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Original commit message: [msvc] fix build with neon intrinsics This compilation error was found by NodeJS when updating V8: #240 MSVC reports an error with "too many initializer" for type uint32x4_t. --- Under gcc/clang, this is a typedef to a builtin type. For MSVC, it is a typedef to this union: typedef union __n128 { unsigned __int64 n128_u64[2]; unsigned __int32 n128_u32[4]; ... } __n128; C++ mandates that only first member of union can be initialized at declaration. Thus, it can only be initialized with {uint64_t, uint64_t}. VS people proposed to use designated initializer instead: var = {.n128_u32={1, 2, 3, 8}} https://developercommunity.visualstudio.com/t/error-c2078-too-many-initializers-when-using-arm-n/402911 But, you need to use /std:c++20 for this, which is not the case in v8. --- Thus, the only solution is to implement a hack specifically for MSVC, where you build two uint64, from four uint32. --------------------------------------- Once solved, another error is reported: templated function extract_first_nonzero_index is specialized twice. This is because, with MSVC, uint32x4_t and uint64x2_t are typedef to the same __n128 union. The fix is to drop templates, and use explicit function names instead. Bug: v8:13312 Change-Id: I231d8cf01c05af01af319d56d5666c415f8b989b Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3913035 Reviewed-by: Igor Sheludko <ishell@chromium.org> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org> Commit-Queue: Jakob Kummerow <jkummerow@chromium.org> Cr-Commit-Position: refs/heads/main@{#83404} Refs: v8/v8@1b3a4f0
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