Change the AST generated for offsetof a bit so that it looks like a

normal expression, and change Evaluate and IRGen to evaluate it like a 
normal expression.  This simplifies the code significantly, and fixes 
PR3396.

llvm-svn: 65622

1 files changed, 2 insertions, 40 deletions

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 020c21f5cbd..c65c0816e2b 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -755,47 +755,9 @@ Value *ScalarExprEmitter::VisitUnaryImag(const UnaryOperator *E) {
 
 Value *ScalarExprEmitter::VisitUnaryOffsetOf(const UnaryOperator *E)
 {
-  const Expr* SubExpr = E->getSubExpr();
+  Value* ResultAsPtr = EmitLValue(E->getSubExpr()).getAddress();
   const llvm::Type* ResultType = ConvertType(E->getType());
-  llvm::Value* Result = llvm::Constant::getNullValue(ResultType);
-  while (!isa<CompoundLiteralExpr>(SubExpr)) {
-    if (const MemberExpr *ME = dyn_cast<MemberExpr>(SubExpr)) {
-      SubExpr = ME->getBase();
-      QualType Ty = SubExpr->getType();
-
-      RecordDecl *RD = Ty->getAsRecordType()->getDecl();
-      const ASTRecordLayout &RL = CGF.getContext().getASTRecordLayout(RD);
-      FieldDecl *FD = cast<FieldDecl>(ME->getMemberDecl());
-
-      // FIXME: This is linear time. And the fact that we're indexing
-      // into the layout by position in the record means that we're
-      // either stuck numbering the fields in the AST or we have to keep
-      // the linear search (yuck and yuck).
-      unsigned i = 0;
-      for (RecordDecl::field_iterator Field = RD->field_begin(),
-                                   FieldEnd = RD->field_end();
-           Field != FieldEnd; (void)++Field, ++i) {
-        if (*Field == FD)
-          break;
-      }
-
-      llvm::Value* Offset =
-          llvm::ConstantInt::get(ResultType, RL.getFieldOffset(i) / 8);
-      Result = Builder.CreateAdd(Result, Offset);
-    } else if (const ArraySubscriptExpr *ASE = dyn_cast<ArraySubscriptExpr>(SubExpr)) {
-      SubExpr = ASE->getBase();
-      int64_t size = CGF.getContext().getTypeSize(ASE->getType()) / 8;
-      llvm::Value* ElemSize = llvm::ConstantInt::get(ResultType, size);
-      llvm::Value* ElemIndex = CGF.EmitScalarExpr(ASE->getIdx());
-      bool IndexSigned = ASE->getIdx()->getType()->isSignedIntegerType();
-      ElemIndex = Builder.CreateIntCast(ElemIndex, ResultType, IndexSigned);
-      llvm::Value* Offset = Builder.CreateMul(ElemSize, ElemIndex);
-      Result = Builder.CreateAdd(Result, Offset);
-    } else {
-      assert(0 && "This should be impossible!");
-    }
-  }
-  return Result;
+  return Builder.CreatePtrToInt(ResultAsPtr, ResultType, "offsetof");
 }
 
 //===----------------------------------------------------------------------===//