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authorBjörn Gustavsson <[email protected]>2016-04-07 15:29:06 +0200
committerBjörn Gustavsson <[email protected]>2016-04-07 15:29:06 +0200
commit5b15c7747c38defc3d7c5ee2e9de58b9f2fed535 (patch)
tree9bb6309673cd45a37fe513c0dfa72fff4cda544e /erts
parent181171aa5ed3a1e7426275abe5ca30bb0db3a731 (diff)
parent921c838b8142d3c8d1739c6b30c6d88e39e5f147 (diff)
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Merge branch 'bjorn/erts/beam_load'
* bjorn/erts/beam_load: Eliminate unnecessary renaming of bs_put_utf16/3 Don't let the loader do the compiler's job Remove unused variables after code generation Avoid rebuilding unchanged instructions Introduce a 'rename' instruction Simplify window management for the transformation engine Eliminate allocation of variables in transform_engine() Refactor calls to transform_engine() ops.tab: Remove useless transformation
Diffstat (limited to 'erts')
-rw-r--r--erts/emulator/beam/beam_emu.c2
-rw-r--r--erts/emulator/beam/beam_load.c174
-rw-r--r--erts/emulator/beam/beam_load.h1
-rw-r--r--erts/emulator/beam/ops.tab10
-rwxr-xr-xerts/emulator/utils/beam_makeops295
5 files changed, 270 insertions, 212 deletions
diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index a390422040..09a41f2b56 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -4102,7 +4102,7 @@ do { \
StoreBifResult(1, result);
}
- OpCase(i_bs_put_utf16_jIs): {
+ OpCase(bs_put_utf16_jIs): {
Eterm arg;
GetArg1(2, arg);
diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c
index 16cbdbffea..a98900460e 100644
--- a/erts/emulator/beam/beam_load.c
+++ b/erts/emulator/beam/beam_load.c
@@ -2028,42 +2028,47 @@ load_code(LoaderState* stp)
ASSERT(arity == last_op->arity);
do_transform:
- if (stp->genop == NULL) {
- last_op_next = NULL;
- goto get_next_instr;
- }
-
+ ASSERT(stp->genop != NULL);
if (gen_opc[stp->genop->op].transform != -1) {
- int need;
- tmp_op = stp->genop;
-
- for (need = gen_opc[stp->genop->op].min_window-1; need > 0; need--) {
- if (tmp_op == NULL) {
- goto get_next_instr;
- }
- tmp_op = tmp_op->next;
+ if (stp->genop->next == NULL) {
+ /*
+ * Simple heuristic: Most transformations requires
+ * at least two instructions, so make sure that
+ * there are. That will reduce the number of
+ * TE_SHORT_WINDOWs.
+ */
+ goto get_next_instr;
}
switch (transform_engine(stp)) {
case TE_FAIL:
- last_op_next = NULL;
- last_op = NULL;
+ /*
+ * No transformation found. stp->genop != NULL and
+ * last_op_next is still valid. Go ahead and load
+ * the instruction.
+ */
break;
case TE_OK:
+ /*
+ * Some transformation was applied. last_op_next is
+ * no longer valid and stp->genop may be NULL.
+ * Try to transform again.
+ */
+ if (stp->genop == NULL) {
+ last_op_next = &stp->genop;
+ goto get_next_instr;
+ }
last_op_next = NULL;
- last_op = NULL;
goto do_transform;
case TE_SHORT_WINDOW:
- last_op_next = NULL;
- last_op = NULL;
+ /*
+ * No transformation applied. stp->genop != NULL and
+ * last_op_next is still valid. Fetch a new instruction
+ * before trying the transformation again.
+ */
goto get_next_instr;
}
}
- if (stp->genop == NULL) {
- last_op_next = NULL;
- goto get_next_instr;
- }
-
/*
* From the collected generic instruction, find the specific
* instruction.
