r242608 - [AST] Cleanup ExprIterator.

Alexandros Tzannes atzannes at illinois.edu
Mon Jul 27 10:09:33 PDT 2015


Hi Benjamin,
is there an advantage to making ExprIterator and ConstExprIterator 
protected in Stmt?

I have some methods that takes arguments of type ExpIterator and used to 
work for several different classes derived from Stmt (e.g., 
CXXConstructExpr, CallExpr, ...). Now that Stmt::ExprIterator is 
protected the code does not compile anymore. (E.g., void 
foo(ExprIterator ArgI, ExprIterator ArgE) which basically factors out a 
loop over expressions).

Right now, I think my best bet is to make these methods generic 
(template for type EXPR_ITERATOR) and have it specialized for the 
different public typedefs of ExprIterator 
(CXXConstructExpr::arg_iterator, CallExpr::arg_iterator). Is there a 
better approach? I'm also thinking of making ExprIterator public in the 
private branch of Clang that I'm working on.

Thanks in advance,
Alex

On 07/18/2015 05:35 PM, Benjamin Kramer wrote:
> Author: d0k
> Date: Sat Jul 18 09:35:53 2015
> New Revision: 242608
>
> URL: http://llvm.org/viewvc/llvm-project?rev=242608&view=rev
> Log:
> [AST] Cleanup ExprIterator.
>
> - Make it a proper random access iterator with a little help from iterator_adaptor_base
> - Clean up users of magic dereferencing. The iterator should behave like an Expr **.
> - Make it an implementation detail of Stmt. This allows inlining of the assertions.
>
> Modified:
>      cfe/trunk/include/clang/AST/Stmt.h
>      cfe/trunk/lib/AST/Expr.cpp
>      cfe/trunk/lib/AST/StmtPrinter.cpp
>      cfe/trunk/lib/CodeGen/CGCall.cpp
>      cfe/trunk/lib/CodeGen/CGClass.cpp
>      cfe/trunk/lib/CodeGen/CGExprCXX.cpp
>      cfe/trunk/lib/CodeGen/CodeGenFunction.h
>      cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp
>
> Modified: cfe/trunk/include/clang/AST/Stmt.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Stmt.h?rev=242608&r1=242607&r2=242608&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/AST/Stmt.h (original)
> +++ cfe/trunk/include/clang/AST/Stmt.h Sat Jul 18 09:35:53 2015
> @@ -22,6 +22,7 @@
>   #include "clang/Basic/SourceLocation.h"
>   #include "llvm/ADT/ArrayRef.h"
>   #include "llvm/ADT/PointerIntPair.h"
> +#include "llvm/ADT/iterator.h"
>   #include "llvm/Support/Compiler.h"
>   #include "llvm/Support/ErrorHandling.h"
>   #include <string>
> @@ -49,57 +50,6 @@ namespace clang {
>     class Token;
>     class VarDecl;
>   
> -  //===--------------------------------------------------------------------===//
> -  // ExprIterator - Iterators for iterating over Stmt* arrays that contain
> -  //  only Expr*.  This is needed because AST nodes use Stmt* arrays to store
> -  //  references to children (to be compatible with StmtIterator).
> -  //===--------------------------------------------------------------------===//
> -
> -  class Stmt;
> -  class Expr;
> -
> -  class ExprIterator : public std::iterator<std::forward_iterator_tag,
> -                                            Expr *&, ptrdiff_t,
> -                                            Expr *&, Expr *&> {
> -    Stmt** I;
> -  public:
> -    ExprIterator(Stmt** i) : I(i) {}
> -    ExprIterator() : I(nullptr) {}
> -    ExprIterator& operator++() { ++I; return *this; }
> -    ExprIterator operator-(size_t i) { return I-i; }
> -    ExprIterator operator+(size_t i) { return I+i; }
> -    Expr* operator[](size_t idx);
> -    // FIXME: Verify that this will correctly return a signed distance.
> -    signed operator-(const ExprIterator& R) const { return I - R.I; }
> -    Expr* operator*() const;
> -    Expr* operator->() const;
> -    bool operator==(const ExprIterator& R) const { return I == R.I; }
> -    bool operator!=(const ExprIterator& R) const { return I != R.I; }
> -    bool operator>(const ExprIterator& R) const { return I > R.I; }
> -    bool operator>=(const ExprIterator& R) const { return I >= R.I; }
> -  };
> -
> -  class ConstExprIterator : public std::iterator<std::forward_iterator_tag,
> -                                                 const Expr *&, ptrdiff_t,
> -                                                 const Expr *&,
> -                                                 const Expr *&> {
> -    const Stmt * const *I;
> -  public:
> -    ConstExprIterator(const Stmt * const *i) : I(i) {}
> -    ConstExprIterator() : I(nullptr) {}
> -    ConstExprIterator& operator++() { ++I; return *this; }
> -    ConstExprIterator operator+(size_t i) const { return I+i; }
> -    ConstExprIterator operator-(size_t i) const { return I-i; }
> -    const Expr * operator[](size_t idx) const;
