[BUG] Regression in CDNA2 AMDGPU kernel compilation between 0.26.3.0.dev2026041605 and 0.26.3.0.dev2026041716: empty kernel crashes with target-incompatible DataLayout

[BenWibking]

Bug description

Summary

Compiling a minimal GPU kernel with DeviceContext.compile_function() crashes in LLVM AMDGPU codegen with:

LLVM ERROR: Can't create a MachineFunction using a Module with a Target-incompatible DataLayout attached

This is a regression in the Mojo nightly compiler.

Regression range

Bisected on the same machine and environment.

• Last good: Mojo 0.26.3.0.dev2026041605 (418f4e71)
• First bad: Mojo 0.26.3.0.dev2026041716 (11668061)

Also confirmed bad:

• Mojo 0.26.3.0.dev2026042005 (32e188d3)
• Mojo 0.26.3.0.dev2026042205 (3d57fbb2)
• Mojo 0.26.3.0.dev2026042305 (d2fb2839)
• Mojo 1.0.0b1.dev2026042317 (3d4362b4)

Expected behavior

The empty GPU kernel should compile successfully.

Actual behavior

Compilation crashes during AMDGPU instruction selection:

Stack dump:

0. Running pass 'CallGraph Pass Manager' on module 'empty_kernel.mojo'.
1. Running pass 'AMDGPU DAG->DAG Pattern Instruction Selection' on function '@empty_kernel_kernel_empty6A6AoApA'

  LLVM ERROR: Can't create a MachineFunction using a Module with a Target-incompatible DataLayout attached
    Target DataLayout: e-m:e-p:64:64-p1:64:64-p2:32:32-p3:32:32-p4:64:64-p5:32:32-p6:32:32-p7:160:256:256:32-p8:128:128:128:48-
  p9:192:256:256:32-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64-S32-A5-G1-ni:7:8:9
    Module DataLayout: e-p:64:64-p1:64:64-p2:32:32-p3:32:32-p4:64:64-p5:32:32-p6:32:32-p7:160:256:256:32-p8:128:128:128:48-p9:192:256:256:32-
  i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64-S32-A5-G1-ni:7:8:9

Steps to reproduce

Minimal reproducer

Single-file reproducer:

  from std.gpu.host import DeviceContext


  def kernel_empty():
      pass


  def main() raises:
      var ctx = DeviceContext()
      _ = ctx.compile_function[kernel_empty, kernel_empty]()

Repro command

mojo build amdgpu_empty_kernel.mojo -o /tmp/amdgpu_empty_kernel

This same reproducer:

• succeeds on 0.26.3.0.dev2026041605
• crashes on 0.26.3.0.dev2026041716

Notes

• An empty kernel compiled via DeviceContext.compile_function() is sufficient to trigger the crash.
• The failure appears specific to AMDGPU codegen.

System information

Pixi env:

System
------------
       Pixi version: 0.63.2
        TLS backend: rustls
           Platform: linux-64
   Virtual packages: __unix=0=0
                   : __linux=6.4.0=0
                   : __glibc=2.38=0
                   : __archspec=1=zen3
          Cache dir: /ccs/home/wibking/.cache/rattler/cache
       Auth storage: /ccs/home/wibking/.rattler/credentials.json
   Config locations: No config files found

Global
------------
            Bin dir: /ccs/home/wibking/.pixi/bin
    Environment dir: /ccs/home/wibking/.pixi/envs
       Manifest dir: /ccs/home/wibking/.pixi/manifests/pixi-global.toml

Workspace
------------
               Name: mojo-amrex
            Version: 0.1.0
      Manifest file: /autofs/nccs-svm1_home1/wibking/mojo-amrex/pixi.toml
       Last updated: 23-04-2026 14:46:49

Environments
------------
        Environment: default
           Features: default
           Channels: https://conda.modular.com/max-nightly, conda-forge
   Dependency count: 7
       Dependencies: mojo, openmpi, jupyterlab, ipykernel, sidecar, matplotlib, ipympl
   Target platforms: linux-64, osx-arm64, linux-aarch64
    Prefix location: /autofs/nccs-svm1_home1/wibking/mojo-amrex/.pixi/envs/default
              Tasks: run-multifab-smoke-mojo-gpu, test-mojo-multifab-mpi, configure, test-mpi, build-multifab-smoke, build-capi-mpi, install-amrex, run-multifab-smoke, install-capi, build-multifab-smoke-mojo-gpu, test-mojo-runtime-mpi, test-mojo-runtime, run-multifab-mpi-exchange, package-mojo, test-capi, run-multifab-smoke-script, configure-mpi, build-capi, test, format-mojo, configure-cray-mpich, install-amrex-cray-mpich, bootstrap-cray-mpich, test-mojo, bootstrap, mojo, build-tests, build-capi-cray-mpich, test-mojo-multifab, install-mojo-package, build-tests-cray-mpich, test-capi-mpi, build-tests-mpi, run-multifab-smoke-mojo-gpu-script

Mojo version:

Name           Version                Build         Size  Kind   Source
mojo           1.0.0b1.dev2026042317  release  89.59 MiB  conda  https://conda.modular.com/max-nightly
mojo-compiler  1.0.0b1.dev2026042317  release  84.94 MiB  conda  https://conda.modular.com/max-nightly
mojo-python    1.0.0b1.dev2026042317  release  22.64 KiB  conda  https://conda.modular.com/max-nightly

[frasercrmck]

Thanks for the report! We've a fix in the works.