test.d:
__gshared t = "text".ptr;


As expected, the "text" literal ends up in a read-only data segment, with a pointer to it stored in a writable data segment (_TMP0 pointing into .rodata.str1.1):

.data   segment
_D4test1tPya:
        dd      offset FLAT:_TMP0@64
        db      000h,000h,000h,000h     ;....
.data   ends

Hex dump of section '.rodata.str1.1':
  0x00000000 74657874 00                         text.



How to achieve the same for an array literal? The closest I could come:

enum immutable(int[3]) _tmp = [1, 2, 3];
__gshared a = _tmp.ptr;

But the array is still placed into the writable segment:

.data   segment
internal:
        db      001h,000h,000h,000h,002h,000h,000h,000h ;........
        db      003h,000h,000h,000h,000h,000h,000h,000h ;........
_D4test1aPyi:
        dd      offset FLAT:internal@64
        db      000h,000h,000h,000h     ;....
.data   ends


Is it possible to force the array into rodata?

On Thursday, 12 September 2019 at 07:04:19 UTC, Max Samukha wrote:
>
> How to achieve the same for an array literal? The closest I could come:
>
> enum immutable(int[3]) _tmp = [1, 2, 3];
> __gshared a = _tmp.ptr;
>
> Is it possible to force the array into rodata?

https://p0nce.github.io/d-idioms/#Precomputed-tables-at-compile-time-through-CTFE

static immutable(int[3]) _tmp = [1, 2, 3];
?

On Thursday, 12 September 2019 at 08:54:09 UTC, a11e99z wrote:
> On Thursday, 12 September 2019 at 07:04:19 UTC, Max Samukha wrote:
>>
>> How to achieve the same for an array literal? The closest I could come:
>>
>> enum immutable(int[3]) _tmp = [1, 2, 3];
>> __gshared a = _tmp.ptr;
>>
>> Is it possible to force the array into rodata?
>
> https://p0nce.github.io/d-idioms/#Precomputed-tables-at-compile-time-through-CTFE
>
> static immutable(int[3]) _tmp = [1, 2, 3];
> ?

That looks the same as my example, where 'static' is redundant at the module level, and enum just removes the unneeded reference to the temporary from the object file. However, __gshared in my example does seem to be redundant - 'immutable' implies thread-shared in this case.