tls: document package and guard helpers

Author: cpunion

runtime/internal/clite/bdwgc/bdwgc.go

@@ -40,9 +40,17 @@ func Realloc(ptr c.Pointer, size uintptr) c.Pointer
 //go:linkname Free C.GC_free
 func Free(ptr c.Pointer)
 
+// AddRoots registers a memory region [start, end) as a GC root. The caller
+// must ensure that the range remains valid until RemoveRoots is invoked with
+// the same boundaries. This is typically used for TLS slots that store Go
+// pointers.
+//
 //go:linkname AddRoots C.GC_add_roots
 func AddRoots(start, end c.Pointer)
 
+// RemoveRoots unregisters a region previously registered with AddRoots. The
+// start and end pointers must exactly match the earlier AddRoots call.
+//
 //go:linkname RemoveRoots C.GC_remove_roots
 func RemoveRoots(start, end c.Pointer)
 

runtime/internal/clite/tls/tls_common.go

@@ -1,5 +1,45 @@
 //go:build llgo
 
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Package tls provides generic thread-local storage backed by POSIX pthread
+// TLS. When built with the GC-enabled configuration (llgo && !nogc), TLS slots
+// are automatically registered with the BDWGC garbage collector so pointers
+// stored in thread-local state remain visible to the collector. Builds without
+// GC integration (llgo && nogc) simply fall back to pthread TLS without root
+// registration.
+//
+// Basic usage:
+//
+//	h := tls.Alloc[int](nil)
+//	h.Set(42)
+//	val := h.Get() // returns 42
+//
+// With destructor:
+//
+//	h := tls.Alloc[*Resource](func(r **Resource) {
+//	    if r != nil && *r != nil {
+//	        (*r).Close()
+//	    }
+//	})
+//
+// Build tags:
+//   - llgo && !nogc: Enables GC-aware slot registration via BDWGC
+//   - llgo && nogc:  Disables GC integration; TLS acts as plain pthread TLS
 package tls
 
 import (

runtime/internal/clite/tls/tls_gc.go

@@ -1,5 +1,21 @@
 //go:build llgo && !nogc
 
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package tls
 
 import (
@@ -48,6 +64,11 @@ func deregisterSlot[T any](s *slot[T]) {
 
 func (s *slot[T]) rootRange() (start, end c.Pointer) {
 	begin := unsafe.Pointer(s)
-	endPtr := unsafe.Pointer(uintptr(begin) + unsafe.Sizeof(*s))
+	size := unsafe.Sizeof(*s)
+	beginAddr := uintptr(begin)
+	if beginAddr > ^uintptr(0)-size {
+		panic("tls: pointer arithmetic overflow in rootRange")
+	}
+	endPtr := unsafe.Pointer(beginAddr + size)
 	return c.Pointer(begin), c.Pointer(endPtr)
 }

runtime/internal/clite/tls/tls_nogc.go

@@ -1,5 +1,21 @@
 //go:build llgo && nogc
 
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package tls
 
 type slot[T any] struct {

runtime/internal/clite/tls/tls_test.go

@@ -1,5 +1,21 @@
 //go:build llgo
 
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package tls_test
 
 import (

ssa/di_test.go

@@ -1,5 +1,21 @@
 //go:build !llgo
 
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package ssa
 
 import (