[DWARF] Fix debug intrinsics on Linux (bytecodealliance#9866)

* Test DWARF with --release

This would have caught the issue in CI.

It is also closer to what the end user will use.

* [prtest:debug] Use volatile for keep-alive

* Drop __attribute__((retain))

* Run tests in debug as well

* Remove debug testing; add comment

Author: SingleAccretion

.github/workflows/main.yml

@@ -860,7 +860,8 @@ jobs:
         # workaround for https://bugs.launchpad.net/ubuntu/+source/llvm-defaults/+bug/1972855
         sudo mkdir -p /usr/lib/local/lib/python3.10/dist-packages/lldb
         sudo ln -s /usr/lib/llvm-15/lib/python3.10/dist-packages/lldb/* /usr/lib/python3/dist-packages/lldb/
-        cargo test --test all -- --ignored --test-threads 1 debug::
+        # Only testing release since it is more likely to expose issues with our low-level symbol handling.
+        cargo test --release --test all -- --ignored --test-threads 1 debug::
       env:
         LLDB: lldb-15 # override default version, 14
 

crates/wasmtime/src/runtime/vm/helpers.c

@@ -131,7 +131,7 @@ void VERSIONED_SYMBOL(wasmtime_longjmp)(void *JmpBuf) {
 #ifdef CFG_TARGET_OS_windows
 #define DEBUG_BUILTIN_EXPORT __declspec(dllexport)
 #else
-#define DEBUG_BUILTIN_EXPORT __attribute__((used, retain))
+#define DEBUG_BUILTIN_EXPORT
 #endif
 
 // This set of symbols is defined here in C because Rust's #[export_name]
@@ -163,6 +163,13 @@ __attribute__((weak, noinline))
     void __jit_debug_register_code() {
 #ifndef CFG_TARGET_OS_windows
   __asm__("");
+#ifdef FEATURE_DEBUG_BUILTINS
+  // Make sure these symbols do not get stripped by the compiler or linker.
+  void *volatile p;
+  p = (void *)&VERSIONED_SYMBOL(wasmtime_resolve_vmctx_memory_ptr);
+  p = (void *)&VERSIONED_SYMBOL(wasmtime_set_vmctx_memory);
+  (void)p;
+#endif // FEATURE_DEBUG_BUILTINS
 #endif
 }