[cfe-dev] Advanced Rewriting

Jonas Toth via cfe-dev cfe-dev at lists.llvm.org
Tue Oct 23 08:56:06 PDT 2018


Hi Rafael,

nice to see your progress!

In my opinion these advancements should go in the Tooling and Rewrite
directly in clang but integrate with the existing facilities. It would
be inconvenient two have two separate ways of doing rewritings.

What I am curious about is how to resolve the macro-situation. If the
refactoring will work directly on the AST and ignore macros, how is the
refactoring translated into real code again?

Having an functional way of doing the refactorings with just
transforming the AST, e.g. replacing one node with a new subtree would
be great and elegant on the AST side, but how would we move back from
AST to code?

Best, Jonas

Am 23.10.18 um 17:32 schrieb Rafael·Stahl:
>
> Hey everyone
>
> the two major limitations are resolved now:
>
> - The macro argument issue
> - Support for replacing Decls using clang::ast_type_traits::DynTypedNode
>
> The macro issue vanished by itself once I figured a little unintuitive
> detail out: The SourceLocations from the original AST and the ones
> from the new Preprocessor Lexer did not compare equal even though they
> refer to the exact same location.
>
> I believe this is because expansion SrcLocs have a kind of pointer
> identity representation and equality just compares raw
> representations, such that even when they point to the same locations,
> they don't compare equal. What worked for me was a kind of "deep"
> comparison:
>
> bool clutil::DeepSrcLocEqual(clang::SourceLocation lhs,
> clang::SourceLocation rhs, const clang::SourceManager &SM)
> {
>     if (lhs == rhs)
>         return true;
>
>     if (SM.getExpansionLoc(lhs) != SM.getExpansionLoc(rhs))
>         return false;
>     if (SM.getSpellingLoc(lhs) != SM.getSpellingLoc(rhs))
>         return false;
>
>     clang::SourceLocation lhsMacro, rhsMacro;
>     if (SM.isMacroArgExpansion(lhs, &lhsMacro))
>     {
>         if (!SM.isMacroArgExpansion(rhs, &rhsMacro))
>             return false;
>         if (!DeepSrcLocEqual(lhsMacro, rhsMacro, SM))
>             return false;
>     }
>
>     return true;
> }
>
> Attached is the cleaned up rewriter that I ended up with now. Still,
> if there is any interest, I'd be happy to contribute this back to
> clangs libraries, but I would require some feedback how this fits into
> existing facilities.
>
> Best regards
> Rafael
>
> On 17.07.18 16:19, Jonas Toth wrote:
>>
>> Hi Rafael,
>>
>> I did read into clang-refactor a while ago but unfortunatly could not
>> follow that up. If I recall correctly its about source-to-source
>> transformation (as you said) and aims at implementing the primitive
>> refactorings that exist (e.g. extract-method, extract-variable, ....).
>>
>> Rewriting itself should happen with the normal tooling framework.
>>
>> (https://clang.llvm.org/docs/RefactoringEngine.html)
>>
>> Maybe the implementers of the existing code can give better comments
>> on you proposal (and might have considered a similar solution to
>> yours already).
>>
>> +Alex Lorenz
>>
>> All the best, Jonas
>>
>>
>> Am 17.07.2018 um 14:46 schrieb Rafael·Stahl:
>>>
>>> Hi Jonas
>>>
>>> Thanks for introducing me to this, I have seen the "Replacement"
>>> before, but not clang-refactor.
>>>
>>> However it seems to only provide management facilities around
>>> rewrite operations and not aid with the rewriting itself. Am I
>>> missing something here?
>>>
>>> The two core problems for me:
>>>
>>> - nesting replacements: When implementing replacements with
>>> clang-refactor, I still have to provide replacements that are closed
>>> in themselves. I cannot make them depend on others, right?
>>> - macros: clang-refactor only seems to work with spelling locations.
>>>
>>> Maybe an even simpler example: Replace all additions with "add(lhs,
>>> rhs)". This in itself is very difficult with clang as soon as the
>>> Stmts are nested or macros are involved.
>>>
>>> Best regards
>>> Rafael
>>>
>>>
>>> On 16.07.2018 19:06, Jonas Toth via cfe-dev wrote:
>>>>
>>>> Hi Rafael,
>>>>
>>>> wouldn't your usecase be a task for clang-refactor?
>>>>
>>>> Best,  Jonas
>>>>
>>>>
>>>> Am 16.07.2018 um 17:08 schrieb Rafael·Stahl via cfe-dev:
>>>>> Hey everyone
>>>>>
>>>>> The rewriting API of Clang operates on the source code in textual
>>>>> form. The user can use AST nodes to figure out what to replace,
>>>>> but in the end he has to remove and insert snippets in a linear
>>>>> piece of text.
>>>>>
>>>>> This is very inconvenient when it is required to restructure and
>>>>> nest replacements. The involvement of macros makes a manual
>>>>> process even more difficult. See some recent threads expressing
>>>>> difficulty with the API [1][2].
>>>>>
>>>>> What do I mean by "nested replacements"? For example in the
>>>>> following:
>>>>>
>>>>>     int i = x + s->a;
>>>>>
>>>>> I would want to replace the BinaryOperator with a function call
>>>>> and the MemberExpr with some constant:
>>>>>
>>>>>     int i = Addition(x, 7);
>>>>>
>>>>> When keeping the two replacement rules independent of each other,
>>>>> achieving this with the current API is extremely difficult. More
>>>>> so when macros are involved.
