如何调整CLANG/LLVM编译选项禁用过度自动向量化？

AI 小北

2026-8-12

禁用Clang/LLVM过度激进的向量化优化

我需要禁用Clang/LLVM的某类优化选项，因为它生成了臃肿的输出，核心问题是过度激进的向量化。

代码示例

typedef                     unsigned char               uint8;
typedef                     unsigned long               ulong;
typedef                     unsigned long long int      uint64;
typedef                     unsigned long long int      size_t;

ulong inline /*__attribute__((optnone))*/ SetMemberMask(uint8* const stream, size_t const length)
{
    size_t                  pos = 0;
    uint64                  compose{};

    do
    {
        auto                bit = stream[pos];

        compose |= 1ULL << bit;
    } while (++pos <= length);

    return compose;
}

uint64 BitFieldStreamMasks_64(uint8* const __restrict p_stream, size_t const p_qry_rows, uint64* const __restrict p_comparand, uint64* const __restrict p_masks)
{
    auto const              bits = static_cast<size_t>(p_stream[0]);
    auto const              memberCount = static_cast<size_t>(p_stream[1]);
    auto const              bitOrderedIx = &p_stream[0];
    auto const              sectionSortedIx = &bitOrderedIx[bits];
    uint64                  stream = SetMemberMask(p_stream, memberCount);

    return stream;
}