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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@65622 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index e309259..d0d14f2 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -1331,49 +1331,6 @@
return getCond()->getIntegerConstantExprValue(C) != 0;
}
-static int64_t evaluateOffsetOf(ASTContext& C, const Expr *E) {
- if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
- QualType Ty = ME->getBase()->getType();
-
- RecordDecl *RD = Ty->getAsRecordType()->getDecl();
- const ASTRecordLayout &RL = C.getASTRecordLayout(RD);
- if (FieldDecl *FD = dyn_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;
- }
-
- return RL.getFieldOffset(i) + evaluateOffsetOf(C, ME->getBase());
- }
- } else if (const ArraySubscriptExpr *ASE = dyn_cast<ArraySubscriptExpr>(E)) {
- const Expr *Base = ASE->getBase();
-
- int64_t size = C.getTypeSize(ASE->getType());
- size *= ASE->getIdx()->getIntegerConstantExprValue(C).getSExtValue();
-
- return size + evaluateOffsetOf(C, Base);
- } else if (isa<CompoundLiteralExpr>(E))
- return 0;
-
- assert(0 && "Unknown offsetof subexpression!");
- return 0;
-}
-
-int64_t UnaryOperator::evaluateOffsetOf(ASTContext& C) const
-{
- assert(Opc == OffsetOf && "Unary operator not offsetof!");
-
- unsigned CharSize = C.Target.getCharWidth();
- return ::evaluateOffsetOf(C, cast<Expr>(Val)) / CharSize;
-}
-
void SizeOfAlignOfExpr::Destroy(ASTContext& C) {
// Override default behavior of traversing children. If this has a type
// operand and the type is a variable-length array, the child iteration
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 4f55f8d..68818db 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -1064,8 +1064,16 @@
bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
// Special case unary operators that do not need their subexpression
// evaluated. offsetof/sizeof/alignof are all special.
- if (E->isOffsetOfOp())
- return Success(E->evaluateOffsetOf(Info.Ctx), E);
+ if (E->isOffsetOfOp()) {
+ // The AST for offsetof is defined in such a way that we can just
+ // directly Evaluate it as an l-value.
+ APValue LV;
+ if (!EvaluateLValue(E->getSubExpr(), LV, Info))
+ return false;
+ if (LV.getLValueBase())
+ return false;
+ return Success(LV.getLValueOffset(), E);
+ }
if (E->getOpcode() == UnaryOperator::LNot) {
// LNot's operand isn't necessarily an integer, so we handle it specially.
diff --git a/lib/AST/StmtPrinter.cpp b/lib/AST/StmtPrinter.cpp
index 4468c79..7e25b46 100644
--- a/lib/AST/StmtPrinter.cpp
+++ b/lib/AST/StmtPrinter.cpp
@@ -724,7 +724,7 @@
}
bool StmtPrinter::PrintOffsetOfDesignator(Expr *E) {
- if (isa<CompoundLiteralExpr>(E)) {
+ if (isa<UnaryOperator>(E)) {
// Base case, print the type and comma.
OS << E->getType().getAsString() << ", ";
return true;
diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp
index 020c21f..c65c081 100644
--- a/lib/CodeGen/CGExprScalar.cpp
+++ b/lib/CodeGen/CGExprScalar.cpp
@@ -755,47 +755,9 @@
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");
}
//===----------------------------------------------------------------------===//
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 29d5f59..43cbe98 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -4270,16 +4270,17 @@
if (!Dependent && !ArgTy->isRecordType())
return Diag(TypeLoc, diag::err_offsetof_record_type) << ArgTy;
- // Otherwise, create a compound literal expression as the base, and
- // iteratively process the offsetof designators.
- InitListExpr *IList =
- new (Context) InitListExpr(SourceLocation(), 0, 0, SourceLocation());
- IList->setType(ArgTy);
- Expr *Res =
- new (Context) CompoundLiteralExpr(SourceLocation(), ArgTy, IList, false);
+ // Otherwise, create a null pointer as the base, and iteratively process
+ // the offsetof designators.
+ QualType ArgTyPtr = Context.getPointerType(ArgTy);
+ Expr* Res = new (Context) ImplicitValueInitExpr(ArgTyPtr);
+ Res = new (Context) UnaryOperator(Res, UnaryOperator::Deref,
+ ArgTy, SourceLocation());
// offsetof with non-identifier designators (e.g. "offsetof(x, a.b[c])") are a
// GCC extension, diagnose them.
+ // FIXME: This diagnostic isn't actually visible because the location is in
+ // a system header!
if (NumComponents != 1)
Diag(BuiltinLoc, diag::ext_offsetof_extended_field_designator)
<< SourceRange(CompPtr[1].LocStart, CompPtr[NumComponents-1].LocEnd);
@@ -4300,6 +4301,10 @@
// FIXME: C++: Verify that operator[] isn't overloaded.
+ // Promote the array so it looks more like a normal array subscript
+ // expression.
+ DefaultFunctionArrayConversion(Res);
+
// C99 6.5.2.1p1
Expr *Idx = static_cast<Expr*>(OC.U.E);
if (!Idx->isTypeDependent() && !Idx->getType()->isIntegerType())