Merge branch 'bjorn/erts/bif-stubs/OTP-9861'

* bjorn/erts/bif-stubs/OTP-9861:
  beam_load.c: Allow stubs for BIFs
  beam_load.c: Don't show unnecessary context in errors
  beam_load.c: Remove useless call to next_heap_size()
  beam_load.c: apply/2 does not need a special case

3 files changed, 111 insertions, 57 deletions

diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c
index dd788df6e4..1f9635a6c1 100644
--- a/erts/emulator/beam/beam_load.c
+++ b/erts/emulator/beam/beam_load.c
@@ -507,6 +507,7 @@ static int verify_chunks(LoaderState* stp);
 static int load_atom_table(LoaderState* stp);
 static int load_import_table(LoaderState* stp);
 static int read_export_table(LoaderState* stp);
+static int is_bif(Eterm mod, Eterm func, unsigned arity);
 static int read_lambda_table(LoaderState* stp);
 static int read_literal_table(LoaderState* stp);
 static int read_line_table(LoaderState* stp);
@@ -666,7 +667,7 @@ erts_prepare_loading(LoaderState* stp, Process *c_p, Eterm group_leader,
     /*
      * Initialize code area.
      */
-    stp->code_buffer_size = erts_next_heap_size(2048 + stp->num_functions, 0);
+    stp->code_buffer_size = 2048 + stp->num_functions;
     stp->code = (BeamInstr *) erts_alloc(ERTS_ALC_T_CODE,
 				    sizeof(BeamInstr) * stp->code_buffer_size);
 
@@ -1218,8 +1219,7 @@ load_atom_table(LoaderState* stp)
     GetInt(stp, 4, stp->num_atoms);
     stp->num_atoms++;
     stp->atom = erts_alloc(ERTS_ALC_T_LOADER_TMP,
-			   erts_next_heap_size((stp->num_atoms*sizeof(Eterm)),
-					       0));
+			   stp->num_atoms*sizeof(Eterm));
 
     /*
      * Read all atoms.
@@ -1264,9 +1264,7 @@ load_import_table(LoaderState* stp)
 
     GetInt(stp, 4, stp->num_imports);
     stp->import = erts_alloc(ERTS_ALC_T_LOADER_TMP,
-			     erts_next_heap_size((stp->num_imports *
-						  sizeof(ImportEntry)),
-						 0));
+			     stp->num_imports * sizeof(ImportEntry));
     for (i = 0; i < stp->num_imports; i++) {
 	int n;
 	Eterm mod;
@@ -1315,16 +1313,8 @@ load_import_table(LoaderState* stp)
 static int
 read_export_table(LoaderState* stp)
 {
-    static struct {
-	Eterm mod;
-	Eterm func;
-	int arity;
-    } allow_redef[] = {
-	/* The BIFs that are allowed to be redefined by Erlang code */
-	{am_erlang,am_apply,2},
-	{am_erlang,am_apply,3},
-    };
     int i;
+    BeamInstr* address;
 
     GetInt(stp, 4, stp->num_exps);
     if (stp->num_exps > stp->num_functions) {
@@ -1340,7 +1330,6 @@ read_export_table(LoaderState* stp)
 	Uint value;
 	Eterm func;
 	Uint arity;
-	Export* e;
 
 	GetInt(stp, 4, n);
 	GetAtom(stp, n, func);
@@ -1358,29 +1347,34 @@ read_export_table(LoaderState* stp)
 	if (value == 0) {
 	    LoadError2(stp, "export table entry %d: label %d not resolved", i, n);
 	}
-	stp->export[i].address = stp->code + value;
+	stp->export[i].address = address = stp->code + value;
 
 	/*
-	 * Check that we are not redefining a BIF (except the ones allowed to
-	 * redefine).
+	 * Find out if there is a BIF with the same name.
 	 */
-	if ((e = erts_find_export_entry(stp->module, func, arity)) != NULL) {
-	    if (e->code[3] == (BeamInstr) em_apply_bif) {
-		int j;
 
