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[rocm] Fix segfault with -O0-compiled kernels #45
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`kernels_[blitType]` yields a null function pointer in `KernelBlitManager::initHeap` due to `KernelBlitManager::createProgram` not initializing all the kernels because of broken layout invariants. `KernBlitManager::NumBlitKernels` has two possible return values: `BlitTotal, and BlitLinearTotal` which are sentinels. These sentinels are used in `KernelBlitManager::createProgram` to initialize the `kernels_` array. It correctly initializes `[0, NumBlitKernels())`, but `InitHeap` is > `NumBlitKernels`, so the `InitHeap` kernel is not loaded. Thus, when images are disabled, and a kernel has an `hidden_heap_v1` entry, the `InitHeap` blitkernel is not loaded, and `kernelBlitManager::initHeap` subsequently gets a null pointer. The kernel always has such `hidden_heap_v1` descriptor entry at -O0, but I believe it's possible (unconfirmed) for this situation to occur in other circumstances. The fix is simply to ensure the `InitHeap` enumeration has a numeric value *less than* `BlitLinearTotal`. n.b. This bug does not exist on the 5.7 release, but it looks like that's by chance.
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kernels_[blitType]yields a null function pointer inKernelBlitManager::initHeapdue toKernelBlitManager::createProgramnot initializing all the kernels because of broken layout invariants.KernBlitManager::NumBlitKernelshas two possible return values:BlitTotal, and BlitLinearTotalwhich are sentinels. These sentinels are used inKernelBlitManager::createProgramto initialize thekernels_array. It correctly initializes[0, NumBlitKernels()), butInitHeapis >NumBlitKernels, so theInitHeapkernel is not loaded.Thus, when images are disabled, and a kernel has an
hidden_heap_v1entry, theInitHeapblitkernel is not loaded, andkernelBlitManager::initHeapsubsequently gets a null pointer. The kernel always has suchhidden_heap_v1descriptor entry at -O0, but I believe it's possible (unconfirmed) for this situation to occur in other circumstances.The fix is simply to ensure the
InitHeapenumeration has a numeric value less thanBlitLinearTotal.n.b. This bug does not exist on the 5.7 release, but it looks like that's by chance.