DWARF output, type of char[]?

What is the DWARF type of char[], as output by the DMD backend? I have compiled this sample: import std.stdio; int main() { char[] greet = "Hello"; writefln(greet); return 0; } Then ran readelf -w hello As shown in this snippet, the type of greet is unsigned long long (entry at offset <c2>): <1><c2>: Abbrev Number: 2 (DW_TAG_base_type) DW_AT_name : unsigned long long DW_AT_byte_size : 8 DW_AT_encoding : 7 (unsigned) <1><d8>: Abbrev Number: 4 (DW_TAG_subprogram) DW_AT_sibling : <104> DW_AT_name : _Dmain DW_AT_decl_file : 1 DW_AT_decl_line : 3 DW_AT_type : <bb> DW_AT_low_pc : 0x804a358 DW_AT_high_pc : 0x804a383 DW_AT_frame_base : 1 byte block: 55 (DW_OP_reg5) <2><f5>: Abbrev Number: 3 (DW_TAG_variable) DW_AT_name : greet DW_AT_type : <c2> DW_AT_location : 2 byte block: 91 78 (DW_OP_fbreg: -8)

Reply to Cristian, > What is the DWARF type of char[], as output by the DMD backend? I've wondered at this kind of thing to. Why isn't it some sort of ptr/length pair struct? Name it something remotely readable and it will be a ton better than unsigned long long. The expression that gets the content of a char[] as something gdb can read is several inches long.

BCS Wrote: > Reply to Cristian, > > > What is the DWARF type of char[], as output by the DMD backend? > > The expression that gets the content of a char[] as something gdb can read is several inches long. > I am not sure that I understand this? Is there is a way of transforming the unsigned long long into something meaningful? Zero treats all types as if the source were C/C++. I am working on allowing the user to customize the way variables are being displayed (via Python scripts). I am doing it mainly for being able to display C++/STL containers in a sane way, but I think that with a little work it may do the trick for D types as well. Cristian

Cristian Vlasceanu wrote: > BCS Wrote: > > >>Reply to Cristian, >> >> >>>What is the DWARF type of char[], as output by the DMD backend? >> >>The expression that gets the content of a char[] as something gdb can read is several inches long. >> > > I am not sure that I understand this? Is there is a way of transforming the unsigned long long into something meaningful? > yes given T[] arr; the contents are: *(cast(T*)(cast(void*)(&arr)[1]) the length is: *cast(size_t*)(&arr) and that's if I remember correctly. It's ugly and messy and a total pain in the whatever. But it works. However if an array of type T[] were to claim to be struct { T* ptr; size_t length; } or something close to that, then you could access it almost as normal. > Zero treats all types as if the source were C/C++. > > I am working on allowing the user to customize the way variables are being displayed (via Python scripts). I am doing it mainly for being able to display C++/STL containers in a sane way, but I think that with a little work it may do the trick for D types as well. > > Cristian

BCS wrote: > Cristian Vlasceanu wrote: >> BCS Wrote: >> >> >>> Reply to Cristian, >>> >>> >>>> What is the DWARF type of char[], as output by the DMD backend? >>> >>> The expression that gets the content of a char[] as something gdb can read is several inches long. >>> >> >> I am not sure that I understand this? Is there is a way of transforming the unsigned long long into something meaningful? >> > > yes > > given T[] arr; > > the contents are: *(cast(T*)(cast(void*)(&arr)[1]) > the length is: *cast(size_t*)(&arr) > > and that's if I remember correctly. It's ugly and messy and a total pain in the whatever. But it works. > > However if an array of type T[] were to claim to be > > struct > { > T* ptr; > size_t length; > } > > or something close to that, then you could access it almost as normal. > I do not know enough D, but is there "unsigned long long" an otherwise legal D type? Because if (as I supsect) it isn't, and it can be unequivocally determined that it stands for a char[] whenever the translation unit's language is D, I could easily make it work in Zero. Out of the box.

Cristian Vlasceanu wrote: > I do not know enough D, but is there "unsigned long long" an otherwise legal D type? Because if (as I supsect) it isn't, and it can be unequivocally determined that it stands for a char[] whenever the translation unit's language is D, I could easily make it work in Zero. Out of the box. You may want to check what type "ulong" is marked as. Since that's a 64-bit unsigned integer (like unsigned long long typically is) it may also be marked as "unsigned long long"...

Frits van Bommel wrote: > Cristian Vlasceanu wrote: > >> I do not know enough D, but is there "unsigned long long" an otherwise legal D type? Because if (as I supsect) it isn't, and it can be unequivocally determined that it stands for a char[] whenever the translation unit's language is D, I could easily make it work in Zero. Out of the box. > > > You may want to check what type "ulong" is marked as. Since that's a 64-bit unsigned integer (like unsigned long long typically is) it may also be marked as "unsigned long long"... What is needed is for T[] to be marked as something special. Then you could treat it as described. FWIW D has it's own DWARF "language number" so we should be able to add new types. Then the debugger could treat it as said struct. A short term hack could be to have the compiler do the magic and mark it as some sort of auto generated struct type. Disclaimer: I know slightly more than 0 about how DWARF works under the hood.