Issue 260305.1: Host a web playground to evaluate DWARF expressions
| Author: | Tankut Baris Aktemur |
|---|---|
| Champion: | Ben Woodard |
| Date submitted: | 2026-03-05 |
| Date revised: | |
| Date closed: | |
| Type: | Other - Website |
| Status: | Open |
| DWARF version: | 6 |
Problem Description
With DWARF expressions becoming considerably more complicated with the structures needed to support GPUs and with the "locations on the stack" change to DWARF expression evaluation, several members of the DWARF for GPUs working group felt that it would be helpful to have an executable, lightweight DWARF expression evaluator. This would allow both producers and consumers to experiment with DWARF expressions and thus expedite their learning process. It would also help stakeholders to share ideas for new operators by defining their semantics in the evaluator.
To this aim, a DWARF expression evaluator implemented in the OCaml functional programming language has been developed. The evaluator's focus at the current phase is to show how locations and values are operated on the same evaluation stack and how locations, in particular composites, can be built. Several examples accompany the implementation. For the purposes of being concise, the evaluator at the moment does not define all DWARF operators. We envision that the implementation would be extended with new cases and examples as a community effort.
A web playground, generated from the tool, is available at
https://intel.github.io/dwarf-evaluator/
Here, users can run experiments and see the progression of the DWARF
evaluation stack. For example, the DW_OP_pick example from DWARF
spec D.1.2 is available here.
The composite location example, again from D.1.3, is here. The result of evaluation precisely shows, as written in D.1.3, "A variable whose first four bytes reside in register 3 and whose next two bytes reside in register 10."
Yet another, and slightly more complicated, composite location example from D.1.3 is here. The result again precisely shows the textual explanation from the spec, that is "the 4 byte value 1 followed by the four byte value computed from the sum of the contents of r3 and r4."
In Issue 251120.1 "DWARF Operation to Create Runtime Overlay Composite Location Description", there are several examples for which a playground link is given (search for "Try it!" links).
In Issue 260227.1 "Multi-Location Storage", there also exist several examples for which playground links are given.
The web playground is generated from an evaluator implemented in OCaml. The tool and the playground was presented at FOSDEM 2026. Those who are interested in seeing more details are invited to watch the recording of the FOSDEM talk.
Proposal
We propose that the playground is hosted at DWARF Debugging Standard Website (https://dwarfstd.org/).
