feat: implement llgo.stackSave

cl/_testrt/stacksave/out.ll

@@ -0,0 +1,34 @@
+; ModuleID = 'github.com/goplus/llgo/cl/_testrt/stacksave'
+source_filename = "github.com/goplus/llgo/cl/_testrt/stacksave"
+
+@"github.com/goplus/llgo/cl/_testrt/stacksave.init$guard" = global i1 false, align 1
+
+define void @"github.com/goplus/llgo/cl/_testrt/stacksave.init"() {
+_llgo_0:
+  %0 = load i1, ptr @"github.com/goplus/llgo/cl/_testrt/stacksave.init$guard", align 1
+  br i1 %0, label %_llgo_2, label %_llgo_1
+
+_llgo_1:                                          ; preds = %_llgo_0
+  store i1 true, ptr @"github.com/goplus/llgo/cl/_testrt/stacksave.init$guard", align 1
+  br label %_llgo_2
+
+_llgo_2:                                          ; preds = %_llgo_1, %_llgo_0
+  ret void
+}
+
+define void @"github.com/goplus/llgo/cl/_testrt/stacksave.main"() {
+_llgo_0:
+  %0 = call ptr @llvm.stacksave()
+  call void @"github.com/goplus/llgo/runtime/internal/runtime.PrintPointer"(ptr %0)
+  call void @"github.com/goplus/llgo/runtime/internal/runtime.PrintByte"(i8 10)
+  ret void
+}
+
+; Function Attrs: nocallback nofree nosync nounwind willreturn
+declare ptr @llvm.stacksave() #0
+
+declare void @"github.com/goplus/llgo/runtime/internal/runtime.PrintPointer"(ptr)
+
+declare void @"github.com/goplus/llgo/runtime/internal/runtime.PrintByte"(i8)
+
+attributes #0 = { nocallback nofree nosync nounwind willreturn }