Rename arch_register_req_type_should_be_different to the more appropriate arch_regist...
[libfirm] / ir / be / scripts / generate_new_opcodes.pl
index 67bdee9..578d5b0 100755 (executable)
@@ -1,7 +1,7 @@
 #!/usr/bin/perl -w
 
 #
-# Copyright (C) 1995-2007 University of Karlsruhe.  All right reserved.
+# Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
 #
 # This file is part of libFirm.
 #
@@ -39,10 +39,15 @@ our $additional_opcodes;
 our %nodes;
 our %operands;
 our %cpu;
+our $default_op_attr_type;
 our $default_attr_type;
 our $default_cmp_attr;
+our $default_copy_attr;
 our %init_attr;
+our $custom_init_attr_func;
 our %compare_attr;
+our %copy_attr;
+our %reg_classes;
 
 # include spec file
 
@@ -64,7 +69,7 @@ if(!defined($default_attr_type)) {
 }
 if(!defined(%init_attr)) {
        %init_attr = (
-               "$default_attr_type" => "\tinit_${arch}_attributes(res, flags, in_reqs, out_reqs, exec_units, n_res, latency);",
+               "$default_attr_type" => "\tinit_${arch}_attributes(res, flags, in_reqs, out_reqs, exec_units, n_res);",
        );
 }
 if(!defined($default_cmp_attr)) {
@@ -95,7 +100,7 @@ foreach my $op (keys(%operands)) {
        }
        $op_node{op_flags} = "O";
        $op_node{cmp_attr} = 'return 1;';
-       $op_node{mode}     = 'mode_any';
+       $op_node{mode}     = 'mode_ANY';
 
        $nodes{$op} = \%op_node;
 }
@@ -105,6 +110,8 @@ foreach my $op (keys(%operands)) {
 
 # create c code file from specs
 
+my @obst_limit_func;
+my @obst_reg_reqs;
 my @obst_opvar;       # stack for the "ir_op *op_<arch>_<op-name> = NULL;" statements
 my @obst_get_opvar;   # stack for the get_op_<arch>_<op-name>() functions
 my @obst_constructor; # stack for node constructor functions
@@ -121,11 +128,37 @@ my $temp;
 my $n_opcodes = 0;    # number of opcodes
 my $ARITY_VARIABLE = -1;
 my $ARITY_DYNAMIC  = -2;
+my %requirements = ();
+my %limit_bitsets = ();
+my %reg2class = ();
+my %regclass2len = ();
+
+# build register->class hashes
+foreach my $class_name (keys(%reg_classes)) {
+       my @class         = @{ $reg_classes{"$class_name"} };
+       my $old_classname = $class_name;
+
+       pop(@class);
+
+       $class_name = $arch."_".$class_name;
+
+       my $idx = 0;
+       foreach (@class) {
+               $reg2class{$_->{name}} = {
+                       "class" => $old_classname,
+                       "index" => $idx
+               };
+               $idx++;
+       }
+
+       $regclass2len{$old_classname} = $idx;
+}
+
 
 # for registering additional opcodes
 $n_opcodes += $additional_opcodes if (defined($additional_opcodes));
 
-push(@obst_header, "void ".$arch."_create_opcodes(void);\n");
+push(@obst_header, "void ".$arch."_create_opcodes(const arch_irn_ops_t *be_ops);\n");
 
 push(@obst_enum_op, "typedef enum _$arch\_opcodes {\n");
 foreach my $op (keys(%nodes)) {
@@ -232,6 +265,12 @@ foreach my $op (keys(%nodes)) {
                $attr_type = $default_attr_type;
        }
 
+       # determine hash function
+       my $hash_func;
+       if (exists($n{"hash_func"})) {
+               $hash_func = $n{"hash_func"};
+       }
+
        # determine compare function
        my $cmp_attr_func;
        if (exists($n{"cmp_attr"})) {
@@ -344,12 +383,6 @@ foreach my $op (keys(%nodes)) {
                                $temp .= "\tint       n_res   = ${out_arity};\n";
                        }
 
