[Bug target/100217] [11/12 Regression] ICE when building valgrind testsuite with -march=z14 since r11-7552

[iii at linux dot ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100217

--- Comment #5 from Ilya Leoshkevich <iii at linux dot ibm.com> ---
That would be an ideal solution, but I wonder how to implement it? Suppose we
find a way to convince expand to pick FPRX2mode for such a long double. What if
the following comes up?

register long double x asm ("v0");  /* FPRX2mode */
long double y;                      /* TFmode */
x += y;                             /* convert? */

Would it be feasible to also teach expand to do the mode conversions?



One other alternative might be to detect `register long double asm("fN")`
declarations and go back to using floating point register pairs for functions
that contain them.