crypto/perlasm/x86_64-xlate.pl

   1 #!/usr/bin/env perl
   2
   3 # Ascetic x86_64 AT&T to MASM/NASM assembler translator by <appro>.
   4 #
   5 # Why AT&T to MASM and not vice versa? Several reasons. Because AT&T
   6 # format is way easier to parse. Because it's simpler to "gear" from
   7 # Unix ABI to Windows one [see cross-reference "card" at the end of
   8 # file]. Because Linux targets were available first...
   9 #
  10 # In addition the script also "distills" code suitable for GNU
  11 # assembler, so that it can be compiled with more rigid assemblers,
  12 # such as Solaris /usr/ccs/bin/as.
  13 #
  14 # This translator is not designed to convert *arbitrary* assembler
  15 # code from AT&T format to MASM one. It's designed to convert just
  16 # enough to provide for dual-ABI OpenSSL modules development...
  17 # There *are* limitations and you might have to modify your assembler
  18 # code or this script to achieve the desired result...
  19 #
  20 # Currently recognized limitations:
  21 #
  22 # - can't use multiple ops per line;
  23 #
  24 # Dual-ABI styling rules.
  25 #
  26 # 1. Adhere to Unix register and stack layout [see cross-reference
  27 #    ABI "card" at the end for explanation].
  28 # 2. Forget about "red zone," stick to more traditional blended
  29 #    stack frame allocation. If volatile storage is actually required
  30 #    that is. If not, just leave the stack as is.
  31 # 3. Functions tagged with ".type name,@function" get crafted with
  32 #    unified Win64 prologue and epilogue automatically. If you want
  33 #    to take care of ABI differences yourself, tag functions as
  34 #    ".type name,@abi-omnipotent" instead.
  35 # 4. To optimize the Win64 prologue you can specify number of input
  36 #    arguments as ".type name,@function,N." Keep in mind that if N is
  37 #    larger than 6, then you *have to* write "abi-omnipotent" code,
  38 #    because >6 cases can't be addressed with unified prologue.
  39 # 5. Name local labels as .L*, do *not* use dynamic labels such as 1:
  40 #    (sorry about latter).
  41 # 6. Don't use [or hand-code with .byte] "rep ret." "ret" mnemonic is
  42 #    required to identify the spots, where to inject Win64 epilogue!
  43 #    But on the pros, it's then prefixed with rep automatically:-)
  44 # 7. Stick to explicit ip-relative addressing. If you have to use
  45 #    GOTPCREL addressing, stick to mov symbol@GOTPCREL(%rip),%r??.
  46 #    Both are recognized and translated to proper Win64 addressing
  47 #    modes. To support legacy code a synthetic directive, .picmeup,
  48 #    is implemented. It puts address of the *next* instruction into
  49 #    target register, e.g.:
  50 #
  51 #               .picmeup        %rax
  52 #               lea             .Label-.(%rax),%rax
  53 #
  54 # 8. In order to provide for structured exception handling unified
  55 #    Win64 prologue copies %rsp value to %rax. For further details
  56 #    see SEH paragraph at the end.
  57 # 9. .init segment is allowed to contain calls to functions only.
  58 \f
  59 my $flavour = shift;
  60 my $output  = shift;
  61 if ($flavour =~ /\./) { $output = $flavour; undef $flavour; }
  62
  63 { my ($stddev,$stdino,@junk)=stat(STDOUT);
  64   my ($outdev,$outino,@junk)=stat($output);
  65
  66     open STDOUT,">$output" || die "can't open $output: $!"
