erts: Refactor header of loaded beam code

to use a real C struct instead of array.

1 files changed, 197 insertions, 187 deletions

diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c
index a846e96204..c56e6732a0 100644
--- a/erts/emulator/beam/beam_load.c
+++ b/erts/emulator/beam/beam_load.c
@@ -80,7 +80,7 @@ ErlDrvBinary* erts_gzinflate_buffer(char*, int);
 
 typedef struct {
     Uint value;			/* Value of label (NULL if not known yet). */
-    Uint patches;		/* Index (into code buffer) to first location
+    Sint patches;		/* Index (into code buffer) to first location
 				 * which must be patched with the value of this label.
 				 */
 #ifdef ERTS_SMP
@@ -284,9 +284,10 @@ typedef struct LoaderState {
     int specific_op;		/* Specific opcode (-1 if not found). */
     int num_functions;		/* Number of functions in module. */
     int num_labels;		/* Number of labels. */
-    int code_buffer_size;	/* Size of code buffer in words.  */
-    BeamInstr* code;		/* Loaded code. */
-    int ci;			/* Current index into loaded code. */
+    BeamCodeHeader* hdr;	/* Loaded code header */
+    BeamInstr* codev;	        /* Loaded code buffer */
+    int        codev_size;      /* Size of code buffer in words. */
+    int ci;			/* Current index into loaded code buffer. */
     Label* labels;
     StringPatch* string_patches; /* Linked list of position into string table to patch. */
     BeamInstr catches;		/* Linked list of catch_yf instructions. */
@@ -480,7 +481,7 @@ static void free_literal_fragment(ErlHeapFragment*);
 static void loader_state_dtor(Binary* magic);
 static Eterm insert_new_code(Process *c_p, ErtsProcLocks c_p_locks,
 			     Eterm group_leader, Eterm module,
-			     BeamInstr* code, Uint size);
+			     BeamCodeHeader* code, Uint size);
 static int init_iff_file(LoaderState* stp, byte* code, Uint size);
 static int scan_iff_file(LoaderState* stp, Uint* chunk_types,
 			 Uint num_types, Uint num_mandatory);
@@ -526,15 +527,15 @@ static void new_string_patch(LoaderState* stp, int pos);
 static Uint new_literal(LoaderState* stp, Eterm** hpp, Uint heap_size);
 static int genopargcompare(GenOpArg* a, GenOpArg* b);
 static Eterm get_module_info(Process* p, ErtsCodeIndex code_ix,
-                             BeamInstr* code, Eterm module, Eterm what);
+                             BeamCodeHeader*, Eterm module, Eterm what);
 static Eterm exported_from_module(Process* p, ErtsCodeIndex code_ix,
                                   Eterm mod);
-static Eterm functions_in_module(Process* p, BeamInstr* code);
-static Eterm attributes_for_module(Process* p, BeamInstr* code);
-static Eterm compilation_info_for_module(Process* p, BeamInstr* code);
-static Eterm md5_of_module(Process* p, BeamInstr* code);
-static Eterm has_native(BeamInstr* code);
-static Eterm native_addresses(Process* p, BeamInstr* code);
+static Eterm functions_in_module(Process* p, BeamCodeHeader*);
+static Eterm attributes_for_module(Process* p, BeamCodeHeader*);
+static Eterm compilation_info_for_module(Process* p, BeamCodeHeader*);
+static Eterm md5_of_module(Process* p, BeamCodeHeader*);
+static Eterm has_native(BeamCodeHeader*);
+static Eterm native_addresses(Process* p, BeamCodeHeader*);
 int patch_funentries(Eterm Patchlist);
 int patch(Eterm Addresses, Uint fe);
 static int safe_mul(UWord a, UWord b, UWord* resp);
@@ -601,6 +602,7 @@ extern void check_allocated_block(Uint type, void *blk);
 #define CHKBLK(TYPE,BLK) /* nothing */
 #endif
 
+
 Eterm
 erts_prepare_loading(Binary* magic, Process *c_p, Eterm group_leader,
 		     Eterm* modp, byte* code, Uint unloaded_size)
@@ -641,21 +643,27 @@ erts_prepare_loading(Binary* magic, Process *c_p, Eterm group_leader,
     /*
      * Initialize code area.
      */
-    stp->code_buffer_size = 2048 + stp->num_functions;
-    stp->code = (BeamInstr *) erts_alloc(ERTS_ALC_T_CODE,
-				    sizeof(BeamInstr) * stp->code_buffer_size);
-
-    stp->code[MI_NUM_FUNCTIONS] = stp->num_functions;
-    stp->ci = MI_FUNCTIONS + stp->num_functions + 1;
-
-    stp->code[MI_ATTR_PTR] = 0;
-    stp->code[MI_ATTR_SIZE] = 0;
-    stp->code[MI_ATTR_SIZE_ON_HEAP] = 0;
-    stp->code[MI_COMPILE_PTR] = 0;
-    stp->code[MI_COMPILE_SIZE] = 0;
-    stp->code[MI_COMPILE_SIZE_ON_HEAP] = 0;
-    stp->code[MI_LITERALS_START] = 0;
-    stp->code[MI_MD5_PTR] = 0;
+    stp->codev_size = 2048 + stp->num_functions;
+    stp->hdr = (BeamCodeHeader*) erts_alloc(ERTS_ALC_T_CODE,
+                                            (offsetof(BeamCodeHeader,functions)
+                                             + sizeof(BeamInstr) * stp->codev_size));
+
+    stp->hdr->num_functions = stp->num_functions;
+
+    /* Let the codev array start at functions[0] in order to index
+     * both function pointers and the loaded code itself that follows.
+     */
+    stp->codev = (BeamInstr*) &stp->hdr->functions;
+    stp->ci = stp->num_functions + 1;
+
+    stp->hdr->attr_ptr = NULL;
+    stp->hdr->attr_size = 0;
+    stp->hdr->attr_size_on_heap = 0;
+    stp->hdr->compile_ptr = NULL;
+    stp->hdr->compile_size = 0;
+    stp->hdr->compile_size_on_heap = 0;
+    stp->hdr->literals_start = NULL;
+    stp->hdr->md5_ptr = NULL;
 
