Merge branch 'sverker/ets_halfword_highmem/OTP-8941' into dev

* sverker/ets_halfword_highmem/OTP-8941:
  HALFWORD ETS Fix copyright year in some source files
  Fix vm crash in kernel test case seq_trace_SUITE:call
  remove NIF compile warning: no previous prototype for ‘nif_init’
  Refuse to load NIF library on wrong VM variant (halfword/fullword)
  HALFWORD ETS match spec heap fragment optimization
  HALFWORD ETS removed eheap and improved test case t_match_spec_run
  HALFWORD ETS Further match spec optimization to minimize copying and garbage
  HALFWORD ETS db_prog_match optimization
  HALFWORD ETS Fix segv for match spec with several function and guards
  HALFWORD Make system_info mseg_alloc report both low/high mem
  HALFWORD Fix segv caused by erlang:halt
  HALFWORD Make more allocators use high mem (binary, fixed and driver)
  HALFWORD ETS 32-bit arch fixes and other cleanups
  HALFWORD ETS nicer update_element
  HALFWORD ETS Real matching on relative terms
  HALFWORD first stab at high mem alloc
  HALFWORD ETS relative terms

Conflicts:
	erts/emulator/test/driver_SUITE.erl

1 files changed, 522 insertions, 251 deletions

diff --git a/erts/emulator/beam/erl_db_util.c b/erts/emulator/beam/erl_db_util.c
index 2852fb93fe..d3e31da413 100644
--- a/erts/emulator/beam/erl_db_util.c
+++ b/erts/emulator/beam/erl_db_util.c
@@ -1,7 +1,7 @@
 /*
  * %CopyrightBegin%
  *
- * Copyright Ericsson AB 1998-2010. All Rights Reserved.
+ * Copyright Ericsson AB 1998-2011. All Rights Reserved.
  *
  * The contents of this file are subject to the Erlang Public License,
  * Version 1.1, (the "License"); you may not use this file except in
@@ -57,6 +57,7 @@
 DBIF_TABLE_GUARD | DBIF_TABLE_BODY | DBIF_TRACE_GUARD | DBIF_TRACE_BODY
 
 
+#define HEAP_XTRA 100
 
 /*
 ** Some convenience macros for stacks (DMC == db_match_compile)
@@ -229,6 +230,11 @@ typedef enum {
     matchCall2,
     matchCall3,
     matchPushV,
+#if HALFWORD_HEAP
+    matchPushVGuard,    /* First guard-only variable reference */
+#endif
+    matchPushVResult, /* First variable reference in result, or (if HALFWORD)
+                         in guard if also referenced in result */
     matchPushExpr, /* Push the whole expression we're matching ('$_') */
     matchPushArrayAsList, /* Only when parameter is an Array and 
 			     not an erlang term  (DCOMP_TRACE) */
@@ -292,11 +298,19 @@ DMC_DECLARE_STACK_TYPE(unsigned);
 ** Data about the heap during compilation
 */
 
+typedef struct DMCVariable {
+    int is_bound;
+    int is_in_body;
+#if HALFWORD_HEAP
+    int first_guard_label;  /* to maybe change from PushVGuard to PushVResult */
+#endif
+} DMCVariable;
+
 typedef struct DMCHeap {
     int size;
-    unsigned def[DMC_DEFAULT_SIZE];
-    unsigned *data;
-    int used;
+    DMCVariable vars_def[DMC_DEFAULT_SIZE];
+    DMCVariable* vars;
+    int vars_used;
 } DMCHeap;
 
 /*
@@ -323,7 +337,6 @@ typedef struct dmc_context {
     Eterm *bodyexpr;
     int num_match;
     int current_match;
-    int eheap_need;
     Uint cflags;
     int is_guard; /* 1 if in guard, 0 if in body */
     int special; /* 1 if the head in the match was a single expression */ 
@@ -346,9 +359,22 @@ typedef struct dmc_context {
 
 #define ERTS_DEFAULT_MS_HEAP_SIZE 128
 
+/* Runtime info about a $-variable
+*/
+typedef struct MatchVariable {
+    Eterm term;
+#ifdef DEBUG
+    Process* proc;
+    Eterm* base;
+#endif
+} MatchVariable;
+
 typedef struct {
     Process process;
-    Eterm *heap;
+    union {
+	Eterm* heap;
+	MatchVariable* variables;   /* first on "heap" */
+    }u;
     Eterm default_heap[ERTS_DEFAULT_MS_HEAP_SIZE];
 } ErtsMatchPseudoProcess;
 
@@ -371,10 +397,10 @@ cleanup_match_pseudo_process(ErtsMatchPseudoProcess *mpsp, int keep_heap)
     }
 #endif
     if (!keep_heap) {
-	if (mpsp->heap != &mpsp->default_heap[0]) {
+	if (mpsp->u.heap != mpsp->default_heap) {
 	    /* Have to be done *after* call to erts_cleanup_empty_process() */
-	    erts_free(ERTS_ALC_T_DB_MS_RUN_HEAP, (void *) mpsp->heap);
-	    mpsp->heap = &mpsp->default_heap[0];
+	    erts_free(ERTS_ALC_T_DB_MS_RUN_HEAP, (void *) mpsp->u.heap);
+	    mpsp->u.heap = mpsp->default_heap;
 	}
 #ifdef DEBUG
 	else {
@@ -398,7 +424,7 @@ create_match_pseudo_process(void)
     mpsp = (ErtsMatchPseudoProcess *)erts_alloc(ERTS_ALC_T_DB_MS_PSDO_PROC,
 						sizeof(ErtsMatchPseudoProcess));
     erts_init_empty_process(&mpsp->process);
-    mpsp->heap = &mpsp->default_heap[0];
+    mpsp->u.heap = mpsp->default_heap;
     return mpsp;
 }
 
@@ -422,11 +448,11 @@ get_match_pseudo_process(Process *c_p, Uint heap_size)
     mpsp = match_pseudo_process;
     cleanup_match_pseudo_process(mpsp, 0);
 #endif
-    if (heap_size > ERTS_DEFAULT_MS_HEAP_SIZE)
-	mpsp->heap = (Eterm *) erts_alloc(ERTS_ALC_T_DB_MS_RUN_HEAP,
-					  heap_size*sizeof(Uint));
+    if (heap_size > ERTS_DEFAULT_MS_HEAP_SIZE*sizeof(Eterm)) {
+	mpsp->u.heap = (Eterm*) erts_alloc(ERTS_ALC_T_DB_MS_RUN_HEAP, heap_size);
+    }
     else {
-	ASSERT(mpsp->heap == &mpsp->default_heap[0]);
+	ASSERT(mpsp->u.heap == mpsp->default_heap);
     }
     return mpsp;
 }
@@ -467,23 +493,6 @@ erts_match_set_release_result(Process* c_p)
 
 static erts_smp_atomic_t trace_control_word;
 
-
-Eterm
-erts_ets_copy_object(Eterm obj, Process* to)
-{
-    Uint size = size_object(obj);
-    Eterm* hp = HAlloc(to, size);
-    Eterm res;
-
-    res = copy_struct(obj, size, &hp, &MSO(to));
-#ifdef DEBUG
-    if (eq(obj, res) == 0) {
-	erl_exit(1, "copy not equal to source\n");
-    }
-#endif
-    return res;
-}
-
 /* This needs to be here, before the bif table... */
 
 static Eterm db_set_trace_control_word_fake_1(Process *p, Eterm val);
@@ -869,9 +878,9 @@ static DMCRet dmc_one_term(DMCContext *context,
 
 #ifdef DMC_DEBUG
 static int test_disassemble_next = 0;
-static void db_match_dis(Binary *prog);
+void db_match_dis(Binary *prog);
 #define TRACE erts_fprintf(stderr,"Trace: %s:%d\n",__FILE__,__LINE__)
-#define FENCE_PATTERN_SIZE 1
+#define FENCE_PATTERN_SIZE (1*sizeof(Uint))
 #define FENCE_PATTERN 0xDEADBEEFUL
 #else
 #define TRACE /* Nothing */
@@ -1179,14 +1188,14 @@ done:
 }
     
 Eterm erts_match_set_run(Process *p, Binary *mpsp, 
-			 Eterm *args, int num_args, 
+			 Eterm *args, int num_args,
+			 enum erts_pam_run_flags in_flags,
 			 Uint32 *return_flags) 
 {
     Eterm ret;
 
