Proof of concept for the support of AMD GPUs

[amontoison]

Adds support for running the first-order PDLP solver on AMD GPUs via HIP/ROCm, alongside the existing NVIDIA/CUDA backend.

The vendor-specific GPU code is refactored behind a thin portability layer so the same sources compile for both, selected at configure time.

• AMD (HIP / ROCm)

cmake -S . -B build -DHIPDLP_HIP=ON -DCMAKE_BUILD_TYPE=Release
cmake --build build --target highs --parallel

• NVIDIA (CUDA) - unchanged

cmake -S . -B build -DCUPDLP_GPU=ON -DCMAKE_BUILD_TYPE=Release
cmake --build build --target highs --parallel

@jajhall I got the green light from AMD to help for the maintenance of the HIP / ROCm backend in HiGHS.

I added a workflow to test the compilation with AMD libraries, it passed:
https://github.com/ERGO-Code/HiGHS/actions/runs/27993664916/job/82851309388?pr=3083

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.05%. Comparing base (569e0c7) to head (d0fd5c8).
⚠️ Report is 140 commits behind head on latest.

Additional details and impacted files

@@            Coverage Diff             @@
##           latest    #3083      +/-   ##
==========================================
- Coverage   73.09%   73.05%   -0.05%     
==========================================
  Files         426      426              
  Lines      103368   102324    -1044     
  Branches    16650    16459     -191     
==========================================
- Hits        75553    74749     -804     
+ Misses      27539    27299     -240     
  Partials      276      276              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[jajhall]

Many thanks @amontoison!

We'll leave this for v1.16, so we don't introduce too many changes into v1.15. That said, we expect v1.16 to follow fairly soon - once users have had the chance to experiment with the parallel MIP solver (which will not be the default). Hence v1.16 will have parallel MIP by default, and AMD GPU!

[galabovaa]

Hi @amontoison, Would it be possible for you to merge latest in, and give it another quick test on AMD, so we can merge the PR?

[amontoison]

Hello @galabovaa, I can do that next Tuesday (25/08/2026), is it fine for you or do you plan to do the new release before?