7087ece044
`mgpuModuleUnload` may be called from a global destructor (registered by
`SelectObjectAttr`'s `appendToGlobalDtors`) after the CUDA primary
context has already been destroyed during program shutdown. In this
case, `cuModuleUnload` returns `CUDA_ERROR_DEINITIALIZED`, which is
benign since the module's resources are already freed with the context.
## Reproduction
Any program that uses `gpu.launch_func` and is AOT-compiled (via
`mlir-translate --mlir-to-llvmir | llc | cc -lmlir_cuda_runtime`) will
print `'cuModuleUnload(module)' failed with '<unknown>'` on exit. This
is because `SelectObjectAttr` registers the module unload as a global
destructor, which runs after the CUDA primary context is released.
This script reproduces the error message from `mgpuModuleUnload` on my
system:
```
#!/bin/bash
set -e
LLVM_BUILD=${LLVM_BUILD:-$HOME/dev/git/llvm-project-22/build}
cat > /tmp/repro.mlir << 'MLIR'
func.func @main() {
%c1 = arith.constant 1 : index
gpu.launch blocks(%bx, %by, %bz) in (%gx = %c1, %gy = %c1, %gz = %c1)
threads(%tx, %ty, %tz) in (%bsx = %c1, %bsy = %c1, %bsz = %c1) {
gpu.terminator
}
return
}
MLIR
$LLVM_BUILD/bin/mlir-opt /tmp/repro.mlir \
-gpu-lower-to-nvvm-pipeline="cubin-format=fatbin" \
| $LLVM_BUILD/bin/mlir-translate --mlir-to-llvmir -o /tmp/repro.ll
$LLVM_BUILD/bin/llc -relocation-model=pic -filetype=obj /tmp/repro.ll -o /tmp/repro.o
cc /tmp/repro.o \
-L$LLVM_BUILD/lib -Wl,-rpath,$LLVM_BUILD/lib \
-lmlir_cuda_runtime -lmlir_runner_utils -o /tmp/repro
echo "Running:"
/tmp/repro 2>&1
echo "Exit code: $?"
```
## Context
This matches how other projects handle the same shutdown ordering issue:
- Clang CUDA (D48613) switched module cleanup from
`__attribute__((destructor))` to `atexit()`
- GCC libgomp checks context validity before `cuModuleUnload`
- Apache TVM silently ignores `CUDA_ERROR_DEINITIALIZED` on module
unload
Fixes #170833
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