     /*
      * Read the atom table.
@@ -777,7 +785,7 @@ erts_finish_loading(Binary* magic, Process* c_p,
 
     CHKBLK(ERTS_ALC_T_CODE,stp->code);
     retval = insert_new_code(c_p, c_p_locks, stp->group_leader, stp->module,
-			     stp->code, stp->loaded_size);
+			     stp->hdr, stp->loaded_size);
     if (retval != NIL) {
 	goto load_error;
     }
@@ -800,7 +808,8 @@ erts_finish_loading(Binary* magic, Process* c_p,
     debug_dump_code(stp->code,stp->ci);
 #endif
 #endif
-    stp->code = NULL;		/* Prevent code from being freed. */
+    stp->hdr = NULL;		/* Prevent code from being freed. */
+    stp->codev = NULL;
     *modp = stp->module;
 
     /*
@@ -832,7 +841,8 @@ erts_alloc_loader_state(void)
     stp->specific_op = -1;
     stp->genop = NULL;
     stp->atom = NULL;
-    stp->code = NULL;
+    stp->hdr = NULL;
+    stp->codev = NULL;
     stp->labels = NULL;
     stp->import = NULL;
     stp->export = NULL;
@@ -871,7 +881,7 @@ erts_module_for_prepared_code(Binary* magic)
 	return NIL;
     }
     stp = ERTS_MAGIC_BIN_DATA(magic);
-    if (stp->code != 0) {
+    if (stp->hdr != 0) {
 	return stp->module;
     } else {
 	return NIL;
@@ -921,12 +931,13 @@ loader_state_dtor(Binary* magic)
 	driver_free_binary(stp->bin);
 	stp->bin = 0;
     }
-    if (stp->code != 0) {
-        if (stp->code[MI_LITERALS_START]) {
-            erts_free(ERTS_ALC_T_LITERAL, (void*) stp->code[MI_LITERALS_START]);
+    if (stp->hdr != 0) {
+        if (stp->hdr->literals_start) {
+            erts_free(ERTS_ALC_T_LITERAL, stp->hdr->literals_start);
         }
-	erts_free(ERTS_ALC_T_CODE, stp->code);
-	stp->code = 0;
+	erts_free(ERTS_ALC_T_CODE, stp->hdr);
+	stp->hdr = 0;
+        stp->codev = 0;
     }
     if (stp->labels != 0) {
 	erts_free(ERTS_ALC_T_PREPARED_CODE, (void *) stp->labels);
@@ -999,7 +1010,7 @@ loader_state_dtor(Binary* magic)
 
 static Eterm
 insert_new_code(Process *c_p, ErtsProcLocks c_p_locks,
-		Eterm group_leader, Eterm module, BeamInstr* code,
+		Eterm group_leader, Eterm module, BeamCodeHeader* code_hdr,
 		Uint size)
 {
     Module* modp;
@@ -1020,7 +1031,7 @@ insert_new_code(Process *c_p, ErtsProcLocks c_p_locks,
 
     erts_total_code_size += size;
     modp = erts_put_module(module);
-    modp->curr.code = code;
+    modp->curr.code_hdr = code_hdr;
     modp->curr.code_length = size;
     modp->curr.catches = BEAM_CATCHES_NIL; /* Will be filled in later. */
 
@@ -1028,7 +1039,7 @@ insert_new_code(Process *c_p, ErtsProcLocks c_p_locks,
      * Update ranges (used for finding a function from a PC value).
      */
 
-    erts_update_ranges(code, size);
+    erts_update_ranges((BeamInstr*)modp->curr.code_hdr, size);
     return NIL;
 }
 
@@ -1377,7 +1388,7 @@ read_export_table(LoaderState* stp)
 	if (value == 0) {
 	    LoadError2(stp, "export table entry %d: label %d not resolved", i, n);
 	}
-	stp->export[i].address = address = stp->code + value;
+	stp->export[i].address = address = stp->codev + value;
 
 	/*
 	 * Find out if there is a BIF with the same name.
@@ -1396,7 +1407,7 @@ read_export_table(LoaderState* stp)
 	 * any other functions that walk through all local functions.
 	 */
 
-	if (stp->labels[n].patches) {
+	if (stp->labels[n].patches >= 0) {
 	    LoadError3(stp, "there are local calls to the stub for "
 		       "the BIF %T:%T/%d",
 		       stp->module, func, arity);
@@ -1739,7 +1750,7 @@ read_code_header(LoaderState* stp)
 				       stp->num_labels * sizeof(Label));
     for (i = 0; i < stp->num_labels; i++) {
 	stp->labels[i].value = 0;
-	stp->labels[i].patches = 0;
+	stp->labels[i].patches = -1;
 #ifdef ERTS_SMP
 	stp->labels[i].looprec_targeted = 0;
 #endif
@@ -1758,13 +1769,14 @@ read_code_header(LoaderState* stp)
     } else {}
 
