llvm dev - Sep 2021 - Disabling inline compilation (Clang with VS2019)

On 22/09/2021 13:53, Eric Astor wrote:
>
> Just as John suggested, disassembling the output shows that clang is 
> inlining this function, even at -O1, where MSVC doesn't, even at /O3.
>
> [...]
>
> One possible workaround: add a noinline marker on functions defined in 
> headers that need to access protected members. 
> (https://godbolt.org/z/Pe67ovMnP)
>
Many thanks Eric,

I'm not quite sure what the difference is between LLVM and Clang so 
sorry if I'm getting them mixed up - but is there a possible fix by just 
extending the implementation for your "/Ob0" handler?  In other words,
if "/Ob0" gets specified during compilation, the compiler would stop 
trying to inline things?

John

> I'm not quite sure what the difference is between LLVM and Clang so
> sorry if I'm getting them mixed up - but is there a possible fix by
just
> extending the implementation for your "/Ob0" handler?  In other
words,
> if "/Ob0" gets specified during compilation, the compiler would
stop
> trying to inline things?
It looks like the driver does translate "/Ob0" to the internal option
"-fno-inline" which ought to prevent inlining of anything that is not
marked as always-inline; I am pretty sure that simply being defined
in-class does not qualify. I tried your example on my machine locally
(adding a function that calls get_keyboard) and it did not inline the
call.  I don't know why this result differs from Eric's.
--paulr