From b079018e38272604ffacfece9b97924a9e39df5c Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Mon, 23 Jan 2017 17:10:18 +0100
Subject: Implement magic references

Magic references are *intentionally* indistinguishable from ordinary
references for the Erlang software. Magic references do not change
the language, and are intended as a pure runtime internal optimization.

An ordinary reference is typically used as a key in some table. A
magic reference has a direct pointer to a reference counted magic
binary. This makes it possible to implement various things without
having to do lookups in a table, but instead access the data directly.
Besides very fast lookups this can also improve scalability by
removing a potentially contended table. A couple of examples of
planned future usage of magic references are ETS table identifiers,
and BIF timer identifiers.

Besides future optimizations using magic references it should also
be possible to replace the exposed magic binary cludge with magic
references. That is, magic binaries that are exposed as empty
binaries to the Erlang software.
---
 erts/etc/unix/etp-commands.in | 53 +++++++++++++++++++++++--------------------
 1 file changed, 29 insertions(+), 24 deletions(-)

(limited to 'erts/etc')

diff --git a/erts/etc/unix/etp-commands.in b/erts/etc/unix/etp-commands.in
index c7e2ac169d..2bf04a6518 100644
--- a/erts/etc/unix/etp-commands.in
+++ b/erts/etc/unix/etp-commands.in
@@ -775,7 +775,7 @@ define etp-pid-1
   set $etp_pid_1 = (Eterm)($arg0)
   if ($etp_pid_1 & 0xF) == 0x3
     if (etp_arch_bits == 64)
-      if (etp_big_endian)
+      if (etp_endianness > 0)
       	set $etp_pid_data = (unsigned) ((((Uint64) $etp_pid_1) >> 35) & 0x0fffffff)
       else
         set $etp_pid_data = (unsigned) ((((Uint64) $etp_pid_1) >> 4) & 0x0fffffff)
@@ -835,7 +835,7 @@ define etp-port-1
   set $etp_port_1 = (Eterm)($arg0)
   if ($etp_port_1 & 0xF) == 0x7
     if (etp_arch_bits == 64)
-      if (etp_big_endian)
+      if (etp_endianness > 0)
       	set $etp_port_data = (unsigned) ((((Uint64) $etp_port_1) >> 36) & 0x0fffffff)
       else
         set $etp_port_data = (unsigned) ((((Uint64) $etp_port_1) >> 4) & 0x0fffffff)
@@ -952,30 +952,31 @@ define etp-ref-1
   if ((Eterm)($arg0) & 0x3) != 0x2
     printf "#NotBoxed<%#x>", (Eterm)($arg0)
   else
-    set $etp_ref_1_p = (RefThing *)((Eterm)($arg0) & ~0x3)
+    set $etp_ref_1_p = (ErtsORefThing *)((Eterm)($arg0) & ~0x3)
     if ($etp_ref_1_p->header & 0x3b) != 0x10
       printf "#NotRef<%#x>", $etp_ref_1_p->header
     else
-      set $etp_ref_1_nump = (Uint32 *) 0
-      set $etp_ref_1_error = 0
-      if ($etp_ref_1_p->header >> 6) == 0
-        set $etp_ref_1_error = 1
+      if $etp_ref_1_p->header != etp_ref_header && $etp_ref_1_p->header != etp_magic_ref_header
+        printf "#InternalRefError<%#x>", ($arg0)
       else
-        if $etp_arch64
-          set $etp_ref_1_i = (int) $etp_ref_1_p->data.ui32[0]
-          if (($etp_ref_1_i + 1) > (2 * ($etp_ref_1_p->header >> 6)))
-            set $etp_ref_1_error = 1
-          else
-            set $etp_ref_1_nump = &$etp_ref_1_p->data.ui32[1]
+	set $etp_magic_ref = 0
+	set $etp_ref_1_i = 3
+	set $etp_ref_1_error = 0
+	set $etp_ref_1_nump = (Uint32 *) 0
+	if etp_ref_header == etp_magic_ref_header
+          if $etp_ref_1_p->marker != 0xffffffff
+      	     set $etp_magic_ref = 1
           end
+	else
+	  if $etp_ref_1_p->header == etp_magic_ref_header
+      	     set $etp_magic_ref = 1
+          end
+	end
+        if $etp_magic_ref == 0
+          set $etp_ref_1_nump = $etp_ref_1_p->num
         else
-          set $etp_ref_1_i = (int) ($etp_ref_1_p->header >> 6)
-          set $etp_ref_1_nump = &$etp_ref_1_p->data.ui32[0]
+          set $etp_ref_1_nump = ((ErtsMRefThing *) $etp_ref_1_p)->mb->refn
         end
-      end
-      if $etp_ref_1_error
-        printf "#InternalRefError<%#x>", ($arg0)
-      else
         printf "#Ref<0"
         set $etp_ref_1_i--
         while $etp_ref_1_i >= 0
@@ -1593,7 +1594,7 @@ define etp-term-dump-pid
   set $etp_pid_1 = (Eterm)($arg0)
   if ($etp_pid_1 & 0xF) == 0x3
     if (etp_arch_bits == 64)
-      if (etp_big_endian)
+      if (etp_endianness > 0)
         set $etp_pid_data = (unsigned) ((((Uint64) $etp_pid_1) >> 36) & 0x0fffffff)
       else
         set $etp_pid_data = (unsigned) ((((Uint64) $etp_pid_1) >> 4) & 0x0fffffff)
@@ -1638,7 +1639,7 @@ define etp-pid2pix-1
 # Args: Eterm
 #
    if (etp_arch_bits == 64)
-      if (etp_big_endian)
+      if (etp_endianness > 0)
       	 set $etp_pix = (int) (((Uint64) $arg0) & 0x0fffffff)
       else
       	 set $etp_pix = (int) ((((Uint64) $arg0) >> 32) & 0x0fffffff)
@@ -2271,7 +2272,7 @@ define etp-port-id2pix-1
 # Args: Eterm
 #
    if (etp_arch_bits == 64)
-      if (etp_big_endian)
+      if (etp_endianness > 0)
       	 set $etp_pix = (int) (((Uint64) $arg0) & 0x0fffffff)
       elser
       	 set $etp_pix = (int) ((((Uint64) $arg0) >> 32) & 0x0fffffff)
@@ -2906,10 +2907,14 @@ define etp-system-info
   printf "Compile date: %s\n", etp_compile_date
   printf "Arch: %s\n", etp_arch
   printf "Endianness: "
-  if (etp_big_endian)
+  if (etp_endianness > 0)
     printf "Big\n"
   else
-    printf "Little\n"
+    if (etp_endianness < 0)
+      printf "Little\n"
+    else
+      printf "Unknown\n"
+    end
   end
   printf "Word size: %d-bit\n", etp_arch_bits
   printf "HiPE support: "
-- 
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