 #define CodeNeed(w) do {						\
-    ASSERT(ci <= code_buffer_size);					\
-    if (code_buffer_size < ci+(w)) {					\
-        code_buffer_size = 2*ci+(w);					\
-	stp->code = code =						\
-	    (BeamInstr *) erts_realloc(ERTS_ALC_T_CODE,			\
-				     (void *) code,			\
-				     code_buffer_size * sizeof(BeamInstr));	\
+    ASSERT(ci <= codev_size);					        \
+    if (codev_size < ci+(w)) {					        \
+        codev_size = 2*ci+(w);	                                        \
+	stp->hdr = (BeamCodeHeader*) erts_realloc(ERTS_ALC_T_CODE,	\
+            (void *) stp->hdr,	                                        \
+            (offsetof(BeamCodeHeader,functions)                         \
+             + codev_size * sizeof(BeamInstr)));                        \
+        code = stp->codev = (BeamInstr*) &stp->hdr->functions;          \
     } 									\
 } while (0)
     
@@ -1780,7 +1792,7 @@ load_code(LoaderState* stp)
     int arg;			/* Number of current argument. */
     int num_specific;		/* Number of specific ops for current. */
     BeamInstr* code;
-    int code_buffer_size;
+    int codev_size;
     int specific;
     Uint last_label = 0;	/* Number of last label. */
     Uint function_number = 0;
@@ -1797,15 +1809,15 @@ load_code(LoaderState* stp)
 	FUNC_INFO_SZ = 5
     };
 
-    code = stp->code;
-    code_buffer_size = stp->code_buffer_size;
+    code = stp->codev;
+    codev_size = stp->codev_size;
     ci = stp->ci;
 
     for (;;) {
 	int new_op;
 	GenOp* tmp_op;
 
-	ASSERT(ci <= code_buffer_size);
+	ASSERT(ci <= codev_size);
 
     get_next_instr:
 	GetByte(stp, new_op);
@@ -2420,8 +2432,7 @@ load_code(LoaderState* stp)
 	switch (stp->specific_op) {
 	case op_i_func_info_IaaI:
 	    {
-		Uint offset;
-
+		Sint offset;
 		if (function_number >= stp->num_functions) {
 		    LoadError1(stp, "too many functions in module (header said %d)",
 			       stp->num_functions); 
@@ -2463,15 +2474,15 @@ load_code(LoaderState* stp)
 		stp->arity = code[ci-1];
 
 		ASSERT(stp->labels[last_label].value == ci - FUNC_INFO_SZ);
-		offset = MI_FUNCTIONS + function_number;
-		code[offset] = stp->labels[last_label].patches;
+		stp->hdr->functions[function_number] = (BeamInstr*) stp->labels[last_label].patches;
+		offset = function_number;
 		stp->labels[last_label].patches = offset;
 		function_number++;
 		if (stp->arity > MAX_ARG) {
 		    LoadError1(stp, "too many arguments: %d", stp->arity);
 		}
 #ifdef DEBUG
-		ASSERT(stp->labels[0].patches == 0); /* Should not be referenced. */
+		ASSERT(stp->labels[0].patches < 0); /* Should not be referenced. */
 		for (i = 1; i < stp->num_labels; i++) {
 		    ASSERT(stp->labels[i].patches < ci);
 		}
@@ -2541,7 +2552,7 @@ load_code(LoaderState* stp)
 	     * End of code found.
 	     */
 	case op_int_code_end:
-	    stp->code_buffer_size = code_buffer_size;
+	    stp->codev_size = codev_size;
 	    stp->ci = ci;
 	    stp->function = THE_NON_VALUE;
 	    stp->genop = NULL;
@@ -4351,7 +4362,8 @@ gen_has_map_fields(LoaderState* stp, GenOpArg Fail, GenOpArg Src,
 static int
 freeze_code(LoaderState* stp)
 {
-    BeamInstr* code = stp->code;
+    BeamCodeHeader* code_hdr = stp->hdr;
+    BeamInstr* codev = (BeamInstr*) &stp->hdr->functions;
     int i;
     byte* str_table;
     unsigned strtab_size = stp->chunks[STR_CHUNK].size;
@@ -4380,53 +4392,50 @@ freeze_code(LoaderState* stp)
 		     (stp->current_li+1) + stp->num_fnames) *
 	    sizeof(Eterm) + (stp->current_li+1) * stp->loc_size;
     }
-    size = (stp->ci * sizeof(BeamInstr)) +
+    size = offsetof(BeamCodeHeader,functions) + (stp->ci * sizeof(BeamInstr)) +
 	strtab_size + attr_size + compile_size + MD5_SIZE + line_size;
 
     /*
      * Move the code to its final location.
      */
 
-    code = (BeamInstr *) erts_realloc(ERTS_ALC_T_CODE, (void *) code, size);
-    CHKBLK(ERTS_ALC_T_CODE,code);
+    code_hdr = (BeamCodeHeader*) erts_realloc(ERTS_ALC_T_CODE, (void *) code_hdr, size);
+    codev = (BeamInstr*) &code_hdr->functions;
+    CHKBLK(ERTS_ALC_T_CODE,code_hdr);
     /*
      * Place a pointer to the op_int_code_end instruction in the
      * function table in the beginning of the file.
      */
 
-    code[MI_FUNCTIONS+stp->num_functions] = (BeamInstr) (code + stp->ci - 1);
-    CHKBLK(ERTS_ALC_T_CODE,code);
+    code_hdr->functions[stp->num_functions] = (codev + stp->ci - 1);
+    CHKBLK(ERTS_ALC_T_CODE,code_hdr);
 
     /*
      * Store the pointer to the on_load function.
      */
 
     if (stp->on_load) {
-	code[MI_ON_LOAD_FUNCTION_PTR] = (BeamInstr) (code + stp->on_load);
+	code_hdr->on_load_function_ptr = codev + stp->on_load;
     } else {
-	code[MI_ON_LOAD_FUNCTION_PTR] = 0;
+	code_hdr->on_load_function_ptr = NULL;
     }
-    CHKBLK(ERTS_ALC_T_CODE,code);
+    CHKBLK(ERTS_ALC_T_CODE,code_hdr);
 
