From 2a30746d09f467c13e9361774867462ae4f2bd32 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Tue, 9 Aug 2011 16:49:39 +0200
Subject: Introduce 'try_me_else_fail'

---
 erts/emulator/beam/beam_load.c   |  6 +++++-
 erts/emulator/utils/beam_makeops | 21 ++++++++++++++++++++-
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c
index 7d2b4dea28..655b5496a8 100644
--- a/erts/emulator/beam/beam_load.c
+++ b/erts/emulator/beam/beam_load.c
@@ -4225,6 +4225,7 @@ transform_engine(LoaderState* st)
     GenOp* instr;
     Uint* pc;
     int rval;
+    static Uint restart_fail[1] = {TOP_fail};
 
     ASSERT(gen_opc[st->genop->op].transform != -1);
     pc = op_transform + gen_opc[st->genop->op].transform;
@@ -4528,10 +4529,13 @@ transform_engine(LoaderState* st)
 	    restart += *pc++;
 	    ASSERT(*pc < NUM_TOPS); /* Valid instruction? */
 	    break;
+	case TOP_try_me_else_fail:
+	    restart = restart_fail;
+	    break;
 	case TOP_end:
 	    RETURN(TE_OK);
 	case TOP_fail:
-	    RETURN(TE_FAIL)
+	    RETURN(TE_FAIL);
 	default:
 	    ASSERT(0);
 	}
diff --git a/erts/emulator/utils/beam_makeops b/erts/emulator/utils/beam_makeops
index 9c7e5e94a5..367f089401 100755
--- a/erts/emulator/utils/beam_makeops
+++ b/erts/emulator/utils/beam_makeops
@@ -186,6 +186,12 @@ sub define_type_bit {
     define_type_bit('Q', $type_bit{'u'});
 }
 
+#
+# Pre-define the 'fail' instruction. It is used internally
+# by the 'try_me_else_fail' instruction.
+#
+$match_engine_ops{'TOP_fail'} = 1;
+
 #
 # Sanity checks.
 #
@@ -1316,7 +1322,20 @@ sub tr_gen {
     print "Uint op_transform[] = {\n";
     foreach $key (keys %gen_transform) {
 	$gen_transform_offset{$key} = $offset;
-	foreach $instr (@{$gen_transform{$key}}) {
+	my @instr = @{$gen_transform{$key}};
+
+	#
+	# If the last instruction is 'fail', remove it and
+	# convert the previous 'try_me_else' to 'try_me_else_fail'.
+	#
+	if (is_instr($instr[$#instr], 'fail')) {
+	    pop(@instr);
+	    my $i = $#instr;
+	    $i-- while !is_instr($instr[$i], 'try_me_else');
+	    $instr[$i] = make_op('', 'try_me_else_fail');
+	}
+
+	foreach $instr (@instr) {
 	    my($size, $instr_ref, $comment) = @$instr;
 	    my($op, @args) = @$instr_ref;
 	    print "    ";
-- 
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