  67         if ($stddev!=$outdev || $stdino!=$outino);
  68 }
  69
  70 my $gas=1;      $gas=0 if ($output =~ /\.asm$/);
  71 my $elf=1;      $elf=0 if (!$gas);
  72 my $win64=0;
  73 my $prefix="";
  74 my $decor=".L";
  75
  76 my $masmref=8 + 50727*2**-32;   # 8.00.50727 shipped with VS2005
  77 my $masm=0;
  78 my $PTR=" PTR";
  79
  80 my $nasmref=2.03;
  81 my $nasm=0;
  82
  83 if    ($flavour eq "mingw64")   { $gas=1; $elf=0; $win64=1; $prefix="_"; }
  84 elsif ($flavour eq "macosx")    { $gas=1; $elf=0; $prefix="_"; $decor="L\$"; }
  85 elsif ($flavour eq "masm")      { $gas=0; $elf=0; $masm=$masmref; $win64=1; $decor="\$L\$"; }
  86 elsif ($flavour eq "nasm")      { $gas=0; $elf=0; $nasm=$nasmref; $win64=1; $decor="\$L\$"; $PTR=""; }
  87 elsif (!$gas)
  88 {   if ($ENV{ASM} =~ m/nasm/ && `nasm -v` =~ m/version ([0-9]+)\.([0-9]+)/i)
  89     {   $nasm = $1 + $2*0.01; $PTR="";  }
  90     elsif (`ml64 2>&1` =~ m/Version ([0-9]+)\.([0-9]+)(\.([0-9]+))?/)
  91     {   $masm = $1 + $2*2**-16 + $4*2**-32;   }
  92     die "no assembler found on %PATH" if (!($nasm || $masm));
  93     $win64=1;
  94     $elf=0;
  95     $decor="\$L\$";
  96 }
  97
  98 my $current_segment;
  99 my $current_function;
 100 my %globals;
 101
 102 { package opcode;       # pick up opcodes
 103     sub re {
 104         my      $self = shift;  # single instance in enough...
 105         local   *line = shift;
 106         undef   $ret;
 107
 108         if ($line =~ /^([a-z][a-z0-9]*)/i) {
 109             $self->{op} = $1;
 110             $ret = $self;
 111             $line = substr($line,@+[0]); $line =~ s/^\s+//;
 112
 113             undef $self->{sz};
 114             if ($self->{op} =~ /^(movz)b.*/) {  # movz is pain...
 115                 $self->{op} = $1;
 116                 $self->{sz} = "b";
 117             } elsif ($self->{op} =~ /call|jmp/) {
 118                 $self->{sz} = ""
 119             } elsif ($self->{op} =~ /([a-z]{3,})([qlwb])$/) {
 120                 $self->{op} = $1;
 121                 $self->{sz} = $2;
 122             }
 123         }
 124         $ret;
 125     }
 126     sub size {
 127         my $self = shift;
 128         my $sz   = shift;
 129         $self->{sz} = $sz if (defined($sz) && !defined($self->{sz}));
 130         $self->{sz};
 131     }
 132     sub out {
 133         my $self = shift;
 134         if ($gas) {
 135             if ($self->{op} eq "movz") {        # movz is pain...
 136                 sprintf "%s%s%s",$self->{op},$self->{sz},shift;
 137             } elsif ($self->{op} =~ /^set/) {
 138                 "$self->{op}";
 139             } elsif ($self->{op} eq "ret") {
 140                 my $epilogue = "";
 141                 if ($win64 && $current_function->{abi} eq "svr4") {
 142                     $epilogue = "movq   8(%rsp),%rdi\n\t" .
 143                                 "movq   16(%rsp),%rsi\n\t";
 144                 }
 145                 $epilogue . ".byte      0xf3,0xc3";
 146             } elsif ($self->{op} eq "call" && !$elf && $current_segment eq ".init") {
 147                 ".p2align\t3\n\t.quad";
 148             } else {
 149                 "$self->{op}$self->{sz}";
 150             }
 151         } else {
 152             $self->{op} =~ s/^movz/movzx/;
 153             if ($self->{op} eq "ret") {
 154                 $self->{op} = "";
 155                 if ($win64 && $current_function->{abi} eq "svr4") {
 156                     $self->{op} = "mov  rdi,QWORD${PTR}[8+rsp]\t;WIN64 epilogue\n\t".
 157                                   "mov  rsi,QWORD${PTR}[16+rsp]\n\t";
 158                 }
 159                 $self->{op} .= "DB\t0F3h,0C3h\t\t;repret";
 160             } elsif ($self->{op} =~ /^(pop|push)f/) {
 161                 $self->{op} .= $self->{sz};
 162             } elsif ($self->{op} eq "call" && $current_segment eq ".CRT\$XCU") {
 163                 $self->{op} = "ALIGN\t8\n\tDQ";
 164             }
 165             $self->{op};
 166         }
 167     }
 168     sub mnemonic {
 169         my $self=shift;
 170         my $op=shift;
 171         $self->{op}=$op if (defined($op));
 172         $self->{op};
 173     }
 174 }
 175 { package const;        # pick up constants, which start with $
 176     sub re {
 177         my      $self = shift;  # single instance in enough...