     /*
      * Place the literals in their own allocated heap (for fast range check)
      * and fix up all instructions that refer to it.
      */
     {
-	Uint* ptr;
-	Uint* low;
-	Uint* high;
+	Eterm* ptr;
 	LiteralPatch* lp;
         ErlOffHeap code_off_heap;
 
         ERTS_INIT_OFF_HEAP(&code_off_heap);
 
-        low = erts_alloc(ERTS_ALC_T_LITERAL,
-                         stp->total_literal_size*sizeof(Eterm));
-	high = low + stp->total_literal_size;
-	code[MI_LITERALS_START] = (BeamInstr) low;
-	code[MI_LITERALS_END] = (BeamInstr) high;
-	ptr = low;
+        ptr = (Eterm*)erts_alloc(ERTS_ALC_T_LITERAL,
+                                 stp->total_literal_size*sizeof(Eterm));
+	code_hdr->literals_start = ptr;
+	code_hdr->literals_end = ptr + stp->total_literal_size;
 	for (i = 0; i < stp->num_literals; i++) {
             if (stp->literals[i].heap_frags) {
                 move_multi_frags(&ptr, &code_off_heap, stp->literals[i].heap_frags,
@@ -4435,13 +4444,13 @@ freeze_code(LoaderState* stp)
             }
             else ASSERT(is_immed(stp->literals[i].term));
 	}
-        code[MI_LITERALS_OFF_HEAP] = (BeamInstr) code_off_heap.first;
+	code_hdr->literals_off_heap = code_off_heap.first;
 	lp = stp->literal_patches;
 	while (lp != 0) {
 	    BeamInstr* op_ptr;
 	    Literal* lit;
 
-	    op_ptr = code + lp->pos;
+	    op_ptr = codev + lp->pos;
 	    lit = &stp->literals[op_ptr[0]];
 	    op_ptr[0] = lit->term;
 	    lp = lp->next;
@@ -4453,16 +4462,16 @@ freeze_code(LoaderState* stp)
      * If there is line information, place it here.
      */
     if (stp->line_instr == 0) {
-	code[MI_LINE_TABLE] = (BeamInstr) 0;
-	str_table = (byte *) (code+stp->ci);
+	code_hdr->line_table = NULL;
+	str_table = (byte *) (codev + stp->ci);
     } else {
-	Eterm* line_tab = (Eterm *) (code+stp->ci);
+	Eterm* line_tab = (Eterm *) (codev+stp->ci);
 	Eterm* p;
 	int ftab_size = stp->num_functions;
 	int num_instrs = stp->current_li;
 	Eterm* first_line_item;
 
-	code[MI_LINE_TABLE] = (BeamInstr) line_tab;
+	code_hdr->line_table = line_tab;
 	p = line_tab + MI_LINE_FUNC_TAB;
 
 	first_line_item = (p + ftab_size + 1);
@@ -4472,9 +4481,9 @@ freeze_code(LoaderState* stp)
 	*p++ = (Eterm) (BeamInstr) (first_line_item + num_instrs);
 	ASSERT(p == first_line_item);
 	for (i = 0; i < num_instrs; i++) {
-		*p++ = (Eterm) (BeamInstr) (code + stp->line_instr[i].pos);
+		*p++ = (Eterm) (BeamInstr) (codev + stp->line_instr[i].pos);
 	}
-	*p++ = (Eterm) (BeamInstr) (code + stp->ci - 1);
+	*p++ = (Eterm) (BeamInstr) (codev + stp->ci - 1);
 
 	line_tab[MI_LINE_FNAME_PTR] = (Eterm) (BeamInstr) p;
 	memcpy(p, stp->fname, stp->num_fnames*sizeof(Eterm));
@@ -4509,13 +4518,13 @@ freeze_code(LoaderState* stp)
     if (attr_size) {
 	byte* attr = str_table + strtab_size;
 	sys_memcpy(attr, stp->chunks[ATTR_CHUNK].start, stp->chunks[ATTR_CHUNK].size);
-	code[MI_ATTR_PTR] = (BeamInstr) attr;
-	code[MI_ATTR_SIZE] = (BeamInstr) stp->chunks[ATTR_CHUNK].size;
+	code_hdr->attr_ptr = attr;
+	code_hdr->attr_size = (BeamInstr) stp->chunks[ATTR_CHUNK].size;
 	decoded_size = erts_decode_ext_size(attr, attr_size);
 	if (decoded_size < 0) {
  	    LoadError0(stp, "bad external term representation of module attributes");
  	}
-	code[MI_ATTR_SIZE_ON_HEAP] = decoded_size;
+	code_hdr->attr_size_on_heap = decoded_size;
     }
     CHKBLK(ERTS_ALC_T_CODE,code);
     if (compile_size) {
@@ -4525,9 +4534,9 @@ freeze_code(LoaderState* stp)
 	       stp->chunks[COMPILE_CHUNK].size);
 