>>>>>
>>>>> I am proposing some kind of helper that aims to solve these issues
>>>>> by providing an interface that offers to directly replace AST
>>>>> nodes and a mechanism to nest AST node replacements - without
>>>>> having to worry about macros.
>>>>>
>>>>> Potential usage:
>>>>>
>>>>> - Develop a class that derives from StmtToRewrite to define how
>>>>> replacements should happen:
>>>>>
>>>>>     class RewriteAdds : public cu::StmtToRewrite
>>>>>     {
>>>>>     public:
>>>>>         std::string makeReplaceStr() const override
>>>>>         {
>>>>>             auto binOp = dyn_cast<BinaryOperator>(replaceS);
>>>>>             return "Addition(" +
>>>>> getMgr()->getReplaced(binOp->getLHS()).strToInsert + ", " +
>>>>> getMgr()->getReplaced(binOp->getRHS()).strToInsert + ")";
>>>>>         }
>>>>>     };
>>>>>
>>>>>     class RewriteMembs : public cu::StmtToRewrite
>>>>>     {
>>>>>     public:
>>>>>         std::string makeReplaceStr() const override
>>>>>         {
>>>>>             return "7";
>>>>>         }
>>>>>     };
>>>>>
>>>>> - Construct a RewriteManager:
>>>>>
>>>>>     cu::RewriteManager mgr(ACtx, PP);
>>>>>
>>>>> - Add rewriting operations to the manager:
>>>>>
>>>>>     // std::vector<const Stmt *> AddStmts = /* matched from
>>>>> binaryOperator() with plus */
>>>>>     // std::vector<const Stmt *> MembStmts = /* matched from
>>>>> memberExpr() */
>>>>>     for (const auto &S : AddStmts) mgr.registerStmt<RewriteAdds>(S);
>>>>>     for (const auto &S : MembStmts)
>>>>> mgr.registerStmt<RewriteMembs>(S);
>>>>>
>>>>> - Retrieve and apply the results:
>>>>>
>>>>>     clang::Rewriter rewriter(SM, LangOpts);
>>>>>     for (const auto &r : mgr.getReplacements()) {
>>>>>         rewriter.RemoveText(r.rangeToRemove);
>>>>>         rewriter.InsertText(r.rangeToRemove.getBegin(),
>>>>> r.strToInsert);
>>>>>     }
>>>>>
>>>>>
>>>>> At the end of this mail is my low quality code that kind-of
>>>>> implements this. TLDR:
>>>>>
>>>>> - Build a hierarchy of stmts to replace and keep track of which
>>>>> replacements must be combined
>>>>> - Move further up in the AST if these replacements are inside a macro
>>>>> - Recursively lex the file and look for replacements outside-in by
>>>>> spelling locations. Expand any macros that are encountered during
>>>>> this. The re-lexing idea is based on the hint in [3].
>>>>>
>>>>> The code has the following shortcomings:
>>>>>
>>>>> - I do not know how to distinguish macro argument expansions
>>>>> within macros. For example in "#define FOO(a) a + a" the two "a"s
>>>>> expand to different AST nodes that could be replaced with
>>>>> different rules. This is an important issue, because it can lead
>>>>> to completely broken code with nesting.
>>>>> - Limited to Stmts, when Decls should be supported too.
>>>>> - Very un-optimized with lexing the entire source file many times.
>>>>> Easy to solve, but didn't want to raise the complexity further for
>>>>> now.
>>>>> - Could keep written code more clean by only expanding macros if
>>>>> required. For example not required if just a macro arg is replaced
>>>>> and all expansions would be the same.
>>>>>
>>>>>
>>>>> I am very interested in your general thoughts. I'm not very
>>>>> experienced with clang, but this was my vision how I would want to
>>>>> do replacements. Are you interested in getting this into clang? I
>>>>> would need help with ironing out the remaining issues.
>>>>>
>>>>> -Rafael
>>>>>
>>>>>
>>>>> [1] http://lists.llvm.org/pipermail/cfe-dev/2018-July/058430.html
>>>>> [2] http://lists.llvm.org/pipermail/cfe-dev/2018-June/058213.html
>>>>> [3] http://lists.llvm.org/pipermail/cfe-dev/2017-August/055079.html
>>>>>
>>>>>
>>>>>
>>>>> ----------------------------------------
>>>>>
>>>>> RewriteManager.h
>>>>>
>>>>> ----------------------------------------
>>>>>
>>>>> #ifndef CLANGUTIL_REWRITEMANAGER_H
>>>>> #define CLANGUTIL_REWRITEMANAGER_H
>>>>>
>>>>> #include "ClangUtil/SourceRangeLess.h"
>>>>> #include "make_unique.h"
>>>>> #include "clang/AST/AST.h"
>>>>> #include <vector>
>>>>> #include <map>
>>>>>
>>>>>
>>>>> // TODO extend to decls
>>>>>
>>>>>
>>>>> namespace cu
>>>>> {
>>>>> // Represents a statement in the original AST that should be
>>>>> rewritten. To implement recursive replacements, call
>>>>> // getMgr()->getReplaced() on any AST node within the
>>>>> makeReplaceStr callback.
>>>>> class StmtToRewrite
>>>>> {
>>>>>     friend class RewriteManager;
>>>>>
>>>>> public:
>>>>>     // Returns the enclosing RewriteManager.
>>>>>     class RewriteManager *getMgr() const;
>>>>>     // Override this to build a replacement string. Implement
>>>>> recursive replacements with RewriteManager::getReplaced.
