A little known fact is dmd actually provides index and length for RangeError in e2ir.d, but druntime doesn't do anything with it.

I just tried defining an object.d in ldc with this:

extern(C) void _d_arraybounds(string file, size_t line, size_t lwr, size_t upr, size_t length) {}


to take advantage of this data and ldc outright rejected it. I don't really know my way around the ldc source... what can I do about this?

On Sunday, 23 August 2020 at 13:25:30 UTC, Adam D. Ruppe wrote:
> A little known fact is dmd actually provides index and length for RangeError in e2ir.d, but druntime doesn't do anything with it.
>
> I just tried defining an object.d in ldc with this:
>
> extern(C) void _d_arraybounds(string file, size_t line, size_t lwr, size_t upr, size_t length) {}
>
>
> to take advantage of this data and ldc outright rejected it. I don't really know my way around the ldc source... what can I do about this?

Such hacks don't work with LDC and its strongly typed IR, so we don't pass these unused extra args. You can grep the src for `_d_arraybounds`, adjusting the signature of this runtime hook and the call site in DtoBoundsCheckFailCall(), but will have to adapt more code to forward the extra args to the latter function.

[e2ir.d is part of DMD's glue layer, not included by LDC.]

On 23 Aug 2020, at 14:25, Adam D. Ruppe via digitalmars-d-ldc wrote:
> I don't really know my way around the ldc source... what can I do about this?

Use grep. :P

---

~/ldc $ rg arraybounds
gen/runtime.cpp
554:  // void _d_arraybounds(string file, uint line)
555:  createFwdDecl(LINKc, Type::tvoid, {"_d_assert", "_d_arraybounds"},

gen/arrays.cpp
1365:        getRuntimeFunction(loc, irs->module, "_d_arraybounds");
---

You can add the extra parameters in gen/runtime.cpp (first hit), but you'll also need to update the bounds checking code to emit the extra argument (second hit).

 — David

On Sunday, 23 August 2020 at 13:41:18 UTC, kinke wrote:
> Such hacks don't work with LDC and its strongly typed IR, so we don't pass these unused extra args. You can grep the src for `_d_arraybounds`, adjusting the signature of this runtime hook and the call site in DtoBoundsCheckFailCall(), but will have to adapt more code to forward the extra args to the latter function.

Blargh.

I plan to get that info used in upstream dmd druntime eventually, but meh I'll keep living in darkness for now.

oh well

On Sunday, 23 August 2020 at 14:19:13 UTC, Adam D. Ruppe wrote:
> I plan to get that info used in upstream dmd druntime eventually, but meh I'll keep living in darkness for now.

Just call the extended function _d_arraybounds2 and you can live with both.