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-rwxr-xr-xerts/emulator/utils/beam_makeops453
1 files changed, 298 insertions, 155 deletions
diff --git a/erts/emulator/utils/beam_makeops b/erts/emulator/utils/beam_makeops
index 16a949c2a6..4407f7e289 100755
--- a/erts/emulator/utils/beam_makeops
+++ b/erts/emulator/utils/beam_makeops
@@ -2,18 +2,19 @@
#
# %CopyrightBegin%
#
-# Copyright Ericsson AB 1998-2012. All Rights Reserved.
+# Copyright Ericsson AB 1998-2016. All Rights Reserved.
#
-# The contents of this file are subject to the Erlang Public License,
-# Version 1.1, (the "License"); you may not use this file except in
-# compliance with the License. You should have received a copy of the
-# Erlang Public License along with this software. If not, it can be
-# retrieved online at http://www.erlang.org/.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
#
-# Software distributed under the License is distributed on an "AS IS"
-# basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
-# the License for the specific language governing rights and limitations
-# under the License.
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
#
# %CopyrightEnd%
#
@@ -53,6 +54,11 @@ $pack_mask[4] = ['BEAM_LOOSE_MASK', # Only for 64 bit wordsize
'BEAM_LOOSE_MASK',
$WHOLE_WORD];
+# Mapping from packagable arguments to number of packed arguments per
+# word. Initialized after the wordsize is known.
+
+my @args_per_word;
+
# There are two types of instructions: generic and specific.
# The generic instructions are those generated by the Beam compiler.
# Corresponding to each generic instruction, there is generally a
@@ -107,7 +113,6 @@ my @if_line;
#
my $te_max_vars = 0; # Max number of variables ever needed.
my %gen_transform;
-my %min_window;
my %match_engine_ops; # All opcodes for the match engine.
my %gen_transform_offset;
my @transformations;
@@ -175,11 +180,12 @@ sub define_type_bit {
}
# Composed types.
- define_type_bit('d', $type_bit{'x'} | $type_bit{'y'} | $type_bit{'r'});
+ define_type_bit('d', $type_bit{'x'} | $type_bit{'y'});
define_type_bit('c', $type_bit{'i'} | $type_bit{'a'} |
$type_bit{'n'} | $type_bit{'q'});
define_type_bit('s', $type_bit{'d'} | $type_bit{'i'} |
- $type_bit{'a'} | $type_bit{'n'});
+ $type_bit{'a'} | $type_bit{'n'} |
+ $type_bit{'q'});
define_type_bit('j', $type_bit{'f'} | $type_bit{'p'});
# Aliases (for matching purposes).
@@ -235,6 +241,21 @@ while (@ARGV && $ARGV[0] =~ /^-(.*)/) {
}
#
+# Initialize number of arguments per packed word.
+#
+
+$args_per_word[2] = 2;
+$args_per_word[3] = 3;
+$args_per_word[4] = 2;
+$args_per_word[5] = 3;
+$args_per_word[6] = 3;
+
+if ($wordsize == 64) {
+ $pack_mask[3] = ['BEAM_TIGHT_MASK', 'BEAM_TIGHT_MASK', $WHOLE_WORD];
+ $args_per_word[4] = 4;
+}
+
+#
# Parse the input files.
#
@@ -361,7 +382,6 @@ while (<>) {
$gen_arity{$name} = $arity;
$gen_to_spec{"$name/$arity"} = undef;
$num_specific{"$name/$arity"} = 0;
- $min_window{"$name/$arity"} = 255;
$obsolete[$op_num] = defined $obsolete;
} else { # Unnumbered generic operation.
