RISC-V: Add Zfbfmin extension
1 In the previous patch, the libcall for BF16 was implemented:
<https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=
8c7cee80eb50792e57d514be1418c453ddd1073e>
2 Riscv provides Zfbfmin extension, which completes the "Scalar BF16 Converts":
<https://github.com/riscv/riscv-bfloat16/blob/main/doc/riscv-bfloat16-zfbfmin.adoc>
3 Implemented replacing libcall with Zfbfmin extension instruction.
4 Reused previous testcases in:
<https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=
8c7cee80eb50792e57d514be1418c453ddd1073e>
gcc/ChangeLog:
* config/riscv/iterators.md: Add mode_iterator between
floating-point modes and BFmode.
* config/riscv/riscv.cc (riscv_output_move): Handle BFmode move
for zfbfmin.
* config/riscv/riscv.md (trunc<mode>bf2): New pattern for BFmode.
(extendbfsf2): Dotto.
(*movhf_hardfloat): Add BFmode.
(*mov<mode>_hardfloat): Dotto.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/zfbfmin-bf16_arithmetic.c: New test.
* gcc.target/riscv/zfbfmin-bf16_comparison.c: New test.
* gcc.target/riscv/zfbfmin-bf16_float_libcall_convert.c: New test.
* gcc.target/riscv/zfbfmin-bf16_integer_libcall_convert.c: New test.