-    ret = db_prog_match(p, mpsp,
-			NIL, args,
-			num_args, return_flags);
+    ret = db_prog_match(p, mpsp, NIL, NULL, args, num_args,
+			in_flags, return_flags);
 #if defined(HARDDEBUG)
     if (is_non_value(ret)) {
 	erts_fprintf(stderr, "Failed\n");
@@ -1210,9 +1219,9 @@ static Eterm erts_match_set_run_ets(Process *p, Binary *mpsp,
 {
     Eterm ret;
 
-    ret = db_prog_match(p, mpsp,
-			args, NULL,
-			num_args, return_flags);
+    ret = db_prog_match(p, mpsp, args, NULL, NULL, num_args,
+			ERTS_PAM_CONTIGUOUS_TUPLE | ERTS_PAM_COPY_RESULT,
+			return_flags);
 #if defined(HARDDEBUG)
     if (is_non_value(ret)) {
 	erts_fprintf(stderr, "Failed\n");
@@ -1280,7 +1289,6 @@ Binary *db_match_compile(Eterm *matchexpr,
     int structure_checked;
     DMCRet res;
     int current_try_label;
-    Uint max_eheap_need;
     Binary *bp = NULL;
     unsigned clause_start;
 
@@ -1293,27 +1301,24 @@ Binary *db_match_compile(Eterm *matchexpr,
     context.matchexpr = matchexpr;
     context.guardexpr = guards;
     context.bodyexpr = body;
-    context.eheap_need = 0;
     context.err_info = err_info;
     context.cflags = flags;
 
     heap.size = DMC_DEFAULT_SIZE;
-    heap.data = heap.def;
+    heap.vars = heap.vars_def;
 
     /*
     ** Compile the match expression
     */
 restart:
-    heap.used = 0;
-    max_eheap_need = 0;
+    heap.vars_used = 0;
     for (context.current_match = 0; 
 	 context.current_match < num_progs; 
 	 ++context.current_match) { /* This loop is long, 
 				       too long */
-	memset(heap.data, 0, heap.size * sizeof(*heap.data));
+	memset(heap.vars, 0, heap.size * sizeof(*heap.vars));
 	t = context.matchexpr[context.current_match];
 	context.stack_used = 0;
-	context.eheap_need = 0;
 	structure_checked = 0;
 	if (context.current_match < num_progs - 1) {
 	    DMC_PUSH(text,matchTryMeElse);
@@ -1485,10 +1490,6 @@ restart:
 	if (current_try_label >= 0) {
 	    DMC_POKE(text, current_try_label, DMC_STACK_NUM(text));
 	}
-	/* So, how much eheap did this part of the match program need? */
-	if (context.eheap_need > max_eheap_need) {
-	    max_eheap_need = context.eheap_need;
-	}
     } /* for (context.current_match = 0 ...) */
 
 
@@ -1524,16 +1525,13 @@ restart:
     ret->saved_program_buf = NULL;
     ret->saved_program = NIL;
     ret->term_save = context.save;
-    ret->num_bindings = heap.used;
+    ret->num_bindings = heap.vars_used;
     ret->single_variable = context.special;
     sys_memcpy(ret->text, DMC_STACK_DATA(text), 
 	       DMC_STACK_NUM(text) * sizeof(UWord));
-    ret->heap_size = ((heap.used * sizeof(Eterm)) +
-		      (max_eheap_need * sizeof(Eterm)) +
-		      (context.stack_need * sizeof(Eterm *)) +
-		      (3 * (FENCE_PATTERN_SIZE * sizeof(Eterm *))));
-    ret->eheap_offset = heap.used + FENCE_PATTERN_SIZE;
-    ret->stack_offset = ret->eheap_offset + max_eheap_need + FENCE_PATTERN_SIZE;
+    ret->stack_offset = heap.vars_used*sizeof(MatchVariable) + FENCE_PATTERN_SIZE;
+    ret->heap_size = ret->stack_offset + context.stack_need * sizeof(Eterm*) + FENCE_PATTERN_SIZE;
+
 #ifdef DMC_DEBUG
     ret->prog_end = ret->text + DMC_STACK_NUM(text);
 #endif
@@ -1551,8 +1549,8 @@ error: /* Here is were we land when compilation failed. */
     DMC_FREE(text);
     if (context.copy != NULL) 
 	free_message_buffer(context.copy);
-    if (heap.data != heap.def)
-	erts_free(ERTS_ALC_T_DB_MS_CMPL_HEAP, (void *) heap.data);
+    if (heap.vars != heap.vars_def)
+	erts_free(ERTS_ALC_T_DB_MS_CMPL_HEAP, (void *) heap.vars);
     return bp;
 }
 
@@ -1597,7 +1595,7 @@ erts_match_prog_foreach_offheap(Binary *bprog,
 */
 static Eterm dpm_array_to_list(Process *psp, Eterm *arr, int arity)
 {
-    Eterm *hp = HAlloc(psp, arity * 2);
+    Eterm *hp = HAllocX(psp, arity * 2, HEAP_XTRA);
     Eterm ret = NIL;
     while (--arity >= 0) {
 	ret = CONS(hp, arr[arity], ret);
@@ -1606,15 +1604,82 @@ static Eterm dpm_array_to_list(Process *psp, Eterm *arr, int arity)
     return ret;
 }
 
+
+#if HALFWORD_HEAP
+struct heap_checkpoint_t
+{
+    Process *p;
+    Eterm* htop;
+    ErlHeapFragment* mbuf;
+    unsigned used_size;
+    ErlOffHeap off_heap;
+};
+
+static void heap_checkpoint_init(Process* p, struct heap_checkpoint_t* hcp)
+{
+    hcp->p = p;
+    hcp->htop = HEAP_TOP(p);
+    hcp->mbuf = MBUF(p);
+    hcp->used_size = hcp->mbuf ? hcp->mbuf->used_size : 0;
+    hcp->off_heap = MSO(p);
+}
+
+static void heap_checkpoint_revert(struct heap_checkpoint_t* hcp)
+{
+    struct erl_off_heap_header* oh = MSO(hcp->p).first;
+
+    if (oh != hcp->off_heap.first) {
+	ASSERT(oh != NULL);
+	if (hcp->off_heap.first) {
+	    while (oh->next != hcp->off_heap.first) {
+		oh = oh->next;
+	    }
+	    oh->next = NULL;
+	}
+	erts_cleanup_offheap(&MSO(hcp->p));
+	MSO(hcp->p) = hcp->off_heap;
+    }
+    if (MBUF(hcp->p) != hcp->mbuf) {
+	ErlHeapFragment* hf = MBUF(hcp->p);
+	ASSERT(hf != NULL);
+	if (hcp->mbuf) {
+	    while (hf->next != hcp->mbuf) {
+		hf = hf->next;
+	    }
+	    hf->next = NULL;
+	}
+	free_message_buffer(MBUF(hcp->p));
+	MBUF(hcp->p) = hcp->mbuf;
+    }
+    if (hcp->mbuf != NULL && hcp->mbuf->used_size != hcp->used_size) {
+	hcp->mbuf->used_size = hcp->used_size;
+    }
+    HEAP_TOP(hcp->p) = hcp->htop;
+}
+#endif /* HALFWORD_HEAP */
+
+static ERTS_INLINE Eterm copy_object_rel(Process* p, Eterm term, Eterm* base)
+{
+    if (!is_immed(term)) {
+	Uint sz = size_object_rel(term, base);
+	Eterm* top = HAllocX(p, sz, HEAP_XTRA);
+	return copy_struct_rel(term, sz, &top, &MSO(p), base, NULL);
+    }
+    return term;
+}
+
+
 /*
 ** Execution of the match program, this is Pam.
 ** May return THE_NON_VALUE, which is a bailout.
-** the para meter 'arity' is only used if 'term' is actually an array,
+** the parameter 'arity' is only used if 'term' is actually an array,
 ** i.e. 'DCOMP_TRACE' was specified 
 */
-Eterm db_prog_match(Process *c_p, Binary *bprog, Eterm term, 
+Eterm db_prog_match(Process *c_p, Binary *bprog,
+		    Eterm term, Eterm* base,
 		    Eterm *termp,
 		    int arity,
+		    enum erts_pam_run_flags in_flags,
 		    Uint32 *return_flags)
 {
     MatchProg *prog = Binary2MatchProg(bprog);
@@ -1623,7 +1688,7 @@ Eterm db_prog_match(Process *c_p, Binary *bprog, Eterm term,
     Eterm t;
     Eterm **sp;
     Eterm *esp;
-    Eterm *hp;
+    MatchVariable* variables;
     BeamInstr *cp;
     UWord *pc = prog->text;
     Eterm *ehp;
@@ -1633,19 +1698,24 @@ Eterm db_prog_match(Process *c_p, Binary *bprog, Eterm term,
     unsigned do_catch;
     ErtsMatchPseudoProcess *mpsp;
     Process *psp;
+    Process* build_proc;
     Process *tmpp;
     Process *current_scheduled;
     ErtsSchedulerData *esdp;
     Eterm (*bif)(Process*, ...);
     int fail_label;
     int atomic_trace;
+#if HALFWORD_HEAP
+    struct heap_checkpoint_t c_p_checkpoint = {};
+#endif
 #ifdef DMC_DEBUG
     Uint *heap_fence;
-    Uint *eheap_fence;
     Uint *stack_fence;
     Uint save_op;
 #endif /* DMC_DEBUG */
 