-		for (j = 0; j < sizeof(allow_redef)/sizeof(allow_redef[0]); j++) {
-		    if (stp->module == allow_redef[j].mod &&
-			func == allow_redef[j].func &&
-			arity == allow_redef[j].arity) {
-			break;
-		    }
-		}
-		if (j == sizeof(allow_redef)/sizeof(allow_redef[0])) {
-		    LoadError2(stp, "exported function %T/%d redefines BIF",
-			       func, arity);
-		}
-	    }
+	if (!is_bif(stp->module, func, arity)) {
+	    continue;
+	}
+
+	/*
+	 * This is a stub for a BIF.
+	 *
+	 * It should not be exported, and the information in its
+	 * func_info instruction should be invalidated so that it
+	 * can be filtered out by module_info(functions) and by
+	 * any other functions that walk through all local functions.
+	 */
+
+	if (stp->labels[n].patches) {
+	    LoadError3(stp, "there are local calls to the stub for "
+		       "the BIF %T:%T/%d",
+		       stp->module, func, arity);
 	}
+	stp->export[i].address = NULL;
+	address[-1] = 0;
+	address[-2] = NIL;
+	address[-3] = NIL;
     }
     return 1;
 
@@ -1388,6 +1382,27 @@ read_export_table(LoaderState* stp)
     return 0;
 }
 
+
+static int
+is_bif(Eterm mod, Eterm func, unsigned arity)
+{
+    Export* e = erts_find_export_entry(mod, func, arity);
+    if (e == NULL) {
+	return 0;
+    }
+    if (e->code[3] != (BeamInstr) em_apply_bif) {
+	return 0;
+    }
+    if (mod == am_erlang && func == am_apply && arity == 3) {
+	/*
+	 * erlang:apply/3 is a special case -- it is implemented
+	 * as an instruction and it is OK to redefine it.
+	 */
+	return 0;
+    }
+    return 1;
+}
+
 static int
 read_lambda_table(LoaderState* stp)
 {
@@ -1703,9 +1718,9 @@ read_code_header(LoaderState* stp)
 #define CodeNeed(w) do {						\
     ASSERT(ci <= code_buffer_size);					\
     if (code_buffer_size < ci+(w)) {					\
-        code_buffer_size = erts_next_heap_size(ci+(w), 0);		\
-	stp->code = code						\
-	    = (BeamInstr *) erts_realloc(ERTS_ALC_T_CODE,			\
+        code_buffer_size = 2*ci+(w);					\
+	stp->code = code =						\
+	    (BeamInstr *) erts_realloc(ERTS_ALC_T_CODE,			\
 				     (void *) code,			\
 				     code_buffer_size * sizeof(BeamInstr));	\
     } 									\
@@ -2457,6 +2472,9 @@ load_code(LoaderState* stp)
 	case op_int_code_end:
 	    stp->code_buffer_size = code_buffer_size;
 	    stp->ci = ci;
+	    stp->function = THE_NON_VALUE;
+	    stp->genop = NULL;
+	    stp->specific_op = -1;
 	    return 1;
 	}
 
@@ -4272,17 +4290,24 @@ final_touch(LoaderState* stp)
      */
 
     for (i = 0; i < stp->num_exps; i++) {
-	Export* ep = erts_export_put(stp->module, stp->export[i].function,
-				     stp->export[i].arity);
+	Export* ep;
+	BeamInstr* address = stp->export[i].address;
+
+	if (address == NULL) {
+	    /* Skip stub for a BIF */
+	    continue;
+	}
+	ep = erts_export_put(stp->module, stp->export[i].function,
+			     stp->export[i].arity);
 	if (!on_load) {
-	    ep->address = stp->export[i].address;
+	    ep->address = address;
 	} else {
 	    /*
 	     * Don't make any of the exported functions
 	     * callable yet.
 	     */
 	    ep->address = ep->code+3;
-	    ep->code[4] = (BeamInstr) stp->export[i].address;
+	    ep->code[4] = (BeamInstr) address;
 	}
     }
 
@@ -5054,7 +5079,9 @@ functions_in_module(Process* p, /* Process whose heap to use. */
     BeamInstr* code;
     int i;
     Uint num_functions;
+    Uint need;
     Eterm* hp;
+    Eterm* hp_end;
     Eterm result = NIL;
 
     if (is_not_atom(mod)) {
@@ -5067,19 +5094,28 @@ functions_in_module(Process* p, /* Process whose heap to use. */
     }
     code = modp->code;
     num_functions = code[MI_NUM_FUNCTIONS];
-    hp = HAlloc(p, 5*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];
 	Eterm name = (Eterm) func_info[3];
 	int arity = (int) func_info[4];
 	Eterm tuple;
 
