compiler: add support for atomic operations

This also implements DisableInterrupts/EnableInterrupts for RISC-V, as
those operations were needed to implement a few libcalls.

testdata/atomic.go

@@ -0,0 +1,95 @@
+package main
+
+import (
+	"sync/atomic"
+	"unsafe"
+)
+
+func main() {
+	i32 := int32(-5)
+	println("AddInt32:", atomic.AddInt32(&i32, 8), i32)
+
+	i64 := int64(-5)
+	println("AddInt64:", atomic.AddInt64(&i64, 8), i64)
+
+	u32 := uint32(5)
+	println("AddUint32:", atomic.AddUint32(&u32, 8), u32)
+
+	u64 := uint64(5)
+	println("AddUint64:", atomic.AddUint64(&u64, 8), u64)
+
+	uptr := uintptr(5)
+	println("AddUintptr:", uint64(atomic.AddUintptr(&uptr, 8)), uint64(uptr))
+
+	println("SwapInt32:", atomic.SwapInt32(&i32, 33), i32)
+	println("SwapInt64:", atomic.SwapInt64(&i64, 33), i64)
+	println("SwapUint32:", atomic.SwapUint32(&u32, 33), u32)
+	println("SwapUint64:", atomic.SwapUint64(&u64, 33), u64)
+	println("SwapUintptr:", uint64(atomic.SwapUintptr(&uptr, 33)), uint64(uptr))
+	ptr := unsafe.Pointer(&i32)
+	println("SwapPointer:", atomic.SwapPointer(&ptr, unsafe.Pointer(&u32)) == unsafe.Pointer(&i32), ptr == unsafe.Pointer(&u32))
+
+	i32 = int32(-5)
+	println("CompareAndSwapInt32:", atomic.CompareAndSwapInt32(&i32, 5, 3), i32)
+	println("CompareAndSwapInt32:", atomic.CompareAndSwapInt32(&i32, -5, 3), i32)
+
+	i64 = int64(-5)
+	println("CompareAndSwapInt64:", atomic.CompareAndSwapInt64(&i64, 5, 3), i64)
+	println("CompareAndSwapInt64:", atomic.CompareAndSwapInt64(&i64, -5, 3), i64)
+
+	u32 = uint32(5)
+	println("CompareAndSwapUint32:", atomic.CompareAndSwapUint32(&u32, 4, 3), u32)
+	println("CompareAndSwapUint32:", atomic.CompareAndSwapUint32(&u32, 5, 3), u32)
+
+	u64 = uint64(5)
+	println("CompareAndSwapUint64:", atomic.CompareAndSwapUint64(&u64, 4, 3), u64)
+	println("CompareAndSwapUint64:", atomic.CompareAndSwapUint64(&u64, 5, 3), u64)
+
+	uptr = uintptr(5)
+	println("CompareAndSwapUintptr:", atomic.CompareAndSwapUintptr(&uptr, 4, 3), uint64(uptr))
+	println("CompareAndSwapUintptr:", atomic.CompareAndSwapUintptr(&uptr, 5, 3), uint64(uptr))
+
+	ptr = unsafe.Pointer(&i32)
+	println("CompareAndSwapPointer:", atomic.CompareAndSwapPointer(&ptr, unsafe.Pointer(&u32), unsafe.Pointer(&i64)), ptr == unsafe.Pointer(&i32))
+	println("CompareAndSwapPointer:", atomic.CompareAndSwapPointer(&ptr, unsafe.Pointer(&i32), unsafe.Pointer(&i64)), ptr == unsafe.Pointer(&i64))
+
+	println("LoadInt32:", atomic.LoadInt32(&i32))
+	println("LoadInt64:", atomic.LoadInt64(&i64))
+	println("LoadUint32:", atomic.LoadUint32(&u32))
+	println("LoadUint64:", atomic.LoadUint64(&u64))
+	println("LoadUintptr:", uint64(atomic.LoadUintptr(&uptr)))
+	println("LoadPointer:", atomic.LoadPointer(&ptr) == unsafe.Pointer(&i64))
+
+	atomic.StoreInt32(&i32, -20)
+	println("StoreInt32:", i32)
+
+	atomic.StoreInt64(&i64, -20)
+	println("StoreInt64:", i64)
+
+	atomic.StoreUint32(&u32, 20)
+	println("StoreUint32:", u32)
+
+	atomic.StoreUint64(&u64, 20)
+	println("StoreUint64:", u64)
+
+	atomic.StoreUintptr(&uptr, 20)
+	println("StoreUintptr:", uint64(uptr))
+
+	atomic.StorePointer(&ptr, unsafe.Pointer(&uptr))
+	println("StorePointer:", ptr == unsafe.Pointer(&uptr))
+
+	// test atomic.Value load/store operations
+	testValue(int(3), int(-2))
+	testValue("", "foobar", "baz")
+}
+
+func testValue(values ...interface{}) {
+	var av atomic.Value
+	for _, val := range values {
+		av.Store(val)
+		loadedVal := av.Load()
+		if loadedVal != val {
+			println("val store/load didn't work, expected", val, "but got", loadedVal)
+		}
+	}
+}

testdata/atomic.txt

@@ -0,0 +1,35 @@
+AddInt32: 3 3
+AddInt64: 3 3
+AddUint32: 13 13
+AddUint64: 13 13
+AddUintptr: 13 13
+SwapInt32: 3 33
+SwapInt64: 3 33
+SwapUint32: 13 33
+SwapUint64: 13 33
+SwapUintptr: 13 33
+SwapPointer: true true
+CompareAndSwapInt32: false -5
+CompareAndSwapInt32: true 3
+CompareAndSwapInt64: false -5
+CompareAndSwapInt64: true 3
+CompareAndSwapUint32: false 5
+CompareAndSwapUint32: true 3
+CompareAndSwapUint64: false 5
+CompareAndSwapUint64: true 3
+CompareAndSwapUintptr: false 5
+CompareAndSwapUintptr: true 3
+CompareAndSwapPointer: false true
+CompareAndSwapPointer: true true
+LoadInt32: 3
+LoadInt64: 3
+LoadUint32: 3
+LoadUint64: 3
+LoadUintptr: 3
+LoadPointer: true
+StoreInt32: -20
+StoreInt64: -20
+StoreUint32: 20
+StoreUint64: 20
+StoreUintptr: 20
+StorePointer: true