+    ASSERT(base==NULL || HALFWORD_HEAP);
+
     mpsp = get_match_pseudo_process(c_p, prog->heap_size);
     psp = &mpsp->process;
 
@@ -1655,7 +1725,6 @@ Eterm db_prog_match(Process *c_p, Binary *bprog, Eterm term,
     esdp = ERTS_GET_SCHEDULER_DATA_FROM_PROC(c_p);
     ASSERT(esdp != NULL);
     current_scheduled = esdp->current_process;
-    esdp->current_process = psp;
     /* SMP: psp->scheduler_data is set by get_match_pseudo_process */
 
     atomic_trace = 0;
@@ -1678,11 +1747,9 @@ Eterm db_prog_match(Process *c_p, Binary *bprog, Eterm term,
 
 #ifdef DMC_DEBUG
     save_op = 0;
-    heap_fence =  (Uint *) mpsp->heap + prog->eheap_offset - 1;
-    eheap_fence = (Uint *) mpsp->heap + prog->stack_offset - 1;
-    stack_fence = (Uint *) mpsp->heap + prog->heap_size - 1;
+    heap_fence = (Eterm*)((char*) mpsp->u.heap + prog->stack_offset) - 1;
+    stack_fence = (Eterm*)((char*) mpsp->u.heap + prog->heap_size) - 1;
     *heap_fence = FENCE_PATTERN;
-    *eheap_fence = FENCE_PATTERN;
     *stack_fence = FENCE_PATTERN;
 #endif /* DMC_DEBUG */
 
@@ -1696,36 +1763,48 @@ Eterm db_prog_match(Process *c_p, Binary *bprog, Eterm term,
 
     *return_flags = 0U;
 
+    variables = mpsp->u.variables;
+#if HALFWORD_HEAP
+    c_p_checkpoint.p = NULL;
+#endif
+
 restart:
     ep = &term;
-    esp = mpsp->heap + prog->stack_offset;
+    esp = (Eterm*)((char*)mpsp->u.heap + prog->stack_offset);
     sp = (Eterm **) esp;
-    hp = mpsp->heap;
-    ehp = mpsp->heap + prog->eheap_offset;
     ret = am_true;
     do_catch = 0;
     fail_label = -1;
+    build_proc = psp;
+    esdp->current_process = psp;
+    ASSERT_HALFWORD(!c_p_checkpoint.p);
+
+#ifdef DEBUG
+    ASSERT(variables == mpsp->u.variables);
+    for (i=0; i<prog->num_bindings; i++) {
+	variables[i].term = THE_NON_VALUE;
+	variables[i].proc = NULL;
+	variables[i].base = base;
+    }
+#endif
 