push(@unnumbered_generic, [$name, $arity]);
@@ -419,7 +439,6 @@ $num_file_opcodes = @gen_opname;
$gen_arity{$name} = $arity;
$gen_to_spec{"$name/$arity"} = undef;
$num_specific{"$name/$arity"} = 0;
- $min_window{"$name/$arity"} = 255;
}
}
@@ -526,12 +545,16 @@ sub emulator_output {
my(@bits) = (0) x ($max_spec_operands/2);
my($i);
+ my $involves_r = 0;
for ($i = 0; $i < $max_spec_operands && defined $args[$i]; $i++) {
my $t = $args[$i];
- if (defined $type_bit{$t}) {
- my $shift = $max_genop_types * ($i % 2);
- $bits[int($i/2)] |= $type_bit{$t} << $shift;
+ my $bits = $type_bit{$t};
+ if ($t eq 'r') {
+ $bits |= $type_bit{'x'};
+ $involves_r |= 1 << $i;
}
+ my $shift = $max_genop_types * ($i % 2);
+ $bits[int($i/2)] |= $bits << $shift;
}
printf "/* %3d */ ", $spec_opnum;
@@ -543,7 +566,7 @@ sub emulator_output {
$sep = ",";
}
$init .= "}";
- &init_item($print_name, $init, $size, $pack, $sign, 0);
+ init_item($print_name, $init, $involves_r, $size, $pack, $sign, 0);
$op_to_name[$spec_opnum] = $instr;
$spec_opnum++;
}
@@ -582,7 +605,7 @@ sub emulator_output {
$is_transformed{$name,$arity} or
error("instruction $key has no specific instruction");
$spec_op = -1 unless defined $spec_op;
- &init_item($name, $arity, $spec_op, $num_specific, $tr, $min_window{$key});
+ &init_item($name, $arity, $spec_op, $num_specific, $tr);
}
}
print "};\n";
@@ -600,24 +623,27 @@ sub emulator_output {
print "#define MAX_GENERIC_OPCODE ", $num_file_opcodes-1, "\n";
print "#define NUM_GENERIC_OPS ", scalar(@gen_opname), "\n";
print "#define NUM_SPECIFIC_OPS ", scalar(@op_to_name), "\n";
+ print "#define SCRATCH_X_REG 1023\n";
print "\n";
- print "#ifdef ARCH_64\n";
- print "# define BEAM_WIDE_MASK 0xFFFFUL\n";
- print "# define BEAM_LOOSE_MASK 0x1FFFUL\n";
- print "#if HALFWORD_HEAP\n";
- print "# define BEAM_TIGHT_MASK 0x1FFCUL\n";
- print "#else\n";
- print "# define BEAM_TIGHT_MASK 0x1FF8UL\n";
- print "#endif\n";
- print "# define BEAM_WIDE_SHIFT 32\n";
- print "# define BEAM_LOOSE_SHIFT 16\n";
- print "# define BEAM_TIGHT_SHIFT 16\n";
- print "#else\n";
- print "# define BEAM_LOOSE_MASK 0xFFF\n";
- print "# define BEAM_TIGHT_MASK 0xFFC\n";
- print "# define BEAM_LOOSE_SHIFT 16\n";
- print "# define BEAM_TIGHT_SHIFT 10\n";
- print "#endif\n";
+ if ($wordsize == 32) {
+ print "#if defined(ARCH_64)\n";
+ print qq[ #error "32-bit architecture assumed, but ARCH_64 is defined"\n];
+ print "#endif\n";
+ print "#define BEAM_LOOSE_MASK 0xFFF\n";
+ print "#define BEAM_TIGHT_MASK 0xFFC\n";
+ print "#define BEAM_LOOSE_SHIFT 16\n";
+ print "#define BEAM_TIGHT_SHIFT 10\n";
+ } elsif ($wordsize == 64) {
+ print "#if !defined(ARCH_64)\n";
+ print qq[ #error "64-bit architecture assumed, but ARCH_64 not defined"\n];
+ print "#endif\n";
+ print "#define BEAM_WIDE_MASK 0xFFFFUL\n";
+ print "#define BEAM_LOOSE_MASK 0xFFFFUL\n";
+ print "#define BEAM_TIGHT_MASK 0xFFFFUL\n";
+ print "#define BEAM_WIDE_SHIFT 32\n";
+ print "#define BEAM_LOOSE_SHIFT 16\n";
+ print "#define BEAM_TIGHT_SHIFT 16\n";
+ }
print "\n";
#
@@ -733,7 +759,7 @@ sub init_item {
print "${sep}NULL";
} elsif (/^\{/) {
print "$sep$_";
- } elsif (/^-?\d/) {
+ } elsif (/^-?\d+$/) {
print "$sep$_";
} else {
print "$sep\"$_\"";
@@ -895,6 +921,7 @@ sub basic_generator {
my($var_decls) = '';
my($gen_dest_arg) = 'StoreSimpleDest';
my($i);
+ my($no_prefetch) = 0;