@@ -2584,7 +2589,10 @@ load_code(LoaderState* stp)
{
GenOp* next = stp->genop->next;
FREE_GENOP(stp, stp->genop);
- stp->genop = next;
+ if ((stp->genop = next) == NULL) {
+ last_op_next = &stp->genop;
+ goto get_next_instr;
+ }
goto do_transform;
}
}
@@ -2728,13 +2736,6 @@ mixed_types(LoaderState* stp, GenOpArg Size, GenOpArg* Rest)
}
static int
-same_label(LoaderState* stp, GenOpArg Target, GenOpArg Label)
-{
- return Target.type = TAG_f && Label.type == TAG_u &&
- Target.val == Label.val;
-}
-
-static int
is_killed_apply(LoaderState* stp, GenOpArg Reg, GenOpArg Live)
{
return Reg.type == TAG_x && Live.type == TAG_u &&
@@ -4805,31 +4806,25 @@ transform_engine(LoaderState* st)
Uint op;
int ap; /* Current argument. */
Uint* restart; /* Where to restart if current match fails. */
- GenOpArg def_vars[TE_MAX_VARS]; /* Default buffer for variables. */
- GenOpArg* var = def_vars;
- int num_vars = 0;
+ GenOpArg var[TE_MAX_VARS]; /* Buffer for variables. */
+ GenOpArg* rest_args = NULL;
+ int num_rest_args = 0;
int i; /* General index. */
Uint mask;
GenOp* instr;
+ GenOp* first = st->genop;
+ GenOp* keep = NULL;
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;
- restart = pc;
+ ASSERT(gen_opc[first->op].transform != -1);
+ restart = op_transform + gen_opc[first->op].transform;
restart:
- if (var != def_vars) {
- erts_free(ERTS_ALC_T_LOADER_TMP, (void *) var);
- var = def_vars;
- }
ASSERT(restart != NULL);
pc = restart;
ASSERT(*pc < NUM_TOPS); /* Valid instruction? */
- instr = st->genop;
-
-#define RETURN(r) rval = (r); goto do_return;
+ instr = first;
#ifdef DEBUG
restart = NULL;
@@ -4847,7 +4842,7 @@ transform_engine(LoaderState* st)
* We'll need at least one more instruction to decide whether
* this combination matches or not.
*/
- RETURN(TE_SHORT_WINDOW);
+ return TE_SHORT_WINDOW;
}
if (*pc++ != instr->op)
goto restart;
@@ -5009,19 +5004,9 @@ transform_engine(LoaderState* st)
#if defined(TOP_rest_args)
case TOP_rest_args:
{
- int n = *pc++;
int formal_arity = gen_opc[instr->op].arity;
- int j = formal_arity;
-
- num_vars = n + (instr->arity - formal_arity);
- var = erts_alloc(ERTS_ALC_T_LOADER_TMP,
- num_vars * sizeof(GenOpArg));
- for (i = 0; i < n; i++) {
- var[i] = def_vars[i];
- }
- while (i < num_vars) {
- var[i++] = instr->a[j++];
- }
+ num_rest_args = instr->arity - formal_arity;
+ rest_args = instr->a + formal_arity;
}
break;
#endif
@@ -5030,21 +5015,22 @@ transform_engine(LoaderState* st)
break;
case TOP_commit:
instr = instr->next; /* The next_instr was optimized away. */
-
- /*
- * The left-hand side of this transformation matched.
- * Delete all matched instructions.
- */
- while (st->genop != instr) {
- GenOp* next = st->genop->next;
- FREE_GENOP(st, st->genop);
- st->genop = next;
- }
+ keep = instr;
+ st->genop = instr;
#ifdef DEBUG
instr = 0;
#endif
break;
-
+#if defined(TOP_keep)
+ case TOP_keep:
+ /* Keep the current instruction unchanged. */
+ keep = instr;
+ st->genop = instr;
+#ifdef DEBUG
+ instr = 0;
+#endif
+ break;
+#endif
#if defined(TOP_call_end)
case TOP_call_end:
{
@@ -5069,22 +5055,19 @@ transform_engine(LoaderState* st)
lastp = &((*lastp)->next);
}
- instr = instr->next; /* The next_instr was optimized away. */
-
- /*
- * The left-hand side of this transformation matched.
- * Delete all matched instructions.
- */
- while (st->genop != instr) {
- GenOp* next = st->genop->next;
- FREE_GENOP(st, st->genop);
- st->genop = next;
- }
- *lastp = st->genop;
+ keep = instr->next; /* The next_instr was optimized away. */
+ *lastp = keep;
st->genop = new_instr;
}
- RETURN(TE_OK);
+ /* FALLTHROUGH */
#endif
+ case TOP_end:
+ while (first != keep) {
+ GenOp* next = first->next;
+ FREE_GENOP(st, first);
+ first = next;
+ }
+ return TE_OK;
case TOP_new_instr:
/*
* Note that the instructions are generated in reverse order.
