8291947: riscv: fail to build after JDK-8290840

Reviewed-by: fyang, fjiang

Author: Yadong Wang

src/hotspot/cpu/riscv/icache_riscv.cpp

@@ -29,27 +29,8 @@
 
 #define __ _masm->
 
-// SYSCALL_RISCV_FLUSH_ICACHE is used to flush instruction cache. The "fence.i" instruction
-// only work on the current hart, so kernel provides the icache flush syscall to flush icache
-// on each hart. You can pass a flag to determine a global or local icache flush.
-static void icache_flush(long int start, long int end)
-{
-  const int SYSCALL_RISCV_FLUSH_ICACHE = 259;
-  register long int __a7 asm ("a7") = SYSCALL_RISCV_FLUSH_ICACHE;
-  register long int __a0 asm ("a0") = start;
-  register long int __a1 asm ("a1") = end;
-  // the flush can be applied to either all threads or only the current.
-  // 0 means a global icache flush, and the icache flush will be applied
-  // to other harts concurrently executing.
-  register long int __a2 asm ("a2") = 0;
-  __asm__ volatile ("ecall\n\t"
-                    : "+r" (__a0)
-                    : "r" (__a0), "r" (__a1), "r" (__a2), "r" (__a7)
-                    : "memory");
-}
-
 static int icache_flush(address addr, int lines, int magic) {
-  icache_flush((long int) addr, (long int) (addr + (lines << ICache::log2_line_size)));
+  __builtin___clear_cache(addr, addr + (lines << ICache::log2_line_size));
   return magic;
 }