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Only use __movsb on architectures that support it (#5147)

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With the introduction of Windows 10 on ARM (ARM64), code that assumes
that Windows targets are always x86 or x86_64 targets needs to be
updated.

The hot function ReadUInt64 has been optimized in MSVC builds using the
compiler intrinsic __movsb. Since this does not exist on ARM64 Windows,
this change uses the pure C++ path that other platforms use instead.
This commit is contained in:
Jon Kunkee
2019-02-04 09:57:34 -08:00
committed by Wouter van Oortmerssen
parent d8210d5a83
commit 4d98faa515
1 changed files with 1 additions and 1 deletions
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2
include/flatbuffers/flexbuffers.h
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@@ -153,7 +153,7 @@ inline uint64_t ReadUInt64(const uint8_t *data, uint8_t byte_width) {
// constant, which here it isn't. Test if memcpy is still faster than // constant, which here it isn't. Test if memcpy is still faster than
// the conditionals in ReadSizedScalar. Can also use inline asm. // the conditionals in ReadSizedScalar. Can also use inline asm.
// clang-format off // clang-format off
#ifdef _MSC_VER #if defined(_MSC_VER) && (defined(_M_X64) || defined _M_IX86)
uint64_t u = 0; uint64_t u = 0;
__movsb(reinterpret_cast<uint8_t *>(&u), __movsb(reinterpret_cast<uint8_t *>(&u),
reinterpret_cast<const uint8_t *>(data), byte_width); reinterpret_cast<const uint8_t *>(data), byte_width);