435 lines
14 KiB
C++
435 lines
14 KiB
C++
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//===--- TransAutoreleasePool.cpp - Transformations to ARC mode -----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// rewriteAutoreleasePool:
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//
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// Calls to NSAutoreleasePools will be rewritten as an @autorelease scope.
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//
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// NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
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// ...
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// [pool release];
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// ---->
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// @autorelease {
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// ...
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// }
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//
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// An NSAutoreleasePool will not be touched if:
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// - There is not a corresponding -release/-drain in the same scope
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// - Not all references of the NSAutoreleasePool variable can be removed
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// - There is a variable that is declared inside the intended @autorelease scope
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// which is also used outside it.
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//
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//===----------------------------------------------------------------------===//
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#include "Transforms.h"
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#include "Internals.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/Basic/SourceManager.h"
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#include "clang/Sema/SemaDiagnostic.h"
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#include <map>
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using namespace clang;
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using namespace arcmt;
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using namespace trans;
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namespace {
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class ReleaseCollector : public RecursiveASTVisitor<ReleaseCollector> {
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Decl *Dcl;
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SmallVectorImpl<ObjCMessageExpr *> &Releases;
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public:
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ReleaseCollector(Decl *D, SmallVectorImpl<ObjCMessageExpr *> &releases)
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: Dcl(D), Releases(releases) { }
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bool VisitObjCMessageExpr(ObjCMessageExpr *E) {
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if (!E->isInstanceMessage())
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return true;
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if (E->getMethodFamily() != OMF_release)
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return true;
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Expr *instance = E->getInstanceReceiver()->IgnoreParenCasts();
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if (DeclRefExpr *DE = dyn_cast<DeclRefExpr>(instance)) {
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if (DE->getDecl() == Dcl)
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Releases.push_back(E);
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}
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return true;
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}
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};
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}
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namespace {
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class AutoreleasePoolRewriter
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: public RecursiveASTVisitor<AutoreleasePoolRewriter> {
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public:
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AutoreleasePoolRewriter(MigrationPass &pass)
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: Body(nullptr), Pass(pass) {
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PoolII = &pass.Ctx.Idents.get("NSAutoreleasePool");
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DrainSel = pass.Ctx.Selectors.getNullarySelector(
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&pass.Ctx.Idents.get("drain"));
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}
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void transformBody(Stmt *body, Decl *ParentD) {
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Body = body;
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TraverseStmt(body);
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}
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~AutoreleasePoolRewriter() {
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SmallVector<VarDecl *, 8> VarsToHandle;
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for (std::map<VarDecl *, PoolVarInfo>::iterator
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I = PoolVars.begin(), E = PoolVars.end(); I != E; ++I) {
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VarDecl *var = I->first;
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PoolVarInfo &info = I->second;
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// Check that we can handle/rewrite all references of the pool.
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clearRefsIn(info.Dcl, info.Refs);
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for (SmallVectorImpl<PoolScope>::iterator
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scpI = info.Scopes.begin(),
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scpE = info.Scopes.end(); scpI != scpE; ++scpI) {
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PoolScope &scope = *scpI;
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clearRefsIn(*scope.Begin, info.Refs);
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clearRefsIn(*scope.End, info.Refs);
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clearRefsIn(scope.Releases.begin(), scope.Releases.end(), info.Refs);
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}
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// Even if one reference is not handled we will not do anything about that
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// pool variable.
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if (info.Refs.empty())
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VarsToHandle.push_back(var);
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}
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for (unsigned i = 0, e = VarsToHandle.size(); i != e; ++i) {
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PoolVarInfo &info = PoolVars[VarsToHandle[i]];
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Transaction Trans(Pass.TA);
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clearUnavailableDiags(info.Dcl);
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Pass.TA.removeStmt(info.Dcl);
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// Add "@autoreleasepool { }"
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for (SmallVectorImpl<PoolScope>::iterator
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scpI = info.Scopes.begin(),
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scpE = info.Scopes.end(); scpI != scpE; ++scpI) {
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PoolScope &scope = *scpI;
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clearUnavailableDiags(*scope.Begin);
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clearUnavailableDiags(*scope.End);
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if (scope.IsFollowedBySimpleReturnStmt) {
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// Include the return in the scope.
