Merge pull request #1304 from MeteorsLiu/impl-stacksave

feat: implement `llgo.stackSave`

_demo/c/stacksave/stacksave_amd64.go

@@ -0,0 +1,22 @@
+//go:build amd64
+
+package main
+
+import (
+	"unsafe"
+	_ "unsafe"
+)
+
+//go:linkname getsp llgo.stackSave
+func getsp() unsafe.Pointer
+
+//go:linkname asmFull llgo.asm
+func asmFull(instruction string, regs map[string]any) uintptr { return 0 }
+
+func main() {
+	sp := asmFull("movq %rsp, {}", nil)
+
+	if sp != uintptr(getsp()) {
+		panic("invalid stack pointer")
+	}
+}

_demo/c/stacksave/stacksave_arm64.go

@@ -0,0 +1,22 @@
+//go:build arm64
+
+package main
+
+import (
+	"unsafe"
+	_ "unsafe"
+)
+
+//go:linkname getsp llgo.stackSave
+func getsp() unsafe.Pointer
+
+//go:linkname asmFull llgo.asm
+func asmFull(instruction string, regs map[string]any) uintptr { return 0 }
+
+func main() {
+	sp := asmFull("mov {}, sp", nil)
+
+	if sp != uintptr(getsp()) {
+		panic("invalid stack pointer")
+	}
+}