[SYCL] Fix SegFault when accessor passed to reduction is destroyed early #3498
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The error may happen when the copy of the accessor passed to ONEAPI::reduction is destroyed right after being passed to reduction. The fix is simple - to create a new copy of the given accessor. Signed-off-by: Vyacheslav N Klochkov <[email protected]>
| @@ -508,30 +508,24 @@ class reduction_impl : private reduction_impl_base { | |||
| } | |||
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| /// Constructs reduction_impl when the identity value is statically known. | |||
| // Note that aliasing constructor was used to initialize MRWAcc to avoid | |||
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Why "aliasing constructor" was not enough?
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The idea of using aliasing constructor was to give the pointer to user's accessor to shared_ptr, but not release memory (i.e. user's accessor) when that shared_ptr is destroyed, at least that is how I understood it when wrote that code.
That was wrong approach for cases where user's accessor is destroyed before the accessor is needed in reduction computation.
At this line: https://github.com/v-klochkov/llvm-test-suite/blob/public_vklochkov_reduction_ctor_acc_destroyed_early/SYCL/Reduction/reduction_nd_lambda.cpp#L41
MRWAcc shared_ptr holded a pointer to released memory.
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OK, thanks for explanation
The corresponding change in SYCL RT: intel/llvm#3498 Signed-off-by: Vyacheslav N Klochkov <[email protected]>
…or (#222) The corresponding change in SYCL RT: intel/llvm#3498 Signed-off-by: Vyacheslav N Klochkov <[email protected]>
…or (intel/llvm-test-suite#222) The corresponding change in SYCL RT: intel#3498 Signed-off-by: Vyacheslav N Klochkov <[email protected]>
The error may happen when the copy of the accessor passed to ONEAPI::reduction
is destroyed right after being passed to reduction.
The fix is simple - to create a new copy of the given accessor.
The corresponding LIT test changes: intel/llvm-test-suite#222
Signed-off-by: Vyacheslav N Klochkov [email protected]