r328749 - [ast] Do not auto-initialize Objective-C for-loop variables in Objective-C++ in templatized code under ARC
George Karpenkov via cfe-commits
cfe-commits at lists.llvm.org
Wed Mar 28 17:56:24 PDT 2018
Author: george.karpenkov
Date: Wed Mar 28 17:56:24 2018
New Revision: 328749
URL: http://llvm.org/viewvc/llvm-project?rev=328749&view=rev
Log:
[ast] Do not auto-initialize Objective-C for-loop variables in Objective-C++ in templatized code under ARC
The AST for the fragment
```
@interface I
@end
template <typename>
void decode(I *p) {
for (I *k in p) {}
}
void decode(I *p) {
decode<int>(p);
}
```
differs heavily when templatized and non-templatized:
```
|-FunctionTemplateDecl 0x7fbfe0863940 <line:4:1, line:7:1> line:5:6 decode
| |-TemplateTypeParmDecl 0x7fbfe0863690 <line:4:11> col:11 typename depth 0 index 0
| |-FunctionDecl 0x7fbfe08638a0 <line:5:1, line:7:1> line:5:6 decode 'void (I *__strong)'
| | |-ParmVarDecl 0x7fbfe08637a0 <col:13, col:16> col:16 referenced p 'I *__strong'
| | `-CompoundStmt 0x7fbfe0863b88 <col:19, line:7:1>
| | `-ObjCForCollectionStmt 0x7fbfe0863b50 <line:6:3, col:20>
| | |-DeclStmt 0x7fbfe0863a50 <col:8, col:13>
| | | `-VarDecl 0x7fbfe08639f0 <col:8, col:11> col:11 k 'I *const __strong'
| | |-ImplicitCastExpr 0x7fbfe0863a90 <col:16> 'I *' <LValueToRValue>
| | | `-DeclRefExpr 0x7fbfe0863a68 <col:16> 'I *__strong' lvalue ParmVar 0x7fbfe08637a0 'p' 'I *__strong'
| | `-CompoundStmt 0x7fbfe0863b78 <col:19, col:20>
| `-FunctionDecl 0x7fbfe0863f80 <line:5:1, line:7:1> line:5:6 used decode 'void (I *__strong)'
| |-TemplateArgument type 'int'
| |-ParmVarDecl 0x7fbfe0863ef8 <col:13, col:16> col:16 used p 'I *__strong'
| `-CompoundStmt 0x7fbfe0890cf0 <col:19, line:7:1>
| `-ObjCForCollectionStmt 0x7fbfe0890cc8 <line:6:3, col:20>
| |-DeclStmt 0x7fbfe0890c70 <col:8, col:13>
| | `-VarDecl 0x7fbfe0890c00 <col:8, col:11> col:11 k 'I *__strong' callinit
| | `-ImplicitValueInitExpr 0x7fbfe0890c60 <<invalid sloc>> 'I *__strong'
| |-ImplicitCastExpr 0x7fbfe0890cb0 <col:16> 'I *' <LValueToRValue>
| | `-DeclRefExpr 0x7fbfe0890c88 <col:16> 'I *__strong' lvalue ParmVar 0x7fbfe0863ef8 'p' 'I *__strong'
| `-CompoundStmt 0x7fbfe0863b78 <col:19, col:20>
```
Note how in the instantiated version ImplicitValueInitExpr unexpectedly appears.
While objects are auto-initialized under ARC, it does not make sense to
have an initializer for a for-loop variable, and it makes even less
sense to have such a different AST for instantiated and non-instantiated
version.
Digging deeper, I have found that there are two separate Sema* files for
dealing with templates and for dealing with non-templatized code.