# The following argument types should be included as macro arguments.
my(%incl_arg) = ('c' => 1,
@@ -993,6 +1020,7 @@ sub basic_generator {
#
$flags =~ /-fail_action/ and do {
+ $no_prefetch = 1;
if (!defined $fail_type) {
my($i);
for ($i = 0; $i < @f_types; $i++) {
@@ -1039,6 +1067,12 @@ sub basic_generator {
"I += $size + 1;",
"goto $goto;",
"}");
+ } elsif ($no_prefetch) {
+ $code = join("\n",
+ "{ $var_decls",
+ $macro_code,
+ "Next($size);",
+ "}", "");
} else {
$code = join("\n",
"{ $var_decls",
@@ -1060,6 +1094,7 @@ sub do_pack {
my($packable_args) = 0;
my @is_packable; # Packability (boolean) for each argument.
my $wide_packing = 0;
+ my(@orig_args) = @args;
#
# Count the number of packable arguments. If we encounter any 's' or 'd'
@@ -1080,6 +1115,18 @@ sub do_pack {
}
} elsif ($arg =~ /^[sd]/) {
return ('', '', @args);
+ } elsif ($arg =~ /^[scq]/ and $packable_args > 0) {
+ # When packing, this operand will be picked up from the
+ # code array, put onto the packing stack, and later put
+ # back into a different location in the code. The problem
+ # is that if this operand is a literal, the original
+ # location in the code would have been remembered in a
+ # literal patch. For packing to work, we would have to
+ # adjust the position in the literal patch. For the
+ # moment, adding additional instructions to the packing
+ # engine to handle this does not seem worth it, so we will
+ # just turn off packing.
+ return ('', '', @args);
} else {
push @is_packable, 0;
}
@@ -1089,7 +1136,6 @@ sub do_pack {
# Get out of here if too few or too many arguments.
#
return ('', '', @args) if $packable_args < 2;
- &error("too many packable arguments") if $packable_args > 4;
my($size) = 0;
my($pack_prefix) = '';
@@ -1097,14 +1143,8 @@ sub do_pack {
# beginning).
my($up) = ''; # Pack commands (storing back while
# moving forward).
- my $args_per_word;
- if ($packable_args < 4 or $wordsize == 64) {
- $args_per_word = $packable_args;
- } else {
- # 4 packable argument, 32 bit wordsize. Need 2 words.
- $args_per_word = 2;
- }
+ my $args_per_word = $args_per_word[$packable_args];
my @shift;
my @mask;
my @instr;
@@ -1202,6 +1242,7 @@ sub parse_transformation {
my($from, $to) = split(/\s*=>\s*/);
my(@op);
+ my $rest_var;