>>>>>     virtual std::string makeReplaceStr() const = 0;
>>>>>
>>>>>     // The statement to replace.
>>>>>     const clang::Stmt *replaceS = nullptr;
>>>>>
>>>>> private:
>>>>>     RewriteManager *m_mgr;
>>>>> };
>>>>>
>>>>> struct RewriteOperation
>>>>> {
>>>>>     clang::SourceRange rangeToRemove;
>>>>>     std::string strToInsert;
>>>>> };
>>>>>
>>>>> // A class for managing replacements of AST nodes. It allows to
>>>>> specifically target AST nodes instead of raw source
>>>>> // locations to enable easy replacements involving macros and
>>>>> nested replacements.
>>>>> // For extended documentation see: doc/rewriting.md
>>>>> class RewriteManager
>>>>> {
>>>>> public:
>>>>>     RewriteManager(clang::ASTContext &ACtx, clang::Preprocessor &PP);
>>>>>
>>>>>     clang::ASTContext &getACtx() const { return ACtx; }
>>>>>
>>>>>     // Registers a StmtToRewrite for use with getReplacements.
>>>>> Call this on all
>>>>>     // statements that should be rewritten before calling any
>>>>> rewriting functions.
>>>>>     void registerStmt(std::unique_ptr<StmtToRewrite> S);
>>>>>
>>>>>     // Helper for constructing the custom type from a Stmt.
>>>>>     template <typename T, typename... Args>
>>>>>     void registerStmt(const clang::Stmt *S, Args... args)
>>>>>     {
>>>>>         auto p = std::make_unique<T>(std::forward<Args>(args)...);
>>>>>         p->replaceS = S;
>>>>>         registerStmt(std::move(p));
>>>>>     }
>>>>>
>>>>>     // Get the full replacement of an AST node. Note that this
>>>>> function removes any replaced statements from the work
>>>>>     // list, so calling it twice will only replace the first time.
>>>>>     RewriteOperation getReplaced(const clang::Stmt *S);
>>>>>     // Get all replacements. These may be fewer than the requested
>>>>> ones because of nesting.
>>>>>     std::vector<RewriteOperation> getReplacements();
>>>>>
>>>>> private:
>>>>>     std::string getExpandedCode(const clang::Stmt *toReplaceS);
>>>>>
>>>>> private:
>>>>>     clang::ASTContext &ACtx;
>>>>>     const clang::LangOptions &LangOpts;
>>>>>     clang::SourceManager &SM;
>>>>>     clang::Preprocessor &PP;
>>>>>
>>>>>     // Manages the pending replacements.
>>>>>     class WorkList
>>>>>     {
>>>>>     public:
>>>>>         typedef std::map<clang::SourceRange, std::vector<const
>>>>> StmtToRewrite *>> RangeToRepMap;
>>>>>
>>>>>         WorkList(clang::ASTContext &ACtx, clang::SourceManager &SM);
>>>>>
>>>>>         bool isStmtPending(const clang::Stmt *S) const;
>>>>>         void addStmt(std::unique_ptr<StmtToRewrite> S);
>>>>>         const RangeToRepMap &getRangeToReplacementsMap() const;
>>>>>         std::vector<const StmtToRewrite *> getSortedReplacements()
>>>>> const;
>>>>>         void markDone(const StmtToRewrite *S);
>>>>>         void cleanup();
>>>>>
>>>>>     private:
>>>>>         clang::ASTContext &ACtx;
>>>>>         clang::SourceManager &SM;
>>>>>         std::vector<std::unique_ptr<StmtToRewrite>> m_pending;
>>>>>         std::vector<std::unique_ptr<StmtToRewrite>> m_done;
>>>>>         RangeToRepMap m_rangeToReplacements;
>>>>>     };
>>>>>
>>>>>     WorkList m_workList;
>>>>> };
>>>>>
>>>>> } // namespace cu
>>>>>
>>>>> #endif
>>>>>
>>>>>
>>>>>
>>>>> ----------------------------------------
>>>>>
>>>>> RewriteManager.cpp
>>>>>
>>>>> ----------------------------------------
>>>>>
>>>>> #include "ClangUtil/RewriteManager.h"
>>>>> #include "ClangUtil/ASTUtil.h"
>>>>> #include "clang/Lex/Lexer.h"
>>>>> #include "clang/Lex/Preprocessor.h"
>>>>> #include "clang/Lex/PreprocessorOptions.h"
>>>>> #include "clang/Lex/TokenConcatenation.h"
>>>>> #include "clang/Lex/MacroArgs.h"
>>>>>
>>>>>
>>>>> using namespace cu;
>>>>>
>>>>>
>>>>> // Returns a Stmt that is the first parent of startS whose
>>>>> expansion range is within the given range.
>>>>> static const clang::Stmt *GetFullMacroStmt(clang::SourceRange
>>>>> range, const clang::Stmt *startS, clang::ASTContext &ACtx)
>>>>> {
>>>>>     auto &SM = ACtx.getSourceManager();
>>>>>
>>>>>     // Walk the tree upwards until ST does no longer expand to
>>>>> within range.