-                       my $latency = $n{"latency"};
-                       if (!defined($latency)) {
-                               $latency = 1;
-                       }
-                       $temp .= "\tunsigned  latency = ${latency};\n";
-
                        if (defined($known_mode)) {
                                $temp .= "\tir_mode  *mode    = ${known_mode};\n";
                        }
@@ -374,6 +407,15 @@ foreach my $op (keys(%nodes)) {
                                undef my @out;
                                @out = @{ $req{"out"} } if exists(($req{"out"}));
 
+                               for(my $idx = 0; $idx < $#in; $idx++) {
+                                       my $req = $in[$idx];
+                                       generate_requirements($req, \%n, $op, $idx, 1);
+                               }
+                               for(my $idx = 0; $idx < $#out; $idx++) {
+                                       my $req = $out[$idx];
+                                       generate_requirements($req, \%n, $op, $idx, 0);
+                               }
+
                                if (@in) {
                                        if($arity >= 0 && scalar(@in) != $arity) {
                                                die "Fatal error: Arity and number of in requirements don't match for ${op}\n";
@@ -382,7 +424,9 @@ foreach my $op (keys(%nodes)) {
                                        $temp .= "\tstatic const arch_register_req_t *in_reqs[] =\n";
                                        $temp .= "\t{\n";
                                        for ($idx = 0; $idx <= $#in; $idx++) {
-                                               $temp .= "\t\t&".$op."_reg_req_in_".$idx.",\n";
+                                               my $req = $in[$idx];
+                                               my $reqstruct = generate_requirements($req, \%n, $op, $idx, 1);
+                                               $temp .= "\t\t& ${reqstruct},\n";
                                        }
                                        $temp .= "\t};\n";
                                } else {
@@ -400,7 +444,9 @@ foreach my $op (keys(%nodes)) {
                                        $temp .= "\tstatic const arch_register_req_t *out_reqs[] =\n";
                                        $temp .= "\t{\n";
                                        for ($idx = 0; $idx <= $#out; $idx++) {
-                                               $temp .= "\t\t&".$op."_reg_req_out_".$idx.",\n";
+                                               my $req = $out[$idx];
+                                               my $reqstruct = generate_requirements($req, \%n, $op, $idx, 0);
+                                               $temp .= "\t\t& ${reqstruct},\n";
                                        }
                                        $temp .= "\t};\n";
                                } else {
@@ -462,32 +508,38 @@ foreach my $op (keys(%nodes)) {
                                die "Fatal error: Couldn't find attribute initialisation code for type '${attr_type}'";
                        }
                        $temp .= "${attr_init_code}\n";
+                       if(defined($custom_init_attr_func)) {
+                               $temp .= &$custom_init_attr_func(\%n, $op);
+                       }
                        $temp .= "\n";
 
                        # set flags for outs
-                       if ($#out_flags >= 0) {
-                               $temp .= "\t/* set flags for outs */\n";
-                               for (my $idx = 0; $idx <= $#out_flags; $idx++) {
-                                       my $flags  = "";
-                                       my $prefix = "";
-
-                                       foreach my $flag (split(/\|/, $out_flags[$idx])) {
-                                               if ($flag eq "I") {
-                                                       $flags .= $prefix."arch_irn_flags_ignore";
-                                                       $prefix = " | ";
-                                               }
-                                               elsif ($flag eq "S") {
-                                                       $flags .= $prefix."arch_irn_flags_modify_sp";
-                                                       $prefix = " | ";
+                       if (exists($n{"outs"})) {
+                               undef my @outs;
+                               @outs     = @{ $n{"outs"} };
+
+                               for (my $idx = 0; $idx <= $#outs; $idx++) {
+                                       # check, if we have additional flags annotated to out
+                                       if ($outs[$idx] =~ /:((S|I)(\|(S|I))*)/) {
+                                               my $flag_string = $1;
+                                               my $prefix = "";
+                                               my $flags  = "";
+
+                                               foreach my $flag (split(/\|/, $flag_string)) {
+                                                       if ($flag eq "I") {
+                                                               $flags .= $prefix."arch_irn_flags_ignore";
+                                                               $prefix = " | ";
+                                                       } elsif ($flag eq "S") {
+                                                               $flags .= $prefix."arch_irn_flags_modify_sp";
+                                                               $prefix = " | ";
+                                                       }
                                                }
-                                       }
 
