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[meta] Use memcpy instead of cast to prevent strict-aliasing error #723

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merged 1 commit into from
Dec 1, 2020
Merged

[meta] Use memcpy instead of cast to prevent strict-aliasing error #723

merged 1 commit into from
Dec 1, 2020

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kcudnik
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@kcudnik kcudnik commented Dec 1, 2020

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kcudnik commented Dec 1, 2020

hope will fix sonic-net/sonic-buildimage#6064

18:28:15  MetaKeyHasher.cpp: In function 'std::size_t sai_get_hash(const sai_fdb_entry_t&)':
18:28:15  MetaKeyHasher.cpp:168:49: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
18:28:15       return *(const uint32_t*)(&fe.mac_address[2]);
18:28:15                                                   ^

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kcudnik commented Dec 1, 2020

retest vs please

@kcudnik kcudnik requested a review from daall December 1, 2020 20:16
qiluo-msft
qiluo-msft reviewed Dec 1, 2020
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meta/MetaKeyHasher.cpp
@@ -160,12 +160,20 @@ static inline std::size_t sai_get_hash(
return ne.ip_address.addr_family;
}

static_assert(sizeof(uint32_t) == 4, "uint32_t expected to be 4 bytes");
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static_assert [](start = 0, length = 13)

This assertion seems not needed. Do you anticipate some failure case?

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just a surprise for some wired platforms :D

@kcudnik kcudnik merged commit d814d2c into sonic-net:master Dec 1, 2020
@kcudnik kcudnik deleted the castfix branch December 1, 2020 23:13
pettershao-ragilenetworks pushed a commit to pettershao-ragilenetworks/sonic-sairedis that referenced this pull request Nov 18, 2022
@kcudnik
[meta] Use memcpy instead of cast to prevent strict-aliasing error (s…
1d4fae5 
…onic-net#723)
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@qiluo-msft qiluo-msft qiluo-msft approved these changes

@lguohan lguohan Awaiting requested review from lguohan

@daall daall Awaiting requested review from daall

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@kcudnik @qiluo-msft