>>>>>     const clang::Stmt *ST = startS;
>>>>>     while (true)
>>>>>     {
>>>>>         const auto &parents = ACtx.getParents(*ST);
>>>>>         if (parents.empty())
>>>>>         {
>>>>>             break;
>>>>>         }
>>>>>         auto childS = ST;
>>>>>         ST = parents[0].get<clang::Stmt>();
>>>>>         if (!ST)
>>>>>         {
>>>>>             if (auto D = parents[0].get<clang::Decl>())
>>>>>             {
>>>>>                 const auto &parentsD = ACtx.getParents(*D);
>>>>>                 if (parentsD.empty())
>>>>>                 {
>>>>>                     break;
>>>>>                 }
>>>>>                 ST = parentsD[0].get<clang::Stmt>();
>>>>>                 if (!ST)
>>>>>                 {
>>>>>                     break;
>>>>>                 }
>>>>>             }
>>>>>             else
>>>>>             {
>>>>>                 break;
>>>>>             }
>>>>>         }
>>>>>
>>>>>         auto exLocS = SM.getExpansionLoc(ST->getLocStart());
>>>>>         auto exLocE = SM.getExpansionLoc(ST->getLocEnd());
>>>>>         if (SM.isBeforeInTranslationUnit(exLocS, range.getBegin()) ||
>>>>>             SM.isBeforeInTranslationUnit(range.getEnd(), exLocE))
>>>>>         {
>>>>>             return childS;
>>>>>         }
>>>>>     }
>>>>>
>>>>>     return nullptr;
>>>>> }
>>>>>
>>>>>
>>>>> RewriteManager *StmtToRewrite::getMgr() const
>>>>> {
>>>>>     return m_mgr;
>>>>> }
>>>>>
>>>>>
>>>>> RewriteManager::WorkList::WorkList(clang::ASTContext &ACtx,
>>>>> clang::SourceManager &SM) : ACtx(ACtx), SM(SM) {}
>>>>> bool RewriteManager::WorkList::isStmtPending(const clang::Stmt *S)
>>>>> const
>>>>> {
>>>>>     for (const auto &r : m_pending)
>>>>>     {
>>>>>         if (r->replaceS == S)
>>>>>         {
>>>>>             return true;
>>>>>         }
>>>>>     }
>>>>>     return false;
>>>>> }
>>>>> void
>>>>> RewriteManager::WorkList::addStmt(std::unique_ptr<StmtToRewrite> S)
>>>>> {
>>>>>     // Use the expansion range for maximal replacement flexibility
>>>>> in macros.
>>>>>     auto replaceRange =
>>>>> SM.getExpansionRange(S->replaceS->getSourceRange());
>>>>>
>>>>>     // TODO not quite correct.
>>>>>     /*auto sortRanges = [&](std::vector<const StmtToRewrite *>
>>>>> &vec) {
>>>>>         std::sort(vec.begin(), vec.end(), [&](const StmtToRewrite
>>>>> *lhs, const StmtToRewrite *rhs) {
>>>>>             auto lhsRange =
>>>>> SM.getExpansionRange(lhs->replaceS->getSourceRange());
>>>>>             auto rhsRange =
>>>>> SM.getExpansionRange(rhs->replaceS->getSourceRange());
>>>>>             return IsContained(rhsRange, lhsRange, SM);
>>>>>         });
>>>>>     };*/
>>>>>
>>>>>     // Establish hierarchical relation between all ranges.
>>>>>     bool found = false;
>>>>>     // First, check if this range is within one we already have.
>>>>>     for (auto &r : m_rangeToReplacements)
>>>>>     {
>>>>>         if (IsContained(replaceRange, r.first, SM))
>>>>>         {
>>>>>             // Insert in a sorted order.
>>>>>             for (auto it = r.second.begin(); it != r.second.end();
>>>>> ++it)
>>>>>             {
>>>>>                 //auto testRange =
>>>>> SM.getExpansionRange((*it)->replaceS->getSourceRange());
>>>>>                 // if (IsContained(testRange, replaceRange, SM))
>>>>>                 if (IsParent(S->replaceS, (*it)->replaceS, ACtx))
>>>>>                 {
>>>>>                     r.second.insert(it, S.get());
>>>>>                     found = true;
>>>>>                     break;
>>>>>                 }
>>>>>             }
>>>>>             if (!found)
>>>>>             {
>>>>>                 r.second.push_back(S.get());
>>>>>                 found = true;
>>>>>             }
>>>>>             break;
>>>>>         }
>>>>>     }
>>>>>     // Not within existing range, add as new top-level range.
>>>>>     if (!found)
>>>>>     {
>>>>>         // Check if any existing ranges are contained within the
>>>>> new one.
>>>>>         std::vector<const StmtToRewrite *> moveThese;
>>>>>         auto it = m_rangeToReplacements.begin();
>>>>>         while (it != m_rangeToReplacements.end())
>>>>>         {
>>>>>             if (IsContained(it->first, replaceRange, SM))
>>>>>             {
>>>>>                 moveThese.insert(moveThese.end(),
>>>>> it->second.begin(), it->second.end());
>>>>>                 it = m_rangeToReplacements.erase(it);
>>>>>             }
>>>>>             else
>>>>>             {
>>>>>                 ++it;
>>>>>             }
>>>>>         }
>>>>>         auto &accesses = m_rangeToReplacements[replaceRange];
>>>>>         // The order is important here. We want the first element
>>>>> to be the one that spans the full range.
>>>>>         accesses.push_back(S.get());
>>>>>         // TODO sort "moveThese".