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Pass.TA.replaceStmt(*scope.Begin, "@autoreleasepool {");
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Pass.TA.removeStmt(*scope.End);
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Stmt::child_iterator retI = scope.End;
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++retI;
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SourceLocation afterSemi =
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findLocationAfterSemi((*retI)->getEndLoc(), Pass.Ctx);
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assert(afterSemi.isValid() &&
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"Didn't we check before setting IsFollowedBySimpleReturnStmt "
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"to true?");
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Pass.TA.insertAfterToken(afterSemi, "\n}");
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Pass.TA.increaseIndentation(
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SourceRange(scope.getIndentedRange().getBegin(),
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(*retI)->getEndLoc()),
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scope.CompoundParent->getBeginLoc());
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} else {
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Pass.TA.replaceStmt(*scope.Begin, "@autoreleasepool {");
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Pass.TA.replaceStmt(*scope.End, "}");
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Pass.TA.increaseIndentation(scope.getIndentedRange(),
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scope.CompoundParent->getBeginLoc());
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}
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}
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// Remove rest of pool var references.
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for (SmallVectorImpl<PoolScope>::iterator
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scpI = info.Scopes.begin(),
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scpE = info.Scopes.end(); scpI != scpE; ++scpI) {
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PoolScope &scope = *scpI;
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for (SmallVectorImpl<ObjCMessageExpr *>::iterator
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relI = scope.Releases.begin(),
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relE = scope.Releases.end(); relI != relE; ++relI) {
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clearUnavailableDiags(*relI);
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Pass.TA.removeStmt(*relI);
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}
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}
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}
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}
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bool VisitCompoundStmt(CompoundStmt *S) {
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SmallVector<PoolScope, 4> Scopes;
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for (Stmt::child_iterator
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I = S->body_begin(), E = S->body_end(); I != E; ++I) {
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Stmt *child = getEssential(*I);
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if (DeclStmt *DclS = dyn_cast<DeclStmt>(child)) {
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if (DclS->isSingleDecl()) {
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if (VarDecl *VD = dyn_cast<VarDecl>(DclS->getSingleDecl())) {
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if (isNSAutoreleasePool(VD->getType())) {
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PoolVarInfo &info = PoolVars[VD];
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info.Dcl = DclS;
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collectRefs(VD, S, info.Refs);
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// Does this statement follow the pattern:
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// NSAutoreleasePool * pool = [NSAutoreleasePool new];
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if (isPoolCreation(VD->getInit())) {
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Scopes.push_back(PoolScope());
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Scopes.back().PoolVar = VD;
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Scopes.back().CompoundParent = S;
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Scopes.back().Begin = I;
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}
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}
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}
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}
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} else if (BinaryOperator *bop = dyn_cast<BinaryOperator>(child)) {
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if (DeclRefExpr *dref = dyn_cast<DeclRefExpr>(bop->getLHS())) {
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if (VarDecl *VD = dyn_cast<VarDecl>(dref->getDecl())) {
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// Does this statement follow the pattern:
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// pool = [NSAutoreleasePool new];
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if (isNSAutoreleasePool(VD->getType()) &&
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isPoolCreation(bop->getRHS())) {
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Scopes.push_back(PoolScope());
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Scopes.back().PoolVar = VD;
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Scopes.back().CompoundParent = S;
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Scopes.back().Begin = I;
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}
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}
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}
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}
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if (Scopes.empty())
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continue;
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if (isPoolDrain(Scopes.back().PoolVar, child)) {
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PoolScope &scope = Scopes.back();
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scope.End = I;
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handlePoolScope(scope, S);
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Scopes.pop_back();
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}
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}
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return true;
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}
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private:
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void clearUnavailableDiags(Stmt *S) {
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if (S)
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Pass.TA.clearDiagnostic(diag::err_unavailable,
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diag::err_unavailable_message,
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S->getSourceRange());
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}
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struct PoolScope {
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VarDecl *PoolVar;
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CompoundStmt *CompoundParent;
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Stmt::child_iterator Begin;
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Stmt::child_iterator End;
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bool IsFollowedBySimpleReturnStmt;
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SmallVector<ObjCMessageExpr *, 4> Releases;
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PoolScope() : PoolVar(nullptr), CompoundParent(nullptr), Begin(), End(),