# The source instructions.
@@ -1212,7 +1253,7 @@ sub parse_transformation {
$_ = (&compile_transform_function($name, split(/\s*,\s*/, $arglist)));
} else {
(@op) = split;
- $_ = &compile_transform(1, @op);
+ ($rest_var,$_) = compile_transform(1, $rest_var, @op);
}
}
@@ -1230,7 +1271,7 @@ sub parse_transformation {
@to = split(/\s*\|\s*/, $to);
foreach (@to) {
(@op) = split;
- $_ = &compile_transform(0, @op);
+ (undef,$_) = compile_transform(0, $rest_var, @op);
}
}
push(@transformations, [$., $orig, [@from], [reverse @to]]);
@@ -1243,12 +1284,18 @@ sub compile_transform_function {
}
sub compile_transform {
- my($src, $name, @ops) = @_;
+ my($src, $rest_var, $name, @ops) = @_;
my $arity = 0;
-
+
foreach (@ops) {
my(@list) = &tr_parse_op($src, $_);
- $arity++ unless $list[1] eq '*';
+ if ($list[1] eq '*') {
+ $rest_var = $list[0];
+ } elsif (defined $rest_var and $list[0] eq $rest_var) {
+ $list[1] = '*';
+ } else {
+ $arity++;
+ }
$_ = [ @list ];
}
@@ -1260,7 +1307,7 @@ sub compile_transform {
$is_transformed{$name,$arity} = 1;
}
- [$name,$arity,@ops];
+ ($rest_var,[$name,$arity,@ops]);
}
sub tr_parse_op {
@@ -1291,6 +1338,8 @@ sub tr_parse_op {
foreach (split('', $type)) {
&error("bad type in $op")
unless defined $type_bit{$_} or $type eq '*';
+ $_ eq 'r' and
+ error("$op: 'r' is not allowed in transformations")
}
}
@@ -1324,7 +1373,10 @@ sub tr_parse_op {
}
# Get an optional value. (In destination.)
+ $type_val = $type eq 'x' ? 1023 : 0;
if (/^=(.*)/) {
+ error("value not allowed in source: $op")
+ if $src;
$type_val = $1;
$_ = '';
}
@@ -1343,11 +1395,6 @@ sub tr_parse_op {
if $var && $type;
}
- # Test that source has no values.
- if ($src) {
- error("value not allowed in source: $op")
- if $type_val;
- }
($var,$type,$type_val,$cond,$cond_val);
}
@@ -1362,8 +1409,7 @@ sub tr_gen {
foreach $ref (@g) {
my($line, $orig_transform, $from_ref, $to_ref) = @$ref;
- my $used_ref = used_vars($from_ref, $to_ref);
- my $so_far = tr_gen_from($line, $used_ref, @$from_ref);
+ my $so_far = tr_gen_from($line, @$from_ref);
tr_gen_to($line, $orig_transform, $so_far, @$to_ref);
}
@@ -1414,58 +1460,14 @@ sub tr_gen {
print "};\n\n";
}
-sub used_vars {
- my($from_ref,$to_ref) = @_;
- my %used;
- my %seen;
-
- foreach my $ref (@$from_ref) {
- my($name,$arity,@ops) = @$ref;
- if ($name =~ /^[.]/) {
- foreach my $var (@ops) {
- $used{$var} = 1;
- }
- } else {
- # Any variable that is used at least twice on the
- # left-hand side is used. (E.g. "move R R".)
- foreach my $op (@ops) {
- my($var, $type, $type_val) = @$op;
- next if $var eq '';
- $used{$var} = 1 if $seen{$var};
- $seen{$var} = 1;
- }
- }
- }
-
- foreach my $ref (@$to_ref) {
- my($name, $arity, @ops) = @$ref;
- if ($name =~ /^[.]/) {
- foreach my $var (@ops) {
- $used{$var} = 1;
- }
- } else {
- foreach my $op (@ops) {
- my($var, $type, $type_val) = @$op;
- next if $var eq '';
- $used{$var} = 1;
- }
- }
- }
- \%used;
-}
-
sub tr_gen_from {
- my($line,$used_ref,@tr) = @_;
+ my($line,@tr) = @_;
my(%var) = ();
my(%var_type);
my($var_num) = 0;
my(@code);
- my($min_window) = 0;
- my(@fix_rest_args);
- my(@fix_pred_funcs);
my($op, $ref); # Loop variables.
