173 lines
7.3 KiB
C
173 lines
7.3 KiB
C
// tiny_front_config_box.h - Phase 4-Step3: Tiny Front Config Box
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// Purpose: Compile-time configuration for dead code elimination
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// Contract: Dual-mode (compile-time fixed vs. runtime ENV checks)
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// Performance: Target +5-8% via branch elimination (57.2M → 60-62M ops/s)
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//
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// Design Principles (Box Pattern):
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// 1. Single Responsibility: Configuration management ONLY
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// 2. Clear Contract: PGO mode = compile-time constants, Normal mode = runtime checks
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// 3. Observable: Config report function (debug builds)
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// 4. Safe: Backward compatible (default runtime mode)
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// 5. Testable: Easy A/B comparison (PGO vs normal builds)
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//
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// Usage:
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// Normal build (runtime config, backward compatible):
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// make bench_random_mixed_hakmem
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//
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// PGO build (compile-time config, dead code elimination):
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// make CFLAGS="-DHAKMEM_TINY_FRONT_PGO=1" bench_random_mixed_hakmem
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//
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// Expected Benefit:
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// - Dead code elimination: Compiler removes disabled code paths
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// - Branch reduction: if (CONSTANT_0) { ... } → eliminated
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// - I-cache improvement: Smaller code size (no dead branches)
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// - Target: +5-8% improvement (even without PGO profiling)
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#ifndef TINY_FRONT_CONFIG_BOX_H
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#define TINY_FRONT_CONFIG_BOX_H
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#include <stdio.h>
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#include "../hakmem_build_flags.h"
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// ============================================================================
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// Build Flag Check (must be defined in hakmem_build_flags.h)
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// ============================================================================
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#ifndef HAKMEM_TINY_FRONT_PGO
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# define HAKMEM_TINY_FRONT_PGO 0
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#endif
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// ============================================================================
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// PGO Mode: Fixed Configuration (Compile-Time Constants)
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// ============================================================================
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#if HAKMEM_TINY_FRONT_PGO
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// PGO-optimized build: All runtime checks become compile-time constants
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// Compiler constant folding eliminates dead branches:
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// if (TINY_FRONT_HEAP_V2_ENABLED) { ... } // 0 → entire block removed
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// if (!TINY_FRONT_SFC_ENABLED) { ... } // !1 → entire block removed
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#define TINY_FRONT_ULTRA_SLIM_ENABLED 0 // Disabled (use normal front)
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#define TINY_FRONT_HEAP_V2_ENABLED 0 // Disabled (use Unified Cache)
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#define TINY_FRONT_SFC_ENABLED 1 // Enabled (SFC cascade)
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#define TINY_FRONT_FASTCACHE_ENABLED 0 // Disabled (use Unified Cache)
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#define TINY_FRONT_TLS_SLL_ENABLED 1 // Enabled (TLS SLL freelist)
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#define TINY_FRONT_UNIFIED_CACHE_ENABLED 1 // Enabled (Unified Cache - tcache-style)
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#define TINY_FRONT_UNIFIED_GATE_ENABLED 1 // Enabled (Front Gate Unification)
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#define TINY_FRONT_METRICS_ENABLED 0 // Disabled (no runtime overhead)
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#define TINY_FRONT_DIAG_ENABLED 0 // Disabled (no diagnostics)
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// Expected code reduction:
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// - Ultra SLIM check: 1 branch removed
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// - Heap V2 check: 1 branch removed
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// - Metrics check: 2-3 branches removed
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// - Diag check: 1 branch removed
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// Total: 5-7 branches eliminated in hot path
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#else
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// ============================================================================
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// Normal Mode: Runtime Configuration (Backward Compatible)
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// ============================================================================
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// Normal build: Checks ENV variables or global config state
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// Preserves backward compatibility with existing ENV variable interface
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//
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// NOTE: The actual runtime config functions (ultra_slim_mode_enabled, etc.)
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// are defined in their respective modules:
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// - front_gate_unified_enabled() → core/front/malloc_tiny_fast.h
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// - sfc_cascade_enabled() → core/hakmem_tiny_sfc.h
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// - tiny_heap_v2_enabled() → core/front/tiny_heap_v2.h
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// - etc.
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//
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// This config box ONLY defines the macros that expand to function calls.
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// The functions themselves are implemented here as static inline to avoid include order issues.
