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[NativeAOT] Migrate GC bridge logging to printf #12211

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[NativeAOT] Migrate GC bridge logging to printf #12211

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[NativeAOT] Migrate GC bridge logging to printf
jonathanpeppers Jul 22, 2026
462c434
Merge remote-tracking branch 'origin/jonathanpeppers-native-printf-lo…
jonathanpeppers Jul 22, 2026
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11 changes: 6 additions & 5 deletions src/native/clr/host/gc-bridge.cc
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
#include <cerrno>
#include <cinttypes>
#include <pthread.h>
#include <semaphore.h>

Expand Down Expand Up @@ -128,13 +129,13 @@ void GCBridge::log_mark_cross_references_args_if_enabled (MarkCrossReferencesArg
return;
}

log_info (LOG_GC, "cross references callback invoked with {} sccs and {} xrefs.", args->ComponentCount, args->CrossReferenceCount);
log_infof (LOG_GC, "cross references callback invoked with %zu sccs and %zu xrefs.", args->ComponentCount, args->CrossReferenceCount);

JNIEnv *env = OSBridge::ensure_jnienv ();

for (size_t i = 0; i < args->ComponentCount; ++i) {
const StronglyConnectedComponent &scc = args->Components [i];
log_info (LOG_GC, "group {} with {} objects", i, scc.Count);
log_infof (LOG_GC, "group %zu with %zu objects", i, scc.Count);
for (size_t j = 0; j < scc.Count; ++j) {
log_handle_context (env, scc.Contexts [j]);
}
Expand All @@ -147,7 +148,7 @@ void GCBridge::log_mark_cross_references_args_if_enabled (MarkCrossReferencesArg
for (size_t i = 0; i < args->CrossReferenceCount; ++i) {
size_t source_index = args->CrossReferences [i].SourceGroupIndex;
size_t dest_index = args->CrossReferences [i].DestinationGroupIndex;
log_info_nocheck_fmt (LOG_GC, "xref [{}] {} -> {}", i, source_index, dest_index);
log_writef (LOG_GC, LogLevel::Info, "xref [%zu] %zu -> %zu", i, source_index, dest_index);
}
}

Expand All @@ -161,10 +162,10 @@ void GCBridge::log_handle_context (JNIEnv *env, HandleContext *ctx) noexcept
jclass java_class = env->GetObjectClass (handle);
if (java_class != nullptr) {
char *class_name = Host::get_java_class_name_for_TypeManager (java_class);

@github-actions github-actions Bot Jul 22, 2026

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🤖 💡 Native memory — Good, necessary change: wrapping class_name in optional_string() guards the %s conversion. Host::get_java_class_name_for_TypeManager() genuinely returns nullptr on several paths (null/failed Class.getName, OOM on UTF8 conversion — see host-shared.cc), and passing a raw nullptr to a printf %s is undefined behavior (crash on most C libraries), whereas the old std::format {} on a char* silently formatted it. This migration is more robust than the code it replaces, not just equivalent.

Rule: Guard printf %s against nullptr (repo optional_string convention)

log_info (LOG_GC, "gref {:#x} [{}]", reinterpret_cast<intptr_t> (handle), class_name);
log_infof (LOG_GC, "gref 0x%" PRIxPTR " [%s]", reinterpret_cast<uintptr_t> (handle), optional_string (class_name));

@github-actions github-actions Bot Jul 22, 2026

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🤖 💡 Native C++ — Nice correctness improvement: switching the handle from intptr_t to uintptr_t here means large 64-bit handle addresses (high bit set) now format as plain 0x... hex. The old std::format {:#x} on a signed intptr_t would render negative values as -0x..., which is misleading for a pointer/gref. The explicit 0x prefix + %" PRIxPTR " correctly mirrors the previous {:#x} output for typical values.

Rule: Use unsigned width-matched types for pointer hex formatting

free (class_name);
env->DeleteLocalRef (java_class);
} else {
log_info (LOG_GC, "gref {:#x} [unknown class]", reinterpret_cast<intptr_t> (handle));
log_infof (LOG_GC, "gref 0x%" PRIxPTR " [unknown class]", reinterpret_cast<uintptr_t> (handle));
}
}