In this PR case LRA needs to provide too many hard regs for insn
reloads, where some reload pseudos require 8 aligned regs for
themselves.  As the last attempt, LRA tries to split live ranges of
hard regs for insn reload pseudos.  It is a very rare case.  An
inheritance pseudo involving a reload pseudo of the insn can be
spilled in the assignment sub-pass run right after splitting and we need
to run split sub-pass for the inheritance pseudo now.

gcc/ChangeLog:

	PR target/115458
	* lra-int.h (LRA_MAX_FAILED_SPLITS): Define and check its value.
	(lra_split_hard_reg_for): Change prototype.
	* lra.cc (lra): Try to split hard reg range several times after a
	failure.
	* lra-assigns.cc (lra_split_hard_reg_for): Add an arg, a flag of
	giving up.  Report asm error and nullify the asm insn depending on
	the arg value.

gcc/testsuite/ChangeLog:

	PR target/115458
	* g++.target/riscv/pr115458.C: New.