     for (;;) {
-#ifdef DMC_DEBUG
+
+    #ifdef DMC_DEBUG
 	if (*heap_fence != FENCE_PATTERN) {
 	    erl_exit(1, "Heap fence overwritten in db_prog_match after op "
 		     "0x%08x, overwritten with 0x%08x.", save_op, *heap_fence);
 	}
-	if (*eheap_fence != FENCE_PATTERN) {
-	    erl_exit(1, "Eheap fence overwritten in db_prog_match after op "
-		     "0x%08x, overwritten with 0x%08x.", save_op, 
-		     *eheap_fence);
-	}
 	if (*stack_fence != FENCE_PATTERN) {
 	    erl_exit(1, "Stack fence overwritten in db_prog_match after op "
 		     "0x%08x, overwritten with 0x%08x.", save_op, 
 		     *stack_fence);
 	}
 	save_op = *pc;
-#endif
+    #endif
 	switch (*pc++) {
 	case matchTryMeElse:
+	    ASSERT(fail_label == -1);
 	    fail_label = *pc++;
 	    break;
 	case matchArray: /* only when DCOMP_TRACE, is always first
@@ -1736,13 +1815,14 @@ restart:
 	    ep = termp;
 	    break;
 	case matchArrayBind: /* When the array size is unknown. */
+	    ASSERT(termp);
 	    n = *pc++;
-	    hp[n] = dpm_array_to_list(psp, termp, arity);
+	    variables[n].term = dpm_array_to_list(psp, termp, arity);
 	    break;
 	case matchTuple: /* *ep is a tuple of arity n */
-	    if (!is_tuple(*ep))
+	    if (!is_tuple_rel(*ep,base))
 		FAIL();
-	    ep = tuple_val(*ep);
+	    ep = tuple_val_rel(*ep,base);
 	    n = *pc++;
 	    if (arityval(*ep) != n)
 		FAIL();
@@ -1750,9 +1830,9 @@ restart:
 	    break;
 	case matchPushT: /* *ep is a tuple of arity n, 
 			    push ptr to first element */
-	    if (!is_tuple(*ep))
+	    if (!is_tuple_rel(*ep,base))
 		FAIL();
-	    tp = tuple_val(*ep);
+	    tp = tuple_val_rel(*ep,base);
 	    n = *pc++;
 	    if (arityval(*tp) != n)
 		FAIL();
@@ -1762,12 +1842,12 @@ restart:
 	case matchList:
 	    if (!is_list(*ep))
 		FAIL();
-	    ep = list_val(*ep);
+	    ep = list_val_rel(*ep,base);
 	    break;
 	case matchPushL:
 	    if (!is_list(*ep))
 		FAIL();
-	    *sp++ = list_val(*ep);
+	    *sp++ = list_val_rel(*ep,base);
 	    ++ep;
 	    break;
 	case matchPop:
@@ -1775,41 +1855,44 @@ restart:
 	    break;
 	case matchBind:
 	    n = *pc++;
-	    hp[n] = *ep++;
+	    variables[n].term = *ep++;
 	    break;
 	case matchCmp:
 	    n = *pc++;
-	    if (!eq(hp[n],*ep))
+	    if (!eq_rel(variables[n].term, base, *ep, base))
 		FAIL();
 	    ++ep;
 	    break;
 	case matchEqBin:
 	    t = (Eterm) *pc++;
-	    if (!eq(*ep,t))
+	    if (!eq_rel(t,NULL,*ep,base))
 		FAIL();
 	    ++ep;
 	    break;
 	case matchEqFloat:
-	    if (!is_float(*ep))
+	    if (!is_float_rel(*ep,base))
 		FAIL();
-	    if (memcmp(float_val(*ep) + 1, pc, sizeof(double)))
+	    if (memcmp(float_val_rel(*ep,base) + 1, pc, sizeof(double)))
 		FAIL();
 	    pc += TermWords(2);
 	    ++ep;
 	    break;
-	case matchEqRef:
-	    if (!is_ref(*ep))
+	case matchEqRef: {
+	    Eterm* epc = (Eterm*)pc;
+	    if (!is_ref_rel(*ep,base))
 		FAIL();
-	    if (!eq(*ep, make_internal_ref((Uint *) pc)))
+	    if (!eq_rel(make_internal_ref_rel(epc, epc), epc, *ep, base)) {
 		FAIL();
-	    i = thing_arityval(*((Uint *) pc));
+	    }
+	    i = thing_arityval(*epc);
 	    pc += TermWords(i+1);
 	    ++ep;
 	    break;
+	}
 	case matchEqBig:
-	    if (!is_big(*ep))
+	    if (!is_big_rel(*ep,base))
 		FAIL();
-	    tp = big_val(*ep);
+	    tp = big_val_rel(*ep,base);
 	    {
 		Eterm *epc = (Eterm *) pc;
 		if (*tp != *epc)
@@ -1825,7 +1908,8 @@ restart:
 	    ++ep;
 	    break;
 	case matchEq:
-	    t = (Eterm) *pc++; 
+	    t = (Eterm) *pc++;
+	    ASSERT(is_immed(t));
 	    if (t != *ep++)
 		FAIL();
 	    break;
@@ -1833,25 +1917,32 @@ restart:
 	    ++ep;
 	    break;
 	/* 
-	 * Here comes guard instructions 
+	 * Here comes guard & body instructions
 	 */
 	case matchPushC: /* Push constant */
-	    *esp++ = *pc++;
+	    if ((in_flags & ERTS_PAM_COPY_RESULT)
+		&& do_catch && !is_immed(*pc)) {
+		*esp++ = copy_object(*pc++, c_p);
+	    }
+	    else {
+		*esp++ = *pc++;
+	    }
 	    break;
 	case matchConsA:
-	    ehp[1] = *--esp;
-	    ehp[0] = esp[-1];
+	    ehp = HAllocX(build_proc, 2, HEAP_XTRA);
+	    CDR(ehp) = *--esp;
+	    CAR(ehp) = esp[-1];
 	    esp[-1] = make_list(ehp);
-	    ehp += 2;
 	    break;
 	case matchConsB:
-	    ehp[0] = *--esp;
-	    ehp[1] = esp[-1];
+	    ehp = HAllocX(build_proc, 2, HEAP_XTRA);
+	    CAR(ehp) = *--esp;
+	    CDR(ehp) = esp[-1];
 	    esp[-1] = make_list(ehp);
-	    ehp += 2;
 	    break;
 	case matchMkTuple:
 	    n = *pc++;
+	    ehp = HAllocX(build_proc, n+1, HEAP_XTRA);
 	    t = make_tuple(ehp);
 	    *ehp++ = make_arityval(n);
 	    while (n--) {
@@ -1861,7 +1952,7 @@ restart:
 	    break;
 	case matchCall0:
 	    bif = (Eterm (*)(Process*, ...)) *pc++;
-	    t = (*bif)(psp);
+	    t = (*bif)(build_proc);
 	    if (is_non_value(t)) {
 		if (do_catch)
 		    t = FAIL_TERM;
@@ -1872,7 +1963,7 @@ restart:
 	    break;
 	case matchCall1:
 	    bif = (Eterm (*)(Process*, ...)) *pc++;
-	    t = (*bif)(psp, esp[-1]);
+	    t = (*bif)(build_proc, esp[-1]);
 	    if (is_non_value(t)) {
 		if (do_catch)
 		    t = FAIL_TERM;
@@ -1883,7 +1974,7 @@ restart:
 	    break;
 	case matchCall2:
 	    bif = (Eterm (*)(Process*, ...)) *pc++;
-	    t = (*bif)(psp, esp[-1], esp[-2]);
+	    t = (*bif)(build_proc, esp[-1], esp[-2]);
 	    if (is_non_value(t)) {
 		if (do_catch)
 		    t = FAIL_TERM;
@@ -1895,7 +1986,7 @@ restart:
 	    break;
 	case matchCall3:
 	    bif = (Eterm (*)(Process*, ...)) *pc++;
-	    t = (*bif)(psp, esp[-1], esp[-2], esp[-3]);
+	    t = (*bif)(build_proc, esp[-1], esp[-2], esp[-3]);
 	    if (is_non_value(t)) {
 		if (do_catch)
 		    t = FAIL_TERM;
@@ -1905,15 +1996,73 @@ restart:
 	    esp -= 2;
 	    esp[-1] = t;
 	    break;
+
+	#if HALFWORD_HEAP
+	case matchPushVGuard:
+	    if (!base) goto case_matchPushV;
+	    /* Build NULL-based copy on pseudo heap for easy disposal */
+	    n = *pc++;
+	    ASSERT(is_value(variables[n].term));
+	    ASSERT(!variables[n].proc);
+	    variables[n].term = copy_object_rel(psp, variables[n].term, base);
+	    *esp++ = variables[n].term;
+	    #ifdef DEBUG
+	    variables[n].proc = psp;
+	    variables[n].base = NULL;
+	    #endif
+	    break;
+	#endif
+	case matchPushVResult:
+	    if (!(in_flags & ERTS_PAM_COPY_RESULT)) goto case_matchPushV;
+
+	    /* Build (NULL-based) copy on callers heap */
+	#if HALFWORD_HEAP
+	    if (!do_catch && !c_p_checkpoint.p) {
+		heap_checkpoint_init(c_p, &c_p_checkpoint);
+	    }
+        #endif
+	    n = *pc++;
+	    ASSERT(is_value(variables[n].term));
+	    ASSERT(!variables[n].proc);
+	    variables[n].term = copy_object_rel(c_p, variables[n].term, base);
+	    *esp++ = variables[n].term;
+	    #ifdef DEBUG
+	    variables[n].proc = c_p;
+	    variables[n].base = NULL;
+	    #endif
+	    break;
 	case matchPushV:
-	    *esp++ = hp[*pc++];
+	case_matchPushV:
+	    n = *pc++;
+	    ASSERT(is_value(variables[n].term));
+	    ASSERT(!variables[n].base);
+	    *esp++ = variables[n].term;
 	    break;
 	case matchPushExpr:
-	    *esp++ = term;
+	    if (in_flags & ERTS_PAM_COPY_RESULT) {
+		Uint sz;
+		Eterm* top;
+		sz = size_object_rel(term, base);
+		top = HAllocX(build_proc, sz, HEAP_XTRA);
+		if (in_flags & ERTS_PAM_CONTIGUOUS_TUPLE) {
+		    ASSERT(is_tuple_rel(term,base));
+		    *esp++ = copy_shallow_rel(tuple_val_rel(term,base), sz,
+					      &top, &MSO(build_proc), base);
+		}
+		else {
+		    *esp++ = copy_struct_rel(term, sz, &top, &MSO(build_proc),
+					     base, NULL);
+		}
+	    }
+	    else {
+		*esp = term;
+	    }
 	    break;
 	case matchPushArrayAsList:
+	    ASSERT_HALFWORD(base == NULL);
 	    n = arity; /* Only happens when 'term' is an array */
 	    tp = termp;
+	    ehp = HAllocX(build_proc, n*2, HEAP_XTRA);
 	    *esp++  = make_list(ehp);
 	    while (n--) {
 		*ehp++ = *tp++;
@@ -1926,7 +2075,8 @@ restart:
 	    break;
 	case matchPushArrayAsListU:
 	    /* This instruction is NOT efficient. */
-	    *esp++  = dpm_array_to_list(psp, termp, arity);
+	    ASSERT_HALFWORD(base == NULL);
+	    *esp++  = dpm_array_to_list(build_proc, termp, arity);
 	    break;
 	case matchTrue:
 	    if (*--esp != am_true)
@@ -2012,7 +2162,7 @@ restart:
 	case matchProcessDump: {
 	    erts_dsprintf_buf_t *dsbufp = erts_create_tmp_dsbuf(0);
 	    print_process_info(ERTS_PRINT_DSBUF, (void *) dsbufp, c_p);
-	    *esp++ = new_binary(psp, (byte *)dsbufp->str, (int)dsbufp->str_len);
+	    *esp++ = new_binary(build_proc, (byte *)dsbufp->str, (int)dsbufp->str_len);
 	    erts_destroy_tmp_dsbuf(dsbufp);
 	    break;
 	}
@@ -2056,29 +2206,24 @@ restart:
 	    if (SEQ_TRACE_TOKEN(c_p) == NIL) 
 		*esp++ = NIL;
 	    else {
+		Eterm sender = SEQ_TRACE_TOKEN_SENDER(c_p);
+		Uint sender_sz = is_immed(sender) ? 0 : size_object(sender);
+		ehp = HAllocX(build_proc, 6 + sender_sz, HEAP_XTRA);
+		if (sender_sz) {
+		    sender = copy_struct(sender, sender_sz, &ehp, &MSO(build_proc));
+		}
  		*esp++ = make_tuple(ehp);
  		ehp[0] = make_arityval(5);
  		ehp[1] = SEQ_TRACE_TOKEN_FLAGS(c_p);
  		ehp[2] = SEQ_TRACE_TOKEN_LABEL(c_p);
  		ehp[3] = SEQ_TRACE_TOKEN_SERIAL(c_p);
- 		ehp[4] = SEQ_TRACE_TOKEN_SENDER(c_p);
+		ehp[4] = sender;
  		ehp[5] = SEQ_TRACE_TOKEN_LASTCNT(c_p);
 		ASSERT(SEQ_TRACE_TOKEN_ARITY(c_p) == 5);
 		ASSERT(is_immed(ehp[1]));
 		ASSERT(is_immed(ehp[2]));
 		ASSERT(is_immed(ehp[3]));
 		ASSERT(is_immed(ehp[5]));
-		if(!is_immed(ehp[4])) {
-		    Eterm *sender = &ehp[4];
-		    ehp += 6;
-		    *sender = copy_struct(*sender,
-					  size_object(*sender),
-					  &ehp,
-					  &MSO(psp));
-		}
-		else
-		    ehp += 6;
-
 	    } 
 	    break;
 	case matchEnableTrace:
@@ -2127,12 +2272,12 @@ restart:
 	    if (!(c_p->cp) || !(cp = find_function_from_pc(c_p->cp))) {
  		*esp++ = am_undefined;
  	    } else {
+		ehp = HAllocX(build_proc, 4, HEAP_XTRA);
  		*esp++ = make_tuple(ehp);
 		ehp[0] = make_arityval(3);
 		ehp[1] = cp[0];
 		ehp[2] = cp[1];
 		ehp[3] = make_small((Uint) cp[2]);
-		ehp += 4;
 	    }
 	    break;
 	case matchSilent:
@@ -2209,8 +2354,12 @@ restart:
 		}
 	    }
 	    break;
-	case matchCatch:
+	case matchCatch:  /* Match success, now build result */
 	    do_catch = 1;
+	    if (in_flags & ERTS_PAM_COPY_RESULT) {
+		build_proc = c_p;
+		esdp->current_process = c_p;
+	    }
 	    break;
 	case matchHalt:
 	    goto success;
@@ -2219,9 +2368,16 @@ restart:
 	}
     }
 fail:
+#if HALFWORD_HEAP
+    if (c_p_checkpoint.p) {
+	/* Dispose garbage built by guards on caller heap */
+	heap_checkpoint_revert(&c_p_checkpoint);
+	c_p_checkpoint.p = NULL;
+    }
+#endif
     *return_flags = 0U;
-    if (fail_label >= 0) { /* We failed during a "TryMeElse", 
-			      lets restart, with the next match 
+    if (fail_label >= 0) { /* We failed during a "TryMeElse",
+			      lets restart, with the next match
 			      program */
 	pc = (prog->text) + fail_label;
 	cleanup_match_pseudo_process(mpsp, 1);
@@ -2235,11 +2391,6 @@ success:
 	erl_exit(1, "Heap fence overwritten in db_prog_match after op "
 		 "0x%08x, overwritten with 0x%08x.", save_op, *heap_fence);
     }
-    if (*eheap_fence != FENCE_PATTERN) {
-	erl_exit(1, "Eheap fence overwritten in db_prog_match after op "
-		 "0x%08x, overwritten with 0x%08x.", save_op, 
-		 *eheap_fence);
-    }
     if (*stack_fence != FENCE_PATTERN) {
 	erl_exit(1, "Stack fence overwritten in db_prog_match after op "
 		 "0x%08x, overwritten with 0x%08x.", save_op, 
@@ -2250,6 +2401,7 @@ success:
     esdp->current_process = current_scheduled;
 