 178         local   *line = shift;
 179         undef   $ret;
 180
 181         if ($line =~ /^\$([^,]+)/) {
 182             $self->{value} = $1;
 183             $ret = $self;
 184             $line = substr($line,@+[0]); $line =~ s/^\s+//;
 185         }
 186         $ret;
 187     }
 188     sub out {
 189         my $self = shift;
 190
 191         if ($gas) {
 192             # Solaris /usr/ccs/bin/as can't handle multiplications
 193             # in $self->{value}
 194             $self->{value} =~ s/(?<![0-9a-f])(0[x0-9a-f]+)/oct($1)/egi;
 195             $self->{value} =~ s/([0-9]+\s*[\*\/\%]\s*[0-9]+)/eval($1)/eg;
 196             sprintf "\$%s",$self->{value};
 197         } else {
 198             $self->{value} =~ s/0x([0-9a-f]+)/0$1h/ig;
 199             sprintf "%s",$self->{value};
 200         }
 201     }
 202 }
 203 { package ea;           # pick up effective addresses: expr(%reg,%reg,scale)
 204     sub re {
 205         my      $self = shift;  # single instance in enough...
 206         local   *line = shift;
 207         undef   $ret;
 208
 209         # optional * ---vvv--- appears in indirect jmp/call
 210         if ($line =~ /^(\*?)([^\(,]*)\(([%\w,]+)\)/) {
 211             $self->{asterisk} = $1;
 212             $self->{label} = $2;
 213             ($self->{base},$self->{index},$self->{scale})=split(/,/,$3);
 214             $self->{scale} = 1 if (!defined($self->{scale}));
 215             $ret = $self;
 216             $line = substr($line,@+[0]); $line =~ s/^\s+//;
 217
 218             if ($win64 && $self->{label} =~ s/\@GOTPCREL//) {
 219                 die if (opcode->mnemonic() ne "mov");
 220                 opcode->mnemonic("lea");
 221             }
 222             $self->{base}  =~ s/^%//;
 223             $self->{index} =~ s/^%// if (defined($self->{index}));
 224         }
 225         $ret;
 226     }
 227     sub size {}
 228     sub out {
 229         my $self = shift;
 230         my $sz = shift;
 231
 232         $self->{label} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
 233         $self->{label} =~ s/\.L/$decor/g;
 234
 235         # Silently convert all EAs to 64-bit. This is required for
 236         # elder GNU assembler and results in more compact code,
 237         # *but* most importantly AES module depends on this feature!
 238         $self->{index} =~ s/^[er](.?[0-9xpi])[d]?$/r\1/;
 239         $self->{base}  =~ s/^[er](.?[0-9xpi])[d]?$/r\1/;
 240
 241         if ($gas) {
 242             # Solaris /usr/ccs/bin/as can't handle multiplications
 243             # in $self->{label}
 244             $self->{label} =~ s/(?<![0-9a-f])(0[x0-9a-f]+)/oct($1)/egi;
 245             $self->{label} =~ s/([0-9]+\s*[\*\/\%]\s*[0-9]+)/eval($1)/eg;
 246             $self->{label} =~ s/^___imp_/__imp__/   if ($flavour eq "mingw64");
 247
 248             if (defined($self->{index})) {
 249                 sprintf "%s%s(%%%s,%%%s,%d)",$self->{asterisk},
 250                                         $self->{label},$self->{base},
 251                                         $self->{index},$self->{scale};
 252             } else {
 253                 sprintf "%s%s(%%%s)",   $self->{asterisk},$self->{label},$self->{base};
 254             }
 255         } else {
 256             %szmap = ( b=>"BYTE$PTR", w=>"WORD$PTR", l=>"DWORD$PTR", q=>"QWORD$PTR" );
 257
 258             $self->{label} =~ s/\./\$/g;
 259             $self->{label} =~ s/0x([0-9a-f]+)/0$1h/ig;
 260             $self->{label} = "($self->{label})" if ($self->{label} =~ /[\*\+\-\/]/);
 261             $sz="q" if ($self->{asterisk});
 262
 263             if (defined($self->{index})) {
 264                 sprintf "%s[%s%s*%d+%s]",$szmap{$sz},
 265                                         $self->{label}?"$self->{label}+":"",
 266                                         $self->{index},$self->{scale},
 267                                         $self->{base};
 268             } elsif ($self->{base} eq "rip") {
 269                 sprintf "%s[%s]",$szmap{$sz},$self->{label};
 270             } else {
 271                 sprintf "%s[%s%s]",$szmap{$sz},
 272                                         $self->{label}?"$self->{label}+":"",
 273                                         $self->{base};
 274             }
 275         }
 276     }
 277 }
 278 { package register;     # pick up registers, which start with %.