In a non-templatized version, an initialization was performed only for
variables which are not loop variables for an Objective-C loop and not
variables for a C++ for-in loop:
```
if (FRI && (Tok.is(tok::colon) || isTokIdentifier_in())) {
bool IsForRangeLoop = false;
if (TryConsumeToken(tok::colon, FRI->ColonLoc)) {
IsForRangeLoop = true;
if (Tok.is(tok::l_brace))
FRI->RangeExpr = ParseBraceInitializer();
else
FRI->RangeExpr = ParseExpression();
}
Decl *ThisDecl = Actions.ActOnDeclarator(getCurScope(), D);
if (IsForRangeLoop)
Actions.ActOnCXXForRangeDecl(ThisDecl);
Actions.FinalizeDeclaration(ThisDecl);
D.complete(ThisDecl);
return Actions.FinalizeDeclaratorGroup(getCurScope(), DS, ThisDecl);
}
SmallVector<Decl *, 8> DeclsInGroup;
Decl *FirstDecl = ParseDeclarationAfterDeclaratorAndAttributes(
D, ParsedTemplateInfo(), FRI);
```
However the code in SemaTemplateInstantiateDecl was inconsistent,
guarding only against C++ for-in loops.
rdar://38391075
Differential Revision: https://reviews.llvm.org/D44989
Added:
cfe/trunk/test/SemaObjC/foreachtemplatized.mm
Modified:
cfe/trunk/include/clang/AST/Decl.h
cfe/trunk/lib/Parse/ParseDecl.cpp
cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
cfe/trunk/lib/Serialization/ASTReaderDecl.cpp
cfe/trunk/lib/Serialization/ASTWriterDecl.cpp
Modified: cfe/trunk/include/clang/AST/Decl.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Decl.h?rev=328749&r1=328748&r2=328749&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Decl.h (original)
+++ cfe/trunk/include/clang/AST/Decl.h Wed Mar 28 17:56:24 2018
@@ -937,6 +937,9 @@ protected:
/// for-range statement.
unsigned CXXForRangeDecl : 1;
+ /// Whether this variable is the for-in loop declaration in Objective-C.
+ unsigned ObjCForDecl : 1;
+
/// Whether this variable is an ARC pseudo-__strong
/// variable; see isARCPseudoStrong() for details.
unsigned ARCPseudoStrong : 1;
@@ -1334,6 +1337,16 @@ public:
NonParmVarDeclBits.CXXForRangeDecl = FRD;
}
+ /// \brief Determine whether this variable is a for-loop declaration for a
+ /// for-in statement in Objective-C.
+ bool isObjCForDecl() const {
+ return NonParmVarDeclBits.ObjCForDecl;
+ }
+
+ void setObjCForDecl(bool FRD) {
+ NonParmVarDeclBits.ObjCForDecl = FRD;
+ }
+
/// \brief Determine whether this variable is an ARC pseudo-__strong
/// variable. A pseudo-__strong variable has a __strong-qualified
/// type but does not actually retain the object written into it.
Modified: cfe/trunk/lib/Parse/ParseDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseDecl.cpp?rev=328749&r1=328748&r2=328749&view=diff
==============================================================================
--- cfe/trunk/lib/Parse/ParseDecl.cpp (original)
+++ cfe/trunk/lib/Parse/ParseDecl.cpp Wed Mar 28 17:56:24 2018
@@ -2027,8 +2027,13 @@ Parser::DeclGroupPtrTy Parser::ParseDecl
}
Decl *ThisDecl = Actions.ActOnDeclarator(getCurScope(), D);
- if (IsForRangeLoop)
+ if (IsForRangeLoop) {
Actions.ActOnCXXForRangeDecl(ThisDecl);
+ } else {
+ // Obj-C for loop
+ if (auto *VD = dyn_cast_or_null<VarDecl>(ThisDecl))
+ VD->setObjCForDecl(true);
+ }
Actions.FinalizeDeclaration(ThisDecl);
D.complete(ThisDecl);
return Actions.FinalizeDeclaratorGroup(getCurScope(), DS, ThisDecl);
Modified: cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp?rev=328749&r1=328748&r2=328749&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp Wed Mar 28 17:56:24 2018
@@ -4083,6 +4083,7 @@ void Sema::BuildVariableInstantiation(
NewVar->setTSCSpec(OldVar->getTSCSpec());
NewVar->setInitStyle(OldVar->getInitStyle());
NewVar->setCXXForRangeDecl(OldVar->isCXXForRangeDecl());
+ NewVar->setObjCForDecl(OldVar->isObjCForDecl());
NewVar->setConstexpr(OldVar->isConstexpr());
NewVar->setInitCapture(OldVar->isInitCapture());
NewVar->setPreviousDeclInSameBlockScope(
@@ -4215,7 +4216,7 @@ void Sema::InstantiateVariableInitialize
}
// We'll add an initializer to a for-range declaration later.
