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Phase 8-Step1-3: Unified Cache hot path optimization (config macro + prewarm + PGO init removal)

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Goal: Reduce branches in Unified Cache hot paths (-2 branches per op)
Expected improvement: +2-3% in PGO mode

Changes:
1. Config Macro (Step 1):
   - Added TINY_FRONT_UNIFIED_CACHE_ENABLED macro to tiny_front_config_box.h
   - PGO mode: compile-time constant (1)
   - Normal mode: runtime function call unified_cache_enabled()
   - Replaced unified_cache_enabled() calls in 3 locations:
     * unified_cache_pop() line 142
     * unified_cache_push() line 182
     * unified_cache_pop_or_refill() line 228

2. Function Declaration Fix:
   - Moved unified_cache_enabled() from static inline to non-static
   - Implementation in tiny_unified_cache.c (was in .h as static inline)
   - Forward declaration in tiny_front_config_box.h
   - Resolves declaration conflict between config box and header

3. Prewarm (Step 2):
   - Added unified_cache_init() call to bench_fast_init()
   - Ensures cache is initialized before benchmark starts
   - Enables PGO builds to remove lazy init checks

4. Conditional Init Removal (Step 3):
   - Wrapped lazy init checks in #if !HAKMEM_TINY_FRONT_PGO
   - PGO builds assume prewarm → no init check needed (-1 branch)
   - Normal builds keep lazy init for safety
   - Applied to 3 functions: unified_cache_pop(), unified_cache_push(), unified_cache_pop_or_refill()

Performance Impact:
  PGO mode: -2 branches per operation (enabled check + init check)
  Normal mode: Same as before (runtime checks)

Branch Elimination (PGO):
  Before: if (!unified_cache_enabled()) + if (slots == NULL)
  After:  if (!1) [eliminated] + [init check removed]
  Result: -2 branches in alloc/free hot paths

Files Modified:
  core/box/tiny_front_config_box.h        - Config macro + forward declaration
  core/front/tiny_unified_cache.h         - Config macro usage + PGO conditionals
  core/front/tiny_unified_cache.c         - unified_cache_enabled() implementation
  core/box/bench_fast_box.c               - Prewarm call in bench_fast_init()

Note: BenchFast mode has pre-existing crash (not caused by these changes)

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>
This commit is contained in:
Moe Charm (CI)
2025-11-29 17:58:42 +09:00
parent 6b75453072
commit cfa587c61d
4 changed files with 65 additions and 26 deletions
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22
core/box/tiny_front_config_box.h
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@ -53,6 +53,7 @@
#define TINY_FRONT_SFC_ENABLED 1 // Enabled (SFC cascade)
#define TINY_FRONT_FASTCACHE_ENABLED 0 // Disabled (use Unified Cache)
#define TINY_FRONT_TLS_SLL_ENABLED 1 // Enabled (TLS SLL freelist)
#define TINY_FRONT_UNIFIED_CACHE_ENABLED 1 // Enabled (Unified Cache - tcache-style)
#define TINY_FRONT_UNIFIED_GATE_ENABLED 1 // Enabled (Front Gate Unification)
#define TINY_FRONT_METRICS_ENABLED 0 // Disabled (no runtime overhead)
#define TINY_FRONT_DIAG_ENABLED 0 // Disabled (no diagnostics)
@ -100,16 +101,21 @@ static inline int tiny_tls_sll_enabled(void) {
return g_tls_sll_enable;
}
// Phase 8-Step1: Unified Cache enabled wrapper
// Forward declaration - actual function is in tiny_unified_cache.c
int unified_cache_enabled(void);
// Config macros (runtime function calls)
// These expand to actual function calls in normal mode
#define TINY_FRONT_ULTRA_SLIM_ENABLED ultra_slim_mode_enabled()
#define TINY_FRONT_HEAP_V2_ENABLED tiny_heap_v2_enabled()
#define TINY_FRONT_SFC_ENABLED tiny_sfc_enabled()
#define TINY_FRONT_FASTCACHE_ENABLED tiny_fastcache_enabled()
#define TINY_FRONT_TLS_SLL_ENABLED tiny_tls_sll_enabled()
#define TINY_FRONT_UNIFIED_GATE_ENABLED front_gate_unified_enabled()
#define TINY_FRONT_METRICS_ENABLED tiny_metrics_enabled()
#define TINY_FRONT_DIAG_ENABLED tiny_diag_enabled()
#define TINY_FRONT_ULTRA_SLIM_ENABLED ultra_slim_mode_enabled()
#define TINY_FRONT_HEAP_V2_ENABLED tiny_heap_v2_enabled()
#define TINY_FRONT_SFC_ENABLED tiny_sfc_enabled()
#define TINY_FRONT_FASTCACHE_ENABLED tiny_fastcache_enabled()
#define TINY_FRONT_TLS_SLL_ENABLED tiny_tls_sll_enabled()
#define TINY_FRONT_UNIFIED_CACHE_ENABLED unified_cache_enabled()
#define TINY_FRONT_UNIFIED_GATE_ENABLED front_gate_unified_enabled()
#define TINY_FRONT_METRICS_ENABLED tiny_metrics_enabled()
#define TINY_FRONT_DIAG_ENABLED tiny_diag_enabled()
#endif // HAKMEM_TINY_FRONT_PGO