diff options
Diffstat (limited to 'erts/emulator')
| -rwxr-xr-x | erts/emulator/utils/beam_makeops | 123 |
1 files changed, 73 insertions, 50 deletions
diff --git a/erts/emulator/utils/beam_makeops b/erts/emulator/utils/beam_makeops index 66ffd83ee9..2e7073a8f0 100755 --- a/erts/emulator/utils/beam_makeops +++ b/erts/emulator/utils/beam_makeops @@ -1402,8 +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); } @@ -1454,55 +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($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; @@ -1534,7 +1492,10 @@ sub tr_gen_from { } } my $pi = tr_next_index(\@pred_table, \%pred_table, $name, @args); - push(@code, make_op("$name()", 'pred', $pi)); + my $op = make_op("$name()", 'pred', $pi); + my @slots = grep(/^\d+/, map { $var{$_} } @ops); + op_slot_usage($op, @slots); + push(@code, $op); next; } @@ -1595,7 +1556,9 @@ 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 '*') { foreach my $type (values %var_type) { error("only one use of a '*' variable is " . @@ -1607,7 +1570,7 @@ sub tr_gen_from { $var{$var} = 'unnumbered'; $var_type{$var} = 'array'; push(@code, make_op($var, 'rest_args')); - } elsif ($var_used{$var}) { + } else { $ignored_var = ''; $var_type{$var} = 'scalar'; $var{$var} = $var_num; @@ -1677,7 +1640,10 @@ sub tr_gen_to { 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, $op); last; } @@ -1703,7 +1669,9 @@ sub tr_gen_to { } elsif ($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) { @@ -1720,6 +1688,7 @@ sub tr_gen_to { tr_maybe_keep(\@code); tr_maybe_rename(\@code); + tr_remove_unused(\@code); # # Chain together all codes segments having the same first operation. @@ -1839,6 +1808,55 @@ sub tr_maybe_rename { } } +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($ref); @@ -1851,7 +1869,12 @@ sub tr_code_len { sub make_op { my($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 { |