alt Hacker NewsI had yet another reason to use inline assemblies in WAH [1]. In some compilers (I think it was GCC) intrinsics are imbued with `target("foo")` attributes, which cause forced-inline via `always_inline` attribute to fail somehow. I really needed that though because I was writing a fast bytecode compiler and being unable to force-inline meant each supported SIMD instruction had to pay function call overhead (which can be significant when your bytecode is literally a single native SIMD operation!).
I’m having vague flashbacks here so I might be guessing wrong, but: the only reason I’ve ever seen an “inlining failed” error from GCC when using intrinsics (and it was an actual error) was when it actually meant “you can’t use this intrinsic in this configuration” (the second half of the message, “target specific option mismatch”, is more helpful if still cryptic). Thus the fix was to change the argument of the -march= option or (for dynamic dispatch) decorate the caller with the correct __attribute__((target)). E.g. if you pass -march=x86-64-v1 but try to use AVX you’ll get such an inlining error. (This is unlike MSVC which will always allow you to use any intrinsic supported by the compiler.)