002a9a7d57
- Add core/ptr_trace.h (ring buffer, env-controlled dump) - Use macros in box/tls_sll_box.h push/pop/splice - Default: enabled for debug builds, zero-overhead in release - How to use: build debug and run with HAKMEM_PTR_TRACE_DUMP=1
94 lines
3.4 KiB
C
94 lines
3.4 KiB
C
// ptr_trace.h - Pointer link read/write tracing (Debug-only, macro-replaceable)
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//
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// Purpose:
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// - Centrally instrument single-linked list next pointer reads/writes
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// - Zero overhead in release builds (macros devolve to raw ops)
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// - Compact TLS ring for triage; optional dump at exit via env
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//
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// Usage:
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// - Replace direct next ops with PTR_NEXT_WRITE / PTR_NEXT_READ
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// - Tag with a short literal (e.g., "tls_push", "tls_pop", "splice")
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// - Offsets should be header-aware (C0–C6: +1, C7: +0)
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//
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// Control:
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// - Compile-time: HAKMEM_PTR_TRACE (default: 1 for debug, 0 for release)
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// - Runtime dump: HAKMEM_PTR_TRACE_DUMP=1 (prints ring at exit)
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#pragma once
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#include <stdint.h>
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#include <stddef.h>
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#ifndef HAKMEM_PTR_TRACE
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# if !HAKMEM_BUILD_RELEASE
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# define HAKMEM_PTR_TRACE 1
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# else
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# define HAKMEM_PTR_TRACE 0
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# endif
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#endif
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#if HAKMEM_PTR_TRACE
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#include <stdio.h>
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typedef struct {
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const char* tag; // literal tag
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int class_idx; // tiny class (0..7)
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void* node; // node address (base)
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void* val; // written/read value
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size_t off; // offset used for access
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} ptr_trace_ev_t;
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#ifndef PTR_TRACE_CAP
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# define PTR_TRACE_CAP 256
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#endif
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static __thread ptr_trace_ev_t g_ptr_trace_ring[PTR_TRACE_CAP];
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static __thread uint32_t g_ptr_trace_idx = 0;
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static __thread int g_ptr_trace_dump_registered = 0;
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static inline void ptr_trace_record(const char* tag, int cls, void* node, void* val, size_t off) {
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uint32_t i = g_ptr_trace_idx++;
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g_ptr_trace_ring[i & (PTR_TRACE_CAP - 1)] = (ptr_trace_ev_t){ tag, cls, node, val, off };
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}
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static inline void ptr_trace_try_register_dump(void) {
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if (g_ptr_trace_dump_registered) return;
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g_ptr_trace_dump_registered = 1;
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const char* env = getenv("HAKMEM_PTR_TRACE_DUMP");
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if (!(env && *env && *env != '0')) return;
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static void __attribute__((destructor)) ptr_trace_dump(void) {
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fprintf(stderr, "\n[PTR_TRACE_DUMP] last=%u (cap=%u)\n", g_ptr_trace_idx, (unsigned)PTR_TRACE_CAP);
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uint32_t n = (g_ptr_trace_idx < PTR_TRACE_CAP) ? g_ptr_trace_idx : PTR_TRACE_CAP;
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for (uint32_t k = 0; k < n; k++) {
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const ptr_trace_ev_t* e = &g_ptr_trace_ring[(g_ptr_trace_idx - n + k) & (PTR_TRACE_CAP - 1)];
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fprintf(stderr, "[%3u] tag=%s cls=%d node=%p val=%p off=%zu\n",
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k, e->tag ? e->tag : "?", e->class_idx, e->node, e->val, e->off);
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}
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}
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}
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#define PTR_NEXT_WRITE(tag, cls, node, off, value) do { \
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void** __p = (void**)((uint8_t*)(node) + (off)); \
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*__p = (value); \
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ptr_trace_record((tag), (cls), (node), (value), (off)); \
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ptr_trace_try_register_dump(); \
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} while(0)
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#define PTR_NEXT_READ(tag, cls, node, off, out_var) do { \
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void** __p = (void**)((uint8_t*)(node) + (off)); \
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(out_var) = *__p; \
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ptr_trace_record((tag), (cls), (node), (out_var), (off)); \
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ptr_trace_try_register_dump(); \
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} while(0)
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#else // HAKMEM_PTR_TRACE == 0
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#define PTR_NEXT_WRITE(tag, cls, node, off, value) \
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(*(void**)((uint8_t*)(node) + (off)) = (value))
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#define PTR_NEXT_READ(tag, cls, node, off, out_var) \
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((out_var) = *(void**)((uint8_t*)(node) + (off)))
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#endif // HAKMEM_PTR_TRACE
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