     END_ATOMIC_TRACE(c_p);
+
     return ret;
 #undef FAIL
 #undef FAIL_TERM
@@ -2261,7 +2413,8 @@ success:
 /*
  * Convert a match program to a "magic" binary to return up to erlang
  */
-Eterm db_make_mp_binary(Process *p, Binary *mp, Eterm **hpp) {
+Eterm db_make_mp_binary(Process *p, Binary *mp, Eterm **hpp)
+{
     return erts_mk_magic_binary_term(hpp, &MSO(p), mp);
 }
 
@@ -2327,13 +2480,13 @@ void db_free_dmc_err_info(DMCErrInfo *ei){
 ** Store bignum in *hpp and increase *hpp accordingly.
 ** *hpp is assumed to be large enough to hold the result.
 */
-Eterm db_add_counter(Eterm** hpp, Eterm counter, Eterm incr)
+Eterm db_add_counter(Eterm** hpp, Wterm counter, Eterm incr)
 {
     DeclareTmpHeapNoproc(big_tmp,2);
     Eterm res;
     Sint ires;
-    Eterm arg1;
-    Eterm arg2;
+    Wterm arg1;
+    Wterm arg2;
 
     if (is_both_small(counter,incr)) {
 	ires = signed_val(counter) + signed_val(incr);
@@ -2374,6 +2527,34 @@ Eterm db_add_counter(Eterm** hpp, Eterm counter, Eterm incr)
     }
 }
 
+/* Must be called to read elements after db_lookup_dbterm.
+** Will decompress if needed.
+** HEALFWORD_HEAP:
+** 	Will convert from relative to Wterm format if needed.
+**      (but only on top level, tuples and lists will still contain rterms)
+*/
+Wterm db_do_read_element(DbUpdateHandle* handle, Sint position)
+{
+    Eterm elem = handle->dbterm->tpl[position];
+    if (!is_header(elem)) {
+#if HALFWORD_HEAP
+	if (!is_immed(elem)
+	    && !handle->tb->common.compress
+	    && !(handle->abs_vec && handle->abs_vec[position])) {
+	    return rterm2wterm(elem, handle->dbterm->tpl);
+	}
+#endif
+	return elem;
+    }
+
+    ASSERT(((DbTableCommon*)handle->tb)->compress);
+    ASSERT(!handle->mustResize);
+    handle->dbterm = db_alloc_tmp_uncompressed(&handle->tb->common,
+					       handle->dbterm);
+    handle->mustResize = 1;
+    return handle->dbterm->tpl[position];
+}
+
 /*
 ** Update one element:
 ** handle:   Initialized by db_lookup_dbterm()
@@ -2390,14 +2571,17 @@ void db_do_update_element(DbUpdateHandle* handle,
     Eterm* oldp;
     Uint newval_sz;
     Uint oldval_sz;
+#if HALFWORD_HEAP
+    Eterm* old_base;
+#endif
 
     if (is_both_immed(newval,oldval)) {
 	handle->dbterm->tpl[position] = newval;
-#ifdef DEBUG_CLONE
+    #ifdef DEBUG_CLONE
 	if (handle->dbterm->debug_clone) {
 	    handle->dbterm->debug_clone[position] = newval;
 	}
-#endif
+    #endif
 	return;
     }
     if (!handle->mustResize) {
@@ -2406,49 +2590,78 @@ void db_do_update_element(DbUpdateHandle* handle,
 						       handle->dbterm);
 	    handle->mustResize = 1;
 	    oldval = handle->dbterm->tpl[position];
+        #if HALFWORD_HEAP
+	    old_base = NULL;
+	#endif
 	}
-	else if (is_boxed(newval)) {
-	    newp = boxed_val(newval);
-	    switch (*newp & _TAG_HEADER_MASK) {
-	    case _TAG_HEADER_POS_BIG:
-	    case _TAG_HEADER_NEG_BIG:
-	    case _TAG_HEADER_FLOAT:
-	    case _TAG_HEADER_HEAP_BIN:
-		newval_sz = header_arity(*newp) + 1;
-		if (is_boxed(oldval)) {
-		    oldp = boxed_val(oldval);
-		    switch (*oldp & _TAG_HEADER_MASK) {
-		    case _TAG_HEADER_POS_BIG:
-		    case _TAG_HEADER_NEG_BIG:
-		    case _TAG_HEADER_FLOAT:
-		    case _TAG_HEADER_HEAP_BIN:
-			oldval_sz = header_arity(*oldp) + 1;
-			if (oldval_sz == newval_sz) {
-			    /* "self contained" terms of same size, do memcpy */
-				sys_memcpy(oldp, newp, newval_sz*sizeof(Eterm));
-			    return;
+	else {
+	#if HALFWORD_HEAP
+	    ASSERT(!handle->abs_vec);
+	    old_base = handle->dbterm->tpl;
+	#endif
+	    if (is_boxed(newval)) {
+		newp = boxed_val(newval);
+		switch (*newp & _TAG_HEADER_MASK) {
+		case _TAG_HEADER_POS_BIG:
+		case _TAG_HEADER_NEG_BIG:
+		case _TAG_HEADER_FLOAT:
+		case _TAG_HEADER_HEAP_BIN:
+		    newval_sz = header_arity(*newp) + 1;
+		    if (is_boxed(oldval)) {
+			oldp = boxed_val_rel(oldval,old_base);
+			switch (*oldp & _TAG_HEADER_MASK) {
+			case _TAG_HEADER_POS_BIG:
+			case _TAG_HEADER_NEG_BIG:
+			case _TAG_HEADER_FLOAT:
+			case _TAG_HEADER_HEAP_BIN:
+			    oldval_sz = header_arity(*oldp) + 1;
+			    if (oldval_sz == newval_sz) {
+				/* "self contained" terms of same size, do memcpy */
+				    sys_memcpy(oldp, newp, newval_sz*sizeof(Eterm));
+				return;
+			    }
+			    goto both_size_set;
 			}
-			goto both_size_set;
 		    }
+		    goto new_size_set;
 		}
-		goto new_size_set;
 	    }
 	}
     }
+#if HALFWORD_HEAP
+    else {
+	old_base = (handle->tb->common.compress
+		    || (handle->abs_vec && handle->abs_vec[position])) ?
+	    NULL : handle->dbterm->tpl;
+    }
+#endif
     /* Not possible for simple memcpy or dbterm is already non-contiguous, */
     /* need to realloc... */
 