-	ASSERT(is_atom(name));
-	tuple = TUPLE2(hp, name, make_small(arity));
-	hp += 3;
-	result = CONS(hp, tuple, result);
-	hp += 2;
+	/*
+	 * If the function name is [], this entry is a stub for
+	 * a BIF that should be ignored.
+	 */
+	ASSERT(is_atom(name) || is_nil(name));
+	if (is_atom(name)) {
+	    tuple = TUPLE2(hp, name, make_small(arity));
+	    hp += 3;
+	    result = CONS(hp, tuple, result);
+	    hp += 2;
+	}
     }
+    HRelease(p, hp_end, hp);
     return result;
 }
 
@@ -5627,19 +5663,28 @@ stub_final_touch(LoaderState* stp, BeamInstr* fp)
 {
     int i;
     int n = stp->num_exps;
+    Eterm mod = fp[2];
     Eterm function = fp[3];
     int arity = fp[4];
 #ifdef HIPE
     Lambda* lp;
 #endif
 
+    if (is_bif(mod, function, arity)) {
+	fp[1] = 0;
+	fp[2] = 0;
+	fp[3] = 0;
+	fp[4] = 0;
+	return;
+    }
+
     /*
      * Test if the function should be exported.
      */
 
     for (i = 0; i < n; i++) {
 	if (stp->export[i].function == function && stp->export[i].arity == arity) {
-	    Export* ep = erts_export_put(fp[2], function, arity);
+	    Export* ep = erts_export_put(mod, function, arity);
 	    ep->address = fp+5;
 	    return;
 	}
diff --git a/erts/emulator/beam/ops.tab b/erts/emulator/beam/ops.tab
index fc53a88a3a..f051f6aa5b 100644
--- a/erts/emulator/beam/ops.tab
+++ b/erts/emulator/beam/ops.tab
@@ -829,16 +829,20 @@ call_ext_only Ar=u==2 Bif=u$bif:erlang:load_nif/2 => allocate u Ar | i_call_ext
 
 
 #
-# The apply/2 and apply/3 BIFs are instructions.
+# apply/2 is an instruction, not a BIF.
 #
 
 call_ext u==2 u$func:erlang:apply/2 => i_apply_fun
 call_ext_last u==2 u$func:erlang:apply/2 D => i_apply_fun_last D
 call_ext_only u==2 u$func:erlang:apply/2 => i_apply_fun_only
 
-call_ext u==3 u$func:erlang:apply/3 => i_apply
-call_ext_last u==3 u$func:erlang:apply/3 D => i_apply_last D
-call_ext_only u==3 u$func:erlang:apply/3 => i_apply_only
+#
+# The apply/3 BIF is an instruction.
+#
+
+call_ext u==3 u$bif:erlang:apply/3 => i_apply
+call_ext_last u==3 u$bif:erlang:apply/3 D => i_apply_last D
+call_ext_only u==3 u$bif:erlang:apply/3 => i_apply_only
 
 #
 # The exit/1 and throw/1 BIFs never execute the instruction following them;
diff --git a/lib/kernel/src/hipe_unified_loader.erl b/lib/kernel/src/hipe_unified_loader.erl
index 8b3aa0286d..1b56cd8d90 100644
--- a/lib/kernel/src/hipe_unified_loader.erl
+++ b/lib/kernel/src/hipe_unified_loader.erl
@@ -330,11 +330,16 @@ exports(ExportMap, BaseAddress) ->
   exports(ExportMap, BaseAddress, [], []).
 
 exports([Offset,M,F,A,IsClosure,IsExported|Rest], BaseAddress, MFAs, Addresses) ->
-  MFA = {M,F,A},
-  Address = BaseAddress + Offset,
-  FunDef = #fundef{address=Address, mfa=MFA, is_closure=IsClosure,
-		   is_exported=IsExported},
-  exports(Rest, BaseAddress, [MFA|MFAs], [FunDef|Addresses]);
+  case IsExported andalso erlang:is_builtin(M, F, A) of
+    true ->
+      exports(Rest, BaseAddress, MFAs, Addresses);
+    _false ->
+      MFA = {M,F,A},
+      Address = BaseAddress + Offset,
+      FunDef = #fundef{address=Address, mfa=MFA, is_closure=IsClosure,
+		       is_exported=IsExported},
+      exports(Rest, BaseAddress, [MFA|MFAs], [FunDef|Addresses])
+  end;
 exports([], _, MFAs, Addresses) ->
   {MFAs, Addresses}.