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Improve _(Add|Multiply)_with_overflow_check #3678

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merged 7 commits into from
May 18, 2023
Merged

Improve _(Add|Multiply)_with_overflow_check #3678

merged 7 commits into from
May 18, 2023

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JMazurkiewicz
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  • Rename _(Add|Multiply)_with_overflow_check to _Add_overflow and _Mul_overflow for simplicity,
    • This matches naming of Clang's builtins (__builtin_add_overflow and __builtin_mul_overflow),
  • Move both functions to <xutility>,
    • Both functions are going to be used in <mdspan> implementation,
  • Add separate tests, which detected two bugs:
    • When both arguments to _Mul_overflow are equal to numeric_limits<uint16_t>::max(), then signed integer overflow occurs,
    • There were missing static_casts in _Mul_overflow's LLVM-based branch,
    • Both bugs are fixed in this PR.

@JMazurkiewicz JMazurkiewicz requested a review from a team as a code owner April 29, 2023 19:23
@StephanTLavavej StephanTLavavej added the bug Something isn't working label May 1, 2023
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StephanTLavavej reviewed May 1, 2023
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@barcharcraz barcharcraz removed their assignment May 4, 2023
strega-nil-ms
strega-nil-ms approved these changes May 16, 2023
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This looks reasonable to me. Thanks for fixing the unsigned short UB!

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jovibor commented May 16, 2023

@StephanTLavavej StephanTLavavej self-assigned this May 17, 2023
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I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

@CaseyCarter CaseyCarter merged commit 1fbf725 into microsoft:main May 18, 2023
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Thanks for fixing bugs in these functions that are supposed to defend against bugs.

@JMazurkiewicz JMazurkiewicz deleted the checked-arithmetics branch May 18, 2023 16:48
This was referenced Jun 15, 2023
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@barcharcraz barcharcraz barcharcraz approved these changes

@StephanTLavavej StephanTLavavej StephanTLavavej approved these changes

@strega-nil-ms strega-nil-ms strega-nil-ms approved these changes

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@JMazurkiewicz @StephanTLavavej @jovibor @CaseyCarter @barcharcraz @frederick-vs-ja @strega-nil-ms