Remove --disable-tcache.

Simplify configuration by removing the --disable-tcache option, but
replace the testing for that configuration with
--with-malloc-conf=tcache:false.

Fix the thread.arena and thread.tcache.flush mallctls to work correctly
if tcache is disabled.

This partially resolves #580.

include/jemalloc/internal/arena_inlines_a.h

@@ -58,7 +58,7 @@ percpu_arena_update(tsd_t *tsd, unsigned cpu) {
 		/* Set new arena/tcache associations. */
 		arena_migrate(tsd, oldind, newind);
 		tcache_t *tcache = tcache_get(tsd);
-		if (config_tcache && tcache) {
+		if (tcache != NULL) {
 			tcache_arena_reassociate(tsd_tsdn(tsd), tcache,
 			    newarena);
 		}

include/jemalloc/internal/jemalloc_internal_defs.h.in

@@ -154,13 +154,6 @@
 /* Use gcc intrinsics for profile backtracing if defined. */
 #undef JEMALLOC_PROF_GCC
 
-/*
- * JEMALLOC_TCACHE enables a thread-specific caching layer for small objects.
- * This makes it possible to allocate/deallocate objects without any locking
- * when the cache is in the steady state.
- */
-#undef JEMALLOC_TCACHE
-
 /*
  * JEMALLOC_DSS enables use of sbrk(2) to allocate extents from the data storage
  * segment (DSS).

include/jemalloc/internal/jemalloc_internal_inlines_a.h

@@ -323,7 +323,8 @@ malloc_getcpu(void) {
 JEMALLOC_ALWAYS_INLINE unsigned
 percpu_arena_choose(void) {
 	unsigned arena_ind;
-	assert(have_percpu_arena && (percpu_arena_mode != percpu_arena_disabled));
+	assert(have_percpu_arena && (percpu_arena_mode !=
+	    percpu_arena_disabled));
 
 	malloc_cpuid_t cpuid = malloc_getcpu();
 	assert(cpuid >= 0);
@@ -420,19 +421,16 @@ tcache_large_bin_get(tcache_t *tcache, szind_t binind) {
 
 JEMALLOC_ALWAYS_INLINE bool
 tcache_available(tsd_t *tsd) {
-	cassert(config_tcache);
-
 	/*
 	 * Thread specific auto tcache might be unavailable if: 1) during tcache
 	 * initialization, or 2) disabled through thread.tcache.enabled mallctl
 	 * or config options.  This check covers all cases.
 	 */
-	if (likely(tsd_tcache_enabled_get(tsd) == true)) {
-		/* Associated arena == null implies tcache init in progress. */
-		if (tsd_tcachep_get(tsd)->arena != NULL) {
-			assert(tcache_small_bin_get(tsd_tcachep_get(tsd),
-			    0)->avail != NULL);
-		}
+	if (likely(tsd_tcache_enabled_get(tsd))) {
+		/* Associated arena == NULL implies tcache init in progress. */
+		assert(tsd_tcachep_get(tsd)->arena == NULL ||
+		    tcache_small_bin_get(tsd_tcachep_get(tsd), 0)->avail !=
+		    NULL);
 		return true;
 	}
 
@@ -441,9 +439,6 @@ tcache_available(tsd_t *tsd) {
 
 JEMALLOC_ALWAYS_INLINE tcache_t *
 tcache_get(tsd_t *tsd) {
-	if (!config_tcache) {
-		return NULL;
-	}
 	if (!tcache_available(tsd)) {
 		return NULL;
 	}

include/jemalloc/internal/jemalloc_internal_inlines_b.h

@@ -24,7 +24,7 @@ arena_choose_impl(tsd_t *tsd, arena_t *arena, bool internal) {
 	if (unlikely(ret == NULL)) {
 		ret = arena_choose_hard(tsd, internal);
 		assert(ret);
-		if (config_tcache && tcache_available(tsd)) {
+		if (tcache_available(tsd)) {
 			tcache_t *tcache = tcache_get(tsd);
 			if (tcache->arena != NULL) {
 				/* See comments in tcache_data_init().*/

include/jemalloc/internal/jemalloc_preamble.h.in

@@ -111,13 +111,6 @@ static const bool config_stats =
     false
 #endif
     ;
-static const bool config_tcache =
-#ifdef JEMALLOC_TCACHE
-    true
-#else
-    false
-#endif
-    ;
 static const bool config_tls =
 #ifdef JEMALLOC_TLS
     true

include/jemalloc/internal/tcache_inlines.h

@@ -6,7 +6,6 @@
 
 #ifndef JEMALLOC_ENABLE_INLINE
 void	tcache_event(tsd_t *tsd, tcache_t *tcache);
-void	tcache_flush(void);
 bool	tcache_enabled_get(tsd_t *tsd);
 tcache_t *tcache_get(tsd_t *tsd);
 void	tcache_enabled_set(tsd_t *tsd, bool enabled);
@@ -25,15 +24,11 @@ tcache_t	*tcaches_get(tsd_t *tsd, unsigned ind);
 #if (defined(JEMALLOC_ENABLE_INLINE) || defined(JEMALLOC_TCACHE_C_))
 JEMALLOC_INLINE bool
 tcache_enabled_get(tsd_t *tsd) {
-	cassert(config_tcache);
-
 	return tsd_tcache_enabled_get(tsd);
 }
 
 JEMALLOC_INLINE void
 tcache_enabled_set(tsd_t *tsd, bool enabled) {
-	cassert(config_tcache);
-
 	bool was_enabled = tsd_tcache_enabled_get(tsd);
 
 	if (!was_enabled && enabled) {

include/jemalloc/internal/tcache_structs.h

@@ -40,23 +40,14 @@ struct tcache_s {
 	 * element of tbins is initialized to point to the proper offset within
 	 * this array.
 	 */
-#ifdef JEMALLOC_TCACHE
 	tcache_bin_t	tbins_small[NBINS];
-#else
-	tcache_bin_t	tbins_small[0];
-#endif
 	/* Data accessed less often below. */
 	ql_elm(tcache_t) link;		/* Used for aggregating stats. */
 	arena_t		*arena;		/* Associated arena. */
 	szind_t		next_gc_bin;	/* Next bin to GC. */
-#ifdef JEMALLOC_TCACHE
 	/* For small bins, fill (ncached_max >> lg_fill_div). */
 	uint8_t		lg_fill_div[NBINS];
 	tcache_bin_t	tbins_large[NSIZES-NBINS];
-#else
-	uint8_t		lg_fill_div[0];
-	tcache_bin_t	tbins_large[0];
-#endif
 };
 
 /* Linkage for list of available (previously used) explicit tcache IDs. */