> -    signed operator-(const ConstExprIterator& R) const { return I - R.I; }
> -    const Expr * operator*() const;
> -    const Expr * operator->() const;
> -    bool operator==(const ConstExprIterator& R) const { return I == R.I; }
> -    bool operator!=(const ConstExprIterator& R) const { return I != R.I; }
> -    bool operator>(const ConstExprIterator& R) const { return I > R.I; }
> -    bool operator>=(const ConstExprIterator& R) const { return I >= R.I; }
> -  };
> -
>   //===----------------------------------------------------------------------===//
>   // AST classes for statements.
>   //===----------------------------------------------------------------------===//
> @@ -337,6 +287,39 @@ public:
>     /// de-serialization).
>     struct EmptyShell { };
>   
> +protected:
> +  /// Iterator for iterating over Stmt * arrays that contain only Expr *
> +  ///
> +  /// This is needed because AST nodes use Stmt* arrays to store
> +  /// references to children (to be compatible with StmtIterator).
> +  struct ExprIterator
> +      : llvm::iterator_adaptor_base<ExprIterator, Stmt **,
> +                                    std::random_access_iterator_tag, Expr *> {
> +    ExprIterator() : iterator_adaptor_base(nullptr) {}
> +    ExprIterator(Stmt **I) : iterator_adaptor_base(I) {}
> +
> +    reference operator*() const {
> +      assert((*I)->getStmtClass() >= firstExprConstant &&
> +             (*I)->getStmtClass() <= lastExprConstant);
> +      return *reinterpret_cast<Expr **>(I);
> +    }
> +  };
> +
> +  /// Const iterator for iterating over Stmt * arrays that contain only Expr *
> +  struct ConstExprIterator
> +      : llvm::iterator_adaptor_base<ConstExprIterator, const Stmt *const *,
> +                                    std::random_access_iterator_tag,
> +                                    const Expr *const> {
> +    ConstExprIterator() : iterator_adaptor_base(nullptr) {}
> +    ConstExprIterator(const Stmt *const *I) : iterator_adaptor_base(I) {}
> +
> +    reference operator*() const {
> +      assert((*I)->getStmtClass() >= firstExprConstant &&
> +             (*I)->getStmtClass() <= lastExprConstant);
> +      return *reinterpret_cast<const Expr *const *>(I);
> +    }
> +  };
> +
>   private:
>     /// \brief Whether statistic collection is enabled.
>     static bool StatisticsEnabled;
>
> Modified: cfe/trunk/lib/AST/Expr.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Expr.cpp?rev=242608&r1=242607&r2=242608&view=diff
> ==============================================================================
> --- cfe/trunk/lib/AST/Expr.cpp (original)
> +++ cfe/trunk/lib/AST/Expr.cpp Sat Jul 18 09:35:53 2015
> @@ -4163,19 +4163,6 @@ PseudoObjectExpr::PseudoObjectExpr(QualT
>   }
>   
>   //===----------------------------------------------------------------------===//
> -//  ExprIterator.
> -//===----------------------------------------------------------------------===//
> -
> -Expr* ExprIterator::operator[](size_t idx) { return cast<Expr>(I[idx]); }
> -Expr* ExprIterator::operator*() const { return cast<Expr>(*I); }
> -Expr* ExprIterator::operator->() const { return cast<Expr>(*I); }
> -const Expr* ConstExprIterator::operator[](size_t idx) const {
> -  return cast<Expr>(I[idx]);
> -}
> -const Expr* ConstExprIterator::operator*() const { return cast<Expr>(*I); }
> -const Expr* ConstExprIterator::operator->() const { return cast<Expr>(*I); }
> -
> -//===----------------------------------------------------------------------===//
>   //  Child Iterators for iterating over subexpressions/substatements
>   //===----------------------------------------------------------------------===//
>   
>
> Modified: cfe/trunk/lib/AST/StmtPrinter.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/StmtPrinter.cpp?rev=242608&r1=242607&r2=242608&view=diff
> ==============================================================================
> --- cfe/trunk/lib/AST/StmtPrinter.cpp (original)
> +++ cfe/trunk/lib/AST/StmtPrinter.cpp Sat Jul 18 09:35:53 2015
> @@ -1768,7 +1768,7 @@ void StmtPrinter::VisitCXXTemporaryObjec
>     for (CXXTemporaryObjectExpr::arg_iterator Arg = Node->arg_begin(),
>                                            ArgEnd = Node->arg_end();
>          Arg != ArgEnd; ++Arg) {
> -    if (Arg->isDefaultArgument())
> +    if ((*Arg)->isDefaultArgument())
>         break;
>       if (Arg != Node->arg_begin())
>         OS << ", ";
>
> Modified: cfe/trunk/lib/CodeGen/CGCall.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGCall.cpp?rev=242608&r1=242607&r2=242608&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGCall.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGCall.cpp Sat Jul 18 09:35:53 2015