-                                       $temp .= "\tset_$arch\_out_flags(res, $flags, $idx);\n";
+                                               $temp .= "\tset_$arch\_out_flags(res, $flags, $idx);\n";
+                                       }
                                }
-                               $temp .= "\n";
                        }
 
-
                        if (exists($n{"init_attr"})) {
                                $temp .= "\tattr = get_irn_generic_attr(res);\n";
                                $temp .= "\t".$n{"init_attr"}."\n";
@@ -516,11 +568,22 @@ foreach my $op (keys(%nodes)) {
 
 
        push(@obst_new_irop, "\n\tmemset(&ops, 0, sizeof(ops));\n");
+       push(@obst_new_irop, "\tops.be_ops        = be_ops;\n");
        push(@obst_new_irop, "\tops.dump_node     = $arch\_dump_node;\n");
 
        if (defined($cmp_attr_func)) {
                push(@obst_new_irop, "\tops.node_cmp_attr = ${cmp_attr_func};\n");
        }
+       my $copy_attr_func = $copy_attr{$attr_type};
+       if (!defined($copy_attr_func)) {
+               $copy_attr_func = $default_copy_attr;
+       }
+       if (defined($copy_attr_func)) {
+               push(@obst_new_irop, "\tops.copy_attr = ${copy_attr_func};\n");
+       }
+       if (defined($hash_func)) {
+               push(@obst_new_irop, "\tops.hash = ${hash_func};\n");
+       }
 
        $n_opcodes++;
        my $n_res = $out_arity;
@@ -530,7 +593,15 @@ foreach my $op (keys(%nodes)) {
        $temp  = "\top_$op = new_ir_op(cur_opcode + iro_$op, \"$op\", op_pin_state_".$n{"state"}.", ".$n{"op_flags"};
        $temp .= "|M, ".translate_arity($arity).", 0, sizeof(${attr_type}), &ops);\n";
        push(@obst_new_irop, $temp);
-       push(@obst_new_irop, "\tset_op_tag(op_$op, &$arch\_op_tag);\n");
+       push(@obst_new_irop, "\tset_op_tag(op_$op, $arch\_op_tag);\n");
+       if(defined($default_op_attr_type)) {
+               push(@obst_new_irop, "\tattr = &attrs[iro_$op];\n");
+               if(defined($n{op_attr_init})) {
+                       push(@obst_new_irop, "\t".$n{op_attr_init}."\n");
+               }
+               push(@obst_new_irop, "\tset_op_attr(op_$op, attr);\n");
+       }
+
        push(@obst_enum_op, "\tiro_$op,\n");
 
        push(@obst_header, "\n");
@@ -544,7 +615,7 @@ push(@obst_enum_op, "\n} $arch\_opcodes;\n\n");
 
 open(OUT, ">$target_c") || die("Fatal error: Could not open $target_c, reason: $!\n");
 
-print OUT "#include \"gen_$arch\_regalloc_if_t.h\"\n\n";
+print OUT "#include \"gen_$arch\_regalloc_if.h\"\n\n";
 print OUT @obst_cmp_attr;
 print OUT "\n";
 print OUT @obst_opvar;
@@ -582,7 +653,7 @@ if (length($arch) >= 4) {
 print OUT<<ENDOFISIRN;
 
