[Bug target/97481] GCC ice when build with RISCV on msys2

["euloanty at live dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97481

--- Comment #3 from fdlbxtqi <euloanty at live dot com> ---
(In reply to Jim Wilson from comment #2)
> riscv-unknown-linux-gnu is not a supported target.  You must use either
> riscv32-unknown-linux-gnu or riscv64-unknwon-linux-gnu.  Both compilers
> support both word sizes, the only difference is which is the default word
> size.  This may be part of the reason why it failed.
> 
> The attachment doesn't show any ICE.  It is just a config.log file, and I
> don't see anything interesting in there.
> 
> Note that mingw64 builds of a linux toolchain are unlikely to work as glibc
> requires a case sensitive file system.  I'd suggest using WSL2 as something
> more likely to work, but I haven't tried that myself.
> 
> It looks like you have a badly broken compiler build.  You will need to
> figure out why it is broken.  This doesn't seem to be a gcc problem, but
> rather a build problem on your side.

I have successfully built that by fixing problems by myself for both
x86_64-linux-gnu and aarch64-linux-gnu. While on riscv, it fails at the
configure for glibc since the compiler encounters ICE.

Here is the proof
https://gcc.gnu.org/pipermail/libstdc++/2020-October/051219.html
https://github.com/riscv/riscv-gnu-toolchain/issues/523#issuecomment-711457612

And this is my detailed building process.

https://github.com/expnkx/GCC-cross-compilation-scripts/blob/master/windows%20hosted/aarch64-linux-gnu.txt