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IsFollowedBySimpleReturnStmt(false) { }
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SourceRange getIndentedRange() const {
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Stmt::child_iterator rangeS = Begin;
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++rangeS;
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if (rangeS == End)
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return SourceRange();
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Stmt::child_iterator rangeE = Begin;
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for (Stmt::child_iterator I = rangeS; I != End; ++I)
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++rangeE;
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return SourceRange((*rangeS)->getBeginLoc(), (*rangeE)->getEndLoc());
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}
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};
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class NameReferenceChecker : public RecursiveASTVisitor<NameReferenceChecker>{
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ASTContext &Ctx;
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SourceRange ScopeRange;
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SourceLocation &referenceLoc, &declarationLoc;
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public:
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NameReferenceChecker(ASTContext &ctx, PoolScope &scope,
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SourceLocation &referenceLoc,
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SourceLocation &declarationLoc)
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: Ctx(ctx), referenceLoc(referenceLoc),
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declarationLoc(declarationLoc) {
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ScopeRange = SourceRange((*scope.Begin)->getBeginLoc(),
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(*scope.End)->getBeginLoc());
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}
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bool VisitDeclRefExpr(DeclRefExpr *E) {
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return checkRef(E->getLocation(), E->getDecl()->getLocation());
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}
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bool VisitTypedefTypeLoc(TypedefTypeLoc TL) {
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return checkRef(TL.getBeginLoc(), TL.getTypedefNameDecl()->getLocation());
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}
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bool VisitTagTypeLoc(TagTypeLoc TL) {
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return checkRef(TL.getBeginLoc(), TL.getDecl()->getLocation());
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}
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private:
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bool checkRef(SourceLocation refLoc, SourceLocation declLoc) {
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if (isInScope(declLoc)) {
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referenceLoc = refLoc;
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declarationLoc = declLoc;
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return false;
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}
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return true;
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}
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bool isInScope(SourceLocation loc) {
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if (loc.isInvalid())
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return false;
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SourceManager &SM = Ctx.getSourceManager();
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if (SM.isBeforeInTranslationUnit(loc, ScopeRange.getBegin()))
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return false;
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return SM.isBeforeInTranslationUnit(loc, ScopeRange.getEnd());
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}
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};
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void handlePoolScope(PoolScope &scope, CompoundStmt *compoundS) {
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// Check that all names declared inside the scope are not used
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// outside the scope.
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{
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bool nameUsedOutsideScope = false;
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SourceLocation referenceLoc, declarationLoc;
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Stmt::child_iterator SI = scope.End, SE = compoundS->body_end();
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++SI;
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// Check if the autoreleasepool scope is followed by a simple return
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// statement, in which case we will include the return in the scope.
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if (SI != SE)
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if (ReturnStmt *retS = dyn_cast<ReturnStmt>(*SI))
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if ((retS->getRetValue() == nullptr ||
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isa<DeclRefExpr>(retS->getRetValue()->IgnoreParenCasts())) &&
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findLocationAfterSemi(retS->getEndLoc(), Pass.Ctx).isValid()) {
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scope.IsFollowedBySimpleReturnStmt = true;
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++SI; // the return will be included in scope, don't check it.
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}
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for (; SI != SE; ++SI) {
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nameUsedOutsideScope = !NameReferenceChecker(Pass.Ctx, scope,
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referenceLoc,
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declarationLoc).TraverseStmt(*SI);
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if (nameUsedOutsideScope)
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break;
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}
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// If not all references were cleared it means some variables/typenames/etc
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// declared inside the pool scope are used outside of it.
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// We won't try to rewrite the pool.
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if (nameUsedOutsideScope) {
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Pass.TA.reportError("a name is referenced outside the "
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"NSAutoreleasePool scope that it was declared in", referenceLoc);
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Pass.TA.reportNote("name declared here", declarationLoc);
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Pass.TA.reportNote("intended @autoreleasepool scope begins here",
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(*scope.Begin)->getBeginLoc());
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Pass.TA.reportNote("intended @autoreleasepool scope ends here",
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(*scope.End)->getBeginLoc());
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return;
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}
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}
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// Collect all releases of the pool; they will be removed.