 /** A tag for the $arch opcodes. Note that the address is used as a tag value, NOT the FOURCC code. */
-static unsigned $arch\_op_tag = FOURCC('$a', '$b', '$c', '$d');
+#define $arch\_op_tag FOURCC('$a', '$b', '$c', '$d')
 
 /** Return the opcode number of the first $arch opcode. */
 int get_$arch\_opcode_first(void) {
@@ -596,7 +667,7 @@ int get_$arch\_opcode_last(void) {
 
 /** Return 1 if the given opcode is a $arch machine op, 0 otherwise */
 int is_$arch\_op(const ir_op *op) {
-       return get_op_tag(op) == &$arch\_op_tag;
+       return get_op_tag(op) == $arch\_op_tag;
 }
 
 /** Return 1 if the given node is a $arch machine node, 0 otherwise */
@@ -612,6 +683,20 @@ int get_$arch\_irn_opcode(const ir_node *node) {
 
 ENDOFISIRN
 
+print OUT <<END;
+#ifdef BIT
+#undef BIT
+#endif
+#define BIT(x)  (1 << (x % 32))
+
+END
+
+print OUT @obst_limit_func;
+print OUT "\n";
+
+print OUT @obst_reg_reqs;
+print OUT "\n";
+
 print OUT @obst_constructor;
 
 print OUT<<ENDOFMAIN;
@@ -619,7 +704,7 @@ print OUT<<ENDOFMAIN;
  * Creates the $arch specific Firm machine operations
  * needed for the assembler irgs.
  */
-void $arch\_create_opcodes(void) {
+void $arch\_create_opcodes(const arch_irn_ops_t *be_ops) {
 #define N   irop_flag_none
 #define L   irop_flag_labeled
 #define C   irop_flag_commutative
@@ -632,21 +717,43 @@ void $arch\_create_opcodes(void) {
 #define K   irop_flag_keep
 #define M   irop_flag_machine
 #define O   irop_flag_machine_op
+#define NB  irop_flag_dump_noblock
+#define NI  irop_flag_dump_noinput
 #define R   (irop_flag_user << 0)
 
        ir_op_ops  ops;
        int        cur_opcode;
        static int run_once = 0;
+       int        i;
+ENDOFMAIN
+
+       if (defined($default_op_attr_type)) {
+               print OUT "\t$default_op_attr_type *attr, *attrs;\n";
+       }
+
+print OUT<<ENDOFMAIN;
 
        if (run_once)
                return;
        run_once = 1;
 
+       /* we handle all middleend nodes as well that have no other handler */
+       for (i = 0; i <= iro_Last; ++i) {
+               ir_op *op      = get_irp_opcode(i);
+               if (op->ops.be_ops == NULL)
+                       op->ops.be_ops = be_ops;
+       }
+
        cur_opcode = get_next_ir_opcodes(iro_$arch\_last);
 
        $arch\_opcode_start = cur_opcode;
 ENDOFMAIN
 
+       if (defined($default_op_attr_type)) {
+               print OUT "\tattrs = xmalloc(sizeof(attr[0]) * iro_$arch\_last);\n";
+               print OUT "\tmemset(attrs, 0, sizeof(attr[0]) * iro_$arch\_last);\n";
+       }
+
 print OUT @obst_new_irop;
 print OUT "\n";
 print OUT "\t$arch\_register_additional_opcodes(cur_opcode);\n" if (defined($additional_opcodes));
@@ -788,3 +895,369 @@ TP_SEARCH:        foreach my $cur_type (keys(%cpu)) {
 
