hakmem/core/hakmem_build_flags.h

// hakmem_build_flags.h - Centralized compile-time feature switches
// Purpose: Define all build-time toggles in one place with safe defaults.
// Usage: Include from common public headers (e.g., hakmem.h / hakmem_tiny.h).

#ifndef HAKMEM_BUILD_FLAGS_H
#define HAKMEM_BUILD_FLAGS_H

// ------------------------------------------------------------
// Release/debug detection
// ------------------------------------------------------------
// HAKMEM_BUILD_RELEASE: 1 in release-like builds, 0 otherwise
#ifndef HAKMEM_BUILD_RELEASE
#  if defined(NDEBUG)
#    define HAKMEM_BUILD_RELEASE 1
#  else
#    define HAKMEM_BUILD_RELEASE 0
#  endif
#endif

// ------------------------------------------------------------
// Instrumentation & counters (compile-time)
// ------------------------------------------------------------
// Enable lightweight path/debug counters (compiled out when 0)
#ifndef HAKMEM_DEBUG_COUNTERS
#  define HAKMEM_DEBUG_COUNTERS 1
#endif

// Enable extended memory profiling (compiled out when 0)
#ifndef HAKMEM_DEBUG_MEMORY
#  define HAKMEM_DEBUG_MEMORY 0
#endif

// Tiny refill optimization helpers (header-only)
#ifndef HAKMEM_TINY_REFILL_OPT
#  define HAKMEM_TINY_REFILL_OPT 1
#endif

// Batch refill P0 (can be toggled for A/B)
#ifndef HAKMEM_TINY_P0_BATCH_REFILL
#  define HAKMEM_TINY_P0_BATCH_REFILL 0
#endif

// Box refactor (Phase 6-1.7) — usually injected from build system
#ifndef HAKMEM_TINY_PHASE6_BOX_REFACTOR
#  define HAKMEM_TINY_PHASE6_BOX_REFACTOR 1
#endif

// SuperSlab backend toggle (compile-time)
// Default: 1 (ON) - SuperSlab is the core architecture.
// Set to 0 only for legacy/compat testing.
#ifndef HAKMEM_TINY_USE_SUPERSLAB
#  define HAKMEM_TINY_USE_SUPERSLAB 1
#endif

// ------------------------------------------------------------
// Phase 7: Region-ID Direct Lookup (Header-based optimization)
// ------------------------------------------------------------
// Phase 7 Task 1: Header-based class_idx for O(1) free
// Default: OFF (enable after full validation in Task 5)
// Build: make HEADER_CLASSIDX=1 or make phase7
#ifndef HAKMEM_TINY_HEADER_CLASSIDX
#  define HAKMEM_TINY_HEADER_CLASSIDX 1
#endif

// Phase 7 Task 2: Aggressive inline TLS cache access
// Default: OFF (enable after full validation in Task 5)
// Build: make AGGRESSIVE_INLINE=1 or make phase7
// Requires: HAKMEM_TINY_HEADER_CLASSIDX=1
#ifndef HAKMEM_TINY_AGGRESSIVE_INLINE
#  define HAKMEM_TINY_AGGRESSIVE_INLINE 0
#endif

// Inline TLS SLL pop (experimental, A/B only)
// Default: OFF (HAKMEM_TINY_INLINE_SLL=0) to keep Box TLS-SLL API as the standard path.
// Enable explicitly via build flag: -DHAKMEM_TINY_INLINE_SLL=1 (bench/debug only).
#ifndef HAKMEM_TINY_INLINE_SLL
#  define HAKMEM_TINY_INLINE_SLL 0
#endif

// Phase 7 Task 3: Pre-warm TLS cache at init
// Default: OFF (enable after implementation)
// Build: make PREWARM_TLS=1 or make phase7
#ifndef HAKMEM_TINY_PREWARM_TLS
#  define HAKMEM_TINY_PREWARM_TLS 0
#endif

// Runtime verbosity (printf-heavy diagnostics). Keep OFF for benches.
#ifndef HAKMEM_DEBUG_VERBOSE
#  define HAKMEM_DEBUG_VERBOSE 0
#endif

// Tiny/Mid safety checks on free path (mincore header validation).
// 0 = performance (boundary-only), 1 = strict (mincore for all)
#ifndef HAKMEM_TINY_SAFE_FREE
#  define HAKMEM_TINY_SAFE_FREE 0
#endif

// Phase 10: Aggressive refill count defaults (tunable via env vars)
// Goal: Reduce backend transitions by refilling in larger batches
// HAKMEM_TINY_REFILL_COUNT: global default (default: 128)
// HAKMEM_TINY_REFILL_COUNT_HOT: class 0-3 (default: 128)
// HAKMEM_TINY_REFILL_COUNT_MID: class 4-7 (default: 96)
// Larson Fix (Priority 1): Increased from 64 to 128 to reduce lock contention
// Expected impact: Lock frequency reduction 19K → ~1.6K locks/sec (12x)
// NOTE: Multi-threaded Larson has pre-existing crash bug (not caused by this change)
#ifndef HAKMEM_TINY_REFILL_DEFAULT
#  define HAKMEM_TINY_REFILL_DEFAULT 128
#endif

