findSemiAfterLocation(AfterMacroLoc, Ctx);
return AfterMacroSemiLoc == SemiLoc;
}
namespace {
/// Returns true if the statement became empty due to previous
/// transformations.
class EmptyChecker : public StmtVisitor<EmptyChecker, bool> {
ASTContext &Ctx;
std::vector<SourceLocation> &MacroLocs;
public:
EmptyChecker(ASTContext &ctx, std::vector<SourceLocation> &macroLocs)
: Ctx(ctx), MacroLocs(macroLocs) { }
bool VisitNullStmt(NullStmt *S) {
return isEmptyARCMTMacroStatement(S, MacroLocs, Ctx);
}
bool VisitCompoundStmt(CompoundStmt *S) {
if (S->body_empty())
return false; // was already empty, not because of transformations.
for (auto *I : S->body())
if (!Visit(I))
return false;
return true;
}
bool VisitIfStmt(IfStmt *S) {
if (S->getConditionVariable())
return false;
Expr *condE = S->getCond();
if (!condE)
return false;
if (hasSideEffects(condE, Ctx))
return false;
if (!S->getThen() || !Visit(S->getThen()))
return false;
return !S->getElse() || Visit(S->getElse());
}
bool VisitWhileStmt(WhileStmt *S) {
if (S->getConditionVariable())
return false;
Expr *condE = S->getCond();
if (!condE)
return false;
if (hasSideEffects(condE, Ctx))
return false;
if (!S->getBody())
return false;
return Visit(S->getBody());
}
bool VisitDoStmt(DoStmt *S) {
Expr *condE = S->getCond();
if (!condE)
return false;
if (hasSideEffects(condE, Ctx))
return false;
if (!S->getBody())
return false;
return Visit(S->getBody());
}
bool VisitObjCForCollectionStmt(ObjCForCollectionStmt *S) {
Expr *Exp = S->getCollection();
if (!Exp)
return false;
if (hasSideEffects(Exp, Ctx))
return false;
if (!S->getBody())
return false;
return Visit(S->getBody());
}
bool VisitObjCAutoreleasePoolStmt(ObjCAutoreleasePoolStmt *S) {
if (!S->getSubStmt())
return false;
return Visit(S->getSubStmt());
}
};
class EmptyStatementsRemover :
public RecursiveASTVisitor<EmptyStatementsRemover> {
MigrationPass &Pass;
public:
EmptyStatementsRemover(MigrationPass &pass) : Pass(pass) { }
bool TraverseStmtExpr(StmtExpr *E) {
CompoundStmt *S = E->getSubStmt();
for (CompoundStmt::body_iterator
I = S->body_begin(), E = S->body_end(); I != E; ++I) {
if (I != E - 1)
check(*I);
TraverseStmt(*I);
}
return true;
}
bool VisitCompoundStmt(CompoundStmt *S) {
for (auto *I : S->body())
check(I);
return true;
}
ASTContext &getContext() { return Pass.Ctx; }
private:
void check(Stmt *S) {
if (!S) return;
if (EmptyChecker(Pass.Ctx, Pass.ARCMTMacroLocs).Visit(S)) {
Transaction Trans(Pass.TA);
Pass.TA.removeStmt(S);
}
}
};
} // anonymous namespace
static bool isBodyEmpty(CompoundStmt *body, ASTContext &Ctx,
std::vector<SourceLocation> &MacroLocs) {
for (auto *I : body->body())
if (!EmptyChecker(Ctx, MacroLocs).Visit(I))
return false;
return true;
}
static void cleanupDeallocOrFinalize(MigrationPass &pass) {
ASTContext &Ctx = pass.Ctx;
TransformActions &TA = pass.TA;
DeclContext *DC = Ctx.getTranslationUnitDecl();
Selector FinalizeSel =
Ctx.Selectors.getNullarySelector(&pass.Ctx.Idents.get("finalize"));
typedef DeclContext::specific_decl_iterator<ObjCImplementationDecl>
impl_iterator;
for (impl_iterator I = impl_iterator(DC->decls_begin()),
E = impl_iterator(DC->decls_end()); I != E; ++I) {
ObjCMethodDecl *DeallocM = nullptr;
ObjCMethodDecl *FinalizeM = nullptr;
for (auto *MD : I->instance_methods()) {
if (!MD->hasBody())
continue;
if (MD->getMethodFamily() == OMF_dealloc) {
DeallocM = MD;
} else if (MD->isInstanceMethod() && MD->getSelector() == FinalizeSel) {
FinalizeM = MD;
}
}
if (DeallocM) {
if (isBodyEmpty(DeallocM->getCompoundBody(), Ctx, pass.ARCMTMacroLocs)) {
Transaction Trans(TA);
TA.remove(DeallocM->getSourceRange());
}
if (FinalizeM) {
Transaction Trans(TA);
TA.remove(FinalizeM->getSourceRange());
}
} else if (FinalizeM) {
if (isBodyEmpty(FinalizeM->getCompoundBody(), Ctx, pass.ARCMTMacroLocs)) {
Transaction Trans(TA);
TA.remove(FinalizeM->getSourceRange());
} else {
Transaction Trans(TA);
TA.replaceText(FinalizeM->getSelectorStartLoc(), "finalize", "dealloc");
}
}
}
}
void trans::removeEmptyStatementsAndDeallocFinalize(MigrationPass &pass) {
EmptyStatementsRemover(pass).TraverseDecl(pass.Ctx.getTranslationUnitDecl());
cleanupDeallocOrFinalize(pass);
for (unsigned i = 0, e = pass.ARCMTMacroLocs.size(); i != e; ++i) {
Transaction Trans(pass.TA);
pass.TA.remove(pass.ARCMTMacroLocs[i]);
}
}