Bug#1025307: yosys mips64el build failure (fix)

[Scott Ashcroft]

On Fri, 2022-12-02 at 14:04 +0000, Scott Ashcroft wrote:
> Hi,
> 
> I agree if you only read the C then the code looks fine, if a bit
> odd.
> However, having looked at the coredump with gdb it seems the compiler
> optomises the dereference out and passes back a pointer to the soon
> to
> be invalid stack address rather than the value.
> It only crashes with the stack protection on and I initially
> struggled
> to reproduce the issue as I was using the upstream compiler flags.
> 
> It isn't even handling endianness conversions as it copies the bytes
> in
> the same order they come in. I think their idea was to support
> architectures where you can't access an 32-bit int at an odd address.
> 
> I'll try you patch and report back.

The patch works!

It does give a build warning due to the return type of sizeof being a
size_t not an int.

If you chnage it to:

for (size_t i = 0; i < sizeof(u.u8); i++)

then everything is fine.

The files produced by running the grom test match exactly those from
your packaged x86_64 version.

Cheers,
Scott