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[C++/SSE4.1] Compiler does not use roundss with float std::trunc/std::ceil/std::round, even with fastmath/AVX

Visual studio 2017 crashes when it has been idling for long time

float TestTruncate(float c) return std::trunc(c); float TestFloor(float c) return std::floor(c); float TestCeil(float c) return std::ceil(c); float TestRound(float c) return std::round(c);

std::round calls _roundf, should be using roundss with _MM_FROUND_TO_NEAREST_INT

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std::trunc calls _truncf, should be using roundss with _MM_FROUND_TO_ZERO

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The only time the compiler uses roundss is with std::floor.

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ReportedbyPoo FlingerJul 14, 2017 at 12:32 AM

[C++] Build fails because of projects that arent supposed to build

Intellisense with project references in c++/cli

C compiler crashes with internal error at msc1.cpp line 1469 on incorrect return statement

We will address this in a future release. The core issue here is that we are treating std::floor and std::ceil as intrinsic functions (where the compiler can assume known behavior) — but we are not treating std::trunc and std::round as intrinsic functions.

We are not emitting consistent vroundss instructions for /arch:AVX2. Furthermore, on x86, TestFloor seems to be emitting vroundsd instead of vroundss. It does work correctly when targeting x64.

fatal error C1001: An internal error has occurred in the compiler

In x64 mode, ceil uses roundss, but trunc and round still call functions.

[C++/SIMD] Cannot efficiently generate SIMD constants

Unexplainable compilation error due to a lambda definition in C++

Attachments:Up to 2 attachments (including images) can be used with a maximum of 2.1 GB each and 2.1 GB total.

Hi, thanks for the report. I confirm what you are seeing.

Hello customer. Thanks for taking the time to report this issue to us. Ive filed a bug for this issue on the C++ team here. The status on this Developer Community item will be updated as that bug is looked at. Thanks again for reporting this to us.

std::ceil uses roundsd, not sure why this is using double precision, this is adding unnecessary conversions, please use roundss with _MM_FROUND_TO_POS_INF

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Available on Visual Studio 2017, Installer, and newer releases

Wrong help displayed for typedef in a c++ file

Well reply to this DevCommunity thread when it is addressed.

[C++] Please allow __forceinline on lambda expressions [C++/SIMD] Bad codegen with vbroadcastss

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