Re: VAX floating point formats & GCC patches

["Maciej W. Rozycki" <macro%linux-mips.org@localhost>]

On Fri, 8 Apr 2016, Jake Hamby wrote:

> I have some good news on the GCC optimization & code gen bug fixing 
> front which I'll share in a separate email. I'm basically finished with 
> the G_float conversion project, so I'll send a diff to the list, 
> probably tomorrow, after I've cleaned it up and tested it a bit more. I 
> didn't rewrite very much code and didn't add or remove any files, so it 
> should be a reasonably clean patch, if I can manage to email it without 
> any glitches.

 FWIW:

#undef TARGET_DEFAULT
#define TARGET_DEFAULT MASK_G_FLOAT

was all I needed to make the Linux port use G-floating, hardcoded.

 As previously noted I think making it a multilib option would be more 
appropriate for NetBSD which has an established ABI already.  This way 
people will have an option for a seamless upgrade if they choose to.  
Both kinds of binaries may then coexist in a single system, and remain 
supported for new user application compilations.

 You may have a look at GCC commit 201313 for how I solved it for IEEE 
754-1985 vs IEEE 754-2008 NaN encodings in the MIPS port, including a way 
to configure the compiler's default, i.e. the setting chosen where no 
respective option has been specified by the user on the command line.  
Please note that you'll need to have suitable support in the assembler, 
static linker and dynamic loader, and possibly the kernel as well, to 
complement such a change though.

  Maciej