- if (Var->isCXXForRangeDecl())
+ if (Var->isCXXForRangeDecl() || Var->isObjCForDecl())
return;
ActOnUninitializedDecl(Var);
Modified: cfe/trunk/lib/Serialization/ASTReaderDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTReaderDecl.cpp?rev=328749&r1=328748&r2=328749&view=diff
==============================================================================
--- cfe/trunk/lib/Serialization/ASTReaderDecl.cpp (original)
+++ cfe/trunk/lib/Serialization/ASTReaderDecl.cpp Wed Mar 28 17:56:24 2018
@@ -1279,6 +1279,7 @@ ASTDeclReader::RedeclarableResult ASTDec
VD->NonParmVarDeclBits.ExceptionVar = Record.readInt();
VD->NonParmVarDeclBits.NRVOVariable = Record.readInt();
VD->NonParmVarDeclBits.CXXForRangeDecl = Record.readInt();
+ VD->NonParmVarDeclBits.ObjCForDecl = Record.readInt();
VD->NonParmVarDeclBits.ARCPseudoStrong = Record.readInt();
VD->NonParmVarDeclBits.IsInline = Record.readInt();
VD->NonParmVarDeclBits.IsInlineSpecified = Record.readInt();
Modified: cfe/trunk/lib/Serialization/ASTWriterDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTWriterDecl.cpp?rev=328749&r1=328748&r2=328749&view=diff
==============================================================================
--- cfe/trunk/lib/Serialization/ASTWriterDecl.cpp (original)
+++ cfe/trunk/lib/Serialization/ASTWriterDecl.cpp Wed Mar 28 17:56:24 2018
@@ -920,6 +920,7 @@ void ASTDeclWriter::VisitVarDecl(VarDecl
Record.push_back(D->isExceptionVariable());
Record.push_back(D->isNRVOVariable());
Record.push_back(D->isCXXForRangeDecl());
+ Record.push_back(D->isObjCForDecl());
Record.push_back(D->isARCPseudoStrong());
Record.push_back(D->isInline());
Record.push_back(D->isInlineSpecified());
@@ -2031,6 +2032,7 @@ void ASTWriter::WriteDeclAbbrevs() {
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isExceptionVariable
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isNRVOVariable
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isCXXForRangeDecl
+ Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isObjCForDecl
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isARCPseudoStrong
Abv->Add(BitCodeAbbrevOp(0)); // isInline
Abv->Add(BitCodeAbbrevOp(0)); // isInlineSpecified
Added: cfe/trunk/test/SemaObjC/foreachtemplatized.mm
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjC/foreachtemplatized.mm?rev=328749&view=auto
==============================================================================
--- cfe/trunk/test/SemaObjC/foreachtemplatized.mm (added)
+++ cfe/trunk/test/SemaObjC/foreachtemplatized.mm Wed Mar 28 17:56:24 2018
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only -fobjc-arc -Wno-objc-root-class -std=c++11 -ast-dump %s | FileCheck %s
+
+// CHECK-NOT: ImplicitValueInitExpr
+
+ at interface I
+ at end
+
+template <typename T>
+void decode(I *p) {
+ for (I *k in p) {}
+}
+
+void decode(I *p) {
+ decode<int>(p);
+}
More information about the cfe-commits
mailing list