my $where = "left side of transformation in line $line: ";
- my %var_used = %$used_ref;
my $may_fail = 0;
my $is_first = 1;
@@ -1487,8 +1489,20 @@ sub tr_gen_from {
my $var;
my(@args);
- push(@fix_pred_funcs, scalar(@code));
- push(@code, [$name, @ops]);
+ foreach $var (@ops) {
+ error($where, "variable '$var' unbound")
+ unless defined $var{$var};
+ if ($var_type{$var} eq 'scalar') {
+ push(@args, "var[$var{$var}]");
+ } else {
+ push(@args, "rest_args");
+ }
+ }
+ my $pi = tr_next_index(\@pred_table, \%pred_table, $name, @args);
+ my $op = make_op("$name()", 'pred', $pi);
+ my @slots = grep(/^\d+/, map { $var{$_} } @ops);
+ op_slot_usage($op, @slots);
+ push(@code, $op);
next;
}
@@ -1501,7 +1515,6 @@ sub tr_gen_from {
$opnum = $gen_opnum{$name,$arity};
push(@code, make_op("$name/$arity", 'next_instr', $opnum));
- $min_window++;
foreach $op (@ops) {
my($var, $type, $type_val, $cond, $val) = @$op;
my $ignored_var = "$var (ignored)";
@@ -1550,15 +1563,21 @@ sub tr_gen_from {
if (defined $var{$var}) {
$ignored_var = '';
$may_fail = 1;
- push(@code, &make_op($var, 'is_same_var', $var{$var}));
+ my $op = make_op($var, 'is_same_var', $var{$var});
+ op_slot_usage($op, $var{$var});
+ push(@code, $op);
} elsif ($type eq '*') {
- #
- # Reserve a hole for a 'rest_args' instruction.
- #
+ foreach my $type (values %var_type) {
+ error("only one use of a '*' variable is " .
+ "allowed on the left hand side of " .
+ "a transformation")
+ if $type eq 'array';
+ }
$ignored_var = '';
- push(@fix_rest_args, scalar(@code));
- push(@code, $var);
- } elsif ($var_used{$var}) {
+ $var{$var} = 'unnumbered';
+ $var_type{$var} = 'array';
+ push(@code, make_op($var, 'rest_args'));
+ } else {
$ignored_var = '';
$var_type{$var} = 'scalar';
$var{$var} = $var_num;
@@ -1586,46 +1605,14 @@ sub tr_gen_from {
#
push(@code, make_op($may_fail ? '' : 'always reached', 'commit'));
- #
- # If there is an rest_args instruction, we must insert its correct
- # variable number (higher than any other).
- #
- my $index;
- &error("only one use of a '*' variable is allowed on the left hand side of a transformation")
- if @fix_rest_args > 1;
- foreach $index (@fix_rest_args) {
- my $var = $code[$index];
- $var{$var} = $var_num++;
- $var_type{$var} = 'array';
- splice(@code, $index, 1, &make_op($var, 'rest_args', $var{$var}));
- }
-
- foreach $index (@fix_pred_funcs) {
- my($name, @ops) = @{$code[$index]};
- my(@args);
- my $var;
-
- foreach $var (@ops) {
- &error($where, "variable '$var' unbound")
- unless defined $var{$var};
- if ($var_type{$var} eq 'scalar') {
- push(@args, "var[$var{$var}]");
- } else {
- push(@args, "var+$var{$var}");
- }
- }
- my $pi = tr_next_index(\@pred_table, \%pred_table, $name, @args);
- splice(@code, $index, 1, make_op("$name()", 'pred', $pi));
- }
-
$te_max_vars = $var_num
if $te_max_vars < $var_num;
