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//===--- TransEmptyStatements.cpp - Tranformations to ARC mode ------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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/StmtVisitor.h"
using namespace clang;
using namespace arcmt;
using namespace trans;
using llvm::StringRef;
namespace {
/// \brief Returns true if the statement became empty due to previous
/// transformations.
class EmptyChecker : public StmtVisitor<EmptyChecker, bool> {
ASTContext &Ctx;
llvm::DenseSet<unsigned> &MacroLocs;
public:
EmptyChecker(ASTContext &ctx, llvm::DenseSet<unsigned> ¯oLocs)
: Ctx(ctx), MacroLocs(macroLocs) { }
bool VisitNullStmt(NullStmt *S) {
return isMacroLoc(S->getLeadingEmptyMacroLoc());
}
bool VisitCompoundStmt(CompoundStmt *S) {
if (S->body_empty())
return false; // was already empty, not because of transformations.
for (CompoundStmt::body_iterator
I = S->body_begin(), E = S->body_end(); I != E; ++I)
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;
if (S->getElse() && !Visit(S->getElse()))
return false;
return true;
}
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());
}
private:
bool isMacroLoc(SourceLocation loc) {
if (loc.isInvalid()) return false;
return MacroLocs.count(loc.getRawEncoding());
}
};
class EmptyStatementsRemover :
public RecursiveASTVisitor<EmptyStatementsRemover> {
MigrationPass &Pass;
llvm::DenseSet<unsigned> &MacroLocs;
public:
EmptyStatementsRemover(MigrationPass &pass,
llvm::DenseSet<unsigned> ¯oLocs)
: Pass(pass), MacroLocs(macroLocs) { }
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 (CompoundStmt::body_iterator
I = S->body_begin(), E = S->body_end(); I != E; ++I)
check(*I);
return true;
}
bool isMacroLoc(SourceLocation loc) {
if (loc.isInvalid()) return false;
return MacroLocs.count(loc.getRawEncoding());
}
ASTContext &getContext() { return Pass.Ctx; }
private:
void check(Stmt *S) {
if (!S) return;
if (EmptyChecker(Pass.Ctx, MacroLocs).Visit(S)) {
Transaction Trans(Pass.TA);
Pass.TA.removeStmt(S);
}
}
};
} // anonymous namespace
static bool isBodyEmpty(CompoundStmt *body,
ASTContext &Ctx, llvm::DenseSet<unsigned> &MacroLocs) {
for (CompoundStmt::body_iterator
I = body->body_begin(), E = body->body_end(); I != E; ++I)
if (!EmptyChecker(Ctx, MacroLocs).Visit(*I))
return false;
return true;
}
static void removeDeallocMethod(MigrationPass &pass,
llvm::DenseSet<unsigned> &MacroLocs) {
ASTContext &Ctx = pass.Ctx;
TransformActions &TA = pass.TA;
DeclContext *DC = Ctx.getTranslationUnitDecl();
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) {
for (ObjCImplementationDecl::instmeth_iterator
MI = (*I)->instmeth_begin(),
ME = (*I)->instmeth_end(); MI != ME; ++MI) {
ObjCMethodDecl *MD = *MI;
if (MD->getMethodFamily() == OMF_dealloc) {
if (MD->hasBody() &&
isBodyEmpty(MD->getCompoundBody(), Ctx, MacroLocs)) {
Transaction Trans(TA);
TA.remove(MD->getSourceRange());
}
break;
}
}
}
}
void trans::removeEmptyStatementsAndDealloc(MigrationPass &pass) {
llvm::DenseSet<unsigned> MacroLocs;
for (unsigned i = 0, e = pass.ARCMTMacroLocs.size(); i != e; ++i)
MacroLocs.insert(pass.ARCMTMacroLocs[i].getRawEncoding());
EmptyStatementsRemover(pass, MacroLocs)
.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
removeDeallocMethod(pass, MacroLocs);
for (unsigned i = 0, e = pass.ARCMTMacroLocs.size(); i != e; ++i) {
Transaction Trans(pass.TA);
pass.TA.remove(pass.ARCMTMacroLocs[i]);
}
}
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