erts: Refactor ESTACK & WSTACK to use a struct easy to "export"

This is not a clean refactor. It changes the behaviour slightly
of E/WSTACK_RESTORE. The allocated stack from E/WSTACK_SAVE is used
as-is and not copied into default_stack. This will hopefully fix an
illusive memory leak that valgrind is reporting.

3 files changed, 211 insertions, 221 deletions

diff --git a/erts/emulator/beam/external.c b/erts/emulator/beam/external.c
index 50831e848e..94acceaaf1 100644
--- a/erts/emulator/beam/external.c
+++ b/erts/emulator/beam/external.c
@@ -1732,8 +1732,7 @@ typedef struct TTBSizeContext_ {
     int level;
     Uint result;
     Eterm obj;
-    UWord* stack;
-    Uint   stack_sz;
+    ErtsEStack estack;
 } TTBSizeContext;
 
 typedef struct TTBEncodeContext_ {
@@ -1741,8 +1740,7 @@ typedef struct TTBEncodeContext_ {
     int level;
     byte* ep;
     Eterm obj;
-    UWord* stack;
-    Uint   stack_sz;
+    ErtsWStack wstack;
     Binary *result_bin;
 } TTBEncodeContext;
 
@@ -1772,16 +1770,10 @@ static void ttb_context_destructor(Binary *context_bin)
 	context->alive = 0;
 	switch (context->state) {
 	case TTBSize:
-	    if (context->s.sc.stack) {
-		erts_free(ERTS_ALC_T_SAVED_ESTACK, context->s.sc.stack);
-		context->s.sc.stack = NULL;
-	    }
+	    DESTROY_SAVED_ESTACK(&context->s.sc.estack);
 	    break;
 	case TTBEncode:
-	    if (context->s.ec.stack) {
-		erts_free(ERTS_ALC_T_SAVED_ESTACK, context->s.ec.stack);
-		context->s.ec.stack = NULL;
-	    }
+	    DESTROY_SAVED_WSTACK(&context->s.ec.wstack);
 	    if (context->s.ec.result_bin != NULL) { /* Set to NULL if ever made alive! */
 		ASSERT(erts_refc_read(&(context->s.ec.result_bin->refc),0) == 0);
 		erts_bin_free(context->s.ec.result_bin);
@@ -1846,7 +1838,7 @@ static Eterm erts_term_to_binary_int(Process* p, Eterm Term, int level, Uint fla
 	/* Setup enough to get started */
 	context->state = TTBSize;
 	context->alive = 1;
-	context->s.sc.stack = NULL;
+	context->s.sc.estack.start = NULL;
 	context->s.sc.flags = flags;
 	context->s.sc.level = level;
     } else {
@@ -1889,7 +1881,7 @@ static Eterm erts_term_to_binary_int(Process* p, Eterm Term, int level, Uint fla
 		context->state = TTBEncode;
 		context->s.ec.flags = flags;
 		context->s.ec.level = level;
-		context->s.ec.stack = NULL;
+		context->s.ec.wstack.wstart = NULL;
 		context->s.ec.result_bin = result_bin;
 		break;
 	    }
@@ -2340,8 +2332,8 @@ enc_term_int(TTBEncodeContext* ctx, ErtsAtomCacheMap *acmp, Eterm obj, byte* ep,
 	WSTACK_CHANGE_ALLOCATOR(s, ERTS_ALC_T_SAVED_ESTACK);
 	r = *reds;
 
