Runtime Library

Runtime Library

Instrumented binaries link ct_instrument_runtime (built from src/runtime/). This library implements all __ct_* hooks inserted by LLVM passes.

Module map

File	Role
ct_runtime_alloc.cpp	allocation tracking, table management, auto-free scan
ct_runtime_bounds.cpp	bounds violation checks and reporting
ct_runtime_trace.cpp	function entry/exit tracing hooks
ct_runtime_vtable.cpp	virtual call and vtable diagnostics
ct_runtime_shadow.cpp	shadow metadata tracking
ct_runtime_state.cpp	feature bitset + legacy globals
ct_runtime_env.cpp	compile-time config globals + env overrides
ct_runtime_logging.cpp	logger adapters/helpers
ct_runtime_backtrace.cpp	optional backtrace setup

Core exported hooks

Allocation hooks (selection)

• void* __ct_malloc(size_t, const char*)
• void* __ct_calloc(size_t, size_t, const char*)
• void* __ct_realloc(void*, size_t, const char*)
• void __ct_free(void*)
• void* __ct_new(size_t, const char*)
• void __ct_delete(void*)
• void* __ct_mmap(..., const char*)
• int __ct_munmap(void*, size_t, const char*)
• void* __ct_sbrk(size_t, const char*)
• void* __ct_brk(void*, const char*)

Bounds hook

• void __ct_check_bounds(const void* base, const void* ptr, size_t access_size, const char* site, int is_write)

Trace hooks

• void __ct_trace_enter(const char* func)
• void __ct_trace_exit_void(const char* func)
• void __ct_trace_exit_i64(const char* func, long long value)
• void __ct_trace_exit_ptr(const char* func, const void* value)
• void __ct_trace_exit_f64(const char* func, double value)
• void __ct_trace_exit_unknown(const char* func)

VTable hooks

• void __ct_vtable_dump(void* this_ptr, const char* site, const char* static_type)
• void __ct_vcall_trace(void* this_ptr, void* target, const char* site, const char* static_type)

Runtime feature model

Feature state is stored in a bitset API (ct_is_enabled, ct_set_enabled, ct_get_features). Default enabled bits include trace, alloc, bounds, autofree, and alloc-trace.

At startup, compile-time globals injected by the compiler can disable/enable features:

• __ct_config_shadow
• __ct_config_shadow_aggressive
• __ct_config_bounds_no_abort
• __ct_config_disable_alloc
• __ct_config_disable_autofree
• __ct_config_disable_alloc_trace
• __ct_config_vtable_diag

Then env vars can override behavior (see below).

Environment overrides

ct_runtime_env.cpp reads:

• CT_DISABLE_TRACE
• CT_DISABLE_ALLOC
• CT_EARLY_TRACE
• CT_DISABLE_BOUNDS
• CT_BOUNDS_NO_ABORT
• CT_SHADOW
• CT_SHADOW_AGGRESSIVE
• CT_DISABLE_AUTOFREE
• CT_DISABLE_ALLOC_TRACE

Auto-free scan env vars are documented in Auto-Free GC.

Notes

• Allocation/shadow tables use lock-protected open addressing.
• VTable diagnostics rely on platform symbol/module resolution (dladdr, dyld, phdr fallback).
• Most diagnostics are emitted through coretrace-logger adapters.