 279     sub re {
 280         my      $class = shift; # muliple instances...
 281         my      $self = {};
 282         local   *line = shift;
 283         undef   $ret;
 284
 285         # optional * ---vvv--- appears in indirect jmp/call
 286         if ($line =~ /^(\*?)%(\w+)/) {
 287             bless $self,$class;
 288             $self->{asterisk} = $1;
 289             $self->{value} = $2;
 290             $ret = $self;
 291             $line = substr($line,@+[0]); $line =~ s/^\s+//;
 292         }
 293         $ret;
 294     }
 295     sub size {
 296         my      $self = shift;
 297         undef   $ret;
 298
 299         if    ($self->{value} =~ /^r[\d]+b$/i)  { $ret="b"; }
 300         elsif ($self->{value} =~ /^r[\d]+w$/i)  { $ret="w"; }
 301         elsif ($self->{value} =~ /^r[\d]+d$/i)  { $ret="l"; }
 302         elsif ($self->{value} =~ /^r[\w]+$/i)   { $ret="q"; }
 303         elsif ($self->{value} =~ /^[a-d][hl]$/i){ $ret="b"; }
 304         elsif ($self->{value} =~ /^[\w]{2}l$/i) { $ret="b"; }
 305         elsif ($self->{value} =~ /^[\w]{2}$/i)  { $ret="w"; }
 306         elsif ($self->{value} =~ /^e[a-z]{2}$/i){ $ret="l"; }
 307
 308         $ret;
 309     }
 310     sub out {
 311         my $self = shift;
 312         if ($gas)       { sprintf "%s%%%s",$self->{asterisk},$self->{value}; }
 313         else            { $self->{value}; }
 314     }
 315 }
 316 { package label;        # pick up labels, which end with :
 317     sub re {
 318         my      $self = shift;  # single instance is enough...
 319         local   *line = shift;
 320         undef   $ret;
 321
 322         if ($line =~ /(^[\.\w]+)\:/) {
 323             $self->{value} = $1;
 324             $ret = $self;
 325             $line = substr($line,@+[0]); $line =~ s/^\s+//;
 326
 327             $self->{value} =~ s/^\.L/$decor/;
 328         }
 329         $ret;
 330     }
 331     sub out {
 332         my $self = shift;
 333
 334         if ($gas) {
 335             my $func = ($globals{$self->{value}} or $self->{value}) . ":";
 336             if ($win64  &&
 337                         $current_function->{name} eq $self->{value} &&
 338                         $current_function->{abi} eq "svr4") {
 339                 $func .= "\n";
 340                 $func .= "      movq    %rdi,8(%rsp)\n";
 341                 $func .= "      movq    %rsi,16(%rsp)\n";
 342                 $func .= "      movq    %rsp,%rax\n";
 343                 $func .= "${decor}SEH_begin_$current_function->{name}:\n";
 344                 my $narg = $current_function->{narg};
 345                 $narg=6 if (!defined($narg));
 346                 $func .= "      movq    %rcx,%rdi\n" if ($narg>0);
 347                 $func .= "      movq    %rdx,%rsi\n" if ($narg>1);
 348                 $func .= "      movq    %r8,%rdx\n"  if ($narg>2);
 349                 $func .= "      movq    %r9,%rcx\n"  if ($narg>3);
 350                 $func .= "      movq    40(%rsp),%r8\n" if ($narg>4);
 351                 $func .= "      movq    48(%rsp),%r9\n" if ($narg>5);
 352             }
 353             $func;
 354         } elsif ($self->{value} ne "$current_function->{name}") {
 355             $self->{value} .= ":" if ($masm && $ret!~m/^\$/);
 356             $self->{value} . ":";
 357         } elsif ($win64 && $current_function->{abi} eq "svr4") {
 358             my $func =  "$current_function->{name}" .