-	if (ctx->stack) { /* restore saved stacks and byte pointer */
-	    WSTACK_RESTORE(s, ctx->stack, ctx->stack_sz);
+	if (ctx->wstack.wstart) { /* restore saved stacks and byte pointer */
+	    WSTACK_RESTORE(s, &ctx->wstack);
 	    ep = ctx->ep;
 	    obj = ctx->obj;
 	}
@@ -2412,7 +2404,7 @@ enc_term_int(TTBEncodeContext* ctx, ErtsAtomCacheMap *acmp, Eterm obj, byte* ep,
 	    *reds = r;
 	    ctx->obj = obj;
 	    ctx->ep = ep;
-	    WSTACK_SAVE(s, ctx->stack, ctx->stack_sz);
+	    WSTACK_SAVE(s, &ctx->wstack);
 	    return -1;
 	}
 	switch(tag_val_def(obj)) {
@@ -2767,10 +2759,7 @@ enc_term_int(TTBEncodeContext* ctx, ErtsAtomCacheMap *acmp, Eterm obj, byte* ep,
     }
     DESTROY_WSTACK(s);
     if (ctx) {
-	if (ctx->stack) {
-	    erts_free(ERTS_ALC_T_SAVED_ESTACK, ctx->stack);
-	    ctx->stack = NULL;
-	}
+	ASSERT(ctx->wstack.wstart == NULL);
 	*reds = r;
     }
     *res = ep;
@@ -3752,8 +3741,8 @@ encode_size_struct_int(TTBSizeContext* ctx, ErtsAtomCacheMap *acmp, Eterm obj,
 	ESTACK_CHANGE_ALLOCATOR(s, ERTS_ALC_T_SAVED_ESTACK);
 	r = *reds;
 
-	if (ctx->stack) { /* restore saved stack */
-	    ESTACK_RESTORE(s, ctx->stack, ctx->stack_sz);
+	if (ctx->estack.start) { /* restore saved stack */
+	    ESTACK_RESTORE(s, &ctx->estack);
 	    result = ctx->result;
 	    obj = ctx->obj;
 	}
@@ -3787,7 +3776,7 @@ encode_size_struct_int(TTBSizeContext* ctx, ErtsAtomCacheMap *acmp, Eterm obj,
 	    *reds = r;
 	    ctx->obj = obj;
 	    ctx->result = result;
-	    ESTACK_SAVE(s, ctx->stack, ctx->stack_sz);
+	    ESTACK_SAVE(s, &ctx->estack);
 	    return -1;
 	}
 	switch (tag_val_def(obj)) {
@@ -3991,10 +3980,7 @@ encode_size_struct_int(TTBSizeContext* ctx, ErtsAtomCacheMap *acmp, Eterm obj,
 
     DESTROY_ESTACK(s);
     if (ctx) {
-	if (ctx->stack) {
-	    erts_free(ERTS_ALC_T_SAVED_ESTACK, ctx->stack);
-	    ctx->stack = NULL;
-	}
+	ASSERT(ctx->estack.start == NULL);
 	*reds = r;
     }
     *res = result;
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 94bc1b172a..c44f532366 100755
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -1,7 +1,7 @@
 /*
  * %CopyrightBegin%
  *
- * Copyright Ericsson AB 1996-2013. All Rights Reserved.
+ * Copyright Ericsson AB 1996-2014. 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
@@ -370,231 +370,233 @@ extern int stackdump_on_exit;
  * DESTROY_ESTACK(Stack)
  */
 
+typedef struct {
+    UWord* start;
+    UWord* sp;
+    UWord* end;
+    ErtsAlcType_t alloc_type;
+}ErtsEStack;
 
-void erl_grow_stack(ErtsAlcType_t a_type, Eterm** start, Eterm** sp, Eterm** end);
-#define ESTK_CONCAT(a,b) a##b
-#define ESTK_SUBSCRIPT(s,i) *((Eterm *)((byte *)ESTK_CONCAT(s,_start) + (i)))
 #define DEF_ESTACK_SIZE (16)
 