 	CHKBLK(ERTS_ALC_T_CODE,code);
-	code[MI_COMPILE_PTR] = (BeamInstr) compile_info;
+	code_hdr->compile_ptr = compile_info;
 	CHKBLK(ERTS_ALC_T_CODE,code);
-	code[MI_COMPILE_SIZE] = (BeamInstr) stp->chunks[COMPILE_CHUNK].size;
+	code_hdr->compile_size = (BeamInstr) stp->chunks[COMPILE_CHUNK].size;
 	CHKBLK(ERTS_ALC_T_CODE,code);
 	decoded_size = erts_decode_ext_size(compile_info, compile_size);
 	CHKBLK(ERTS_ALC_T_CODE,code);
@@ -4535,7 +4544,7 @@ freeze_code(LoaderState* stp)
  	    LoadError0(stp, "bad external term representation of compilation information");
  	}
 	CHKBLK(ERTS_ALC_T_CODE,code);
-	code[MI_COMPILE_SIZE_ON_HEAP] = decoded_size;
+	code_hdr->compile_size_on_heap = decoded_size;
     }
     CHKBLK(ERTS_ALC_T_CODE,code);
     {
@@ -4543,7 +4552,7 @@ freeze_code(LoaderState* stp)
 	CHKBLK(ERTS_ALC_T_CODE,code);
 	sys_memcpy(md5_sum, stp->mod_md5, MD5_SIZE);
 	CHKBLK(ERTS_ALC_T_CODE,code);
-	code[MI_MD5_PTR] = (BeamInstr) md5_sum;
+	code_hdr->md5_ptr = md5_sum;
 	CHKBLK(ERTS_ALC_T_CODE,code);
     }
     CHKBLK(ERTS_ALC_T_CODE,code);
@@ -4552,7 +4561,7 @@ freeze_code(LoaderState* stp)
      * Make sure that we have not overflowed the allocated code space.
      */
     ASSERT(str_table + strtab_size + attr_size + compile_size + MD5_SIZE ==
-	   ((byte *) code) + size);
+	   ((byte *) code_hdr) + size);
 
     /*
      * Patch all instructions that refer to the string table.
@@ -4564,46 +4573,47 @@ freeze_code(LoaderState* stp)
 	    BeamInstr* op_ptr;
 	    byte* strp;
 
-	    op_ptr = code + sp->pos;
+	    op_ptr = codev + sp->pos;
 	    strp = str_table + op_ptr[0];
 	    op_ptr[0] = (BeamInstr) strp;
 	    sp = sp->next;
 	}
     }
-    CHKBLK(ERTS_ALC_T_CODE,code);
+    CHKBLK(ERTS_ALC_T_CODE,code_hdr);
 
     /*
      * Resolve all labels.
      */
 
     for (i = 0; i < stp->num_labels; i++) {
-	Uint this_patch;
-	Uint next_patch;
+	Sint this_patch;
+	Sint next_patch;
 	Uint value = stp->labels[i].value;
 	
-	if (value == 0 && stp->labels[i].patches != 0) {
+	if (value == 0 && stp->labels[i].patches >= 0) {
 	    LoadError1(stp, "label %d not resolved", i);
 	}
 	ASSERT(value < stp->ci);
 	this_patch = stp->labels[i].patches;
-	while (this_patch != 0) {
+	while (this_patch >= 0) {
 	    ASSERT(this_patch < stp->ci);
-	    next_patch = code[this_patch];
+	    next_patch = codev[this_patch];
 	    ASSERT(next_patch < stp->ci);
-	    code[this_patch] = (BeamInstr) (code + value);
+	    codev[this_patch] = (BeamInstr) (codev + value);
 	    this_patch = next_patch;
 	}
     }
-    CHKBLK(ERTS_ALC_T_CODE,code);
+    CHKBLK(ERTS_ALC_T_CODE,code_hdr);
 
     /*
      * Save the updated code pointer and code size.
      */
 
-    stp->code = code;
+    stp->hdr = code_hdr;
+    stp->codev = codev;
     stp->loaded_size = size;
 
-    CHKBLK(ERTS_ALC_T_CODE,code);
+    CHKBLK(ERTS_ALC_T_CODE,code_hdr);
     return 1;
 
  load_error:
@@ -4611,7 +4621,8 @@ freeze_code(LoaderState* stp)
      * Make sure that the caller frees the newly reallocated block, and
      * not the old one (in case it has moved).
      */
-    stp->code = code;
+    stp->hdr = code_hdr;
+    stp->codev = codev;
     return 0;
 }
 
@@ -4622,7 +4633,7 @@ final_touch(LoaderState* stp)
     int on_load = stp->on_load;
     unsigned catches;
     Uint index;
-    BeamInstr* code = stp->code;
+    BeamInstr* codev = stp->codev;
     Module* modp;
 
     /*
@@ -4632,10 +4643,10 @@ final_touch(LoaderState* stp)
     index = stp->catches;
     catches = BEAM_CATCHES_NIL;
     while (index != 0) {
-	BeamInstr next = code[index];
-	code[index] = BeamOpCode(op_catch_yf);
-	catches = beam_catches_cons((BeamInstr *)code[index+2], catches);
-	code[index+2] = make_catch(catches);
+	BeamInstr next = codev[index];
+	codev[index] = BeamOpCode(op_catch_yf);
+	catches = beam_catches_cons((BeamInstr *)codev[index+2], catches);
+	codev[index+2] = make_catch(catches);
 	index = next;
     }
     modp = erts_put_module(stp->module);
@@ -4686,8 +4697,8 @@ final_touch(LoaderState* stp)
 	current = stp->import[i].patches;
 	while (current != 0) {
 	    ASSERT(current < stp->ci);
-	    next = stp->code[current];
-	    stp->code[current] = import;
+	    next = stp->codev[current];
+	    stp->codev[current] = import;
 	    current = next;
 	}
     }
@@ -4700,7 +4711,7 @@ final_touch(LoaderState* stp)
 	for (i = 0; i < stp->num_lambdas; i++) {
 	    unsigned entry_label = stp->lambdas[i].label;
 	    ErlFunEntry* fe = stp->lambdas[i].fe;
-	    BeamInstr* code_ptr = (BeamInstr *) (stp->code + stp->labels[entry_label].value);
+	    BeamInstr* code_ptr = stp->codev + stp->labels[entry_label].value;
 
 	    if (fe->address[0] != 0) {
 		/*
@@ -5324,7 +5335,7 @@ new_label(LoaderState* stp)
 					 (void *) stp->labels,
 					 stp->num_labels * sizeof(Label));
     stp->labels[num].value = 0;
-    stp->labels[num].patches = 0;
+    stp->labels[num].patches = -1;
     return num;
 }
 