 359                         ($nasm ? ":" : "\tPROC $current_function->{scope}") .
 360                         "\n";
 361             $func .= "  mov     QWORD${PTR}[8+rsp],rdi\t;WIN64 prologue\n";
 362             $func .= "  mov     QWORD${PTR}[16+rsp],rsi\n";
 363             $func .= "  mov     rax,rsp\n";
 364             $func .= "${decor}SEH_begin_$current_function->{name}:";
 365             $func .= ":" if ($masm);
 366             $func .= "\n";
 367             my $narg = $current_function->{narg};
 368             $narg=6 if (!defined($narg));
 369             $func .= "  mov     rdi,rcx\n" if ($narg>0);
 370             $func .= "  mov     rsi,rdx\n" if ($narg>1);
 371             $func .= "  mov     rdx,r8\n"  if ($narg>2);
 372             $func .= "  mov     rcx,r9\n"  if ($narg>3);
 373             $func .= "  mov     r8,QWORD${PTR}[40+rsp]\n" if ($narg>4);
 374             $func .= "  mov     r9,QWORD${PTR}[48+rsp]\n" if ($narg>5);
 375             $func .= "\n";
 376         } else {
 377            "$current_function->{name}".
 378                         ($nasm ? ":" : "\tPROC $current_function->{scope}");
 379         }
 380     }
 381 }
 382 { package expr;         # pick up expressioins
 383     sub re {
 384         my      $self = shift;  # single instance is enough...
 385         local   *line = shift;
 386         undef   $ret;
 387
 388         if ($line =~ /(^[^,]+)/) {
 389             $self->{value} = $1;
 390             $ret = $self;
 391             $line = substr($line,@+[0]); $line =~ s/^\s+//;
 392
 393             $self->{value} =~ s/\@PLT// if (!$elf);
 394             $self->{value} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
 395             $self->{value} =~ s/\.L/$decor/g;
 396         }
 397         $ret;
 398     }
 399     sub out {
 400         my $self = shift;
 401         if ($nasm && opcode->mnemonic()=~m/^j/) {
 402             "NEAR ".$self->{value};
 403         } else {
 404             $self->{value};
 405         }
 406     }
 407 }
 408 { package directive;    # pick up directives, which start with .
 409     sub re {
 410         my      $self = shift;  # single instance is enough...
 411         local   *line = shift;
 412         undef   $ret;
 413         my      $dir;
 414         my      %opcode =       # lea 2f-1f(%rip),%dst; 1: nop; 2:
 415                 (       "%rax"=>0x01058d48,     "%rcx"=>0x010d8d48,
 416                         "%rdx"=>0x01158d48,     "%rbx"=>0x011d8d48,
 417                         "%rsp"=>0x01258d48,     "%rbp"=>0x012d8d48,
 418                         "%rsi"=>0x01358d48,     "%rdi"=>0x013d8d48,
 419                         "%r8" =>0x01058d4c,     "%r9" =>0x010d8d4c,
 420                         "%r10"=>0x01158d4c,     "%r11"=>0x011d8d4c,
 421                         "%r12"=>0x01258d4c,     "%r13"=>0x012d8d4c,
 422                         "%r14"=>0x01358d4c,     "%r15"=>0x013d8d4c      );
 423
 424         if ($line =~ /^\s*(\.\w+)/) {
 425             $dir = $1;
 426             $ret = $self;
 427             undef $self->{value};
 428             $line = substr($line,@+[0]); $line =~ s/^\s+//;
 429
 430             SWITCH: for ($dir) {
 431                 /\.picmeup/ && do { if ($line =~ /(%r[\w]+)/i) {
 432                                         $dir="\t.long";
 433                                         $line=sprintf "0x%x,0x90000000",$opcode{$1};
 434                                     }
 435                                     last;
 436                                   };
 437                 /\.global|\.globl|\.extern/
 438                             && do { $globals{$line} = $prefix . $line;
 439                                     $line = $globals{$line} if ($prefix);
 440                                     last;
 441                                   };
 442                 /\.type/    && do { ($sym,$type,$narg) = split(',',$line);
 443                                     if ($type eq "\@function") {
 444                                         undef $current_function;
 445                                         $current_function->{name} = $sym;
 446                                         $current_function->{abi}  = "svr4";
 447                                         $current_function->{narg} = $narg;
 448                                         $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE";
 449                                     } elsif ($type eq "\@abi-omnipotent") {
 450                                         undef $current_function;
 451                                         $current_function->{name} = $sym;
 452                                         $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE";
 453                                     }