-#define DECLARE_ESTACK(s)						\
-    Eterm ESTK_CONCAT(s,_default_stack)[DEF_ESTACK_SIZE];		\
-    Eterm* ESTK_CONCAT(s,_start) = ESTK_CONCAT(s,_default_stack);	\
-    Eterm* ESTK_CONCAT(s,_sp) = ESTK_CONCAT(s,_start);			\
-    Eterm* ESTK_CONCAT(s,_end) = ESTK_CONCAT(s,_start) + DEF_ESTACK_SIZE;\
-    ErtsAlcType_t ESTK_CONCAT(s,_alloc_type) = ERTS_ALC_T_ESTACK
+void erl_grow_estack(ErtsEStack*, Eterm* def_stack);
+#define ESTK_CONCAT(a,b) a##b
+#define ESTK_DEF_STACK(s) ESTK_CONCAT(s,_default_estack)
+
+#define DECLARE_ESTACK(s)				\
+    UWord ESTK_DEF_STACK(s)[DEF_ESTACK_SIZE];		\
+    ErtsEStack s = {					\
+        ESTK_DEF_STACK(s),  /* start */ 		\
+        ESTK_DEF_STACK(s),  /* sp */			\
+        ESTK_DEF_STACK(s) + DEF_ESTACK_SIZE, /* end */	\
+        ERTS_ALC_T_ESTACK /* alloc_type */		\
+    }
 
 #define ESTACK_CHANGE_ALLOCATOR(s,t)					\
 do {									\
-    if (ESTK_CONCAT(s,_start) != ESTK_CONCAT(s,_default_stack)) {	\
+    if (s.start != ESTK_DEF_STACK(s)) {					\
 	erl_exit(1, "Internal error - trying to change allocator "	\
 		 "type of active estack\n");				\
     }									\
-    ESTK_CONCAT(s,_alloc_type) = (t);					\
+    s.alloc_type = (t);							\
  } while (0)
 
+#define DESTROY_ESTACK(s)				\
+do {							\
+    if (s.start != ESTK_DEF_STACK(s)) {			\
+	erts_free(s.alloc_type, s.start); 		\
+    }							\
+} while(0)
+
+
 /*
- * Do not free the stack after this, it may have pointers into what 
- * was saved in 'v'. 'v' and 'vsize' are changed by this macro. If
- * 'v' points to anything, it should have been allocated by a previous 
- * call to this macro. Be careful to set a correct allocator prior to 
- * saving.
- * 'v' can be any lvalue pointer, it will point to an array of UWord
- * after calling this macro.
+ * Do not free the stack after this, it may have pointers into what
+ * was saved in 'dst'.
  */
-#define ESTACK_SAVE(s,v,vsize) /* v and vsize are "name parameters" */	\
-do {									\
-    Uint _esz = ESTACK_COUNT(s);					\
-    if (ESTK_CONCAT(s,_start) == ESTK_CONCAT(s,_default_stack)) {	\
-	if ((v) == NULL) {						\
-	    (v) = erts_alloc(ESTK_CONCAT(s,_alloc_type),		\
-			     DEF_ESTACK_SIZE * sizeof(Eterm));		\
-	}								\
-	memcpy((v),ESTK_CONCAT(s,_start),_esz*sizeof(Eterm));		\
-    } else {								\
-	(v) = (void *) ESTK_CONCAT(s,_start);				\
-    }									\
-    (vsize) = _esz;							\
+#define ESTACK_SAVE(s,dst)\
+do {\
+    if (s.start == ESTK_DEF_STACK(s)) {\
+	UWord _wsz = ESTACK_COUNT(s);\
+	(dst)->start = erts_alloc(s.alloc_type,\
+				  DEF_ESTACK_SIZE * sizeof(UWord));\
+	memcpy((dst)->start, s.start,_wsz*sizeof(UWord));\
+	(dst)->sp = (dst)->start + _wsz;\
+	(dst)->end = (dst)->start + DEF_ESTACK_SIZE;\
+	(dst)->alloc_type = s.alloc_type;\
+    } else\
+        *(dst) = s;\
  } while (0)
 