@@ -5384,7 +5395,7 @@ erts_module_info_0(Process* p, Eterm module)
 {
     Module* modp;
     ErtsCodeIndex code_ix = erts_active_code_ix();
-    BeamInstr* code;
+    BeamCodeHeader* code_hdr;
     Eterm *hp;
     Eterm list = NIL;
     Eterm tup;
@@ -5398,13 +5409,13 @@ erts_module_info_0(Process* p, Eterm module)
 	return THE_NON_VALUE;
     }
 
-    code = modp->curr.code;
-    if (code == NULL) {
+    code_hdr = modp->curr.code_hdr;
+    if (code_hdr == NULL) {
         return THE_NON_VALUE;
     }
 
 #define BUILD_INFO(What) \
-    tup = get_module_info(p, code_ix, code, module, What); \
+    tup = get_module_info(p, code_ix, code_hdr, module, What); \
     hp = HAlloc(p, 5); \
     tup = TUPLE2(hp, What, tup); \
     hp += 3; \
@@ -5427,7 +5438,7 @@ erts_module_info_1(Process* p, Eterm module, Eterm what)
 {
     Module* modp;
     ErtsCodeIndex code_ix = erts_active_code_ix();
-    BeamInstr* code;
+    BeamCodeHeader* code_hdr;
 
     if (is_not_atom(module)) {
         return THE_NON_VALUE;
@@ -5438,34 +5449,34 @@ erts_module_info_1(Process* p, Eterm module, Eterm what)
         return THE_NON_VALUE;
     }
 
-    code = modp->curr.code;
-    if (code == NULL) {
+    code_hdr = modp->curr.code_hdr;
+    if (code_hdr == NULL) {
         return THE_NON_VALUE;
     }
 
-    return get_module_info(p, code_ix, code, module, what);
+    return get_module_info(p, code_ix, code_hdr, module, what);
 }
 
 static Eterm
-get_module_info(Process* p, ErtsCodeIndex code_ix, BeamInstr* code,
+get_module_info(Process* p, ErtsCodeIndex code_ix, BeamCodeHeader* code_hdr,
                 Eterm module, Eterm what)
 {
     if (what == am_module) {
 	return module;
     } else if (what == am_md5) {
-	return md5_of_module(p, code);
+	return md5_of_module(p, code_hdr);
     } else if (what == am_exports) {
 	return exported_from_module(p, code_ix, module);
     } else if (what == am_functions) {
-	return functions_in_module(p, code);
+	return functions_in_module(p, code_hdr);
     } else if (what == am_attributes) {
-	return attributes_for_module(p, code);
+	return attributes_for_module(p, code_hdr);
     } else if (what == am_compile) {
-	return compilation_info_for_module(p, code);
+	return compilation_info_for_module(p, code_hdr);
     } else if (what == am_native_addresses) {
-	return native_addresses(p, code);
+	return native_addresses(p, code_hdr);
     } else if (what == am_native) {
-	return has_native(code);
+	return has_native(code_hdr);
     }
     return THE_NON_VALUE;
 }
@@ -5477,7 +5488,7 @@ get_module_info(Process* p, ErtsCodeIndex code_ix, BeamInstr* code,
 
 Eterm
 functions_in_module(Process* p, /* Process whose heap to use. */
-		    BeamInstr* code)
+		    BeamCodeHeader* code_hdr)
 {
     int i;
     Uint num_functions;
@@ -5486,12 +5497,12 @@ functions_in_module(Process* p, /* Process whose heap to use. */
     Eterm* hp_end;
     Eterm result = NIL;
 
-    num_functions = code[MI_NUM_FUNCTIONS];
+    num_functions = code_hdr->num_functions;
     need = 5*num_functions;
     hp = HAlloc(p, need);
     hp_end = hp + need;
     for (i = num_functions-1; i >= 0 ; i--) {
-	BeamInstr* func_info = (BeamInstr *) code[MI_FUNCTIONS+i];
+	BeamInstr* func_info = code_hdr->functions[i];
 	Eterm name = (Eterm) func_info[3];
 	int arity = (int) func_info[4];
 	Eterm tuple;
@@ -5517,11 +5528,11 @@ functions_in_module(Process* p, /* Process whose heap to use. */
  */
 
 static Eterm
-has_native(BeamInstr *code)
+has_native(BeamCodeHeader *code_hdr)
 {
     Eterm result = am_false;
 #ifdef HIPE
-    if (erts_is_module_native(code)) {
+    if (erts_is_module_native(code_hdr)) {
         result = am_true;
     }
 #endif
@@ -5529,15 +5540,15 @@ has_native(BeamInstr *code)
 }
 
 int
-erts_is_module_native(BeamInstr* code)
+erts_is_module_native(BeamCodeHeader* code_hdr)
 {
     Uint i, num_functions;
 
