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authorDouglas Gregor <dgregor@apple.com>2012-01-05 22:27:05 +0000
committerDouglas Gregor <dgregor@apple.com>2012-01-05 22:27:05 +0000
commit64af53c364bcc20d18210432dbaa6d94186858ff (patch)
tree2c03835cca08077dd592fc50b0849a5042be05ca /clang/lib/AST
parentf740db31e20e18c02ef29e02f1a61900f2be8403 (diff)
downloadbcm5719-llvm-64af53c364bcc20d18210432dbaa6d94186858ff.tar.gz
bcm5719-llvm-64af53c364bcc20d18210432dbaa6d94186858ff.zip
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. llvm-svn: 147617
Diffstat (limited to 'clang/lib/AST')
-rw-r--r--clang/lib/AST/DeclBase.cpp15
1 files changed, 14 insertions, 1 deletions
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 55484188c86..f4e5d43ee6c 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -44,7 +44,20 @@ static bool StatSwitch = false;
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 {
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