     newval_sz = is_immed(newval) ? 0 : size_object(newval);
 new_size_set:
-	
-    oldval_sz = is_immed(oldval) ? 0 : size_object(oldval);
+
+    oldval_sz = is_immed(oldval) ? 0 : size_object_rel(oldval,old_base);
 both_size_set:
 
     handle->new_size = handle->new_size - oldval_sz + newval_sz;
 
-    /* write new value in old dbterm, finalize will make a flat copy */	
+    /* write new value in old dbterm, finalize will make a flat copy */
     handle->dbterm->tpl[position] = newval;
     handle->mustResize = 1;
+
+#if HALFWORD_HEAP
+    if (old_base && newval_sz > 0) {
+	ASSERT(!handle->tb->common.compress);
+	if (!handle->abs_vec) {
+	    int i = header_arity(handle->dbterm->tpl[0]);
+	    handle->abs_vec = erts_alloc(ERTS_ALC_T_TMP, (i+1)*sizeof(char));
+	    sys_memset(handle->abs_vec, 0, i+1);
+	    /* abs_vec[0] not used */
+	}
+	handle->abs_vec[position] = 1;
+    }
+#endif
 }
 
 static ERTS_INLINE byte* db_realloc_term(DbTableCommon* tb, void* old,
@@ -2547,7 +2760,7 @@ static void* copy_to_comp(DbTableCommon* tb, Eterm obj, DbTerm* dest,
     tpl[arity + 1] = alloc_size;
 
     tmp_offheap.first = NULL;
-    tpl[tb->keypos] = copy_struct(key, size_object(key), &top.ep, &tmp_offheap);
+    tpl[tb->keypos] = copy_struct_rel(key, size_object(key), &top.ep, &tmp_offheap, NULL, tpl);
     dest->first_oh = tmp_offheap.first;
     for (i=1; i<=arity; i++) {
 	if (i != tb->keypos) {
@@ -2566,7 +2779,7 @@ static void* copy_to_comp(DbTableCommon* tb, Eterm obj, DbTerm* dest,
 	Eterm* dbg_top = erts_alloc(ERTS_ALC_T_DB_TERM, dest->size * sizeof(Eterm));
 	dest->debug_clone = dbg_top;
 	tmp_offheap.first = dest->first_oh;
-	copy_struct(obj, dest->size, &dbg_top, &tmp_offheap);
+	copy_struct_rel(obj, dest->size, &dbg_top, &tmp_offheap, NULL, dbg_top);
 	dest->first_oh = tmp_offheap.first;
 	ASSERT(dbg_top == dest->debug_clone + dest->size);
     }
@@ -2613,7 +2826,7 @@ void* db_store_term(DbTableCommon *tb, DbTerm* old, Uint offset, Eterm obj)
     newp->size = size;
     top = newp->tpl;
     tmp_offheap.first  = NULL;
-    copy_struct(obj, size, &top, &tmp_offheap);
+    copy_struct_rel(obj, size, &top, &tmp_offheap, NULL, top);
     newp->first_oh = tmp_offheap.first;
 #ifdef DEBUG_CLONE
     newp->debug_clone = NULL;
@@ -2652,7 +2865,7 @@ void* db_store_term_comp(DbTableCommon *tb, DbTerm* old, Uint offset, Eterm obj)
     top = copy_to_comp(tb, obj, newp, new_sz);
     ASSERT(top <= basep + new_sz);
 
-    // SVERK: realloc?
+    /* ToDo: Maybe realloc if ((basep+new_sz) - top) > WASTED_SPACE_LIMIT */
 
     return basep;
 }
@@ -2673,6 +2886,9 @@ void db_finalize_resize(DbUpdateHandle* handle, Uint offset)
     *(handle->bp) = newp;
     newDbTerm = (DbTerm*) (newp + offset);
     newDbTerm->size = handle->new_size;
+#ifdef DEBUG_CLONE
+    newDbTerm->debug_clone = NULL;
+#endif
 
     /* make a flat copy */
 
@@ -2682,17 +2898,38 @@ void db_finalize_resize(DbUpdateHandle* handle, Uint offset)
 	db_free_tmp_uncompressed(handle->dbterm);
     }
     else {
-	Eterm* top;
 	ErlOffHeap tmp_offheap;
+	Eterm* tpl = handle->dbterm->tpl;
+	Eterm* top = newDbTerm->tpl;
+
 	tmp_offheap.first = NULL;
-	top = newDbTerm->tpl;
-	copy_struct(make_tuple(handle->dbterm->tpl), handle->new_size,
-		    &top, &tmp_offheap);
-	newDbTerm->first_oh = tmp_offheap.first;
-#ifdef DEBUG_CLONE
-	newDbTerm->debug_clone = NULL;
-#endif
-	ASSERT((byte*)top <= (newp + alloc_sz));
+
+    #if HALFWORD_HEAP
+	if (handle->abs_vec) {
+	    int i, arity = header_arity(handle->dbterm->tpl[0]);
+
+	    top[0] = tpl[0];
+	    top += arity + 1;
+	    for (i=1; i<=arity; i++) {
+		Eterm* src_base = handle->abs_vec[i] ? NULL : tpl;
+
+		newDbTerm->tpl[i] = copy_struct_rel(tpl[i],
+						    size_object_rel(tpl[i],src_base),
+						    &top, &tmp_offheap, src_base,
+						    newDbTerm->tpl);
+	    }
+	    newDbTerm->first_oh = tmp_offheap.first;
+	    ASSERT((byte*)top <= (newp + alloc_sz));
+	    erts_free(ERTS_ALC_T_TMP, handle->abs_vec);
+	}
+	else
+    #endif /* HALFWORD_HEAP */
+	{
+	    copy_struct_rel(make_tuple_rel(tpl,tpl), handle->new_size, &top,
+			    &tmp_offheap, tpl, top);
+	    newDbTerm->first_oh = tmp_offheap.first;
+	    ASSERT((byte*)top == (newp + alloc_sz));
+	}
     }
 }
 
@@ -2705,9 +2942,9 @@ Eterm db_copy_from_comp(DbTableCommon* tb, DbTerm* bp, Eterm** hpp,
     hp[0] = bp->tpl[0];
     *hpp += arity + 1;
 
-    hp[tb->keypos] = copy_struct(bp->tpl[tb->keypos],
-				 size_object(bp->tpl[tb->keypos]),
-				 hpp, off_heap);
+    hp[tb->keypos] = copy_struct_rel(bp->tpl[tb->keypos],
+				     size_object_rel(bp->tpl[tb->keypos], bp->tpl),
+				     hpp, off_heap, bp->tpl, NULL);
     for (i=arity; i>0; i--) {
 	if (i != tb->keypos) {
 	    if (is_immed(bp->tpl[i])) {
@@ -2721,7 +2958,7 @@ Eterm db_copy_from_comp(DbTableCommon* tb, DbTerm* bp, Eterm** hpp,
     }
     ASSERT((*hpp - hp) <= bp->size);
 #ifdef DEBUG_CLONE
-    ASSERT(eq(make_tuple(hp),make_tuple(bp->debug_clone)));
+    ASSERT(eq_rel(make_tuple(hp),make_tuple(bp->debug_clone),bp->debug_clone));
 #endif
     return make_tuple(hp);
 }
@@ -2744,14 +2981,14 @@ Eterm db_copy_element_from_ets(DbTableCommon* tb, Process* p,
 	hp += extra;
 	HRelease(p, endp, hp);
 #ifdef DEBUG_CLONE
-	ASSERT(eq(copy,obj->debug_clone[pos]));
+	ASSERT(eq_rel(copy, obj->debug_clone[pos], obj->debug_clone));
 #endif
 	return copy;
     }
     else {
-	Uint sz = size_object(obj->tpl[pos]);
+	Uint sz = size_object_rel(obj->tpl[pos], obj->tpl);
 	*hpp = HAlloc(p, sz + extra);
-	return copy_struct(obj->tpl[pos], sz, hpp, &MSO(p));
+	return copy_struct_rel(obj->tpl[pos], sz, hpp, &MSO(p), obj->tpl, NULL);
     }
 }
 