> @@ -2829,7 +2829,7 @@ void CodeGenFunction::EmitCallArgs(CallA
>       for (int I = ArgTypes.size() - 1; I >= 0; --I) {
>         CallExpr::const_arg_iterator Arg = ArgBeg + I;
>         EmitCallArg(Args, *Arg, ArgTypes[I]);
> -      EmitNonNullArgCheck(Args.back().RV, ArgTypes[I], Arg->getExprLoc(),
> +      EmitNonNullArgCheck(Args.back().RV, ArgTypes[I], (*Arg)->getExprLoc(),
>                             CalleeDecl, ParamsToSkip + I);
>       }
>   
> @@ -2843,7 +2843,7 @@ void CodeGenFunction::EmitCallArgs(CallA
>       CallExpr::const_arg_iterator Arg = ArgBeg + I;
>       assert(Arg != ArgEnd);
>       EmitCallArg(Args, *Arg, ArgTypes[I]);
> -    EmitNonNullArgCheck(Args.back().RV, ArgTypes[I], Arg->getExprLoc(),
> +    EmitNonNullArgCheck(Args.back().RV, ArgTypes[I], (*Arg)->getExprLoc(),
>                           CalleeDecl, ParamsToSkip + I);
>     }
>   }
>
> Modified: cfe/trunk/lib/CodeGen/CGClass.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGClass.cpp?rev=242608&r1=242607&r2=242608&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGClass.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGClass.cpp Sat Jul 18 09:35:53 2015
> @@ -1832,7 +1832,7 @@ CodeGenFunction::EmitSynthesizedCXXCopyC
>              "trivial 1-arg ctor not a copy/move ctor");
>       EmitAggregateCopyCtor(This, Src,
>                             getContext().getTypeDeclType(D->getParent()),
> -                          E->arg_begin()->getType());
> +                          (*E->arg_begin())->getType());
>       return;
>     }
>     llvm::Value *Callee = CGM.getAddrOfCXXStructor(D, StructorType::Complete);
>
> Modified: cfe/trunk/lib/CodeGen/CGExprCXX.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprCXX.cpp?rev=242608&r1=242607&r2=242608&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGExprCXX.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGExprCXX.cpp Sat Jul 18 09:35:53 2015
> @@ -196,7 +196,7 @@ RValue CodeGenFunction::EmitCXXMemberOrO
>           // Trivial move and copy ctor are the same.
>           assert(CE->getNumArgs() == 1 && "unexpected argcount for trivial ctor");
>           llvm::Value *RHS = EmitLValue(*CE->arg_begin()).getAddress();
> -        EmitAggregateCopy(This, RHS, CE->arg_begin()->getType());
> +        EmitAggregateCopy(This, RHS, (*CE->arg_begin())->getType());
>           return RValue::get(This);
>         }
>         llvm_unreachable("unknown trivial member function");
> @@ -1089,8 +1089,7 @@ RValue CodeGenFunction::EmitBuiltinNewDe
>                                                    bool IsDelete) {
>     CallArgList Args;
>     const Stmt *ArgS = Arg;
> -  EmitCallArgs(Args, *Type->param_type_begin(),
> -               ConstExprIterator(&ArgS), ConstExprIterator(&ArgS + 1));
> +  EmitCallArgs(Args, *Type->param_type_begin(), &ArgS, &ArgS + 1);
>     // Find the allocation or deallocation function that we're calling.
>     ASTContext &Ctx = getContext();
>     DeclarationName Name = Ctx.DeclarationNames
>
> Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.h?rev=242608&r1=242607&r2=242608&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CodeGenFunction.h (original)
> +++ cfe/trunk/lib/CodeGen/CodeGenFunction.h Sat Jul 18 09:35:53 2015
> @@ -2992,7 +2992,7 @@ public:
>                            .getCanonicalType((*I).getNonReferenceType())
>                            .getTypePtr() ==
>                        getContext()
> -                         .getCanonicalType(Arg->getType())
> +                         .getCanonicalType((*Arg)->getType())
>                            .getTypePtr())) &&
>                  "type mismatch in call argument!");
>           ArgTypes.push_back(*I);
>
> Modified: cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp?rev=242608&r1=242607&r2=242608&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp (original)
> +++ cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp Sat Jul 18 09:35:53 2015
> @@ -3803,9 +3803,8 @@ MicrosoftCXXABI::getAddrOfCXXCtorClosure
>     CodeGenFunction::RunCleanupsScope Cleanups(CGF);
>   
>     const auto *FPT = CD->getType()->castAs<FunctionProtoType>();
> -  ConstExprIterator ArgBegin(ArgVec.data()),
> -      ArgEnd(ArgVec.data() + ArgVec.size());
> -  CGF.EmitCallArgs(Args, FPT, ArgBegin, ArgEnd, CD, IsCopy ? 1 : 0);
> +  CGF.EmitCallArgs(Args, FPT, &*ArgVec.begin(), &*ArgVec.end(), CD,
> +                   IsCopy ? 1 : 0);
>   
>     // Insert any ABI-specific implicit constructor arguments.
>     unsigned ExtraArgs = addImplicitConstructorArgs(CGF, CD, Ctor_Complete,
>
>
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