@@ -5096,6 +5079,12 @@ transform_engine(LoaderState* st)
instr->arity = gen_opc[op].arity;
ap = 0;
break;
+#ifdef TOP_rename
+ case TOP_rename:
+ instr->op = op = *pc++;
+ instr->arity = gen_opc[op].arity;
+ return TE_OK;
+#endif
case TOP_store_type:
i = *pc++;
instr->a[ap].type = i;
@@ -5115,14 +5104,10 @@ transform_engine(LoaderState* st)
#if defined(TOP_store_rest_args)
case TOP_store_rest_args:
{
- int n = *pc++;
- int num_extra = num_vars - n;
-
- ASSERT(n <= num_vars);
- GENOP_ARITY(instr, instr->arity+num_extra);
+ GENOP_ARITY(instr, instr->arity+num_rest_args);
memcpy(instr->a, instr->def_args, ap*sizeof(GenOpArg));
- memcpy(instr->a+ap, var+n, num_extra*sizeof(GenOpArg));
- ap += num_extra;
+ memcpy(instr->a+ap, rest_args, num_rest_args*sizeof(GenOpArg));
+ ap += num_rest_args;
}
break;
#endif
@@ -5134,21 +5119,12 @@ transform_engine(LoaderState* st)
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);
}
}
-#undef RETURN
-
- do_return:
- if (var != def_vars) {
- erts_free(ERTS_ALC_T_LOADER_TMP, (void *) var);
- }
- return rval;
}
static void
diff --git a/erts/emulator/beam/beam_load.h b/erts/emulator/beam/beam_load.h
index 22ab71c868..68f4b96893 100644
--- a/erts/emulator/beam/beam_load.h
+++ b/erts/emulator/beam/beam_load.h
@@ -33,7 +33,6 @@ typedef struct gen_op_entry {
int specific;
int num_specific;
int transform;
- int min_window;
} GenOpEntry;
extern GenOpEntry gen_opc[];
diff --git a/erts/emulator/beam/ops.tab b/erts/emulator/beam/ops.tab
index 772460c177..15f27835a8 100644
--- a/erts/emulator/beam/ops.tab
+++ b/erts/emulator/beam/ops.tab
@@ -181,11 +181,6 @@ i_jump_on_val_zero y f I
i_jump_on_val x f I I
i_jump_on_val y f I I
-jump Target | label Lbl | same_label(Target, Lbl) => label Lbl
-
-is_ne_exact L1 S1 S2 | jump Fail | label L2 | same_label(L1, L2) => \
- is_eq_exact Fail S1 S2 | label L2
-
%macro: get_list GetList -pack
get_list x x x
get_list x x y
@@ -1355,9 +1350,7 @@ bs_put_utf8 Fail u Src=s => i_bs_put_utf8 Fail Src
i_bs_put_utf8 j s
-bs_put_utf16 Fail Flags=u Src=s => i_bs_put_utf16 Fail Flags Src
-
-i_bs_put_utf16 j I s
+bs_put_utf16 j I s
bs_put_utf32 Fail=j Flags=u Src=s => \
i_bs_validate_unicode Fail Src | bs_put_integer Fail i=32 u=1 Flags Src
@@ -1539,7 +1532,6 @@ gen_minus p Live Reg=d Int=i Dst | negation_is_small(Int) => \
# GCing arithmetic instructions.
#
-gen_plus Fail Live Y=y X=x Dst => i_plus Fail Live X Y Dst
gen_plus Fail Live S1 S2 Dst => i_plus Fail Live S1 S2 Dst
gen_minus Fail Live S1 S2 Dst => i_minus Fail Live S1 S2 Dst
diff --git a/erts/emulator/utils/beam_makeops b/erts/emulator/utils/beam_makeops
index f805e7cc64..2e7073a8f0 100755
--- a/erts/emulator/utils/beam_makeops
+++ b/erts/emulator/utils/beam_makeops
@@ -113,7 +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;
@@ -382,7 +381,6 @@ 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]);
@@ -440,7 +438,6 @@ $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;
}
}
@@ -607,7 +604,7 @@ 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";
@@ -1405,8 +1402,7 @@ 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);
}
@@ -1457,58 +1453,14 @@ 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;
@@ -1530,8 +1482,20 @@ 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;
}
@@ -1544,7 +1508,6 @@ 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)";
@@ -1593,15 +1556,21 @@ 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} = $var_num;
@@ -1629,46 +1598,14 @@ sub tr_gen_from {
#
push(@code, make_op($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) = @$code_ref;
@@ -1697,13 +1634,16 @@ sub tr_gen_to {
if ($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, $op);
last;
}
@@ -1725,11 +1665,13 @@ sub tr_gen_to {
my($var, $type, $type_val) = @$op;
if ($type eq '*') {
- push(@code, make_op($var, 'store_rest_args', $var{$var}));
+ 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) {
@@ -1744,6 +1686,10 @@ 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.
#
@@ -1752,8 +1698,6 @@ 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{$key}})
@@ -1771,6 +1715,148 @@ sub tr_gen_to {
push(@{$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($ref);
@@ -1783,7 +1869,12 @@ sub tr_code_len {
sub make_op {
my($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 {