sub re()

in ring/crypto/perlasm/x86_64-xlate.pl [633:706]

• 65 lines of code
• 21 McCabe index (conditional complexity)

    sub re {
	my	($class, $line) = @_;
	my	$self = {};
	my	$ret;

	if ($$line =~ s/^\s*\.cfi_(\w+)\s*//) {
	    bless $self,$class;
	    $ret = $self;
	    undef $self->{value};
	    my $dir = $1;

	    SWITCH: for ($dir) {
	    # What is $cfa_rsp? Effectively it's difference between %rsp
	    # value and current CFA, Canonical Frame Address, which is
	    # why it starts with -8. Recall that CFA is top of caller's
	    # stack...
	    /startproc/	&& do {	($cfa_reg, $cfa_rsp) = ("%rsp", -8); last; };
	    /endproc/	&& do {	($cfa_reg, $cfa_rsp) = ("%rsp",  0); last; };
	    /def_cfa_register/
			&& do {	$cfa_reg = $$line; last; };
	    /def_cfa_offset/
			&& do {	$cfa_rsp = -1*eval($$line) if ($cfa_reg eq "%rsp");
				last;
			      };
	    /adjust_cfa_offset/
			&& do {	$cfa_rsp -= 1*eval($$line) if ($cfa_reg eq "%rsp");
				last;
			      };
	    /def_cfa/	&& do {	if ($$line =~ /(%r\w+)\s*,\s*(.+)/) {
				    $cfa_reg = $1;
				    $cfa_rsp = -1*eval($2) if ($cfa_reg eq "%rsp");
				}
				last;
			      };
	    /push/	&& do {	$dir = undef;
				$cfa_rsp -= 8;
				if ($cfa_reg eq "%rsp") {
				    $self->{value} = ".cfi_adjust_cfa_offset\t8\n";
				}
				$self->{value} .= ".cfi_offset\t$$line,$cfa_rsp";
				last;
			      };
	    /pop/	&& do {	$dir = undef;
				$cfa_rsp += 8;
				if ($cfa_reg eq "%rsp") {
				    $self->{value} = ".cfi_adjust_cfa_offset\t-8\n";
				}
				$self->{value} .= ".cfi_restore\t$$line";
				last;
			      };
	    /cfa_expression/
			&& do {	$dir = undef;
				$self->{value} = ".cfi_escape\t" .
					join(",", map(sprintf("0x%02x", $_),
						      cfa_expression($$line)));
				last;
			      };
	    /remember_state/
			&& do {	push @cfa_stack, [$cfa_reg, $cfa_rsp];
				last;
			      };
	    /restore_state/
			&& do {	($cfa_reg, $cfa_rsp) = @{pop @cfa_stack};
				last;
			      };
	    }

	    $self->{value} = ".cfi_$dir\t$$line" if ($dir);

	    $$line = "";
	}

	return $ret;
    }