maixbit: remove atomic operations

src/runtime/arch_tinygoriscv64.go

@@ -17,76 +17,3 @@ func align(ptr uintptr) uintptr {
 func getCurrentStackPointer() uintptr {
 	return riscv.AsmFull("mv {}, sp", nil)
 }
-
-// Documentation:
-// * https://llvm.org/docs/Atomics.html
-// * https://gcc.gnu.org/onlinedocs/gcc/_005f_005fsync-Builtins.html
-//
-// In the case of RISC-V, some operations may be implemented with libcalls if
-// the operation is too big to be handled by assembly. Officially, these calls
-// should be implemented with a lock-free algorithm but as (as of this time) all
-// supported RISC-V chips have a single hart, we can simply disable interrupts
-// to get the same behavior.
-
-//export __atomic_load_8
-func __atomic_load_8(ptr *uint64, ordering int32) uint64 {
-	mask := riscv.DisableInterrupts()
-	value := *ptr
-	riscv.EnableInterrupts(mask)
-	return value
-}
-
-//export __atomic_store_8
-func __atomic_store_8(ptr *uint64, value uint64, ordering int32) {
-	mask := riscv.DisableInterrupts()
-	*ptr = value
-	riscv.EnableInterrupts(mask)
-}
-
-//export __atomic_exchange_8
-func __atomic_exchange_8(ptr *uint64, value uint64, ordering int32) uint64 {
-	mask := riscv.DisableInterrupts()
-	oldValue := *ptr
-	*ptr = value
-	riscv.EnableInterrupts(mask)
-	return oldValue
-}
-
-//export __atomic_compare_exchange_8
-func __atomic_compare_exchange_8(ptr, expected *uint64, desired uint64, success_ordering, failure_ordering int32) bool {
-	mask := riscv.DisableInterrupts()
-	oldValue := *ptr
-	success := oldValue == *expected
-	if success {
-		*ptr = desired
-	} else {
-		*expected = oldValue
-	}
-	riscv.EnableInterrupts(mask)
-	return success
-}
-
-//export __atomic_fetch_add_8
-func __atomic_fetch_add_8(ptr *uint64, value uint64, ordering int32) uint64 {
-	mask := riscv.DisableInterrupts()
-	oldValue := *ptr
-	*ptr = oldValue + value
-	riscv.EnableInterrupts(mask)
-	return oldValue
-}
-
-// The safest thing to do here would just be to disable interrupts for
-// procPin/procUnpin. Note that a global variable is safe in this case, as any
-// access to procPinnedMask will happen with interrupts disabled.
-
-var procPinnedMask uintptr
-
-//go:linkname procPin sync/atomic.runtime_procPin
-func procPin() {
-	procPinnedMask = riscv.DisableInterrupts()
-}
-
-//go:linkname procUnpin sync/atomic.runtime_procUnpin
-func procUnpin() {
-	riscv.EnableInterrupts(procPinnedMask)
-}