Standardize async id creation and setting

This will make sure we don't forget to reset async ids
in 'create_reset_ids' and also makes sure we're incrementing
the id whenever we get it (instead of doing it at some
later, random instruction).

This is follow up to a conversation here:
bpftrace/bpftrace#3249 (comment)

src/ast/async_ids.h

@@ -0,0 +1,54 @@
+#pragma once
+
+namespace bpftrace {
+namespace ast {
+
+// Add new ids here
+#define FOR_LIST_OF_ASYNC_IDS(DO)                                              \
+  DO(cat)                                                                      \
+  DO(cgroup_path)                                                              \
+  DO(helper_error)                                                             \
+  DO(join)                                                                     \
+  DO(mapped_printf)                                                            \
+  DO(non_map_print)                                                            \
+  DO(printf)                                                                   \
+  DO(skb_output)                                                               \
+  DO(strftime)                                                                 \
+  DO(str)                                                                      \
+  DO(system)                                                                   \
+  DO(time)                                                                     \
+  DO(watchpoint)
+
+#define DEFINE_MEMBER_VAR(id, ...) int _##id = 0;
+#define DEFINE_ACCESS_METHOD(id, ...)                                          \
+  int id()                                                                     \
+  {                                                                            \
+    return _##id++;                                                            \
+  }
+#define LOCAL_SAVE(id, ...) local_##id = _##id,
+#define LOCAL_RESTORE(id, ...) this->_##id = local_##id;
+
+class AsyncIds {
+public:
+  explicit AsyncIds() = default;
+
+  FOR_LIST_OF_ASYNC_IDS(DEFINE_ACCESS_METHOD)
+
+  /*
+   * For 'create_reset_ids' return a lambda that has captured-by-value
+   * CodegenLLVM's async id state. Running the returned lambda will restore
+   * `CodegenLLVM`s async id state back to when this function was first called.
+   */
+  std::function<void()> create_reset_ids()
+  {
+    return [FOR_LIST_OF_ASYNC_IDS(LOCAL_SAVE) this] {
+      FOR_LIST_OF_ASYNC_IDS(LOCAL_RESTORE)
+    };
+  }
+
+private:
+  FOR_LIST_OF_ASYNC_IDS(DEFINE_MEMBER_VAR)
+};
+
+} // namespace ast
+} // namespace bpftrace

src/ast/irbuilderbpf.cpp

@@ -124,8 +124,12 @@ StructType *IRBuilderBPF::GetStructType(
 
 IRBuilderBPF::IRBuilderBPF(LLVMContext &context,
                            Module &module,
-                           BPFtrace &bpftrace)
-    : IRBuilder<>(context), module_(module), bpftrace_(bpftrace)
+                           BPFtrace &bpftrace,
+                           AsyncIds &async_ids)
+    : IRBuilder<>(context),
+      module_(module),
+      bpftrace_(bpftrace),
+      async_ids_(async_ids)
 {
   // Declare external LLVM function
   FunctionType *pseudo_func_type = FunctionType::get(
@@ -2246,7 +2250,7 @@ void IRBuilderBPF::CreateHelperError(Value *ctx,
       (bpftrace_.helper_check_level_ == 1 && return_zero_if_err(func_id)))
     return;
 
-  int error_id = helper_error_id_++;
+  int error_id = async_ids_.helper_error();
   bpftrace_.resources.helper_error_info[error_id] = { .func_id = func_id,
                                                       .loc = loc };
 

src/ast/irbuilderbpf.h

@@ -8,6 +8,7 @@
 #include <optional>
 
 #include "ast/ast.h"
+#include "ast/async_ids.h"
 #include "bpftrace.h"
 #include "types.h"
 
@@ -51,7 +52,10 @@ using namespace llvm;
 
 class IRBuilderBPF : public IRBuilder<> {
 public:
-  IRBuilderBPF(LLVMContext &context, Module &module, BPFtrace &bpftrace);
+  IRBuilderBPF(LLVMContext &context,
+               Module &module,
+               BPFtrace &bpftrace,
+               AsyncIds &async_ids);
 
   AllocaInst *CreateAllocaBPF(llvm::Type *ty, const std::string &name = "");
   AllocaInst *CreateAllocaBPF(const SizedType &stype,
@@ -279,14 +283,14 @@ class IRBuilderBPF : public IRBuilder<> {
   // both branches here:
   // BEGIN { if (nsecs > 0) { $a = 1 } else { $a = 2 } print($a); exit() }
   void hoist(const std::function<void()> &functor);
-  int helper_error_id_ = 0;
 
   // Returns the integer type used to represent pointers in traced code.
   llvm::Type *getPointerStorageTy(AddrSpace as);
 
 private:
   Module &module_;
   BPFtrace &bpftrace_;
+  AsyncIds &async_ids_;
 
   Value *CreateUSDTReadArgument(Value *ctx,
                                 struct bcc_usdt_argument *argument,