        return $ret;
 }
+
+sub mangle_requirements {
+       my $reqs  = shift;
+       my $class = shift;
+
+       my @alternatives = split(/ /, $reqs);
+       for(my $idx = 0; $idx < scalar(@alternatives); $idx++) {
+               $alternatives[$idx] =~ s/!/not_/g;
+       }
+
+       @alternatives = sort @alternatives;
+
+       my $name = $class."_".join('_', @alternatives);
+
+       return $name;
+}
+
+###
+# Determines whether $name is a specified register class or not.
+# @return 1 if name is register class, 0 otherwise
+###
+sub is_reg_class {
+    my $name = shift;
+    return 1 if exists($reg_classes{"$name"});
+    return 0;
+}
+
+###
+# Returns the register class for a given register.
+# @return class or undef
+###
+sub get_reg_class {
+    my $reg = shift;
+    $reg = substr($reg, 1) if ($reg =~ /!.*/);
+    return $reg2class{"$reg"}{"class"} if (exists($reg2class{"$reg"}));
+    return undef;
+}
+
+###
+# Returns the index of a given register within it's register class.
+# @return index or undef
+###
+sub get_reg_index {
+    my $reg = shift;
+    return $reg2class{"$reg"}{"index"} if (exists($reg2class{"$reg"}));
+    return undef;
+}
+
+###
+# Remember the register class for each index in the given requirements.
+# We need this information for requirements like "in_sX" or "out_dX"
+# @return array of classes corresponding to the requirement for each index
+###
+sub build_inout_idx_class {
+       my $n     = shift;
+       my $op    = shift;
+       my $is_in = shift;
+       my @idx_class;
+
+       my $inout = ($is_in ? "in" : "out");
+
+       if (exists($n->{"reg_req"}{"$inout"})) {
+               my @reqs = @{ $n->{"reg_req"}{"$inout"} };
+
+               for (my $idx = 0; $idx <= $#reqs; $idx++) {
+                       my $class = undef;
+
+                       if ($reqs[$idx] eq "none") {
+                               $class = "none";
+                       } elsif (is_reg_class($reqs[$idx])) {
+                               $class = $reqs[$idx];
+                       } else {
+                               my @regs = split(/ /, $reqs[$idx]);
+GET_CLASS:             foreach my $reg (@regs) {
+                                       if ($reg =~ /!?(in|out)\_r\d+/ || $reg =~ /!in/) {
+                                               $class = "UNKNOWN_CLASS";
+                                       } else {
+                                               $class = get_reg_class($reg);
+                                               if (!defined $class) {
+                                                       die("Fatal error: Could not get ".uc($inout)." register class for '$op' pos $idx (reg $reg) ... exiting.\n");
+                                               } else {
+                                                       last GET_CLASS;
+                                               } # !defined class
+                                       } # if (reg =~ ...
+                               } # foreach
+                       } # if
+
+                       push(@idx_class, $class);
+               } # for
+       } # if
+
+       return @idx_class;
+}
+
+###
+# Generates the function for a given $op and a given IN-index
+# which returns a subset of possible register from a register class
+# @return classname from which the subset is derived or undef and
+#         pos which corresponds to in/out reference position or undef
+###
+sub build_subset_class_func {
+       my $neg           = undef;
+       my $class         = undef;
+       my $has_limit     = 0;
+       my $limit_name;
+       my $same_pos      = 0;
+       my $different_pos = 0;
+       my $temp;
+       my @obst_init;
+       my @obst_limits;
+       my @obst_ignore;
+       my @limit_array;
+       my $limit_reqs;   #used for name mangling
+
+       # build function header
+       my $node  = shift;
+       my $op    = shift;
+       my $idx   = shift;
+       my $is_in = shift;
+       my @regs  = split(/ /, shift);
+
+       my @idx_class = build_inout_idx_class($node, $op, !$is_in);
+
+       # set/unset registers
+CHECK_REQS: foreach (@regs) {
+               if (!$is_in && /(!)?in_r(\d+)/) {
+                       my $bit_pos = 1 << ($2 - 1);
+                       if ($different_pos & $bit_pos) {
+                               if ($1) {
+                                       print STDERR "duplicate !in constraint\n";
+                               } else {