>>>>>         accesses.insert(accesses.end(), moveThese.begin(),
>>>>> moveThese.end());
>>>>>     }
>>>>>
>>>>>     int count = 0;
>>>>>     for (const auto &r : m_rangeToReplacements)
>>>>>     {
>>>>>         printf("range %i\n", count++);
>>>>>         for (const auto &a : r.second)
>>>>>         {
>>>>>             printf("replacement:\n");
>>>>>             a->replaceS->dump();
>>>>>         }
>>>>>     }
>>>>>
>>>>>     m_pending.push_back(std::move(S));
>>>>> }
>>>>> const RewriteManager::WorkList::RangeToRepMap
>>>>> &RewriteManager::WorkList::getRangeToReplacementsMap() const
>>>>> {
>>>>>     return m_rangeToReplacements;
>>>>> }
>>>>> std::vector<const StmtToRewrite *>
>>>>> RewriteManager::WorkList::getSortedReplacements() const
>>>>> {
>>>>>     std::vector<const StmtToRewrite *> result;
>>>>>     for (auto &r : m_rangeToReplacements)
>>>>>     {
>>>>>         result.insert(result.end(), r.second.begin(),
>>>>> r.second.end());
>>>>>     }
>>>>>     return result;
>>>>> }
>>>>> void RewriteManager::WorkList::markDone(const StmtToRewrite *S)
>>>>> {
>>>>>     // Remove from hierarchy.
>>>>>     for (auto &r : m_rangeToReplacements)
>>>>>     {
>>>>>         r.second.erase(std::remove(r.second.begin(),
>>>>> r.second.end(), S), r.second.end());
>>>>>     }
>>>>>
>>>>>     // Move from pending to done list.
>>>>>     auto it = std::find_if(m_pending.begin(), m_pending.end(),
>>>>>                            [&](const
>>>>> std::unique_ptr<StmtToRewrite> &rep) { return rep.get() == S; });
>>>>>     if (it == m_pending.end())
>>>>>     {
>>>>>         throw std::runtime_error("Did not find replacement to mark
>>>>> as done");
>>>>>     }
>>>>>     m_done.push_back(std::move(*it));
>>>>>     m_pending.erase(it);
>>>>> }
>>>>> void RewriteManager::WorkList::cleanup()
>>>>> {
>>>>>     m_done.clear();
>>>>> }
>>>>>
>>>>>
>>>>> RewriteManager::RewriteManager(clang::ASTContext &ACtx,
>>>>> clang::Preprocessor &PP)
>>>>>     : ACtx(ACtx), LangOpts(ACtx.getLangOpts()),
>>>>> SM(ACtx.getSourceManager()), PP(PP), m_workList(ACtx, SM)
>>>>> {
>>>>> }
>>>>>
>>>>> void RewriteManager::registerStmt(std::unique_ptr<StmtToRewrite> S)
>>>>> {
>>>>>     if (!S->replaceS)
>>>>>     {
>>>>>         throw std::runtime_error("Must set replaceS");
>>>>>     }
>>>>>
>>>>>     if (m_workList.isStmtPending(S->replaceS))
>>>>>     {
>>>>>         throw std::runtime_error("This Stmt will already be
>>>>> replaced");
>>>>>     }
>>>>>
>>>>>     S->m_mgr = this;
>>>>>     m_workList.addStmt(std::move(S));
>>>>> }
>>>>>
>>>>> RewriteOperation RewriteManager::getReplaced(const clang::Stmt *S)
>>>>> {
>>>>>     auto range = SM.getExpansionRange(S->getSourceRange());
>>>>>     return { range, getExpandedCode(S) };
>>>>> }
>>>>>
>>>>> std::vector<RewriteOperation> RewriteManager::getReplacements()
>>>>> {
>>>>>     std::vector<RewriteOperation> results;
>>>>>
>>>>>     for (auto &rangeAndAccesses :
>>>>> m_workList.getRangeToReplacementsMap())
>>>>>     {
>>>>>         auto &range = rangeAndAccesses.first;
>>>>>         auto &accesses = rangeAndAccesses.second;
>>>>>
>>>>>         // Cannot replace something inside a macro because it
>>>>> would replace all expansions instead of just the selected
>>>>>         // AST node. So in a first step, get an enclosing
>>>>> statement that is no longer inside a macro.
>>>>>         // TODO we could keep the original code more clean by not
>>>>> expanding macro args if the whole expansion does not
>>>>>         // contain the macro arg more than once.
>>>>>         auto macroS = GetFullMacroStmt(range,
>>>>> accesses[0]->replaceS, ACtx);
>>>>>
>>>>>         results.push_back(getReplaced(macroS));
>>>>>
>>>>>         // TODO we could run clang-format on the replacements.
>>>>> this would especially benefit long macro expansions.
>>>>>     }
>>>>>
>>>>>     m_workList.cleanup();
>>>>>
>>>>>     return results;
>>>>> }
>>>>>
>>>>> std::string RewriteManager::getExpandedCode(const clang::Stmt
>>>>> *toReplaceS)
>>>>> {
>>>>>     // TODO performance optimization. this is parsing way more
>>>>> than required.