     /* Check NativeAdress of first real function in module */
-    if (code != NULL) {
-        num_functions = code[MI_NUM_FUNCTIONS];
+    if (code_hdr != NULL) {
+        num_functions = code_hdr->num_functions;
         for (i=0; i<num_functions; i++) {
-            BeamInstr* func_info = (BeamInstr *) code[MI_FUNCTIONS+i];
+            BeamInstr* func_info = (BeamInstr *) code_hdr->functions[i];
             Eterm name = (Eterm) func_info[3];
             if (is_atom(name)) {
                 return func_info[1] != 0;
@@ -5554,7 +5565,7 @@ erts_is_module_native(BeamInstr* code)
  */
 
 static Eterm
-native_addresses(Process* p, BeamInstr* code)
+native_addresses(Process* p, BeamCodeHeader* code_hdr)
 {
     int i;
     Eterm* hp;
@@ -5563,12 +5574,12 @@ native_addresses(Process* p, BeamInstr* code)
     Eterm* hp_end;
     Eterm result = NIL;
 
-    num_functions = code[MI_NUM_FUNCTIONS];
+    num_functions = code_hdr->num_functions;
     need = (6+BIG_UINT_HEAP_SIZE)*num_functions;
     hp = HAlloc(p, need);
     hp_end = hp + need;
     for (i = num_functions-1; i >= 0 ; i--) {
-	BeamInstr* func_info = (BeamInstr *) code[MI_FUNCTIONS+i];
+	BeamInstr* func_info = code_hdr->functions[i];
 	Eterm name = (Eterm) func_info[3];
 	int arity = (int) func_info[4];
 	Eterm tuple;
@@ -5634,15 +5645,15 @@ exported_from_module(Process* p, /* Process whose heap to use. */
 
 Eterm
 attributes_for_module(Process* p, /* Process whose heap to use. */
-                      BeamInstr* code)
+                      BeamCodeHeader* code_hdr)
 {
     byte* ext;
     Eterm result = NIL;
 
-    ext = (byte *) code[MI_ATTR_PTR];
+    ext = code_hdr->attr_ptr;
     if (ext != NULL) {
 	ErtsHeapFactory factory;
-	erts_factory_proc_prealloc_init(&factory, p, code[MI_ATTR_SIZE_ON_HEAP]);
+	erts_factory_proc_prealloc_init(&factory, p, code_hdr->attr_size_on_heap);
 	result = erts_decode_ext(&factory, &ext);
 	if (is_value(result)) {
 	    erts_factory_close(&factory);
@@ -5657,15 +5668,15 @@ attributes_for_module(Process* p, /* Process whose heap to use. */
 
 Eterm
 compilation_info_for_module(Process* p, /* Process whose heap to use. */
-                            BeamInstr* code)
+                            BeamCodeHeader* code_hdr)
 {
     byte* ext;
     Eterm result = NIL;
 
-    ext = (byte *) code[MI_COMPILE_PTR];
+    ext = code_hdr->compile_ptr;
     if (ext != NULL) {
 	ErtsHeapFactory factory;
-	erts_factory_proc_prealloc_init(&factory, p, code[MI_COMPILE_SIZE_ON_HEAP]);
+	erts_factory_proc_prealloc_init(&factory, p, code_hdr->compile_size_on_heap);
 	result = erts_decode_ext(&factory, &ext);
 	if (is_value(result)) {
 	    erts_factory_close(&factory);
@@ -5680,9 +5691,9 @@ compilation_info_for_module(Process* p, /* Process whose heap to use. */
 
 Eterm
 md5_of_module(Process* p, /* Process whose heap to use. */
-              BeamInstr* code)
+              BeamCodeHeader* code_hdr)
 {
-    return new_binary(p, (byte *) code[MI_MD5_PTR], MD5_SIZE);
+    return new_binary(p, code_hdr->md5_ptr, MD5_SIZE);
 }
 
 /*
@@ -5893,7 +5904,7 @@ static byte*
 stub_copy_info(LoaderState* stp,
 	       int chunk,	/* Chunk: ATTR_CHUNK or COMPILE_CHUNK */
 	       byte* info,	/* Where to store info. */
-	       BeamInstr* ptr_word,	/* Where to store pointer into info. */
+	       byte** ptr_word,	/* Where to store pointer into info. */
 	       BeamInstr* size_word,	/* Where to store size into info. */
 	       BeamInstr* size_on_heap_word) /* Where to store size on heap. */
 {
@@ -5901,7 +5912,7 @@ stub_copy_info(LoaderState* stp,
     Uint size = stp->chunks[chunk].size;
     if (size != 0) {
 	memcpy(info, stp->chunks[chunk].start, size);
-	*ptr_word = (BeamInstr) info;
+	*ptr_word = info;
 	decoded_size = erts_decode_ext_size(info, size);
 	if (decoded_size < 0) {
  	    return 0;
@@ -6156,11 +6167,10 @@ erts_make_stub_module(Process* p, Eterm Mod, Eterm Beam, Eterm Info)
     BeamInstr Patchlist;
     Eterm MD5Bin;
     Eterm* tp;
-    BeamInstr* code = NULL;
-    BeamInstr* ptrs;
+    BeamCodeHeader* code_hdr;
+    BeamInstr* code_base;
     BeamInstr* fp;
     byte* info;
-    Uint ci;
     int n;
     int code_size;
     int rval;
@@ -6238,39 +6248,39 @@ erts_make_stub_module(Process* p, Eterm Mod, Eterm Beam, Eterm Info)
      * Allocate memory for the stub module.
      */
 
