Zoltán Borók-Nagy created IMPALA-15369:
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Summary: Check for the CRC32 extension at startup on ARM64
Key: IMPALA-15369
URL: https://issues.apache.org/jira/browse/IMPALA-15369
Project: IMPALA
Issue Type: Improvement
Components: Backend
Reporter: Zoltán Borók-Nagy
On x86-64, {{CpuInfo::EnforceCpuRequirements()}} makes every Impala daemon
(impalad, catalogd, statestored, admissiond) exit with a clear error message
when the CPU lacks AVX2, or AVX in legacy mode (IMPALA-9690). There is no such
check on
ARM64: the function does nothing outside {{{}#ifdef _{_}x86_64{_}_{}}}.
The ARM64 build still assumes the CRC32 extension. Native code and
cross-compiled IR are compiled with {{-march=armv8-a+crc}} (be/CMakeLists.txt).
CRC32 instructions are used without checking for the extension:
* {{SSE4_crc32_u8/u16/u32/u64}} in be/src/util/sse-util.h emit
{{crc32cb/ch/cw/cx}} as inline asm, or ACLE {{__crc32c*}} intrinsics in IR.
* {{HashUtil::Hash()}} always selects {{CrcHash()}} on aarch64 ({{{}IS_AARCH64
|| ...{}}}).
* {{LlvmCodeGen::GetHashFunction()}} emits {{aarch64_crc32c*}} intrinsics,
also skipping the feature check on aarch64.
CRC32 is optional in ARMv8.0 and only mandatory from ARMv8.1. On an ARMv8.0 CPU
without it, Impala does not fail at startup. It crashes with SIGILL once one of
the code paths above runs: join/aggregation hash
tables, Parquet dictionary encoding, the scheduler's hash ring, etc.
Such CPUs are rare today, but the failure is confusing and hard to diagnose.
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