From a58daf5c38b4921c82008c811cd5dd178deef49f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Fri, 8 Sep 2017 14:07:41 +0200
Subject: Add built-in macros $ARG_POSITION() and $IS_PACKED()

---
 erts/emulator/utils/beam_makeops | 55 ++++++++++++++++++++++++++++++++--------
 1 file changed, 44 insertions(+), 11 deletions(-)

(limited to 'erts/emulator/utils')

diff --git a/erts/emulator/utils/beam_makeops b/erts/emulator/utils/beam_makeops
index e55d3eadb5..8e34e07035 100755
--- a/erts/emulator/utils/beam_makeops
+++ b/erts/emulator/utils/beam_makeops
@@ -267,6 +267,16 @@ if ($wordsize == 64) {
     $pack_mask[3] = ['BEAM_TIGHT_MASK', 'BEAM_TIGHT_MASK', $WHOLE_WORD];
 }
 
+#
+# Add placeholders for built-in macros.
+#
+
+$c_code{'IS_PACKED'} = ['$Expr',"built-in macro",('Expr')];
+$c_code{'ARG_POSITION'} = ['$Expr',"built-in macro",('Expr')];
+foreach my $name (keys %c_code) {
+    $c_code_used{$name} = 1;
+}
+
 #
 # Parse the input files.
 #
@@ -1382,14 +1392,8 @@ sub expand_all {
         my $keep = substr($code, 0, $-[0]);
         my $after = substr($code, $+[0]);
 
-        # Keep the special, pre-defined bindings.
-        my %new_bindings;
-        foreach my $key (qw(NEXT_INSTRUCTION)) {
-            $new_bindings{$key} = $bindings{$key};
-        }
-
         my $body;
-        ($body,$code) = expand_macro($macro_name, $after, \%new_bindings);
+        ($body,$code) = expand_macro($macro_name, $after, \%bindings);
         $res .= "$keep$body";
     }
 
@@ -1436,21 +1440,49 @@ sub expand_macro {
         $arg =~ s/^\s*//;
     }
 
-    # Now combine bindings from the parameter names and arguments.
-    my %bindings = %{$bindings_ref};
+    # Make sure that the number of arguments are correct.
     if (@vars != @args) {
         error("calling $name with ", scalar(@args),
               " arguments instead of expected ", scalar(@vars), " arguments...");
     }
+
+    # Now combine bindings from the parameter names and arguments.
+    my %bindings = %{$bindings_ref};
+    my %new_bindings;
+
+    # Keep the special, pre-defined bindings.
+    foreach my $key (qw(NEXT_INSTRUCTION)) {
+        $new_bindings{$key} = $bindings{$key};
+    }
+
     for (my $i = 0; $i < @vars; $i++) {
-        $bindings{$vars[$i]} = $args[$i];
+        my $arg = $args[$i];
+        $arg = eval { expand_all($arg, \%bindings) };
+        unless (defined $arg) {
+            warn $@;
+            die "... from the body of $name at $where\n";
+        }
+        $new_bindings{$vars[$i]} = $arg;
     }
 
-    $body = eval { expand_all($body, \%bindings) };
+    $body = eval { expand_all($body, \%new_bindings) };
     unless (defined $body) {
         warn $@;
         die "... from the body of $name at $where\n";
     }
+
+    # Handle built-in macros.
+    if ($name eq 'ARG_POSITION') {
+        if ($body =~ /^I\[(\d+)\]$/) {
+            $body = $1;
+        } else {
+            $body = 0;
+        }
+    } elsif ($name eq 'IS_PACKED') {
+        $body = ($body =~ /^I\[\d+\]$/) ? 0 : 1;
+    }
+
+    # Wrap body if needed and return resul.t
     $body = "do {\n$body\n} while (0)"
         if needs_do_wrapper($body);
     ($body,$rest);
@@ -1476,6 +1508,7 @@ sub needs_do_wrapper {
     return 0 if /^[A-Z_]*SWAPOUT/;
     return 0 if /^if\s*[(]/;
     return 0 if /^goto\b/;
+    return 0 if /^\d+/;
     return 1;                   # Not sure, say that it is needed.
 }
 
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