-/* 
- * Use on empty stack, only the allocator can be changed before this 
- * The vector parameter is reset to NULL if the vector is moved to stack,
- * otherwise it's kept for reuse, so a saved and restored vector might 
- * need freeing using the correct allocator parameter.
- * 'v' can be any lvalue pointer, it's cast to an (Eterm *).
+#define DESTROY_SAVED_ESTACK(estack)\
+do {\
+    if ((estack)->start) {\
+	erts_free((estack)->alloc_type, (estack)->start);\
+	(estack)->start = NULL;\
+    }\
+} while(0)
+
+/*
+ * Use on empty stack, only the allocator can be changed before this.
+ * The src stack is reset to NULL.
  */
-#define ESTACK_RESTORE(s, v, vsize) /*v is a "name parameter"*/ \
-do {								\
-    if ((vsize) > DEF_ESTACK_SIZE) {				\
-	Uint _ca = DEF_ESTACK_SIZE;				\
-	while (_ca < (vsize))					\
-	    _ca = _ca * 2;					\
-	ESTK_CONCAT(s,_start) = (Eterm *) (v);			\
-	ESTK_CONCAT(s,_end) = ((Eterm *)(v)) + _ca;		\
-	ESTK_CONCAT(s,_sp) = ESTK_CONCAT(s,_start) + (vsize);	\
-	(v) = NULL;                                             \
-    } else {							\
-	memcpy(ESTK_CONCAT(s,_start),(v),(vsize)*sizeof(Eterm));\
-	ESTK_CONCAT(s,_sp) = ESTK_CONCAT(s,_start) + (vsize);	\
-    }								\
- } while (0)
+#define ESTACK_RESTORE(s, src)			\
+do {						\
+    ASSERT(s.start == ESTK_DEF_STACK(s));	\
+    s = *(src);  /* struct copy */		\
+    (src)->start = NULL;			\
+    ASSERT(s.sp >= s.start);			\
+    ASSERT(s.sp <= s.end);			\
+} while (0)
 
-#define ESTACK_IS_STATIC(s) (ESTK_CONCAT(s,_start) == ESTK_CONCAT(s,_default_stack))
+#define ESTACK_IS_STATIC(s) (s.start == ESTK_DEF_STACK(s)))
 
-#define DESTROY_ESTACK(s)						\
-do {									\
-    if (ESTK_CONCAT(s,_start) != ESTK_CONCAT(s,_default_stack)) {	\
-	erts_free(ESTK_CONCAT(s,_alloc_type), ESTK_CONCAT(s,_start));		\
-    }									\
+#define ESTACK_PUSH(s, x)				\
+do {							\
+    if (s.sp == s.end) {				\
+	erl_grow_estack(&s, ESTK_DEF_STACK(s)); 	\
+    }							\
+    *s.sp++ = (x);					\
 } while(0)
 
-#define ESTACK_PUSH(s, x)						\
-do {									\
-    if (ESTK_CONCAT(s,_sp) == ESTK_CONCAT(s,_end)) {			\
-	erl_grow_stack(ESTK_CONCAT(s,_alloc_type),&ESTK_CONCAT(s,_start), \
-		       &ESTK_CONCAT(s,_sp), &ESTK_CONCAT(s,_end));	\
-    }									\
-    *ESTK_CONCAT(s,_sp)++ = (x);					\
+#define ESTACK_PUSH2(s, x, y)			\
+do {						\
+    if (s.sp > s.end - 2) {			\
+	erl_grow_estack(&s, ESTK_DEF_STACK(s)); \
+    }						\
+    *s.sp++ = (x);				\
+    *s.sp++ = (y);				\
 } while(0)
 
