[PATCH] D141074: Avoid converting 64-bit integers to floating point using x87 on Windows

Fri Jan 6 05:59:13 PST 2023

pengfei added a comment.

In D141074#4031117 <https://reviews.llvm.org/D141074#4031117>, @icedrocket wrote:

>> What to do if user changes the default precision?
>
> If users change the precision control to 64-bit, we can allow the use of x87 instructions by adding a compiler option. However, this is probably only for Windows 32-bit, and I don't know if it's appropriate to add a new option because there aren't that many users on that platform.
>
>> Besides, our down stream offers option to help user to set higher percision.
>
> I'm sorry, but I'm not sure exactly what that option is. Is it an option to increase x87 precision, or an option to operate on floats at higher precision like double?

It's /Qpc80 that to be compatible with ICC https://www.intel.com/content/www/us/en/develop/documentation/cpp-compiler-developer-guide-and-reference/top/optimization-and-programming/intel-c-compiler-classic-math-library/use-the-intel-c-compiler-classic-math-library.html
It's intended design for Windows, especially for 32-bits.

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