From fb94cd974dc03baf149264ca4f4d50c6d1f80f21 Mon Sep 17 00:00:00 2001
From: Patrik Nyblom <pan@erlang.org>
Date: Wed, 20 Jan 2010 16:26:14 +0100
Subject: Store pointers to heap data in 32-bit words

Store Erlang terms in 32-bit entities on the heap, expanding the
pointers to 64-bit when needed. This works because all terms are stored
on addresses in the 32-bit address range (the 32 most significant bits
of pointers to term data are always 0).

Introduce a new datatype called UWord (along with its companion SWord),
which is an integer having the exact same size as the machine word
(a void *), but might be larger than Eterm/Uint.

Store code as machine words, as the instructions are pointers to
executable code which might reside outside the 32-bit address range.

Continuation pointers are stored on the 32-bit stack and hence must
point to addresses in the low range, which means that loaded beam code
much be placed in the low 32-bit address range (but, as said earlier,
the instructions themselves are full words).

No Erlang term data can be stored on C stacks (enforced by an
earlier commit).

This version gives a prompt, but test cases still fail (and dump core).

The loader (and emulator loop) has instruction packing disabled.

The main issues has been in rewriting loader and actual virtual
machine. Subsystems (like distribution) does not work yet.
---
 erts/emulator/utils/beam_makeops | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

(limited to 'erts/emulator/utils/beam_makeops')

diff --git a/erts/emulator/utils/beam_makeops b/erts/emulator/utils/beam_makeops
index 4a859c3094..1a76e80620 100755
--- a/erts/emulator/utils/beam_makeops
+++ b/erts/emulator/utils/beam_makeops
@@ -812,9 +812,10 @@ sub basic_generator {
     # Pack arguments if requested.
     #
 
-    if ($flags =~ /-pack/ && $hot) {
-	($prefix, $pack_spec, @args) = &do_pack(@args);
-    }
+    # /* XXX:PaN temporarilly disabled during halfword implementation step 1 */
+    #if ($flags =~ /-pack/ && $hot) {
+    #    ($prefix, $pack_spec, @args) = &do_pack(@args);
+    #}
 
     #
     # Calculate the size of the instruction and generate each argument for
@@ -916,7 +917,7 @@ sub basic_generator {
 	} else {
 	    $code = join("\n",
 			 "{ $var_decls",
-			 "Eterm* next;",
+			 "UWord* next;",
 			 "PreFetch($size, next);",
 			 "$macro_code",
 			 "NextPF($size, next);",
-- 
cgit v1.2.3


From 64415f09de0691c2ccdf65df169a211b7917728b Mon Sep 17 00:00:00 2001
From: Patrik Nyblom <pan@erlang.org>
Date: Fri, 5 Feb 2010 11:03:51 +0100
Subject: Turn on instruction packing in the loader and virtual machine

---
 erts/emulator/utils/beam_makeops | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

(limited to 'erts/emulator/utils/beam_makeops')

diff --git a/erts/emulator/utils/beam_makeops b/erts/emulator/utils/beam_makeops
index 1a76e80620..7b1cd817cf 100755
--- a/erts/emulator/utils/beam_makeops
+++ b/erts/emulator/utils/beam_makeops
@@ -499,7 +499,11 @@ sub emulator_output {
     print "\n";
     print "#ifdef ARCH_64\n";
     print "#  define BEAM_LOOSE_MASK 0x1FFFUL\n";
+    print "#if HALFWORD_HEAP\n";
+    print "#  define BEAM_TIGHT_MASK 0x1FFCUL\n";
+    print "#else\n";
     print "#  define BEAM_TIGHT_MASK 0x1FF8UL\n";
+    print "#endif\n";
     print "#  define BEAM_LOOSE_SHIFT 16\n";
     print "#  define BEAM_TIGHT_SHIFT 16\n";
     print "#else\n";
@@ -812,10 +816,9 @@ sub basic_generator {
     # Pack arguments if requested.
     #
 
-    # /* XXX:PaN temporarilly disabled during halfword implementation step 1 */
-    #if ($flags =~ /-pack/ && $hot) {
-    #    ($prefix, $pack_spec, @args) = &do_pack(@args);
-    #}
+    if ($flags =~ /-pack/ && $hot) {
+        ($prefix, $pack_spec, @args) = &do_pack(@args);
+    }
 
     #
     # Calculate the size of the instruction and generate each argument for
@@ -908,16 +911,16 @@ sub basic_generator {
     my($code);
     if (defined $macro{$name}) {
 	my($macro_code) = "$prefix$macro(" . join(', ', @f) . ");";
-	$var_decls .= "Uint tmp_packed1;"
+	$var_decls .= "BeamInstr tmp_packed1;"
 	    if $macro_code =~ /tmp_packed1/;
-	$var_decls .= "Uint tmp_packed2;"
+	$var_decls .= "BeamInstr tmp_packed2;"
 	    if $macro_code =~ /tmp_packed2/;
 	if ($flags =~ /-nonext/) {
 	    $code = "$macro_code\n";
 	} else {
 	    $code = join("\n",
 			 "{ $var_decls",
-			 "UWord* next;",
+			 "BeamInstr* next;",
 			 "PreFetch($size, next);",
 			 "$macro_code",
 			 "NextPF($size, next);",
-- 
cgit v1.2.3