8352897: RISC-V: Change default value for UseConservativeFence

Reviewed-by: luhenry, fyang

Author: robehn

src/hotspot/cpu/riscv/globals_riscv.hpp

@@ -90,8 +90,7 @@ define_pd_global(intx, InlineSmallCode,          1000);
           "Size in bytes of a CPU cache line")                                   \
           range(wordSize, max_jint)                                              \
   product(bool, TraceTraps, false, "Trace all traps the signal handler")         \
-  /* For now we're going to be safe and add the I/O bits to userspace fences. */ \
-  product(bool, UseConservativeFence, true,                                      \
+  product(bool, UseConservativeFence, false,                                     \
           "Extend i for r and o for w in the pred/succ flags of fence")          \
   product(bool, AvoidUnalignedAccesses, true,                                    \
           "Avoid generating unaligned memory accesses")                          \