 454                                     $line =~ s/\@abi\-omnipotent/\@function/;
 455                                     $line =~ s/\@function.*/\@function/;
 456                                     last;
 457                                   };
 458                 /\.asciz/   && do { if ($line =~ /^"(.*)"$/) {
 459                                         $dir  = ".byte";
 460                                         $line = join(",",unpack("C*",$1),0);
 461                                     }
 462                                     last;
 463                                   };
 464                 /\.rva|\.long|\.quad/
 465                             && do { $line =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
 466                                     $line =~ s/\.L/$decor/g;
 467                                     last;
 468                                   };
 469             }
 470
 471             if ($gas) {
 472                 $self->{value} = $dir . "\t" . $line;
 473
 474                 if ($dir =~ /\.extern/) {
 475                     $self->{value} = ""; # swallow extern
 476                 } elsif (!$elf && $dir =~ /\.type/) {
 477                     $self->{value} = "";
 478                     $self->{value} = ".def\t" . ($globals{$1} or $1) . ";\t" .
 479                                 (defined($globals{$1})?".scl 2;":".scl 3;") .
 480                                 "\t.type 32;\t.endef"
 481                                 if ($win64 && $line =~ /([^,]+),\@function/);
 482                 } elsif (!$elf && $dir =~ /\.size/) {
 483                     $self->{value} = "";
 484                     if (defined($current_function)) {
 485                         $self->{value} .= "${decor}SEH_end_$current_function->{name}:"
 486                                 if ($win64 && $current_function->{abi} eq "svr4");
 487                         undef $current_function;
 488                     }
 489                 } elsif (!$elf && $dir =~ /\.align/) {
 490                     $self->{value} = ".p2align\t" . (log($line)/log(2));
 491                 } elsif ($dir eq ".section") {
 492                     $current_segment=$line;
 493                     if (!$elf && $current_segment eq ".init") {
 494                         if      ($flavour eq "macosx")  { $self->{value} = ".mod_init_func"; }
 495                         elsif   ($flavour eq "mingw64") { $self->{value} = ".section\t.ctors"; }
 496                     }
 497                 } elsif ($dir =~ /\.(text|data)/) {
 498                     $current_segment=".$1";
 499                 }
 500                 $line = "";
 501                 return $self;
 502             }
 503
 504             # non-gas case or nasm/masm
 505             SWITCH: for ($dir) {
 506                 /\.text/    && do { my $v=undef;
 507                                     if ($nasm) {
 508                                         $v="section     .text code align=64\n";
 509                                     } else {
 510                                         $v="$current_segment\tENDS\n" if ($current_segment);
 511                                         $current_segment = ".text\$";
 512                                         $v.="$current_segment\tSEGMENT ";
 513                                         $v.=$masm>=$masmref ? "ALIGN(64)" : "PAGE";
 514                                         $v.=" 'CODE'";
 515                                     }
 516                                     $self->{value} = $v;
 517                                     last;
 518                                   };
 519                 /\.data/    && do { my $v=undef;
 520                                     if ($nasm) {
 521                                         $v="section     .data data align=8\n";
 522                                     } else {
 523                                         $v="$current_segment\tENDS\n" if ($current_segment);
 524                                         $current_segment = "_DATA";
 525                                         $v.="$current_segment\tSEGMENT";
 526                                     }
 527                                     $self->{value} = $v;
 528                                     last;
 529                                   };
 530                 /\.section/ && do { my $v=undef;
 531                                     $line =~ s/([^,]*).*/$1/;
 532                                     $line = ".CRT\$XCU" if ($line eq ".init");
 533                                     if ($nasm) {
 534                                         $v="section     $line";
 535                                         if ($line=~/\.([px])data/) {
 536                                             $v.=" rdata align=";
