type as a target independent constant expression. I confess
that I didn't check that this method works as intended (though
I did test the equivalent hand-written IR a little). But what
could possibly go wrong!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72213
91177308-0d34-0410-b5e6-
96231b3b80d8
(** {7 Constant expressions} *)
+(** [align_of ty] returns the alignof constant for the type [ty]. This is
+ equivalent to [const_ptrtoint (const_gep (const_null (pointer_type {i8,ty}))
+ (const_int i32_type 0) (const_int i32_type 1)) i32_type], but considerably
+ more readable. See the method [llvm::ConstantExpr::getAlignOf]. *)
+external align_of : lltype -> llvalue = "LLVMAlignOf"
+
(** [size_of ty] returns the sizeof constant for the type [ty]. This is
equivalent to [const_ptrtoint (const_gep (const_null (pointer_type ty))
- (const_int i64_type 1)) i64_type], but considerably more readable.
+ (const_int i32_type 1)) i64_type], but considerably more readable.
See the method [llvm::ConstantExpr::getSizeOf]. *)
external size_of : lltype -> llvalue = "LLVMSizeOf"
return getSelectTy(V1->getType(), C, V1, V2);
}
+ /// getAlignOf constant expr - computes the alignment of a type in a target
+ /// independent way (Note: the return type is an i32; Note: assumes that i8
+ /// is byte aligned).
+ ///
+ static Constant *getAlignOf(const Type *Ty);
+
/// getSizeOf constant expr - computes the size of a type in a target
/// independent way (Note: the return type is an i64).
///
return getFoldedCast(Instruction::BitCast, C, DstTy);
}
+Constant *ConstantExpr::getAlignOf(const Type *Ty) {
+ // alignof is implemented as: (i64) gep ({i8,Ty}*)null, 0, 1
+ const Type *AligningTy = StructType::get(Type::Int8Ty, Ty, NULL);
+ Constant *NullPtr = getNullValue(AligningTy->getPointerTo());
+ Constant *Zero = ConstantInt::get(Type::Int32Ty, 0);
+ Constant *One = ConstantInt::get(Type::Int32Ty, 1);
+ Constant *Indices[2] = { Zero, One };
+ Constant *GEP = getGetElementPtr(NullPtr, Indices, 2);
+ return getCast(Instruction::PtrToInt, GEP, Type::Int32Ty);
+}
+
Constant *ConstantExpr::getSizeOf(const Type *Ty) {
// sizeof is implemented as: (i64) gep (Ty*)null, 1
Constant *GEPIdx = ConstantInt::get(Type::Int32Ty, 1);
/*--.. Constant expressions ................................................--*/
+LLVMValueRef LLVMAlignOf(LLVMTypeRef Ty) {
+ return wrap(ConstantExpr::getAlignOf(unwrap(Ty)));
+}
+
LLVMValueRef LLVMSizeOf(LLVMTypeRef Ty) {
return wrap(ConstantExpr::getSizeOf(unwrap(Ty)));
}