OT Recompiling GCC libraries in MinGW environment

I'm not a MinGW user, but there are a few hints about possibly related issues:

Seems like a well-known problem.

Cheers

Phil Hobbs

Thanks very much Phil for the pointer. It seems I'm not alone.

I didn't find that in any of my searches partly because I assumed that it has always been like that!

It was becoming annoying since nothing I did made it any better. I do have an older version on another machine so I'll see if that is better behaved. The irony is that I downloaded the latest and greatest version specifically to avoid tripping up over known legacy bugs!

I could see from the debugger that it was using x87 library code and infer from the error histograms that it was doing 80 bit rather than 64 bit computation and rounding down right at the end. Remarkably accurate but a tremendous hit when moving non-aligned 10 byte objects around.

I got around it by cloning a chunk of the trig implementations at code level so that I could benchmark GCC code despite the failings of the MinGW system libraries. I'm sure I ought to be able to rebuild the full system library if I knew exactly how to do it but that also eludes me.

I have subverted MSC to allow me to use 80 bit computations which make handy reference implementations with the extra bits for guard digits. I used to keep a copy of MSC 6.0 around (the last version with native 80 bit FP support) but it too long in the tooth now to be worthwhile.

Can’t you hack up the linker script to get the 64-bit libraries?

Cheers

Phil Hobbs

Having worked on embedded Linux(and still do) your suggestion, I am afraid is going to lead to endless misery, unless the person writing the hack knows exactly what he|she is doing. All the OP has to do is get a new motherboard, the matching microprocessor, RAM and a solid state harddrive. Linux distributions, in particular Fedora and Ubuntu are very easy to install these days. Once the OS is installed, the good old gcc compiler is readily installed using: sudo su - dnf install gcc

And then .. happy programming days. I have recently configured a machine this way to do band structure calculations wit Quantum Expresso.

For a code like that, I’d just use static linking and forget about it.

Cheers

Phil Hobbs