[Issue 15873] In order to implement std.simd, compile time info about CPU specifics is needed

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15873

--- Comment #3 from Walter Bright <bugzilla at digitalmars.com> ---
DMD predefines "D_SIMD" for:

1. all 64 bit code generation
2. OSX 32 bit code generation

and does generate SIMD instructions for those platforms. DMD does not have
compiler switches to select SIMD levels.

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