+/// getFoldedSizeOf - Return a ConstantExpr with type DestTy for sizeof
+/// on Ty, with any known factors factored out. If Folded is false,
+/// return null if no factoring was possible, to avoid endlessly
+/// bouncing an unfoldable expression back into the top-level folder.
+///
+static Constant *getFoldedSizeOf(const Type *Ty, const Type *DestTy,
+ bool Folded) {
+ if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
+ Constant *N = ConstantInt::get(DestTy, ATy->getNumElements());
+ Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true);
+ return ConstantExpr::getNUWMul(E, N);
+ }
+ if (const VectorType *VTy = dyn_cast<VectorType>(Ty)) {
+ Constant *N = ConstantInt::get(DestTy, VTy->getNumElements());
+ Constant *E = getFoldedSizeOf(VTy->getElementType(), DestTy, true);
+ return ConstantExpr::getNUWMul(E, N);
+ }
+ if (const StructType *STy = dyn_cast<StructType>(Ty))
+ if (!STy->isPacked()) {
+ unsigned NumElems = STy->getNumElements();
+ // An empty struct has size zero.
+ if (NumElems == 0)
+ return ConstantExpr::getNullValue(DestTy);
+ // Check for a struct with all members having the same size.
+ Constant *MemberSize =
+ getFoldedSizeOf(STy->getElementType(0), DestTy, true);
+ bool AllSame = true;
+ for (unsigned i = 1; i != NumElems; ++i)
+ if (MemberSize !=
+ getFoldedSizeOf(STy->getElementType(i), DestTy, true)) {
+ AllSame = false;
+ break;
+ }
+ if (AllSame) {
+ Constant *N = ConstantInt::get(DestTy, NumElems);
+ return ConstantExpr::getNUWMul(MemberSize, N);
+ }
+ }
+
+ // Pointer size doesn't depend on the pointee type, so canonicalize them
+ // to an arbitrary pointee.
+ if (const PointerType *PTy = dyn_cast<PointerType>(Ty))
+ if (!PTy->getElementType()->isIntegerTy(1))
+ return
+ getFoldedSizeOf(PointerType::get(IntegerType::get(PTy->getContext(), 1),
+ PTy->getAddressSpace()),
+ DestTy, true);
+
+ // If there's no interesting folding happening, bail so that we don't create
+ // a constant that looks like it needs folding but really doesn't.
+ if (!Folded)
+ return 0;
+
+ // Base case: Get a regular sizeof expression.
+ Constant *C = ConstantExpr::getSizeOf(Ty);
+ C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
+ DestTy, false),
+ C, DestTy);
+ return C;
+}
+
+/// getFoldedAlignOf - Return a ConstantExpr with type DestTy for alignof
+/// on Ty, with any known factors factored out. If Folded is false,
+/// return null if no factoring was possible, to avoid endlessly
+/// bouncing an unfoldable expression back into the top-level folder.
+///
+static Constant *getFoldedAlignOf(const Type *Ty, const Type *DestTy,
+ bool Folded) {
+ // The alignment of an array is equal to the alignment of the
+ // array element. Note that this is not always true for vectors.
+ if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
+ Constant *C = ConstantExpr::getAlignOf(ATy->getElementType());
+ C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
+ DestTy,
+ false),
+ C, DestTy);
+ return C;
+ }
+
+ if (const StructType *STy = dyn_cast<StructType>(Ty)) {
+ // Packed structs always have an alignment of 1.
+ if (STy->isPacked())
+ return ConstantInt::get(DestTy, 1);
+
+ // Otherwise, struct alignment is the maximum alignment of any member.
+ // Without target data, we can't compare much, but we can check to see
+ // if all the members have the same alignment.
+ unsigned NumElems = STy->getNumElements();
+ // An empty struct has minimal alignment.
+ if (NumElems == 0)
+ return ConstantInt::get(DestTy, 1);
+ // Check for a struct with all members having the same alignment.
+ Constant *MemberAlign =
+ getFoldedAlignOf(STy->getElementType(0), DestTy, true);
+ bool AllSame = true;
+ for (unsigned i = 1; i != NumElems; ++i)
+ if (MemberAlign != getFoldedAlignOf(STy->getElementType(i), DestTy, true)) {
+ AllSame = false;
+ break;
+ }
+ if (AllSame)
+ return MemberAlign;
+ }
+
+ // Pointer alignment doesn't depend on the pointee type, so canonicalize them
+ // to an arbitrary pointee.
+ if (const PointerType *PTy = dyn_cast<PointerType>(Ty))
+ if (!PTy->getElementType()->isIntegerTy(1))
+ return
+ getFoldedAlignOf(PointerType::get(IntegerType::get(PTy->getContext(),
+ 1),
+ PTy->getAddressSpace()),
+ DestTy, true);
+
+ // If there's no interesting folding happening, bail so that we don't create
+ // a constant that looks like it needs folding but really doesn't.
+ if (!Folded)
+ return 0;
+
+ // Base case: Get a regular alignof expression.
+ Constant *C = ConstantExpr::getAlignOf(Ty);
+ C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
+ DestTy, false),
+ C, DestTy);
+ return C;
+}
+
+/// getFoldedOffsetOf - Return a ConstantExpr with type DestTy for offsetof
+/// on Ty and FieldNo, with any known factors factored out. If Folded is false,
+/// return null if no factoring was possible, to avoid endlessly
+/// bouncing an unfoldable expression back into the top-level folder.
+///
+static Constant *getFoldedOffsetOf(const Type *Ty, Constant *FieldNo,
+ const Type *DestTy,
+ bool Folded) {
+ if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
+ Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, false,
+ DestTy, false),
+ FieldNo, DestTy);
+ Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true);
+ return ConstantExpr::getNUWMul(E, N);
+ }
+ if (const VectorType *VTy = dyn_cast<VectorType>(Ty)) {
+ Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, false,
+ DestTy, false),
+ FieldNo, DestTy);
+ Constant *E = getFoldedSizeOf(VTy->getElementType(), DestTy, true);
+ return ConstantExpr::getNUWMul(E, N);
+ }
+ if (const StructType *STy = dyn_cast<StructType>(Ty))
+ if (!STy->isPacked()) {
+ unsigned NumElems = STy->getNumElements();
+ // An empty struct has no members.
+ if (NumElems == 0)
+ return 0;
+ // Check for a struct with all members having the same size.
+ Constant *MemberSize =
+ getFoldedSizeOf(STy->getElementType(0), DestTy, true);
+ bool AllSame = true;
+ for (unsigned i = 1; i != NumElems; ++i)
+ if (MemberSize !=
+ getFoldedSizeOf(STy->getElementType(i), DestTy, true)) {
+ AllSame = false;
+ break;
+ }
+ if (AllSame) {
+ Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo,
+ false,
+ DestTy,
+ false),
+ FieldNo, DestTy);
+ return ConstantExpr::getNUWMul(MemberSize, N);
+ }
+ }
+
+ // If there's no interesting folding happening, bail so that we don't create
+ // a constant that looks like it needs folding but really doesn't.
+ if (!Folded)
+ return 0;
+
+ // Base case: Get a regular offsetof expression.
+ Constant *C = ConstantExpr::getOffsetOf(Ty, FieldNo);
+ C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
+ DestTy, false),
+ C, DestTy);
+ return C;
+}