runtime: use riscv64 RDTIME instruction

Use the actual RDTIME instruction, rather than a WORD.
Generated code is the same.

Change-Id: I6f6f5a1836eae2d05af34d4a22db2ede4fdcb458
Reviewed-on: https://go-review.googlesource.com/c/go/+/231997
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/runtime/asm_riscv64.s b/src/runtime/asm_riscv64.s
index d7c45a183dca1cf8ae8dcce063aa8497657cbb65..8f6c8773eb089409259a4cc1c8726c5a908865fd 100644 (file)
--- a/src/runtime/asm_riscv64.s
+++ b/src/runtime/asm_riscv64.s
@@ -79,7 +79,7 @@ TEXT setg_gcc<>(SB),NOSPLIT,$0-0
 
 // func cputicks() int64
 TEXT runtime·cputicks(SB),NOSPLIT,$0-8
-       WORD    $0xc0102573     // rdtime a0
+       RDTIME  A0
        MOV     A0, ret+0(FP)
        RET