- [$min_window, \%var, \%var_type, \@code];
+ [\%var, \%var_type, \@code];
}
sub tr_gen_to {
my($line, $orig_transform, $so_far, @tr) = @_;
- my($min_window, $var_ref, $var_type_ref, $code_ref) = @$so_far;
+ my($var_ref, $var_type_ref, $code_ref) = @$so_far;
my(%var) = %$var_ref;
my(%var_type) = %$var_type_ref;
my(@code) = @$code_ref;
@@ -1654,13 +1641,16 @@ sub tr_gen_to {
if ($var_type{$var} eq 'scalar') {
push(@args, "var[$var{$var}]");
} else {
- push(@args, "var+$var{$var}");
+ push(@args, "rest_args");
}
}
pop(@code); # Get rid of 'commit' instruction
my $index = tr_next_index(\@call_table, \%call_table,
$name, @args);
- push(@code, make_op("$name()", 'call_end', $index));
+ my $op = make_op("$name()", 'call_end', $index);
+ my @slots = grep(/^\d+/, map { $var{$_} } @ops);
+ op_slot_usage($op, @slots);
+ push(@code, $op);
last;
}
@@ -1681,10 +1671,14 @@ sub tr_gen_to {
foreach $op (@ops) {
my($var, $type, $type_val) = @$op;
- if ($var ne '') {
+ if ($type eq '*') {
+ push(@code, make_op($var, 'store_rest_args'));
+ } elsif ($var ne '') {
&error($where, "variable '$var' unbound")
unless defined $var{$var};
- push(@code, &make_op($var, 'store_var_next_arg', $var{$var}));
+ my $op = make_op($var, 'store_var_next_arg', $var{$var});
+ op_slot_usage($op, $var{$var});
+ push(@code, $op);
} elsif ($type ne '') {
push(@code, &make_op('', 'store_type', "TAG_$type"));
if ($type_val) {
@@ -1699,6 +1693,10 @@ sub tr_gen_to {
push(@code, make_op('', 'end'))
unless is_instr($code[$#code], 'call_end');
+ tr_maybe_keep(\@code);
+ tr_maybe_rename(\@code);
+ tr_remove_unused(\@code);
+
#
# Chain together all codes segments having the same first operation.
#
@@ -1707,8 +1705,6 @@ sub tr_gen_to {
my($dummy, $arity);
($dummy, $op, $arity) = @$first;
my($comment) = "\n/*\n * Line $line:\n * $orig_transform\n */\n\n";
- $min_window{$key} = $min_window
- if $min_window{$key} > $min_window;
my $prev_last;
$prev_last = pop(@{$gen_transform{$key}})
@@ -1726,6 +1722,148 @@ sub tr_gen_to {
push(@{$gen_transform{$key}}, @code),
}
+sub tr_maybe_keep {
+ my($ref) = @_;
+ my @last_instr;
+ my $pos;
+ my $reused_instr;
+
+ for (my $i = 0; $i < @$ref; $i++) {
+ my $instr = $$ref[$i];
+ my($size, $instr_ref, $comment) = @$instr;
+ my($op, @args) = @$instr_ref;
+ if ($op eq 'next_instr') {
+ @last_instr = ($args[0]);
+ } elsif ($op eq 'set_var_next_arg') {
+ push @last_instr, $args[0];
+ } elsif ($op eq 'next_arg') {
+ push @last_instr, 'ignored';
+ } elsif ($op eq 'new_instr') {
+ unless (defined $pos) {
+ # 'new_instr' immediately after 'commit'.
+ $reused_instr = $args[0];
+ return unless shift(@last_instr) == $reused_instr;
+ $pos = $i - 1;
+ } else {
+ # Second 'new_instr' after 'commit'. The instructions
+ # from $pos up to and including $i - 1 rebuilds the
+ # existing instruction exactly.