+                                       print STDERR "conflicting !in and in constraints\n";
+                               }
+                               return (undef, undef, undef, undef);
+                       }
+
+                       if ($same_pos & $bit_pos) {
+                               if ($1) {
+                                       print STDERR "conflicting !in and in constraints\n";
+                               } else {
+                                       print STDERR "duplicate in constraint\n";
+                               }
+                               return (undef, undef, undef, undef);
+                       }
+
+                       if ($1) {
+                               $different_pos |= $bit_pos;
+                       } else {
+                               $same_pos      |= $bit_pos;
+                       }
+
+                       $class = $idx_class[$2 - 1];
+                       next CHECK_REQS;
+               }
+
+               # check for negate
+               if (substr($_, 0, 1) eq "!") {
+                       if (defined($neg) && $neg == 0) {
+                               # we have seen a positiv constraint as first one but this one is negative
+                               # this doesn't make sense
+                               print STDERR "Mixed positive and negative constraints for the same slot are not allowed.\n";
+                               return (undef, undef, undef, undef);
+                       }
+
+                       if (!defined($neg)) {
+                               $has_limit = 1;
+                       }
+
+                       $_   = substr($_, 1); # skip '!'
+                       $neg = 1;
+               } else {
+                       if (defined($neg) && $neg == 1) {
+                               # we have seen a negative constraint as first one but this one is positive
+                               # this doesn't make sense
+                               print STDERR "Mixed positive and negative constraints for the same slot are not allowed.\n";
+                               return (undef, undef, undef, undef);
+                       }
+
+                       $has_limit = 1;
+                       $neg = 0;
+               }
+
+               # check if register belongs to one of the given classes
+               $temp = get_reg_class($_);
+               if (!defined($temp)) {
+                       print STDERR "Unknown register '$_'!\n";
+                       return (undef, undef, undef, undef);
+               }
+
+               # set class
+               if (!defined($class)) {
+                       $class = $temp;
+               } elsif ($class ne $temp) {
+                       # all registers must belong to the same class
+                       print STDERR "Registerclass mismatch. '$_' is not member of class '$class'.\n";
+                       return (undef, undef, undef, undef);
+               }
+
+               # calculate position inside the initializer bitfield (only 32 bits per
+               # element)
+               my $regidx = get_reg_index($_);
+               my $arrayp = $regidx / 32;
+               push(@{$limit_array[$arrayp]}, $_);
+               $limit_reqs .= "$_ ";
+       }
+
+       # don't allow ignore regs in negative constraints
+       if($neg) {
+               my @cur_class = @{ $reg_classes{"$class"} };
+               for (my $idx = 0; $idx <= $#cur_class; $idx++) {
+                       if (defined($cur_class[$idx]{"type"}) && ($cur_class[$idx]{"type"} & 4)) {
+                               my $reg    = $cur_class[$idx]{"name"};
+                               my $regix  = get_reg_index($reg);
+                               my $arrayp = $regix / 32;
+                               push(@{$limit_array[$arrayp]}, $reg);
+                               $limit_reqs .= "$reg ";
+                       }
+               }
+       }
+
+       if ($has_limit == 1) {
+               $limit_name = "${arch}_limit_".mangle_requirements($limit_reqs, $class);
+
+               if(defined($limit_bitsets{$limit_name})) {
+                       $limit_name = $limit_bitsets{$limit_name};
+                       return ($class, $limit_name, $same_pos, $different_pos);
+               }
+
+               $limit_bitsets{$limit_name} = $limit_name;
+
+               push(@obst_limit_func, "static const unsigned " . $limit_name . "[] = { ");
+               my $first = 1;