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{
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ReleaseCollector releaseColl(scope.PoolVar, scope.Releases);
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Stmt::child_iterator I = scope.Begin;
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++I;
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for (; I != scope.End; ++I)
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releaseColl.TraverseStmt(*I);
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}
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PoolVars[scope.PoolVar].Scopes.push_back(scope);
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}
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bool isPoolCreation(Expr *E) {
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if (!E) return false;
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E = getEssential(E);
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ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E);
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if (!ME) return false;
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if (ME->getMethodFamily() == OMF_new &&
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ME->getReceiverKind() == ObjCMessageExpr::Class &&
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isNSAutoreleasePool(ME->getReceiverInterface()))
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return true;
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if (ME->getReceiverKind() == ObjCMessageExpr::Instance &&
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ME->getMethodFamily() == OMF_init) {
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Expr *rec = getEssential(ME->getInstanceReceiver());
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if (ObjCMessageExpr *recME = dyn_cast_or_null<ObjCMessageExpr>(rec)) {
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if (recME->getMethodFamily() == OMF_alloc &&
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recME->getReceiverKind() == ObjCMessageExpr::Class &&
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||
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|
isNSAutoreleasePool(recME->getReceiverInterface()))
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool isPoolDrain(VarDecl *poolVar, Stmt *S) {
|
||
|
|
if (!S) return false;
|
||
|
|
S = getEssential(S);
|
||
|
|
ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(S);
|
||
|
|
if (!ME) return false;
|
||
|
|
if (ME->getReceiverKind() == ObjCMessageExpr::Instance) {
|
||
|
|
Expr *rec = getEssential(ME->getInstanceReceiver());
|
||
|
|
if (DeclRefExpr *dref = dyn_cast<DeclRefExpr>(rec))
|
||
|
|
if (dref->getDecl() == poolVar)
|
||
|
|
return ME->getMethodFamily() == OMF_release ||
|
||
|
|
ME->getSelector() == DrainSel;
|
||
|
|
}
|
||
|
|
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool isNSAutoreleasePool(ObjCInterfaceDecl *IDecl) {
|
||
|
|
return IDecl && IDecl->getIdentifier() == PoolII;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool isNSAutoreleasePool(QualType Ty) {
|
||
|
|
QualType pointee = Ty->getPointeeType();
|
||
|
|
if (pointee.isNull())
|
||
|
|
return false;
|
||
|
|
if (const ObjCInterfaceType *interT = pointee->getAs<ObjCInterfaceType>())
|
||
|
|
return isNSAutoreleasePool(interT->getDecl());
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
static Expr *getEssential(Expr *E) {
|
||
|
|
return cast<Expr>(getEssential((Stmt*)E));
|
||
|
|
}
|
||
|
|
static Stmt *getEssential(Stmt *S) {
|
||
|
|
if (FullExpr *FE = dyn_cast<FullExpr>(S))
|
||
|
|
S = FE->getSubExpr();
|
||
|
|
if (Expr *E = dyn_cast<Expr>(S))
|
||
|
|
S = E->IgnoreParenCasts();
|
||
|
|
return S;
|
||
|
|
}
|
||
|
|
|
||
|
|
Stmt *Body;
|
||
|
|
MigrationPass &Pass;
|
||
|
|
|
||
|
|
IdentifierInfo *PoolII;
|
||
|
|
Selector DrainSel;
|
||
|
|
|
||
|
|
struct PoolVarInfo {
|
||
|
|
DeclStmt *Dcl;
|
||
|
|
ExprSet Refs;
|
||
|
|
SmallVector<PoolScope, 2> Scopes;
|
||
|
|
|
||
|
|
PoolVarInfo() : Dcl(nullptr) { }
|
||
|
|
};
|
||
|
|
|
||
|
|
std::map<VarDecl *, PoolVarInfo> PoolVars;
|
||
|
|
};
|
||
|
|
|
||
|
|
} // anonymous namespace
|
||
|
|
|
||
|
|
void trans::rewriteAutoreleasePool(MigrationPass &pass) {
|
||
|
|
BodyTransform<AutoreleasePoolRewriter> trans(pass);
|
||
|
|
trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
|
||
|
|
}
|