-    code_size = ((WORDS_PER_FUNCTION+1)*n + MI_FUNCTIONS + 2) * sizeof(BeamInstr);
-    code_size += stp->chunks[ATTR_CHUNK].size;
-    code_size += stp->chunks[COMPILE_CHUNK].size;
-    code_size += MD5_SIZE;
-    code = erts_alloc_fnf(ERTS_ALC_T_CODE, code_size);
-    if (!code) {
+    code_size = (offsetof(BeamCodeHeader,functions)
+                 + ((n+1) * sizeof(BeamInstr*))
+                 + (WORDS_PER_FUNCTION*n + 1) * sizeof(BeamInstr)
+                 + stp->chunks[ATTR_CHUNK].size
+                 + stp->chunks[COMPILE_CHUNK].size
+                 + MD5_SIZE);
+    code_hdr = erts_alloc_fnf(ERTS_ALC_T_CODE, code_size);
+    if (!code_hdr) {
 	goto error;
     }
 
     /*
-     * Initialize code area.
+     * Initialize code header.
      */
 
-    code[MI_NUM_FUNCTIONS] = n;
-    code[MI_ATTR_PTR] = 0;
-    code[MI_ATTR_SIZE] = 0;
-    code[MI_ATTR_SIZE_ON_HEAP] = 0;
-    code[MI_COMPILE_PTR] = 0;
-    code[MI_COMPILE_SIZE] = 0;
-    code[MI_COMPILE_SIZE_ON_HEAP] = 0;
-    code[MI_LITERALS_START] = 0;
-    code[MI_LITERALS_END] = 0;
-    code[MI_LITERALS_OFF_HEAP] = 0;
-    code[MI_ON_LOAD_FUNCTION_PTR] = 0;
-    code[MI_MD5_PTR] = 0;
-    ci = MI_FUNCTIONS + n + 1;
+    code_hdr->num_functions = n;
+    code_hdr->attr_ptr = NULL;
+    code_hdr->attr_size = 0;
+    code_hdr->attr_size_on_heap = 0;
+    code_hdr->compile_ptr = NULL;
+    code_hdr->compile_size = 0;
+    code_hdr->compile_size_on_heap = 0;
+    code_hdr->literals_start = NULL;
+    code_hdr->literals_end = NULL;
+    code_hdr->literals_off_heap = 0;
+    code_hdr->on_load_function_ptr = NULL;
+    code_hdr->md5_ptr = NULL;
 
     /*
      * Make stubs for all functions.
      */
 
-    ptrs = code + MI_FUNCTIONS;
-    fp = code + ci;
+    fp = code_base = (BeamInstr*) &code_hdr->functions[n+1];
     for (i = 0; i < n; i++) {
 	Eterm* listp;
 	Eterm tuple;
@@ -6313,7 +6323,7 @@ erts_make_stub_module(Process* p, Eterm Mod, Eterm Beam, Eterm Info)
 	 * Set the pointer and make the stub. Put a return instruction
 	 * as the body until we know what kind of trap we should put there.
 	 */
-	ptrs[i] = (BeamInstr) fp;
+	code_hdr->functions[i] = fp;
 #ifdef HIPE
 	op = (Eterm) BeamOpCode(op_hipe_trap_call); /* Might be changed later. */
 #else
@@ -6326,7 +6336,7 @@ erts_make_stub_module(Process* p, Eterm Mod, Eterm Beam, Eterm Info)
      * Insert the last pointer and the int_code_end instruction.
      */
 
-    ptrs[i] = (BeamInstr) fp;
+    code_hdr->functions[i] = fp;
     *fp++ = (BeamInstr) BeamOp(op_int_code_end);
 
     /*
@@ -6335,16 +6345,16 @@ erts_make_stub_module(Process* p, Eterm Mod, Eterm Beam, Eterm Info)
 
     info = (byte *) fp;
     info = stub_copy_info(stp, ATTR_CHUNK, info,
-			  code+MI_ATTR_PTR,
-			  code+MI_ATTR_SIZE,
-			  code+MI_ATTR_SIZE_ON_HEAP);
+			  &code_hdr->attr_ptr,
+			  &code_hdr->attr_size,
+			  &code_hdr->attr_size_on_heap);
     if (info == NULL) {
 	goto error;
     }
     info = stub_copy_info(stp, COMPILE_CHUNK, info,
-			  code+MI_COMPILE_PTR,
-			  code+MI_COMPILE_SIZE,
-			  code+MI_COMPILE_SIZE_ON_HEAP);
+			  &code_hdr->compile_ptr,
+			  &code_hdr->compile_size,
+			  &code_hdr->compile_size_on_heap);
     if (info == NULL) {
 	goto error;
     }
@@ -6353,7 +6363,7 @@ erts_make_stub_module(Process* p, Eterm Mod, Eterm Beam, Eterm Info)
       byte *md5 = NULL;
       if ((md5 = erts_get_aligned_binary_bytes(MD5Bin, &tmp)) != NULL) {
         sys_memcpy(info, md5, MD5_SIZE);
-        code[MI_MD5_PTR] = (BeamInstr) info;
+        code_hdr->md5_ptr = info;
       }
       erts_free_aligned_binary_bytes(tmp);
     }
@@ -6362,7 +6372,7 @@ erts_make_stub_module(Process* p, Eterm Mod, Eterm Beam, Eterm Info)
      * Insert the module in the module table.
      */
 
-    rval = insert_new_code(p, 0, p->group_leader, Mod, code, code_size);
+    rval = insert_new_code(p, 0, p->group_leader, Mod, code_hdr, code_size);
     if (rval != NIL) {
 	goto error;
     }
@@ -6371,7 +6381,7 @@ erts_make_stub_module(Process* p, Eterm Mod, Eterm Beam, Eterm Info)
      * Export all stub functions and insert the correct type of HiPE trap.
      */
 
-    fp = code + ci;
+    fp = code_base;
     for (i = 0; i < n; i++) {
 	stub_final_touch(stp, fp);
 	fp += WORDS_PER_FUNCTION;