-#define ESTACK_PUSH2(s, x, y)						\
-do {									\
-    if (ESTK_CONCAT(s,_sp) > ESTK_CONCAT(s,_end) - 2) {			\
-	erl_grow_stack(ESTK_CONCAT(s,_alloc_type),&ESTK_CONCAT(s,_start), \
-		&ESTK_CONCAT(s,_sp), &ESTK_CONCAT(s,_end));	\
-    }									\
-    *ESTK_CONCAT(s,_sp)++ = (x);					\
-    *ESTK_CONCAT(s,_sp)++ = (y);					\
+#define ESTACK_PUSH3(s, x, y, z)		\
+do {						\
+    if (s.sp > s.end - 3) {			\
+	erl_grow_estack(&s, ESTK_DEF_STACK(s)); \
+    }						\
+    *s.sp++ = (x);				\
+    *s.sp++ = (y);				\
+    *s.sp++ = (z);				\
 } while(0)
 
-#define ESTACK_PUSH3(s, x, y, z)					\
-do {									\
-    if (ESTK_CONCAT(s,_sp) > ESTK_CONCAT(s,_end) - 3) {			\
-	erl_grow_stack(&ESTK_CONCAT(s,_start), &ESTK_CONCAT(s,_sp),	\
-		&ESTK_CONCAT(s,_end));					\
-    }									\
-    *ESTK_CONCAT(s,_sp)++ = (x);					\
-    *ESTK_CONCAT(s,_sp)++ = (y);					\
-    *ESTK_CONCAT(s,_sp)++ = (z);					\
-} while(0)
+#define ESTACK_COUNT(s) (s.sp - s.start)
+#define ESTACK_ISEMPTY(s) (s.sp == s.start)
+#define ESTACK_POP(s) (*(--s.sp))
 
-#define ESTACK_COUNT(s) (ESTK_CONCAT(s,_sp) - ESTK_CONCAT(s,_start))
 
-#define ESTACK_ISEMPTY(s) (ESTK_CONCAT(s,_sp) == ESTK_CONCAT(s,_start))
-#define ESTACK_POP(s) (*(--ESTK_CONCAT(s,_sp)))
+/*
+ * WSTACK: same as ESTACK but with UWord instead of Eterm
+ */
 
+typedef struct {
+    UWord* wstart;
+    UWord* wsp;
+    UWord* wend;
+    ErtsAlcType_t alloc_type;
+}ErtsWStack;
 
-void erl_grow_wstack(ErtsAlcType_t a_type, UWord** start, UWord** sp, UWord** end);
-#define WSTK_CONCAT(a,b) a##b
-#define WSTK_SUBSCRIPT(s,i) *((UWord *)((byte *)WSTK_CONCAT(s,_start) + (i)))
 #define DEF_WSTACK_SIZE (16)
 
-#define DECLARE_WSTACK(s)						\
-    UWord WSTK_CONCAT(s,_default_stack)[DEF_WSTACK_SIZE];		\
-    UWord* WSTK_CONCAT(s,_start) = WSTK_CONCAT(s,_default_stack);	\
-    UWord* WSTK_CONCAT(s,_sp) = WSTK_CONCAT(s,_start);			\
-    UWord* WSTK_CONCAT(s,_end) = WSTK_CONCAT(s,_start) + DEF_WSTACK_SIZE; \
-    ErtsAlcType_t WSTK_CONCAT(s,_alloc_type) = ERTS_ALC_T_ESTACK
+void erl_grow_wstack(ErtsWStack*, Eterm* def_stack);
+#define WSTK_CONCAT(a,b) a##b
+#define WSTK_DEF_STACK(s) WSTK_CONCAT(s,_default_wstack)
+
+#define DECLARE_WSTACK(s)				\
+    UWord WSTK_DEF_STACK(s)[DEF_WSTACK_SIZE];		\
+    ErtsWStack s = {					\
+        WSTK_DEF_STACK(s),  /* wstart */ 		\
+        WSTK_DEF_STACK(s),  /* wsp */			\
+        WSTK_DEF_STACK(s) + DEF_WSTACK_SIZE, /* wend */	\
+        ERTS_ALC_T_ESTACK /* alloc_type */		\
+    }
 
