From ea0e763e953f9c7d1fa9c142f24cb95f56119c56 Mon Sep 17 00:00:00 2001
From: Richard Carlsson <richardc@klarna.com>
Date: Mon, 28 Jan 2019 19:05:28 +0100
Subject: Add -ztma option for enabling tuple calls

---
 erts/doc/src/erl.xml          |  9 +++++++++
 erts/emulator/beam/beam_emu.c |  5 +++--
 erts/emulator/beam/erl_init.c | 14 ++++++++++++++
 erts/emulator/beam/erl_vm.h   |  2 ++
 erts/etc/common/erlexec.c     |  1 +
 5 files changed, 29 insertions(+), 2 deletions(-)

(limited to 'erts')

diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index 05a9895687..133f160dc9 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -1552,6 +1552,15 @@
               parameter determines. The lingering prevents repeated
               deletions and insertions in the tables from occurring.</p>
           </item>
+          <tag><marker id="+ztma"/><c>+ztma true | false</c></tag>
+          <item>
+            <p>Enables or disables support for tuple module apply in
+            the emulator. This is a transitional flag for running code
+            that uses parameterized modules and was compiled under OTP 20
+            or earlier. For future compatibility, the modules will need
+            to be recompiled with the +tuple_calls compiler option.
+            Defaults to false.</p>
+          </item>
         </taglist>
       </item>
     </taglist>
diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index aa6e7d3de2..4351dda5a7 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -379,6 +379,7 @@ do {                                            \
 #  define NOINLINE
 #endif
 
+int tuple_module_apply;
 
 /*
  * The following functions are called directly by process_main().
@@ -2240,7 +2241,7 @@ apply(Process* p, Eterm* reg, BeamInstr *I, Uint stack_offset)
 	if (is_not_atom(module)) {
 	    Eterm* tp;
 
-	    if (is_not_tuple(module)) goto error;
+	    if (!tuple_module_apply || is_not_tuple(module)) goto error;
 	    tp = tuple_val(module);
 	    if (arityval(tp[0]) < 1) goto error;
 	    this = module;
@@ -2346,7 +2347,7 @@ fixed_apply(Process* p, Eterm* reg, Uint arity,
      */
     if (is_not_atom(module)) {
 	Eterm* tp;
-        if (is_not_tuple(module)) goto error;
+        if (!tuple_module_apply || is_not_tuple(module)) goto error;
         tp = tuple_val(module);
         if (arityval(tp[0]) < 1) goto error;
         module = tp[1];
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index 41bec17dfa..da8b998d61 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -729,6 +729,9 @@ void erts_usage(void)
     erts_fprintf(stderr, "-zebwt  val    set ets busy wait threshold, valid values are:\n");
     erts_fprintf(stderr, "               none|very_short|short|medium|long|very_long|extremely_long\n");
 #endif
+    erts_fprintf(stderr, "-ztma bool     enable/disable tuple module apply support in emulator\n");
+    erts_fprintf(stderr, "               (transitional flag for parameterized modules; recompile\n");
+    erts_fprintf(stderr, "               with +tuple_calls for compatibility with future versions)\n");
     erts_fprintf(stderr, "\n");
     erts_fprintf(stderr, "Note that if the emulator is started with erlexec (typically\n");
     erts_fprintf(stderr, "from the erl script), these flags should be specified with +.\n");
@@ -2212,6 +2215,17 @@ erl_start(int argc, char **argv)
 		    erts_usage();
 		}
 	    }
+	    else if (has_prefix("tma", sub_param)) {
+		arg = get_arg(sub_param+3, argv[i+1], &i);
+		if (sys_strcmp(arg,"true") == 0) {
+                    tuple_module_apply = 1;
+                } else if (sys_strcmp(arg,"false") == 0) {
+                    tuple_module_apply = 0;
+                } else {
+		    erts_fprintf(stderr, "bad tuple module apply %s\n", arg);
+		    erts_usage();
+		}
+            }
 	    else {
 		erts_fprintf(stderr, "bad -z option %s\n", argv[i]);
 		erts_usage();
diff --git a/erts/emulator/beam/erl_vm.h b/erts/emulator/beam/erl_vm.h
index 4089fac48e..d37c2940c4 100644
--- a/erts/emulator/beam/erl_vm.h
+++ b/erts/emulator/beam/erl_vm.h
@@ -167,6 +167,8 @@ extern const int num_instructions; /* Number of instruction in opc[]. */
 
 extern Uint erts_instr_count[];
 
+extern int tuple_module_apply;
+
 /* some constants for various table sizes etc */
 
 #define ATOM_TEXT_SIZE  32768	/* Increment for allocating atom text space */
diff --git a/erts/etc/common/erlexec.c b/erts/etc/common/erlexec.c
index 0cb01fd4ef..23bbb86333 100644
--- a/erts/etc/common/erlexec.c
+++ b/erts/etc/common/erlexec.c
@@ -174,6 +174,7 @@ static char *plusz_val_switches[] = {
     "dbbl",
     "dntgc",
     "ebwt",
+    "tma",
     NULL
 };
 
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