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// Phase 7-Step6-Fix: Config wrapper functions (for normal mode)
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// These are static inline to access static global variables from any include order
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static inline int tiny_fastcache_enabled(void) {
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extern int g_fastcache_enable;
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return g_fastcache_enable;
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}
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static inline int tiny_sfc_enabled(void) {
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extern int g_sfc_enabled;
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return g_sfc_enabled;
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}
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static inline int tiny_tls_sll_enabled(void) {
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extern int g_tls_sll_enable;
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return g_tls_sll_enable;
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}
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// Phase 8-Step1: Unified Cache enabled wrapper
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// Forward declaration - actual function is in tiny_unified_cache.c
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int unified_cache_enabled(void);
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// Config macros (runtime function calls)
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// These expand to actual function calls in normal mode
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#define TINY_FRONT_ULTRA_SLIM_ENABLED ultra_slim_mode_enabled()
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#define TINY_FRONT_HEAP_V2_ENABLED tiny_heap_v2_enabled()
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#define TINY_FRONT_SFC_ENABLED tiny_sfc_enabled()
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#define TINY_FRONT_FASTCACHE_ENABLED tiny_fastcache_enabled()
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#define TINY_FRONT_TLS_SLL_ENABLED tiny_tls_sll_enabled()
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#define TINY_FRONT_UNIFIED_CACHE_ENABLED unified_cache_enabled()
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#define TINY_FRONT_UNIFIED_GATE_ENABLED front_gate_unified_enabled()
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#define TINY_FRONT_METRICS_ENABLED tiny_metrics_enabled()
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#define TINY_FRONT_DIAG_ENABLED tiny_diag_enabled()
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#endif // HAKMEM_TINY_FRONT_PGO
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// ============================================================================
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// Configuration Helpers
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// ============================================================================
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// Check if running in PGO-optimized build
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static inline int tiny_front_is_pgo_build(void) {
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return HAKMEM_TINY_FRONT_PGO;
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}
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// Get effective configuration (for diagnostics)
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static inline void tiny_front_config_report(void) {
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#if 0 // !HAKMEM_BUILD_RELEASE
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// Disabled to avoid circular dependency / implicit declaration issues
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// re-enable when include order is fixed
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fprintf(stderr, "[TINY_FRONT_CONFIG]\n");
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fprintf(stderr, " PGO Build: %d\n", HAKMEM_TINY_FRONT_PGO);
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fprintf(stderr, " Ultra SLIM: %d\n", TINY_FRONT_ULTRA_SLIM_ENABLED);
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fprintf(stderr, " Heap V2: %d\n", TINY_FRONT_HEAP_V2_ENABLED);
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fprintf(stderr, " SFC: %d\n", TINY_FRONT_SFC_ENABLED);
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fprintf(stderr, " FastCache: %d\n", TINY_FRONT_FASTCACHE_ENABLED);
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fprintf(stderr, " Unified Gate: %d\n", TINY_FRONT_UNIFIED_GATE_ENABLED);
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fprintf(stderr, " Metrics: %d\n", TINY_FRONT_METRICS_ENABLED);
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fprintf(stderr, " Diag: %d\n", TINY_FRONT_DIAG_ENABLED);
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fflush(stderr);
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#endif
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}
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// ============================================================================
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// Performance Notes
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// ============================================================================
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// Expected improvements (Phase 4-Step3):
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// - Random Mixed 256: 57.2M → 60-62M ops/s (+5-8%)
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// - Tiny Hot 64B: Current → +5-8%
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//
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// Key optimizations:
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// 1. Dead code elimination: Compiler removes disabled code paths
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// 2. Branch reduction: if (CONSTANT) → compile-time evaluation
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// 3. I-cache improvement: Smaller code size (no dead branches)
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// 4. Constant propagation: Compiler optimizes based on known values
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//
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// Trade-offs:
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// 1. Binary size: PGO build is specialized (not configurable at runtime)
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// 2. Flexibility: PGO build ignores ENV variables (fixed config)
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// 3. Testing: Need separate builds for A/B testing (PGO vs normal)
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//
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// Recommendation:
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// - Development: Use normal build (runtime config, flexible)
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// - Production: Use PGO build after profiling (maximum performance)
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#endif // TINY_FRONT_CONFIG_BOX_H
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