 #define WSTACK_CHANGE_ALLOCATOR(s,t)					\
 do {									\
-    if (WSTK_CONCAT(s,_start) != WSTK_CONCAT(s,_default_stack)) {	\
+    if (s.wstart != WSTK_DEF_STACK(s)) {				\
 	erl_exit(1, "Internal error - trying to change allocator "	\
 		 "type of active wstack\n");				\
     }									\
-    WSTK_CONCAT(s,_alloc_type) = (t);					\
+    s.alloc_type = (t);							\
  } while (0)
 
-#define DESTROY_WSTACK(s)						\
-do {									\
-    if (WSTK_CONCAT(s,_start) != WSTK_CONCAT(s,_default_stack)) {	\
-	erts_free(WSTK_CONCAT(s,_alloc_type), WSTK_CONCAT(s,_start));		\
-    }									\
+#define DESTROY_WSTACK(s)				\
+do {							\
+    if (s.wstart != WSTK_DEF_STACK(s)) {		\
+	erts_free(s.alloc_type, s.wstart); 		\
+    }							\
 } while(0)
 
+
 /*
- * Do not free the stack after this, it may have pointers into what 
- * was saved in 'v'. 'v' and 'vsize' are changed by this macro. If
- * 'v' points to anything, it should have been allocated by a previous 
- * call to this macro. Be careful to set a correct allocator prior to 
- * saving.
- * 'v' can be any lvalue pointer, it will point to an array of UWord
- * after calling this macro.
+ * Do not free the stack after this, it may have pointers into what
+ * was saved in 'dst'.
  */
-#define WSTACK_SAVE(s,v,vsize) /* v and vsize are "name parameters" */	\
-do {									\
-    Uint _wsz = WSTACK_COUNT(s);					\
-    if (WSTK_CONCAT(s,_start) == WSTK_CONCAT(s,_default_stack)) {	\
-	if ((v) == NULL) {						\
-	    (v) = erts_alloc(WSTK_CONCAT(s,_alloc_type),		\
-			     DEF_WSTACK_SIZE * sizeof(UWord));		\
-	}								\
-	memcpy((v),WSTK_CONCAT(s,_start),_wsz*sizeof(UWord));		\
-    } else {								\
-	(v) = (void *) WSTK_CONCAT(s,_start);				\
-    }									\
-    (vsize) = _wsz;							\
+#define WSTACK_SAVE(s,dst)\
+do {\
+    if (s.wstart == WSTK_DEF_STACK(s)) {\
+	UWord _wsz = WSTACK_COUNT(s);\
+	(dst)->wstart = erts_alloc(s.alloc_type,\
+				  DEF_WSTACK_SIZE * sizeof(UWord));\
+	memcpy((dst)->wstart, s.wstart,_wsz*sizeof(UWord));\
+	(dst)->wsp = (dst)->wstart + _wsz;\
+	(dst)->wend = (dst)->wstart + DEF_WSTACK_SIZE;\
+	(dst)->alloc_type = s.alloc_type;\
+    } else\
+        *(dst) = s;\
  } while (0)
 
-/* 
- * Use on empty stack, only the allocator can be changed before this 
- * The vector parameter is reset to NULL if the vector is moved to stack,
- * otherwise it's kept for reuse, so a saved and restored vector might 
- * need freeing using the correct allocator parameter.
- * 'v' can be any lvalue pointer, it's cast to an (UWord *).
+#define DESTROY_SAVED_WSTACK(wstack)\
+do {\
+    if ((wstack)->wstart) {\
+	erts_free((wstack)->alloc_type, (wstack)->wstart);\
+	(wstack)->wstart = NULL;\
+    }\
+} while(0)
+
+/*
+ * Use on empty stack, only the allocator can be changed before this.
+ * The src stack is reset to NULL.
  */
-#define WSTACK_RESTORE(s, v, vsize) /*v is a "name parameter"*/ \
-do {								\
-    if ((vsize) > DEF_WSTACK_SIZE) {				\
-	Uint _ca = DEF_WSTACK_SIZE;				\
-	while (_ca < (vsize))					\
-	    _ca = _ca * 2;					\
-	WSTK_CONCAT(s,_start) = (UWord *) (v);			\
-	WSTK_CONCAT(s,_end) = ((UWord *)(v)) + _ca;		\
-	WSTK_CONCAT(s,_sp) = WSTK_CONCAT(s,_start) + (vsize);	\
-	(v) = NULL;                                             \
-    } else {							\
-	memcpy(WSTK_CONCAT(s,_start),(v),(vsize)*sizeof(UWord));\
-	WSTK_CONCAT(s,_sp) = WSTK_CONCAT(s,_start) + (vsize);	\
-    }								\
- } while (0)
+#define WSTACK_RESTORE(s, src)			\
+do {						\
+    ASSERT(s.wstart == WSTK_DEF_STACK(s));	\
+    s = *(src);  /* struct copy */		\
+    (src)->wstart = NULL;			\
+    ASSERT(s.wsp >= s.wstart);			\
+    ASSERT(s.wsp <= s.wend);			\
+} while (0)
 