+               my $limitbitsetlen = $regclass2len{$class};
+               my $limitarraylen = $limitbitsetlen / 32 + ($limitbitsetlen % 32 > 0 ? 1 : 0);
+               for(my $i = 0; $i < $limitarraylen; $i++) {
+
+                       my $limitarraypart = $limit_array[$i];
+                       if($first) {
+                               $first = 0;
+                       } else {
+                               push(@obst_limit_func, ", ");
+                       }
+                       my $temp;
+                       if($neg) {
+                               $temp = "0xFFFFFFFF";
+                       }
+                       foreach my $reg (@{$limitarraypart}) {
+                               if($neg) {
+                                       $temp .= " & ~";
+                               } elsif(defined($temp)) {
+                                       $temp .= " | ";
+                               }
+                               $temp .= "BIT(REG_".uc(${reg}).")";
+                       }
+                       if(defined($temp)) {
+                               push(@obst_limit_func, "${temp}");
+                       } else {
+                               push(@obst_limit_func, "0");
+                       }
+               }
+               push(@obst_limit_func, " };\n");
+       }
+
+       return ($class, $limit_name, $same_pos, $different_pos);
+}
+
+###
+# Generate register requirements structure
+###
+sub generate_requirements {
+       my $reqs  = shift;
+       my $node  = shift;
+       my $op    = shift;
+       my $idx   = shift;
+       my $is_in = shift;
+       my $class = "";
+       my $result;
+
+       if ($reqs eq "none") {
+
+               $result = <<EOF;
+{
+       arch_register_req_type_none,
+       NULL,                         /* regclass */
+       NULL,                         /* limit bitset */
+       0,                            /* same pos */
+       0                             /* different pos */
+};
+
+EOF
+       } elsif ($reqs =~ /^new_reg_(.*)$/) {
+               if(!is_reg_class($1)) {
+                       die "$1 is not a register class in requirements for $op\n";
+               }
+               $class  = $1;
+               $result = <<EOF;
+{
+       arch_register_req_type_should_be_different_from_all,
+       & ${arch}_reg_classes[CLASS_${arch}_${class}],
+       NULL,        /* limit bitset */
+       0,           /* same pos */
+       0            /* different pos */
+};
+
+EOF
+       } elsif (is_reg_class($reqs)) {
+               $class  = $reqs;
+               $result = <<EOF;
+{
+       arch_register_req_type_normal,
+       & ${arch}_reg_classes[CLASS_${arch}_${class}],
+       NULL,        /* limit bitset */
+       0,           /* same pos */
+       0            /* different pos */
+};
+
+EOF
+
+       } else {
+               my @req_type_mask;
+               my ($regclass, $limit_bitset, $same_pos, $different_pos)
+                       = build_subset_class_func($node, $op, $idx, $is_in, $reqs);
+
+               if (!defined($regclass)) {
+                       die("Fatal error: Could not build subset for requirements '$reqs' of '$op' pos $idx ... exiting.\n");
+               }
+
+               if (defined($limit_bitset) && $limit_bitset ne "NULL") {
+                       push(@req_type_mask, "arch_register_req_type_limited");
+               }
+               if ($same_pos != 0) {
+                       push(@req_type_mask, "arch_register_req_type_should_be_same");
+               }
+               if ($different_pos != 0) {
+                       push(@req_type_mask, "arch_register_req_type_must_be_different");
+               }
+               my $reqtype      = join(" | ", @req_type_mask);
+
+               if(!defined($limit_bitset)) {
+                       $limit_bitset = "NULL";
+               }
+
+               $class  = $regclass;
+               $result = <<EOF;
+{
+       ${reqtype},
+       & ${arch}_reg_classes[CLASS_${arch}_${class}],
+       ${limit_bitset},
+       ${same_pos},        /* same pos */
+       ${different_pos}        /* different pos */
+};
+
+EOF
+       }
+
+       my $name = "${arch}_requirements_".mangle_requirements($reqs, $class);
+       if(defined($requirements{$name})) {
+               return $name;
+       }
+       $requirements{$name} = $name;
+       push(@obst_reg_reqs, <<EOF);
+static const arch_register_req_t ${name} = ${result}
+EOF
+
+       return $name;
+}