HADOOP-19616. Add bswap support for RISC-V (apache#7809). Contributed by Lei Wen.

Author: leiwen2025

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/primitives.h

@@ -99,7 +99,7 @@ inline void simple_memcpy(void * dest, const void * src, size_t len) {
 inline uint32_t bswap(uint32_t val) {
 #ifdef __aarch64__
   __asm__("rev %w[dst], %w[src]" : [dst]"=r"(val) : [src]"r"(val));
-#elif defined(__ppc64__)||(__PPC64__)||(__powerpc64__)||(__loongarch64)
+#elif defined(__ppc64__)||(__PPC64__)||(__powerpc64__)||(__loongarch64)||(__riscv)
   return  __builtin_bswap32(val);
 #else
   __asm__("bswap %0" : "=r" (val) : "0" (val));
@@ -110,7 +110,7 @@ inline uint32_t bswap(uint32_t val) {
 inline uint64_t bswap64(uint64_t val) {
 #ifdef __aarch64__
   __asm__("rev %[dst], %[src]" : [dst]"=r"(val) : [src]"r"(val));
-#elif defined(__ppc64__)||(__PPC64__)||(__powerpc64__)||(__loongarch64)
+#elif defined(__ppc64__)||(__PPC64__)||(__powerpc64__)||(__loongarch64)||(__riscv)
   return __builtin_bswap64(val);
 #else
 #ifdef __X64