-#define WSTACK_IS_STATIC(s) (WSTK_CONCAT(s,_start) == WSTK_CONCAT(s,_default_stack))
+#define WSTACK_IS_STATIC(s) (s.wstart == WSTK_DEF_STACK(s)))
 
-#define WSTACK_PUSH(s, x)						\
-do {									\
-    if (WSTK_CONCAT(s,_sp) == WSTK_CONCAT(s,_end)) {			\
-	erl_grow_wstack(WSTK_CONCAT(s,_alloc_type), &WSTK_CONCAT(s,_start), \
-			&WSTK_CONCAT(s,_sp), &WSTK_CONCAT(s,_end));	\
-    }									\
-    *WSTK_CONCAT(s,_sp)++ = (x);					\
+#define WSTACK_PUSH(s, x)				\
+do {							\
+    if (s.wsp == s.wend) {				\
+	erl_grow_wstack(&s, WSTK_DEF_STACK(s)); 	\
+    }							\
+    *s.wsp++ = (x);					\
 } while(0)
 
-#define WSTACK_PUSH2(s, x, y)						\
-do {									\
-    if (WSTK_CONCAT(s,_sp) > WSTK_CONCAT(s,_end) - 2) {			\
-	erl_grow_wstack(WSTK_CONCAT(s,_alloc_type), &WSTK_CONCAT(s,_start), \
-		 &WSTK_CONCAT(s,_sp), &WSTK_CONCAT(s,_end));	        \
-    }									\
-    *WSTK_CONCAT(s,_sp)++ = (x);					\
-    *WSTK_CONCAT(s,_sp)++ = (y);					\
+#define WSTACK_PUSH2(s, x, y)			\
+do {						\
+    if (s.wsp > s.wend - 2) {			\
+	erl_grow_wstack(&s, WSTK_DEF_STACK(s)); \
+    }						\
+    *s.wsp++ = (x);				\
+    *s.wsp++ = (y);				\
 } while(0)
 
-#define WSTACK_PUSH3(s, x, y, z)					\
-do {									\
-    if (WSTK_CONCAT(s,_sp) > WSTK_CONCAT(s,_end) - 3) {			\
-	erl_grow_wstack(WSTK_CONCAT(s,_alloc_type), &WSTK_CONCAT(s,_start), \
-		&WSTK_CONCAT(s,_sp), &WSTK_CONCAT(s,_end));		\
-    }									\
-    *WSTK_CONCAT(s,_sp)++ = (x);					\
-    *WSTK_CONCAT(s,_sp)++ = (y);					\
-    *WSTK_CONCAT(s,_sp)++ = (z);					\
+#define WSTACK_PUSH3(s, x, y, z)		\
+do {						\
+    if (s.wsp > s.wend - 3) {	\
+	erl_grow_wstack(&s, WSTK_DEF_STACK(s)); \
+    }						\
+    *s.wsp++ = (x);				\
+    *s.wsp++ = (y);				\
+    *s.wsp++ = (z);				\
 } while(0)
 
