Completely reimplement __builtin_offsetof, based on a patch by Roberto
Amadini.
This change introduces a new expression node type, OffsetOfExpr, that
describes __builtin_offsetof. Previously, __builtin_offsetof was
implemented using a unary operator whose subexpression involved
various synthesized array-subscript and member-reference expressions,
which was ugly and made it very hard to instantiate as a
template. OffsetOfExpr represents the AST more faithfully, with proper
type source information and a more compact representation.
OffsetOfExpr also has support for dependent __builtin_offsetof
expressions; it can be value-dependent, but will never be
type-dependent (like sizeof or alignof). This commit introduces
template instantiation for __builtin_offsetof as well.
There are two major caveats to this patch:
1) CodeGen cannot handle the case where __builtin_offsetof is not a
constant expression, so it produces an error. So, to avoid
regressing in C, we retain the old UnaryOperator-based
__builtin_offsetof implementation in C while using the shiny new
OffsetOfExpr implementation in C++. The old implementation can go
away once we have proper CodeGen support for this case, which we
expect won't cause much trouble in C++.
2) __builtin_offsetof doesn't work well with non-POD class types,
particularly when the designated field is found within a base
class. I will address this in a subsequent patch.
Fixes PR5880 and a bunch of assertions when building Boost.Python
tests.
llvm-svn: 102542
diff --git a/clang/lib/Frontend/PCHReaderStmt.cpp b/clang/lib/Frontend/PCHReaderStmt.cpp
index 5e08be1..8588c8a 100644
--- a/clang/lib/Frontend/PCHReaderStmt.cpp
+++ b/clang/lib/Frontend/PCHReaderStmt.cpp
@@ -71,6 +71,7 @@
unsigned VisitCharacterLiteral(CharacterLiteral *E);
unsigned VisitParenExpr(ParenExpr *E);
unsigned VisitUnaryOperator(UnaryOperator *E);
+ unsigned VisitOffsetOfExpr(OffsetOfExpr *E);
unsigned VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E);
unsigned VisitArraySubscriptExpr(ArraySubscriptExpr *E);
unsigned VisitCallExpr(CallExpr *E);
@@ -432,6 +433,44 @@
return 1;
}
+unsigned PCHStmtReader::VisitOffsetOfExpr(OffsetOfExpr *E) {
+ typedef OffsetOfExpr::OffsetOfNode Node;
+ VisitExpr(E);
+ assert(E->getNumComponents() == Record[Idx]);
+ ++Idx;
+ assert(E->getNumExpressions() == Record[Idx]);
+ ++Idx;
+ E->setOperatorLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
+ E->setRParenLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
+ E->setTypeSourceInfo(Reader.GetTypeSourceInfo(Record, Idx));
+ for (unsigned I = 0, N = E->getNumComponents(); I != N; ++I) {
+ Node::Kind Kind = static_cast<Node::Kind>(Record[Idx++]);
+ SourceLocation Start = SourceLocation::getFromRawEncoding(Record[Idx++]);
+ SourceLocation End = SourceLocation::getFromRawEncoding(Record[Idx++]);
+ switch (Kind) {
+ case Node::Array:
+ E->setComponent(I, Node(Start, Record[Idx++], End));
+ break;
+
+ case Node::Field:
+ E->setComponent(I,
+ Node(Start,
+ dyn_cast_or_null<FieldDecl>(Reader.GetDecl(Record[Idx++])),
+ End));
+ break;
+
+ case Node::Identifier:
+ E->setComponent(I, Node(Start, Reader.GetIdentifier(Record[Idx++]), End));
+ break;
+ }
+ }
+
+ for (unsigned I = 0, N = E->getNumExpressions(); I != N; ++I)
+ E->setIndexExpr(I, cast_or_null<Expr>(StmtStack[StmtStack.size() - N + I]));
+
+ return E->getNumExpressions();
+}
+
unsigned PCHStmtReader::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E) {
VisitExpr(E);
E->setSizeof(Record[Idx++]);
@@ -1105,6 +1144,12 @@
S = new (Context) UnaryOperator(Empty);
break;
+ case pch::EXPR_OFFSETOF:
+ S = OffsetOfExpr::CreateEmpty(*Context,
+ Record[PCHStmtReader::NumExprFields],
+ Record[PCHStmtReader::NumExprFields + 1]);
+ break;
+
case pch::EXPR_SIZEOF_ALIGN_OF:
S = new (Context) SizeOfAlignOfExpr(Empty);
break;