riscv: lib: Check if output in asm goto supported

The output field of an asm goto statement is not supported by all
compilers. If it is not supported, fallback to the non-optimized code.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Fixes: a04c192eabfb ("riscv: Add checksum library")
Link: https://lore.kernel.org/r/20240118-csum_remove_output_operands_asm_goto-v2-1-5d1b73cf93d4@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/lib/csum.c b/arch/riscv/lib/csum.c
index 06ce8e7250d982332ad6acc19d24380301347bf0..af3df5274ccbae0118488080040f45881a3e025a 100644 (file)
--- a/arch/riscv/lib/csum.c
+++ b/arch/riscv/lib/csum.c
@@ -156,6 +156,7 @@ do_csum_with_alignment(const unsigned char *buff, int len)
        end = (const unsigned long *)(buff + len);
        csum = do_csum_common(ptr, end, data);
 
+#ifdef CC_HAS_ASM_GOTO_TIED_OUTPUT
        /*
         * Zbb support saves 6 instructions, so not worth checking without
         * alternatives if supported
@@ -214,6 +215,7 @@ end:
                return csum >> 16;
        }
 no_zbb:
+#endif /* CC_HAS_ASM_GOTO_TIED_OUTPUT */
 #ifndef CONFIG_32BIT
        csum += ror64(csum, 32);
        csum >>= 32;