@@ -2765,7 +3002,7 @@ void db_cleanup_offheap_comp(DbTerm* obj)
     ProcBin tmp;
 
     for (u.hdr = obj->first_oh; u.hdr; u.hdr = u.hdr->next) {
-	if ((UWord)u.voidp % sizeof(UWord) != 0) { /* unaligned ptr */
+	if ((UWord)u.voidp % sizeof(Uint) != 0) { /* unaligned ptr */
 	    sys_memcpy(&tmp, u.voidp, sizeof(tmp));
 	    /* Warning, must pass (void*)-variable to memcpy. Otherwise it will
 	       cause Bus error on Sparc due to false compile time assumptions
@@ -2961,7 +3198,7 @@ static DMCRet dmc_one_term(DMCContext *context,
 		** Ouch, big integer in match variable.
 		*/
 		Eterm *save_hp;
-		ASSERT(heap->data == heap->def);
+		ASSERT(heap->vars == heap->vars_def);
 		sz = sz2 = sz3 = 0;
 		for (j = 0; j < context->num_match; ++j) {
 		    sz += size_object(context->matchexpr[j]);
@@ -2999,24 +3236,23 @@ static DMCRet dmc_one_term(DMCContext *context,
 		       may be atoms that changed */
 		    context->matchexpr[j] = context->copy->mem[j];
 		}
-		heap->data = erts_alloc(ERTS_ALC_T_DB_MS_CMPL_HEAP,
-					heap->size*sizeof(unsigned));
-		sys_memset(heap->data, 0, 
-			   heap->size * sizeof(unsigned));
+		heap->vars = erts_alloc(ERTS_ALC_T_DB_MS_CMPL_HEAP,
+					heap->size*sizeof(DMCVariable));
+		sys_memset(heap->vars, 0, heap->size * sizeof(DMCVariable));
 		DMC_CLEAR(*stack);
 		/*DMC_PUSH(*stack,NIL);*/
 		DMC_CLEAR(*text);
 		return retRestart;
 	    }
-	    if (heap->data[n]) { /* already bound ? */
+	    if (heap->vars[n].is_bound) {
 		DMC_PUSH(*text,matchCmp);
 		DMC_PUSH(*text,n);
 	    } else { /* Not bound, bind! */
-		if (n >= heap->used)
-		    heap->used = n + 1;
+		if (n >= heap->vars_used)
+		    heap->vars_used = n + 1;
 		DMC_PUSH(*text,matchBind);
 		DMC_PUSH(*text,n);
-		heap->data[n] = 1;
+		heap->vars[n].is_bound = 1;
 	    }
 	} else if (c == am_Underscore) {
 	    DMC_PUSH(*text, matchSkip);
@@ -3041,6 +3277,8 @@ static DMCRet dmc_one_term(DMCContext *context,
 	    DMC_PUSH(*stack, c);
 	    break;
 	case (_TAG_HEADER_REF >> _TAG_PRIMARY_SIZE):
+	{
+	    Eterm* ref_val = internal_ref_val(c);
 	    DMC_PUSH(*text, matchEqRef);
 #if HALFWORD_HEAP
 	    {
@@ -3048,25 +3286,27 @@ static DMCRet dmc_one_term(DMCContext *context,
 		    UWord u;
 		    Uint t[2];
 		} fiddle;
-		ASSERT(thing_arityval(*internal_ref_val(c)) == 3);
-		fiddle.t[0] = *internal_ref_val(c);
-		fiddle.t[1] = (Uint) internal_ref_val(c)[1];
+		ASSERT(thing_arityval(ref_val[0]) == 3);
+		fiddle.t[0] = ref_val[0];
+		fiddle.t[1] = ref_val[1];
 		DMC_PUSH(*text, fiddle.u);
-		fiddle.t[0] = (Uint) internal_ref_val(c)[2];
-		fiddle.t[1] = (Uint) internal_ref_val(c)[3];
+		fiddle.t[0] = ref_val[2];
+		fiddle.t[1] = ref_val[3];
 		DMC_PUSH(*text, fiddle.u);
 	    }
 #else
-	    n = thing_arityval(*internal_ref_val(c));
-	    DMC_PUSH(*text, *internal_ref_val(c));
-	    for (i = 1; i <= n; ++i) {
-		DMC_PUSH(*text, (Uint) internal_ref_val(c)[i]);
+	    n = thing_arityval(ref_val[0]);
+	    for (i = 0; i <= n; ++i) {
+		DMC_PUSH(*text, ref_val[i]);
 	    }
 #endif
 	    break;
+	}
 	case (_TAG_HEADER_POS_BIG >> _TAG_PRIMARY_SIZE):
 	case (_TAG_HEADER_NEG_BIG >> _TAG_PRIMARY_SIZE):
-	    n = thing_arityval(*big_val(c));
+	{
+	    Eterm* bval = big_val(c);
+	    n = thing_arityval(bval[0]);
 	    DMC_PUSH(*text, matchEqBig);
 #if HALFWORD_HEAP
 	    {
@@ -3075,13 +3315,13 @@ static DMCRet dmc_one_term(DMCContext *context,
 		    Uint t[2];
 		} fiddle;
 		ASSERT(n >= 1);
-		fiddle.t[0] = *big_val(c);
-		fiddle.t[1] = big_val(c)[1];
+		fiddle.t[0] = bval[0];
+		fiddle.t[1] = bval[1];
 		DMC_PUSH(*text, fiddle.u);
 		for (i = 2; i <= n; ++i) {
-		    fiddle.t[0] = big_val(c)[i];
+		    fiddle.t[0] = bval[i];
 		    if (++i <= n) {
-			fiddle.t[1] = big_val(c)[i];
+			fiddle.t[1] = bval[i];
 		    } else {
 			fiddle.t[1] = (Uint) 0;
 		    }
@@ -3089,12 +3329,12 @@ static DMCRet dmc_one_term(DMCContext *context,
 		}
 	    }
 #else
-	    DMC_PUSH(*text, *big_val(c));
-	    for (i = 1; i <= n; ++i) {
-		DMC_PUSH(*text, (Uint) big_val(c)[i]);
+	    for (i = 0; i <= n; ++i) {
+		DMC_PUSH(*text, (Uint) bval[i]);
 	    }
 #endif
 	    break;
+	}
 	case (_TAG_HEADER_FLOAT >> _TAG_PRIMARY_SIZE):
 	    DMC_PUSH(*text,matchEqFloat);
 #if HALFWORD_HEAP
@@ -3227,7 +3467,6 @@ static DMCRet dmc_list(DMCContext *context,
 	DMC_PUSH(*text, matchConsB);
     }
     --context->stack_used; /* Two objects on stack becomes one */
-    context->eheap_need += 2;
     return retOk;
 }
 
@@ -3286,7 +3525,6 @@ static DMCRet dmc_tuple(DMCContext *context,
     DMC_PUSH(*text, matchMkTuple);
     DMC_PUSH(*text, nelems);
     context->stack_used -= (nelems - 1);
-    context->eheap_need += (nelems + 1);
     *constant = 0;
     return retOk;
 }
@@ -3304,9 +3542,6 @@ static DMCRet dmc_whole_expression(DMCContext *context,
 	} else { 
 	    ASSERT(is_tuple(context->matchexpr
 			    [context->current_match]));
-	    context->eheap_need += 
-		arityval(*(tuple_val(context->matchexpr
-				     [context->current_match]))) * 2;
 	    DMC_PUSH(*text, matchPushArrayAsList);
 	}
     } else {
@@ -3319,6 +3554,41 @@ static DMCRet dmc_whole_expression(DMCContext *context,
     return retOk;
 }
 