// ------------------------------------------------------------
// Tiny front architecture toggles (compile-time defaults)
// ------------------------------------------------------------
// New 3-layer Tiny front (A/B via build flag)
#ifndef HAKMEM_TINY_USE_NEW_3LAYER
#  define HAKMEM_TINY_USE_NEW_3LAYER 0
#endif

// Minimal/strict front variants (bench/debug only)
#ifndef HAKMEM_TINY_MINIMAL_FRONT
#  define HAKMEM_TINY_MINIMAL_FRONT 1
#endif
#ifndef HAKMEM_TINY_STRICT_FRONT
#  define HAKMEM_TINY_STRICT_FRONT 0
#endif

// ------------------------------------------------------------
// Phase 4-Step3: Tiny Front PGO Config Box
// ------------------------------------------------------------
// HAKMEM_TINY_FRONT_PGO:
//   0 = Normal build with runtime configuration (default, backward compatible)
//       Configuration checked via ENV variables at runtime (flexible)
//   1 = PGO-optimized build with compile-time configuration (performance)
//       Configuration fixed at compile time (dead code elimination)
//       Eliminates runtime branches for maximum performance.
//       Use with: make CFLAGS="-DHAKMEM_TINY_FRONT_PGO=1" bench_random_mixed_hakmem
// Expected benefit: +5-8% improvement via dead code elimination (57.2 → 60-62 M ops/s)
#ifndef HAKMEM_TINY_FRONT_PGO
#  define HAKMEM_TINY_FRONT_PGO 0
#endif

// Phase 5-Step3: Mid/Large PGO Config Box
// ------------------------------------------------------------
// HAKMEM_MID_LARGE_PGO:
//   0 = Normal build with runtime configuration (default, backward compatible)
//       Configuration checked via ENV variables at runtime (flexible)
//   1 = PGO-optimized build with compile-time configuration (performance)
//       Configuration fixed at compile time (dead code elimination)
//       Eliminates runtime branches for Mid/Large allocation paths.
//       Use with: make EXTRA_CFLAGS="-DHAKMEM_MID_LARGE_PGO=1" bench_random_mixed_hakmem
// Expected benefit: +2-4% improvement via dead code elimination
#ifndef HAKMEM_MID_LARGE_PGO
#  define HAKMEM_MID_LARGE_PGO 0
#endif

// Route fingerprint (compile-time gate; runtime ENV still required)
#ifndef HAKMEM_ROUTE
#  define HAKMEM_ROUTE 0
#endif

// Bench-only knobs (default values; can be overridden via build flags)
#ifndef HAKMEM_TINY_BENCH_REFILL
#  define HAKMEM_TINY_BENCH_REFILL 8
#endif
#ifndef HAKMEM_TINY_BENCH_REFILL8
#  define HAKMEM_TINY_BENCH_REFILL8 HAKMEM_TINY_BENCH_REFILL
#endif
#ifndef HAKMEM_TINY_BENCH_REFILL16
#  define HAKMEM_TINY_BENCH_REFILL16 HAKMEM_TINY_BENCH_REFILL
#endif
#ifndef HAKMEM_TINY_BENCH_REFILL32
#  define HAKMEM_TINY_BENCH_REFILL32 HAKMEM_TINY_BENCH_REFILL
#endif
#ifndef HAKMEM_TINY_BENCH_REFILL64
#  define HAKMEM_TINY_BENCH_REFILL64 HAKMEM_TINY_BENCH_REFILL
#endif

#ifndef HAKMEM_TINY_BENCH_WARMUP8
#  define HAKMEM_TINY_BENCH_WARMUP8 64
#endif
#ifndef HAKMEM_TINY_BENCH_WARMUP16
#  define HAKMEM_TINY_BENCH_WARMUP16 96
#endif
#ifndef HAKMEM_TINY_BENCH_WARMUP32
#  define HAKMEM_TINY_BENCH_WARMUP32 160
#endif
#ifndef HAKMEM_TINY_BENCH_WARMUP64
#  define HAKMEM_TINY_BENCH_WARMUP64 192
#endif

// ------------------------------------------------------------
// Helper enum (for documentation / logging)
// ------------------------------------------------------------
typedef enum {
  HAK_FLAG_BUILD_RELEASE = HAKMEM_BUILD_RELEASE,
  HAK_FLAG_DEBUG_COUNTERS = HAKMEM_DEBUG_COUNTERS,
  HAK_FLAG_DEBUG_MEMORY   = HAKMEM_DEBUG_MEMORY,
  HAK_FLAG_REFILL_OPT     = HAKMEM_TINY_REFILL_OPT,
  HAK_FLAG_P0_BATCH       = HAKMEM_TINY_P0_BATCH_REFILL,
  HAK_FLAG_BOX_REFACTOR   = HAKMEM_TINY_PHASE6_BOX_REFACTOR,
  HAK_FLAG_NEW_3LAYER     = HAKMEM_TINY_USE_NEW_3LAYER,
} hak_build_flags_t;

#endif // HAKMEM_BUILD_FLAGS_H