Re: [PATCH] RISC-V: Add the option "-mdisable-multilib-check" to avoid multilib checks breaking the compilation.

["Maciej W. Rozycki" <macro@embecosm.com>]

On Tue, 23 May 2023, Jin Ma via Gcc-patches wrote:

> When testing a extension, it is often necessary for a certain program not to
> need some kind of extension, such as the bitmanip extension, to evaluate the
> performance or codesize of the extension. However, the current multilib rules
> will report an error when it is not a superset of the MULTILIB_REQUIRED list,
> which will cause the program to be unable to link normally, thus failing to
> achieve the expected purpose.

 Hmm, I have troubles understanding what is going on here.  What do you 
refer to by saying: "it is not a superset of the MULTILIB_REQUIRED list"?  

 There should be no problem with linking compiled modules together that 
make use of different extensions, with the static linker figuring out the 
combined set of extensions actually required at run time for the program 
loader to consider, as long as the modules do not have contradicting 
requirements, e.g. big vs little endianness or RV32 vs RV64.

 Can you give me a specific example (compilation options and multilibs 
available) of a failure you refer to?

 Is this something that could be solved without resorting to a possibly 
dangerous hack, by making use of MULTILIB_REUSE?

  Maciej