+/* Figure out which PushV instruction to use.
+*/
+static void dmc_add_pushv_variant(DMCContext *context, DMCHeap *heap,
+				  DMC_STACK_TYPE(UWord) *text, Uint n)
+{
+    DMCVariable* v = &heap->vars[n];
+    MatchOps instr = matchPushV;
+
+    ASSERT(n < heap->vars_used && v->is_bound);
+    if (context->is_guard) {
+	#if HALFWORD_HEAP
+	if (!v->first_guard_label) {
+	    v->first_guard_label = DMC_STACK_NUM(*text);
+	    ASSERT(v->first_guard_label);
+	    instr = matchPushVGuard; /* may be changed to PushVResult below */
+	}
+	#endif
+    }
+    else { /* body */
+	#if HALFWORD_HEAP
+	if (v->first_guard_label) {
+	    /* Avoid double-copy, copy to result heap at first encounter in guard */
+	    DMC_POKE(*text, v->first_guard_label, matchPushVResult);
+	    v->is_in_body = 1;
+	}
+	#endif
+	if (!v->is_in_body) {
+	    instr = matchPushVResult;
+	    v->is_in_body = 1;
+	}
+    }
+    DMC_PUSH(*text, instr);
+    DMC_PUSH(*text, n);
+}
+
 static DMCRet dmc_variable(DMCContext *context,
 			   DMCHeap *heap,
 			   DMC_STACK_TYPE(UWord) *text,
@@ -3326,13 +3596,13 @@ static DMCRet dmc_variable(DMCContext *context,
 			   int *constant)
 {
     Uint n = db_is_variable(t);
-    ASSERT(n >= 0);
-    if (n >= heap->used) 
-	RETURN_VAR_ERROR("Variable $%d is unbound.", n, context, *constant);
-    if (heap->data[n] == 0U)
+
+    if (n >= heap->vars_used || !heap->vars[n].is_bound) {
 	RETURN_VAR_ERROR("Variable $%d is unbound.", n, context, *constant);
-    DMC_PUSH(*text, matchPushV);
-    DMC_PUSH(*text, n);
+    }
+
+    dmc_add_pushv_variant(context, heap, text, n);
+
     ++context->stack_used;
     if (context->stack_used > context->stack_need)
 	context->stack_need = context->stack_used;
@@ -3351,10 +3621,9 @@ static DMCRet dmc_all_bindings(DMCContext *context,
 
     DMC_PUSH(*text, matchPushC);
     DMC_PUSH(*text, NIL);
-    for (i = heap->used - 1; i >= 0; --i) { 
-	if (heap->data[i]) {
-	    DMC_PUSH(*text, matchPushV);
-	    DMC_PUSH(*text, i);
+    for (i = heap->vars_used - 1; i >= 0; --i) {
+	if (heap->vars[i].is_bound) {
+	    dmc_add_pushv_variant(context, heap, text, i);
 	    DMC_PUSH(*text, matchConsB);
 	    heap_used += 2;
 	}
@@ -3362,7 +3631,6 @@ static DMCRet dmc_all_bindings(DMCContext *context,
     ++context->stack_used;
     if ((context->stack_used + 1) > context->stack_need)
 	context->stack_need = (context->stack_used + 1);
-    context->eheap_need += heap_used;
     *constant = 0;
     return retOk;
 }
@@ -3765,10 +4033,6 @@ static DMCRet dmc_get_seq_token(DMCContext *context,
 
     *constant = 0;
     DMC_PUSH(*text, matchGetSeqToken);
-    context->eheap_need += (6 /* A 5-tuple is built */
-			    + EXTERNAL_THING_HEAD_SIZE + 2 /* Sender can
-							      be an external
-							      pid */);
     if (++context->stack_used > context->stack_need)
  	context->stack_need = context->stack_used;
     return retOk;
@@ -4065,7 +4329,6 @@ static DMCRet dmc_caller(DMCContext *context,
     }
     *constant = 0;
     DMC_PUSH(*text, matchCaller); /* Creates binary */
-    context->eheap_need += 4;     /* A 3-tuple is built */
     if (++context->stack_used > context->stack_need)
  	context->stack_need = context->stack_used;
     return retOk;
@@ -4663,7 +4926,8 @@ static Eterm match_spec_test(Process *p, Eterm against, Eterm spec, int trace)
 	    }
 	    save_cp = p->cp;
 	    p->cp = NULL;
-	    res = erts_match_set_run(p, mps, arr, n, &ret_flags);
+	    res = erts_match_set_run(p, mps, arr, n,
+				     ERTS_PAM_COPY_RESULT, &ret_flags);
 	    p->cp = save_cp;
 	} else {
 	    n = 0;
@@ -4676,11 +4940,10 @@ static Eterm match_spec_test(Process *p, Eterm against, Eterm spec, int trace)
 	if (is_non_value(res)) {
 	    res = am_false;
 	}
-	sz = size_object(res);
+	sz = 0;
 	if (ret_flags & MATCH_SET_EXCEPTION_TRACE) sz += 2;
 	if (ret_flags & MATCH_SET_RETURN_TRACE) sz += 2;
 	hp = HAlloc(p, 5 + sz);
-	res = copy_struct(res, sz, &hp, &MSO(p));
 	flg = NIL;
 	if (ret_flags & MATCH_SET_EXCEPTION_TRACE) {
 	    flg = CONS(hp, am_exception_trace, flg);
@@ -4735,28 +4998,24 @@ void db_free_tmp_uncompressed(DbTerm* obj)
     erts_free(ERTS_ALC_T_TMP, obj);
 }
 
-Eterm db_prog_match_and_copy(DbTableCommon* tb, Process* c_p, Binary* bprog,
+Eterm db_match_dbterm(DbTableCommon* tb, Process* c_p, Binary* bprog,
 			     int all, DbTerm* obj, Eterm** hpp, Uint extra)
 {
     Uint32 dummy;
+    Eterm* base;
     Eterm res;
 
     if (tb->compress) {
 	obj = db_alloc_tmp_uncompressed(tb, obj);
+	base = NULL;
     }
+    else base = HALFWORD_HEAP ? obj->tpl : NULL;
 
-    res = db_prog_match(c_p, bprog, make_tuple(obj->tpl), NULL, 0, &dummy);
+    res = db_prog_match(c_p, bprog, make_tuple_rel(obj->tpl,base), base, NULL, 0,
+			ERTS_PAM_COPY_RESULT|ERTS_PAM_CONTIGUOUS_TUPLE, &dummy);
 
     if (is_value(res) && hpp!=NULL) {
-	if (all) {
-	    *hpp = HAlloc(c_p, obj->size + extra);
-	    res = copy_shallow(obj->tpl, obj->size, hpp, &MSO(c_p));
-	}
-	else {
-	    Uint sz = size_object(res);
-	    *hpp = HAlloc(c_p, sz + extra);
-	    res = copy_struct(res, sz, hpp, &MSO(c_p));
-	}
+	*hpp = HAlloc(c_p, extra);
     }
 
     if (tb->compress) {
@@ -4767,10 +5026,11 @@ Eterm db_prog_match_and_copy(DbTableCommon* tb, Process* c_p, Binary* bprog,
 
 
 #ifdef DMC_DEBUG
+
 /*
 ** Disassemble match program
 */
-static void db_match_dis(Binary *bp)
+void db_match_dis(Binary *bp)
 {
     MatchProg *prog = Binary2MatchProg(bp);
     UWord *t = prog->text;
@@ -4985,6 +5245,18 @@ static void db_match_dis(Binary *bp)
 	    ++t;
 	    erts_printf("PushV\t%bpu\n", n);
 	    break;
+    #if HALFWORD_HEAP
+	case matchPushVGuard:
+	    n = (Uint) *++t;
+	    ++t;
+	    erts_printf("PushVGuard\t%bpu\n", n);
+	    break;
+    #endif
+	case matchPushVResult:
+	    n = (Uint) *++t;
+	    ++t;
+	    erts_printf("PushVResult\t%bpu\n", n);
+	    break;
 	case matchTrue:
 	    ++t;
 	    erts_printf("True\n");
@@ -5095,7 +5367,6 @@ static void db_match_dis(Binary *bp)
     erts_printf("}\n");
     erts_printf("num_bindings: %d\n", prog->num_bindings);
     erts_printf("heap_size: %bpu\n", prog->heap_size);
-    erts_printf("eheap_offset: %bpu\n", prog->eheap_offset);
     erts_printf("stack_offset: %bpu\n", prog->stack_offset);
     erts_printf("text: 0x%08x\n", (unsigned long) prog->text);
     erts_printf("stack_size: %d (words)\n", prog->heap_size-prog->stack_offset);