When we deserialize a declaration from a module file, allocate extra
storage for the global declaration ID. Declarations that are parsed
(rather than deserialized) are unaffected, so the number of
declarations that pay this cost tends to be relatively small (since
relatively few declarations are ever deserialized).
This replaces a largish DenseMap within the AST reader. It's not
strictly a win in terms of memory use---not every declaration was
added to that DenseMap in the first place---but it's cleaner to have
this information available for every deserialized declaration, so that
future clients can rely on it.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@147617 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/AST/DeclBase.h b/include/clang/AST/DeclBase.h
index 12f37e5..09e1fdc 100644
--- a/include/clang/AST/DeclBase.h
+++ b/include/clang/AST/DeclBase.h
@@ -532,6 +532,14 @@
/// a precompiled header or module) rather than having been parsed.
bool isFromASTFile() const { return FromASTFile; }
+ /// \brief Retrieve the global declaration ID associated with this
+ /// declaration, which specifies where in the
+ unsigned getGlobalID() const {
+ if (isFromASTFile())
+ return *((const unsigned*)this - 1);
+ return 0;
+ }
+
unsigned getIdentifierNamespace() const {
return IdentifierNamespace;
}
diff --git a/include/clang/Serialization/ASTReader.h b/include/clang/Serialization/ASTReader.h
index f808b96..4a704d0 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -675,13 +675,6 @@
/// \brief Keeps track of the elements added to PendingDeclChains.
llvm::SmallSet<serialization::DeclID, 16> PendingDeclChainsKnown;
- /// \brief Reverse mapping from declarations to their global declaration IDs.
- ///
- /// FIXME: This data structure is currently only used for ObjCInterfaceDecls
- /// and ObjCProtocolDecls to support declaration merging. If we must have
- /// this for other declarations, allocate it along with the Decl itself.
- llvm::DenseMap<Decl *, serialization::GlobalDeclID> DeclToID;
-
typedef llvm::DenseMap<Decl *, llvm::SmallVector<serialization::DeclID, 2> >
MergedDeclsMap;
diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index 5548418..f4e5d43 100644
--- a/lib/AST/DeclBase.cpp
+++ b/lib/AST/DeclBase.cpp
@@ -44,7 +44,20 @@
void *Decl::AllocateDeserializedDecl(const ASTContext &Context,
unsigned ID,
unsigned Size) {
- return Context.Allocate(Size);
+ // Allocate an extra pointer's worth of storage, which ensures that
+ // (1) We have enough storage to stash the global declaration ID, and
+ // (2) We maintain pointer alignment.
+ //
+ // Note that this wastes 4 bytes on x86-64, which we'll undoubtedly end up
+ // finding a use for later.
+ void *Start = Context.Allocate(Size + sizeof(void*));
+ void *Result = (char*)Start + sizeof(void*);
+
+ // Store the global declaration ID
+ unsigned *IDPtr = (unsigned*)Result - 1;
+ *IDPtr = ID;
+
+ return Result;
}
const char *Decl::getDeclKindName() const {
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index cff8667..0672129 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -402,9 +402,6 @@
}
void ASTDeclReader::VisitTypedefNameDecl(TypedefNameDecl *TD) {
- // Record the declaration -> global ID mapping.
- Reader.DeclToID[TD] = ThisDeclID;
-
RedeclarableResult Redecl = VisitRedeclarable(TD);
VisitTypeDecl(TD);
@@ -421,9 +418,6 @@
}
void ASTDeclReader::VisitTagDecl(TagDecl *TD) {
- // Record the declaration -> global ID mapping.
- Reader.DeclToID[TD] = ThisDeclID;
-
RedeclarableResult Redecl = VisitRedeclarable(TD);
VisitTypeDecl(TD);
@@ -490,9 +484,6 @@
}
void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
- // Record the declaration -> global ID mapping.
- Reader.DeclToID[FD] = ThisDeclID;
-
RedeclarableResult Redecl = VisitRedeclarable(FD);
VisitDeclaratorDecl(FD);
@@ -673,9 +664,6 @@
}
void ASTDeclReader::VisitObjCInterfaceDecl(ObjCInterfaceDecl *ID) {
- // Record the declaration -> global ID mapping.
- Reader.DeclToID[ID] = ThisDeclID;
-
RedeclarableResult Redecl = VisitRedeclarable(ID);
VisitObjCContainerDecl(ID);
TypeIDForTypeDecl = Reader.getGlobalTypeID(F, Record[Idx++]);
@@ -746,9 +734,6 @@
}
void ASTDeclReader::VisitObjCProtocolDecl(ObjCProtocolDecl *PD) {
- // Record the declaration -> global ID mapping.
- Reader.DeclToID[PD] = ThisDeclID;
-
RedeclarableResult Redecl = VisitRedeclarable(PD);
VisitObjCContainerDecl(PD);
mergeRedeclarable(PD, Redecl);
@@ -880,9 +865,6 @@
}
void ASTDeclReader::VisitVarDecl(VarDecl *VD) {
- // Record the declaration -> global ID mapping.
- Reader.DeclToID[VD] = ThisDeclID;
-
RedeclarableResult Redecl = VisitRedeclarable(VD);
VisitDeclaratorDecl(VD);
@@ -1561,7 +1543,7 @@
// Introduce ExistingCanon into the set of pending declaration chains,
// if in fact it came from a module file.
if (ExistingCanon->isFromASTFile()) {
- GlobalDeclID ExistingCanonID = Reader.DeclToID[ExistingCanon];
+ GlobalDeclID ExistingCanonID = ExistingCanon->getGlobalID();
assert(ExistingCanonID && "Unrecorded canonical declaration ID?");
if (Reader.PendingDeclChainsKnown.insert(ExistingCanonID))
Reader.PendingDeclChains.push_back(ExistingCanonID);
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 1317525..5257859 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -2914,7 +2914,7 @@
for (ASTReader::MergedDeclsMap::iterator I = Chain->MergedDecls.begin(),
IEnd = Chain->MergedDecls.end();
I != IEnd; ++I) {
- DeclID CanonID = I->first->isFromASTFile()? Chain->DeclToID[I->first]
+ DeclID CanonID = I->first->isFromASTFile()? I->first->getGlobalID()
: getDeclID(I->first);
assert(CanonID && "Merged declaration not known?");
