The TYnptr type in DMD [1], what is the corresponding type, in LLVM? I'm referring to a instance of `llvm::Type` [2] that can be used in global variable, `llvm::GlobalVarible`.

[1] https://github.com/dlang/dmd/blob/master/src/dmd/backend/ty.d#L66
[2] http://llvm.org/doxygen/classllvm_1_1Type.html

--
/Jacob Carlborg

On Monday, 16 July 2018 at 06:38:01 UTC, Jacob Carlborg wrote:
> The TYnptr type in DMD [1], what is the corresponding type, in LLVM? I'm referring to a instance of `llvm::Type` [2] that can be used in global variable, `llvm::GlobalVarible`.
>
> [1] https://github.com/dlang/dmd/blob/master/src/dmd/backend/ty.d#L66
> [2] http://llvm.org/doxygen/classllvm_1_1Type.html
>
> --
> /Jacob Carlborg

No idea about the DMD backend, but in LLVM you generally just declare a global of some arbitrary IR type (e.g., from a D type: `DtoType(dtype)`), and the resulting GlobalVariable will always be a pointer to that type. You define the global by setting an initializer. See the pretty new `{declare,define}Global()` helpers.

On Monday, 16 July 2018 at 09:29:59 UTC, kinke wrote:

> No idea about the DMD backend, but in LLVM you generally just declare a global of some arbitrary IR type (e.g., from a D type: `DtoType(dtype)`), and the resulting GlobalVariable will always be a pointer to that type. You define the global by setting an initializer. See the pretty new `{declare,define}Global()` helpers.

Hmm. I don't have a D type. This is for when referencing an Objective-C class defined externally. The compiler generates a symbol like _OBJC_CLASS_$_<name>. I need a type for that symbol. The IR code generated by Clang looks like this

%struct._class_t = type { %struct._class_t*, %struct._class_t*, %struct._objc_cache*, i8* (i8*, i8*)**, %struct._class_ro_t* }
%struct._objc_cache = type opaque
%struct._class_ro_t = type { i32, i32, i32, i8*, i8*, %struct.__method_list_t*, %struct._objc_protocol_list*, %struct._ivar_list_t*, i8*, %struct._prop_list_t* }
%struct.__method_list_t = type { i32, i32, [0 x %struct._objc_method] }
%struct._objc_method = type { i8*, i8*, i8* }
%struct._objc_protocol_list = type { i64, [0 x %struct._protocol_t*] }
%struct._protocol_t = type { i8*, i8*, %struct._objc_protocol_list*, %struct.__method_list_t*, %struct.__method_list_t*, %struct.__method_list_t*, %struct.__method_list_t*, %struct._prop_list_t*, i32, i32, i8**, i8*, %struct._prop_list_t* }
%struct._ivar_list_t = type { i32, i32, [0 x %struct._ivar_t] }
%struct._ivar_t = type { i64*, i8*, i8*, i32, i32 }
%struct._prop_list_t = type { i32, i32, [0 x %struct._prop_t] }
%struct._prop_t = type { i8*, i8* }

@"OBJC_CLASS_$_NSObject" = external global %struct._class_t
@"OBJC_CLASSLIST_REFERENCES_$_" = private global %struct._class_t* @"OBJC_CLASS_$_NSObject", section "__DATA,__objc_classrefs,regular,no_dead_strip", align 8

--
/Jacob Carlborg

On Monday, 16 July 2018 at 13:40:35 UTC, Jacob Carlborg wrote:
> Hmm. I don't have a D type. This is for when referencing an Objective-C class defined externally. The compiler generates a symbol like _OBJC_CLASS_$_<name>. I need a type for that symbol. The IR code generated by Clang looks like this
>
> %struct._class_t = type { %struct._class_t*, %struct._class_t*, %struct._objc_cache*, i8* (i8*, i8*)**, %struct._class_ro_t* }
> %struct._objc_cache = type opaque
> %struct._class_ro_t = type { i32, i32, i32, i8*, i8*, %struct.__method_list_t*, %struct._objc_protocol_list*, %struct._ivar_list_t*, i8*, %struct._prop_list_t* }
> %struct.__method_list_t = type { i32, i32, [0 x %struct._objc_method] }
> %struct._objc_method = type { i8*, i8*, i8* }
> %struct._objc_protocol_list = type { i64, [0 x %struct._protocol_t*] }
> %struct._protocol_t = type { i8*, i8*, %struct._objc_protocol_list*, %struct.__method_list_t*, %struct.__method_list_t*, %struct.__method_list_t*, %struct.__method_list_t*, %struct._prop_list_t*, i32, i32, i8**, i8*, %struct._prop_list_t* }
> %struct._ivar_list_t = type { i32, i32, [0 x %struct._ivar_t] }
> %struct._ivar_t = type { i64*, i8*, i8*, i32, i32 }
> %struct._prop_list_t = type { i32, i32, [0 x %struct._prop_t] }
> %struct._prop_t = type { i8*, i8* }
>
> @"OBJC_CLASS_$_NSObject" = external global %struct._class_t
> @"OBJC_CLASSLIST_REFERENCES_$_" = private global %struct._class_t* @"OBJC_CLASS_$_NSObject", section "__DATA,__objc_classrefs,regular,no_dead_strip", align 8
>
> --
> /Jacob Carlborg

Assuming you only need an opaque pointer to that symbol (and you don't mix LDC/clang bitcode, e.g., via LTO), any type should do (see clang's opaque `%struct._objc_cache` - I think you create an opaque type as IR struct without elements via `llvm::StructType::create(gIR->context(), "name")`).

Otherwise, you'll have to define these types like clang does (using another `StructType::create()` overload, one taking the array of element types). LDC's `getVoidPtrType()` helpers returns the common `i8*` IR type, `llvm::IntegerType::get(gIR->context(), 32)` returns `i32` etc.

On 2018-07-16 20:37, kinke wrote:

> Assuming you only need an opaque pointer to that symbol (and you don't mix LDC/clang bitcode, e.g., via LTO), any type should do (see clang's opaque `%struct._objc_cache` - I think you create an opaque type as IR struct without elements via `llvm::StructType::create(gIR->context(), "name")`).
> 
> Otherwise, you'll have to define these types like clang does (using another `StructType::create()` overload, one taking the array of element types). LDC's `getVoidPtrType()` helpers returns the common `i8*` IR type, `llvm::IntegerType::get(gIR->context(), 32)` returns `i32` etc.

Thanks. Ideally it should be full compatible with Clang so I'll go with trying to define the structs exactly as Clang outputs them.

-- 
/Jacob Carlborg

On Tuesday, 17 July 2018 at 17:34:46 UTC, Jacob Carlborg wrote:
> Thanks. Ideally it should be full compatible with Clang so I'll go with trying to define the structs exactly as Clang outputs them.

Well just using an opaque `struct._class_t` IR struct may work too when mixing bitcode, so I'd give that a try first.