[committed] [PR target/109508] Adjust conditional move expansion for SFB

[committed] [PR target/109508] Adjust conditional move expansion for SFB

Recently the conditional move expander's predicates were loosened for the
benefit of the THEAD processors.  In particular one operand that was
previously "register_operand" is now "reg_or_0_operand".  That's fine for
THEAD, but breaks for SFB which requires a register for that operand.

This results in an ICE when compiling the testcase an SFB target such as
the sifive s76.

This change adjusts the expansion code slightly to copy the value into
a register for SFB.

Bootstrapped and regression tested (c,c++,fortran only) with a toolchain
configured to enable SFB by default.

	PR target/109508
gcc/

	* config/riscv/riscv.cc (riscv_expand_conditional_move): For
	TARGET_SFB_ALU, force the true arm into a register.

gcc/testsuite
	* gcc.target/riscv/pr109508.c: New test.