-#define WSTACK_COUNT(s) (WSTK_CONCAT(s,_sp) - WSTK_CONCAT(s,_start))
+#define WSTACK_COUNT(s) (s.wsp - s.wstart)
+#define WSTACK_ISEMPTY(s) (s.wsp == s.wstart)
+#define WSTACK_POP(s) (*(--s.wsp))
 
-#define WSTACK_ISEMPTY(s) (WSTK_CONCAT(s,_sp) == WSTK_CONCAT(s,_start))
-#define WSTACK_POP(s) (*(--WSTK_CONCAT(s,_sp)))
 
 /* binary.c */
 
diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index 216952e2ac..7f8bdcb2ca 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -185,39 +185,41 @@ erts_set_hole_marker(Eterm* ptr, Uint sz)
  * Helper function for the ESTACK macros defined in global.h.
  */
 void
-erl_grow_stack(ErtsAlcType_t a_type, Eterm** start, Eterm** sp, Eterm** end)
+erl_grow_estack(ErtsEStack* s, Eterm* default_estack)
 {
-    Uint old_size = (*end - *start);
+    Uint old_size = (s->end - s->start);
     Uint new_size = old_size * 2;
-    Uint sp_offs = *sp - *start;
-    if (new_size > 2 * DEF_ESTACK_SIZE) {
-	*start = erts_realloc(a_type, (void *) *start, new_size*sizeof(Eterm));
+    Uint sp_offs = s->sp - s->start;
+    if (s->start != default_estack) {
+	s->start = erts_realloc(s->alloc_type, s->start,
+				new_size*sizeof(Eterm));
     } else {
-	Eterm* new_ptr = erts_alloc(a_type, new_size*sizeof(Eterm));
-	sys_memcpy(new_ptr, *start, old_size*sizeof(Eterm));
-	*start = new_ptr;
+	Eterm* new_ptr = erts_alloc(s->alloc_type, new_size*sizeof(Eterm));
+	sys_memcpy(new_ptr, s->start, old_size*sizeof(Eterm));
+	s->start = new_ptr;
     }
-    *end = *start + new_size;
-    *sp = *start + sp_offs;
+    s->end = s->start + new_size;
+    s->sp = s->start + sp_offs;
 }
 /*
- * Helper function for the ESTACK macros defined in global.h.
+ * Helper function for the WSTACK macros defined in global.h.
  */
 void
-erl_grow_wstack(ErtsAlcType_t a_type, UWord** start, UWord** sp, UWord** end)
+erl_grow_wstack(ErtsWStack* s, UWord* default_wstack)
 {
-    Uint old_size = (*end - *start);
+    Uint old_size = (s->wend - s->wstart);
     Uint new_size = old_size * 2;
-    Uint sp_offs = *sp - *start;
-    if (new_size > 2 * DEF_ESTACK_SIZE) {
-	*start = erts_realloc(a_type, (void *) *start, new_size*sizeof(UWord));
+    Uint sp_offs = s->wsp - s->wstart;
+    if (s->wstart != default_wstack) {
+	s->wstart = erts_realloc(s->alloc_type, s->wstart,
+				 new_size*sizeof(UWord));
     } else {
-	UWord* new_ptr = erts_alloc(a_type, new_size*sizeof(UWord));
-	sys_memcpy(new_ptr, *start, old_size*sizeof(UWord));
-	*start = new_ptr;
+	UWord* new_ptr = erts_alloc(s->alloc_type, new_size*sizeof(UWord));
+	sys_memcpy(new_ptr, s->wstart, old_size*sizeof(UWord));
+	s->wstart = new_ptr;
     }
-    *end = *start + new_size;
-    *sp = *start + sp_offs;
+    s->wend = s->wstart + new_size;
+    s->wsp = s->wstart + sp_offs;
 }
 
 /* CTYPE macros */