>>>>>
>>>>>     using namespace clang;
>>>>>
>>>>>     printf("getExpandedCode:\n");
>>>>>     toReplaceS->dump();
>>>>>
>>>>>     std::string out;
>>>>>
>>>>>     auto toReplaceExpStart =
>>>>> SM.getExpansionLoc(toReplaceS->getLocStart());
>>>>>     auto toReplaceExpEnd =
>>>>> SM.getExpansionLoc(toReplaceS->getLocEnd());
>>>>>     auto toReplaceSpellStart =
>>>>> SM.getSpellingLoc(toReplaceS->getLocStart());
>>>>>     auto toReplaceSpellEnd =
>>>>> SM.getSpellingLoc(toReplaceS->getLocEnd());
>>>>>
>>>>>     auto FID =
>>>>> SM.getFileID(SM.getExpansionLoc(toReplaceS->getLocStart()));
>>>>>
>>>>>     // The following is inspired by:
>>>>> clang/Rewrite/HTMLRewrite.cpp:HighlightMacros
>>>>>
>>>>>     // Re-lex the raw token stream into a token buffer.
>>>>>     std::vector<Token> TokenStream;
>>>>>
>>>>>     const llvm::MemoryBuffer *FromFile = SM.getBuffer(FID);
>>>>>     Lexer L(FID, FromFile, SM, PP.getLangOpts());
>>>>>
>>>>>     // Lex all the tokens in raw mode, to avoid entering #includes
>>>>> or expanding
>>>>>     // macros.
>>>>>     while (1)
>>>>>     {
>>>>>         Token Tok;
>>>>>         L.LexFromRawLexer(Tok);
>>>>>
>>>>>         // If this is a # at the start of a line, discard it from
>>>>> the token stream.
>>>>>         // We don't want the re-preprocess step to see #defines,
>>>>> #includes or other
>>>>>         // preprocessor directives.
>>>>>         if (Tok.is(tok::hash) && Tok.isAtStartOfLine())
>>>>>             continue;
>>>>>
>>>>>         // If this is a ## token, change its kind to unknown so
>>>>> that repreprocessing
>>>>>         // it will not produce an error.
>>>>>         if (Tok.is(tok::hashhash))
>>>>>             Tok.setKind(tok::unknown);
>>>>>
>>>>>         // If this raw token is an identifier, the raw lexer won't
>>>>> have looked up
>>>>>         // the corresponding identifier info for it.  Do this now
>>>>> so that it will be
>>>>>         // macro expanded when we re-preprocess it.
>>>>>         if (Tok.is(tok::raw_identifier))
>>>>>             PP.LookUpIdentifierInfo(Tok);
>>>>>
>>>>>         TokenStream.push_back(Tok);
>>>>>
>>>>>         for (auto &rep : m_workList.getSortedReplacements())
>>>>>         {
>>>>>             auto repS = rep->replaceS;
>>>>>             auto spellLoc = SM.getSpellingLoc(repS->getLocStart());
>>>>>             if (SM.getSpellingLoc(Tok.getLocation()) == spellLoc)
>>>>>             {
>>>>>                 //
>>>>>             }
>>>>>         }
>>>>>
>>>>>         if (Tok.is(tok::eof))
>>>>>             break;
>>>>>     }
>>>>>
>>>>>     // Temporarily change the diagnostics object so that we ignore
>>>>> any generated
>>>>>     // diagnostics from this pass.
>>>>>     DiagnosticsEngine
>>>>> TmpDiags(PP.getDiagnostics().getDiagnosticIDs(),
>>>>> &PP.getDiagnostics().getDiagnosticOptions(),
>>>>>                                new IgnoringDiagConsumer);
>>>>>
>>>>>     // Copy the preprocessor and all of its state.
>>>>>     auto PPOpts =
>>>>> std::make_shared<PreprocessorOptions>(PP.getPreprocessorOpts());
>>>>>     LangOptions LO = PP.getLangOpts();
>>>>>     Preprocessor TmpPP(PPOpts, TmpDiags, LO, SM, PP.getPCMCache(),
>>>>> PP.getHeaderSearchInfo(), PP.getModuleLoader(),
>>>>> PP.getIdentifierTable().getExternalIdentifierLookup());
>>>>>     TmpPP.Initialize(PP.getTargetInfo(), PP.getAuxTargetInfo());
>>>>>     TmpPP.setExternalSource(PP.getExternalSource());
>>>>>     TmpPP.setPreprocessedOutput(true);
>>>>>
>>>>>     std::map<const clang::IdentifierInfo *, bool>
>>>>> MacroPreviouslyEnabled;
>>>>>     for (const auto &m : PP.macros())
>>>>>     {
>>>>>         // printf("PREDEF MACRO: %s\n",
>>>>> m.first->getName().str().c_str());
>>>>>         TmpPP.getMacroDefinition(m.first);
>>>>>
>>>>>         for (const auto &tmpm : TmpPP.macros())
>>>>>         {
>>>>>             if (tmpm.first == m.first)
>>>>>             {
>>>>>                 auto MD = m.second.getLatest();
>>>>>                 auto MI = MD->getMacroInfo();
>>>>>                 // If this is a recursive call we might be in a
>>>>> macro expansion and the macro might be disabled. We need
>>>>>                 // to enable it for now so that all expansions
>>>>> work. Restore it later.
>>>>>                 MacroPreviouslyEnabled[tmpm.first] = MI->isEnabled();
>>>>>                 if (!MI->isEnabled())
>>>>>                 {
>>>>>                     MD->getMacroInfo()->EnableMacro();
>>>>>                 }
>>>>>
>>>>>                 // This should not change anything since we just
>>>>> copy data over.
