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Test loops that exit when their counter wraps around #696

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Merged
maleadt merged 1 commit into from
Oct 15, 2026
Merged

Test loops that exit when their counter wraps around #696

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27 changes: 27 additions & 0 deletions test/execution.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -1068,3 +1068,30 @@ end
@test occursin(r"%heap\d* = alloca", sprint(io -> oneAPI.code_llvm(io, ref_kernel, T; kernel = true)))
@test !occursin(r"%heap\d* = alloca", sprint(io -> oneAPI.code_llvm(io, plain_kernel, T; kernel = true)))
end

@testset "loop exiting on counter wrap-around" begin
# The SPIR-V back-end turns `i += 1; i == 0` into OpIAddCarry, and IGC's optimizer sinks
# the extracts of its {i64, i1} result through the loop PHI. Before libigc_jll 2.34.4+5,
# IGC's legalization then erased the intrinsic while that PHI still referenced it, a
# use-after-free that crashed or silently corrupted the host
# (https://buildkite.com/julialang/oneapi-dot-jl/builds/1800).
function count_until_wrap(out, flags, n)
i = n
while true
i += one(i)
i == 0 && break
if @inbounds(flags[1])
@inbounds out[1] = i
break
end
end
return
end
out = oneAPI.zeros(UInt64, 1)
flags = oneArray([false])
@oneapi count_until_wrap(out, flags, typemax(UInt64) - 3)
@test Array(out) == [0]
copyto!(flags, [true])
@oneapi count_until_wrap(out, flags, typemax(UInt64) - 3)
@test Array(out) == [typemax(UInt64) - 2]
end
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