+ my $name = $gen_opname[$reused_instr];
+ my $arity = $gen_arity[$reused_instr];
+ my $reuse = make_op("$name/$arity", 'keep');
+ splice @$ref, $pos, $i-$pos, ($reuse);
+ return;
+ }
+ } elsif ($op eq 'store_var_next_arg') {
+ return unless shift(@last_instr) eq $args[0];
+ } elsif (defined $pos) {
+ return;
+ }
+ }
+}
+
+sub tr_maybe_rename {
+ my($ref) = @_;
+ my $s = 'left';
+ my $a = 0;
+ my $num_args = 0;
+ my $new_instr;
+ my $first;
+ my $i;
+
+ for ($i = 1; $i < @$ref; $i++) {
+ my $instr = $$ref[$i];
+ my($size, $instr_ref, $comment) = @$instr;
+ my($op, @args) = @$instr_ref;
+
+ if ($s eq 'left') {
+ if ($op eq 'set_var_next_arg') {
+ if ($num_args == $a and $args[0] == $a) {
+ $num_args++;
+ }
+ $a++;
+ } elsif ($op eq 'next_arg') {
+ $a++;
+ } elsif ($op eq 'commit') {
+ $a = 0;
+ $first = $i;
+ $s = 'committed';
+ } elsif ($op eq 'next_instr') {
+ return;
+ }
+ } elsif ($s eq 'committed') {
+ if ($op eq 'new_instr') {
+ $new_instr = $args[0];
+ $a = 0;
+ $s = 'right';
+ } else {
+ return;
+ }
+ } elsif ($s eq 'right') {
+ if ($op eq 'store_var_next_arg' && $args[0] == $a) {
+ $a++;
+ } elsif ($op eq 'end' && $a <= $num_args) {
+ my $name = $gen_opname[$new_instr];
+ my $arity = $gen_arity[$new_instr];
+ my $new_op = make_op("$name/$arity", 'rename', $new_instr);
+ splice @$ref, $first, $i-$first+1, ($new_op);
+ return;
+ } else {
+ return;
+ }
+ }
+ }
+}
+
+sub tr_remove_unused {
+ my($ref) = @_;
+ my %used;
+
+ # Collect all used variables.
+ for my $instr (@$ref) {
+ my $uref = $$instr[3];
+ for my $slot (@$uref) {
+ $used{$slot} = 1;
+ }
+ }
+
+ # Replace 'set_var_next_arg' with 'next_arg' if the variable
+ # is never used.
+ for my $instr (@$ref) {
+ my($size, $instr_ref, $comment) = @$instr;
+ my($op, @args) = @$instr_ref;
+ if ($op eq 'set_var_next_arg') {
+ my $var = $args[0];
+ next if $used{$var};
+ $instr = make_op("$comment (ignored)", 'next_arg');
+ }
+ }
+
+ # Delete a sequence of 'next_arg' instructions when they are
+ # redundant before instructions such as 'commit'.
+ my @opcode;
+ my %ending = (call_end => 1,
+ commit => 1,
+ next_instr => 1,
+ pred => 1,
+ rename => 1,
+ keep => 1);
+ for (my $i = 0; $i < @$ref; $i++) {
+ my $instr = $$ref[$i];
+ my($size, $instr_ref, $comment) = @$instr;
+ my($opcode) = @$instr_ref;
+
+ if ($ending{$opcode}) {
+ my $first = $i;
+ $first-- while $first > 0 and $opcode[$first-1] eq 'next_arg';
+ my $n = $i - $first;
+ splice @$ref, $first, $n;
+ $i -= $n;
+ }
+ $opcode[$i] = $opcode;
+ }
+}
+
sub tr_code_len {
my($sum) = 0;
my($ref);
@@ -1738,7 +1876,12 @@ sub tr_code_len {
sub make_op {
my($comment, @op) = @_;
- [scalar(@op), [@op], $comment];
+ [scalar(@op), [@op], $comment, []];
+}
+
+sub op_slot_usage {
+ my($op_ref, @slots) = @_;
+ $$op_ref[3] = \@slots;
}
sub is_instr {