>>>>>                 auto &mutableState =
>>>>> const_cast<std::remove_const<decltype(tmpm.second)>::type
>>>>> &>(tmpm.second);
>>>>>                 mutableState.setLatest(MD);
>>>>>                 break;
>>>>>             }
>>>>>         }
>>>>>     }
>>>>>
>>>>>     class MacroArgCollector : public clang::PPCallbacks
>>>>>     {
>>>>>     public:
>>>>>         MacroArgCollector(Preprocessor &TmpPP) : TmpPP(TmpPP) {}
>>>>>
>>>>>         void MacroExpands(const Token &Tok, const MacroDefinition
>>>>> &MD, SourceRange Range, const MacroArgs *Args) override
>>>>>         {
>>>>>             if (!Args)
>>>>>             {
>>>>>                 return;
>>>>>             }
>>>>>             printf("GOT MACRO ARGS EXPANSION CALLBACK\n");
>>>>>             for (int i = 0; i < (int)Args->getNumMacroArguments();
>>>>> i++)
>>>>>             {
>>>>>                 auto TokUnex = Args->getUnexpArgument(i);
>>>>>                 // Thats just non-const for a cache, so should be
>>>>> fine.
>>>>>                 auto TokPreExp = const_cast<MacroArgs
>>>>> *>(Args)->getPreExpArgument(i, TmpPP);
>>>>>                 printf("unexp: %s\n",
>>>>> TmpPP.getSpelling(*TokUnex).c_str());
>>>>>                 for (const auto &T : TokPreExp)
>>>>>                 {
>>>>>                     printf("preexp: %s\n",
>>>>> TmpPP.getSpelling(T).c_str());
>>>>>                 }
>>>>>             }
>>>>>         }
>>>>>
>>>>>         Preprocessor &TmpPP;
>>>>>     };
>>>>> TmpPP.addPPCallbacks(std::make_unique<MacroArgCollector>(TmpPP));
>>>>>     // Instead: collect the macro arg info in the law lexing step
>>>>> above. or do another pass that uses the PP but without expansions.
>>>>>
>>>>>     /*printf("DUMP MACRO INFO\n");
>>>>>     for (const auto &m : PP.macros())
>>>>>         PP.dumpMacroInfo(m.first);
>>>>>     printf("---\n");
>>>>>     for (const auto &m : TmpPP.macros())
>>>>>         TmpPP.dumpMacroInfo(m.first);
>>>>>     printf("DUMP MACRO INFO END\n");*/
>>>>>
>>>>>     DiagnosticsEngine *OldDiags = &TmpPP.getDiagnostics();
>>>>>
>>>>>     // Inform the preprocessor that we don't want comments.
>>>>>     TmpPP.SetCommentRetentionState(false, false);
>>>>>
>>>>>     // We don't want pragmas either. Although we filtered out
>>>>> #pragma, removing
>>>>>     // _Pragma and __pragma is much harder.
>>>>>     bool PragmasPreviouslyEnabled = TmpPP.getPragmasEnabled();
>>>>>     TmpPP.setPragmasEnabled(false);
>>>>>
>>>>>     // Enter the tokens we just lexed.  This will cause them to be
>>>>> macro expanded
>>>>>     // but won't enter sub-files (because we removed #'s).
>>>>>     TmpPP.EnterTokenStream(TokenStream, false);
>>>>>
>>>>>     TokenConcatenation ConcatInfo(TmpPP);
>>>>>
>>>>>     // Lex all the tokens.
>>>>>     Token Tok;
>>>>>     TmpPP.Lex(Tok);
>>>>>
>>>>>     std::map<SourceLocation, int> slocIdx;
>>>>>
>>>>>     auto checkReplacement = [&]() {
>>>>>         for (auto &rep : m_workList.getSortedReplacements())
>>>>>         {
>>>>>             // auto rep = r.second.get();
>>>>>             auto repS = rep->replaceS;
>>>>>             auto spellLoc = SM.getSpellingLoc(repS->getLocStart());
>>>>>             // TODO we need to check here if the repS spans the
>>>>> full range (or largest?)
>>>>>             if (SM.getSpellingLoc(Tok.getLocation()) == spellLoc)
>>>>>             {
>>>>>                 if (slocIdx[spellLoc] == 7)
>>>>>                 {
>>>>>                     // replace
>>>>>                 }
>>>>>                 slocIdx[spellLoc]++;
>>>>>
>>>>>                 // Done replacing that one, but have to keep it
>>>>> alive until we're done with it.
>>>>>                 m_workList.markDone(rep);
>>>>>
>>>>>                 printf("[[[\n");
>>>>>                 auto repStr = rep->makeReplaceStr();
>>>>>                 printf("REPLACED: %s ]]]\n", repStr.c_str());
>>>>>                 out += repStr;
>>>>>
>>>>>                 // Skip ahead until after the whole replacement.
>>>>>                 auto repEnd = SM.getSpellingLoc(repS->getLocEnd());
>>>>>                 while (repEnd !=
>>>>> SM.getSpellingLoc(Tok.getLocation()))
>>>>>                 {
>>>>>                     TmpPP.Lex(Tok);
>>>>>                     assert(!Tok.is(tok::eof) && "End not found");
>>>>>                 }
>>>>>
>>>>>                 // Eat one more since we stopped at the end token
>>>>> and we want to continue after it.
>>>>>                 TmpPP.Lex(Tok);
>>>>>
>>>>>                 return true;
>>>>>             }
>>>>>         }
>>>>>         return false;
>>>>>     };
>>>>>
>>>>>     while (Tok.isNot(tok::eof))
>>>>>     {
>>>>>         printf("TOKEN: %s\n", TmpPP.getSpelling(Tok).c_str());
>>>>>
>>>>>         auto TokLoc = Tok.getLocation();
>>>>>         auto TokExp = SM.getExpansionLoc(TokLoc);
>>>>>         if (SM.isBeforeInTranslationUnit(toReplaceExpEnd, TokExp))
>>>>>         {
>>>>>             // Anything after the Stmt we want to replace is not
>>>>> interesting.
