tls: add gc-aware pthread slots

runtime/internal/clite/tls/tls_gc.go

@@ -0,0 +1,53 @@
+//go:build llgo && !nogc
+
+package tls
+
+import (
+	"unsafe"
+
+	c "github.com/goplus/llgo/runtime/internal/clite"
+	"github.com/goplus/llgo/runtime/internal/clite/bdwgc"
+)
+
+const slotRegistered = 1 << iota
+
+const maxSlotSize = 1 << 20 // 1 MiB sanity cap
+
+type slot[T any] struct {
+	value      T
+	state      uintptr
+	destructor func(*T)
+}
+
+func registerSlot[T any](s *slot[T]) {
+	if s.state&slotRegistered != 0 {
+		return
+	}
+	start, end := s.rootRange()
+	size := uintptr(end) - uintptr(start)
+	if size == 0 {
+		return
+	}
+	if size > maxSlotSize {
+		panic("tls: slot size exceeds maximum")
+	}
+	bdwgc.AddRoots(start, end)
+	s.state |= slotRegistered
+}
+
+func deregisterSlot[T any](s *slot[T]) {
+	if s == nil || s.state&slotRegistered == 0 {
+		return
+	}
+	s.state &^= slotRegistered
+	start, end := s.rootRange()
+	if uintptr(end) > uintptr(start) {
+		bdwgc.RemoveRoots(start, end)
+	}
+}
+
+func (s *slot[T]) rootRange() (start, end c.Pointer) {
+	begin := unsafe.Pointer(s)
+	endPtr := unsafe.Pointer(uintptr(begin) + unsafe.Sizeof(*s))
+	return c.Pointer(begin), c.Pointer(endPtr)
+}