>>>>>             break;
>>>>>         }
>>>>>
>>>>>         // Skip ahead until we are at the expansion start of the
>>>>> Stmt we want to replace.
>>>>>         if (!SM.isBeforeInTranslationUnit(TokLoc, toReplaceExpStart))
>>>>>         {
>>>>>             if (TokLoc.isMacroID())
>>>>>             {
>>>>>                 // This is the first token of a macro expansion.
>>>>>                 auto LLoc = SM.getExpansionRange(TokLoc);
>>>>>
>>>>>                 // Ignore tokens whose instantiation location was
>>>>> not the main file.
>>>>>                 if (SM.getFileID(LLoc.first) != FID)
>>>>>                 {
>>>>>                     TmpPP.Lex(Tok);
>>>>>                     continue;
>>>>>                 }
>>>>>
>>>>>                 assert(SM.getFileID(LLoc.second) == FID &&
>>>>>                        "Start and end of expansion must be in the
>>>>> same ultimate file!");
>>>>>
>>>>>                 bool stopOutputOnNextToken = false;
>>>>>                 bool toReplaceStartsInMacro = toReplaceExpStart ==
>>>>> TokExp;
>>>>>                 bool toReplaceEndsInMacro = toReplaceExpEnd ==
>>>>> TokExp;
>>>>>                 bool startedOutput = false;
>>>>>
>>>>>                 Token PrevPrevTok;
>>>>>                 Token PrevTok = Tok;
>>>>>
>>>>>                 while (!Tok.is(tok::eof) &&
>>>>> SM.getExpansionLoc(Tok.getLocation()) == LLoc.first)
>>>>>                 {
>>>>>                     printf("TOKEN (in macro): %s\n",
>>>>> TmpPP.getSpelling(Tok).c_str());
>>>>>
>>>>>                     auto TokSpell =
>>>>> SM.getSpellingLoc(Tok.getLocation());
>>>>>                     if (stopOutputOnNextToken)
>>>>>                     {
>>>>>                         break;
>>>>>                     }
>>>>>                     if (toReplaceEndsInMacro && TokSpell ==
>>>>> toReplaceSpellEnd)
>>>>>                     {
>>>>>                         stopOutputOnNextToken = true;
>>>>>                     }
>>>>>
>>>>>                     if (toReplaceStartsInMacro && !startedOutput)
>>>>>                     {
>>>>>                         if (TokSpell == toReplaceSpellStart)
>>>>>                         {
>>>>>                             startedOutput = true;
>>>>>                         }
>>>>>                         else
>>>>>                         {
>>>>>                             TmpPP.Lex(Tok);
>>>>>                             continue;
>>>>>                         }
>>>>>                     }
>>>>>
>>>>>                     // If the tokens were already space separated,
>>>>> or if they must be to avoid
>>>>>                     // them being implicitly pasted, add a space
>>>>> between them.
>>>>>                     if (Tok.hasLeadingSpace() ||
>>>>> ConcatInfo.AvoidConcat(PrevPrevTok, PrevTok, Tok))
>>>>>                         out += ' ';
>>>>>
>>>>>                     if (checkReplacement())
>>>>>                     {
>>>>>                         continue;
>>>>>                     }
>>>>>
>>>>>                     out += TmpPP.getSpelling(Tok);
>>>>>                     TmpPP.Lex(Tok);
>>>>>                 }
>>>>>                 if (stopOutputOnNextToken)
>>>>>                 {
>>>>>                     break;
>>>>>                 }
>>>>>             }
>>>>>             else
>>>>>             {
>>>>>                 if (checkReplacement())
>>>>>                 {
>>>>>                     continue;
>>>>>                 }
>>>>>
>>>>>                 // Output original code because we are outside of
>>>>> a replacement.
>>>>>                 out += TmpPP.getSpelling(Tok);
>>>>>                 TmpPP.Lex(Tok);
>>>>>             }
>>>>>         }
>>>>>         else
>>>>>         {
>>>>>             TmpPP.Lex(Tok);
>>>>>         }
>>>>>     }
>>>>>
>>>>>     // Restore the preprocessor's old state.
>>>>>     TmpPP.setDiagnostics(*OldDiags);
>>>>>     TmpPP.setPragmasEnabled(PragmasPreviouslyEnabled);
>>>>>
>>>>>     for (const auto &tmpm : TmpPP.macros())
>>>>>     {
>>>>>         auto it = MacroPreviouslyEnabled.find(tmpm.first);
>>>>>         if (it != MacroPreviouslyEnabled.end())
>>>>>         {
>>>>>             auto MD = tmpm.second.getLatest();
>>>>>             auto MI = MD->getMacroInfo();
>>>>>             if (MI->isEnabled() && !it->second)
>>>>>             {
>>>>>                 MI->DisableMacro();
>>>>>             }
>>>>>             else if (!MI->isEnabled() && it->second)
>>>>>             {
>>>>>                 MI->EnableMacro();
>>>>>             }
>>>>>         }
>>>>>     }
>>>>>
>>>>>     return out;
>>>>> }
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> cfe-dev mailing list
>>>>> cfe-dev at lists.llvm.org
>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> cfe-dev mailing list
>>>> cfe-dev at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>
>>
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