 537                                             $v.=$1 eq "p"? 4 : 8;
 538                                         }
 539                                     } else {
 540                                         $v="$current_segment\tENDS\n" if ($current_segment);
 541                                         $v.="$line\tSEGMENT";
 542                                         if ($line=~/\.([px])data/) {
 543                                             $v.=" READONLY";
 544                                             $v.=" ALIGN(".($1 eq "p" ? 4 : 8).")" if ($masm>=$masmref);
 545                                         }
 546                                     }
 547                                     $current_segment = $line;
 548                                     $self->{value} = $v;
 549                                     last;
 550                                   };
 551                 /\.extern/  && do { $self->{value}  = "EXTERN\t".$line;
 552                                     $self->{value} .= ":NEAR" if ($masm);
 553                                     last;
 554                                   };
 555                 /\.globl|.global/
 556                             && do { $self->{value}  = $masm?"PUBLIC":"global";
 557                                     $self->{value} .= "\t".$line;
 558                                     last;
 559                                   };
 560                 /\.size/    && do { if (defined($current_function)) {
 561                                         undef $self->{value};
 562                                         if ($current_function->{abi} eq "svr4") {
 563                                             $self->{value}="${decor}SEH_end_$current_function->{name}:";
 564                                             $self->{value}.=":\n" if($masm);
 565                                         }
 566                                         $self->{value}.="$current_function->{name}\tENDP" if($masm);
 567                                         undef $current_function;
 568                                     }
 569                                     last;
 570                                   };
 571                 /\.align/   && do { $self->{value} = "ALIGN\t".$line; last; };
 572                 /\.(value|long|rva|quad)/
 573                             && do { my $sz  = substr($1,0,1);
 574                                     my @arr = split(',',$line);
 575                                     my $last = pop(@arr);
 576                                     my $conv = sub  {   my $var=shift;
 577                                                         $var=~s/0x([0-9a-f]+)/0$1h/ig;
 578                                                         if ($sz eq "D" && ($current_segment=~/.[px]data/ || $dir eq ".rva"))
 579                                                         { $var=~s/([_a-z\$\@][_a-z0-9\$\@]*)/$nasm?"$1 wrt ..imagebase":"imagerel $1"/egi; }
 580                                                         $var;
 581                                                     };
 582
 583                                     $sz =~ tr/bvlrq/BWDDQ/;
 584                                     $self->{value} = "\tD$sz\t";
 585                                     for (@arr) { $self->{value} .= &$conv($_).","; }
 586                                     $self->{value} .= &$conv($last);
 587                                     last;
 588                                   };
 589                 /\.byte/    && do { my @str=split(",",$line);
 590                                     while ($#str>15) {
 591                                         $self->{value}.="DB\t"
 592                                                 .join(",",@str[0..15])."\n";
 593                                         foreach (0..15) { shift @str; }
 594                                     }
 595                                     $self->{value}.="DB\t"
 596                                                 .join(",",@str) if (@str);
 597                                     last;
 598                                   };
 599             }
 600             $line = "";
 601         }
 602
 603         $ret;
 604     }
 605     sub out {
 606         my $self = shift;
 607         $self->{value};
 608     }
 609 }
 610
 611 if ($nasm) {
 612     print <<___;
 613 default rel
 614 ___
 615 } elsif ($masm) {
 616     print <<___;
 617 OPTION  DOTNAME
 618 ___
 619 }
 620 while($line=<>) {
 621
 622     chomp($line);
 623
 624     $line =~ s|[#!].*$||;       # get rid of asm-style comments...
 625     $line =~ s|/\*.*\*/||;      # ... and C-style comments...
 626     $line =~ s|^\s+||;          # ... and skip white spaces in beginning
 627
 628     undef $label;
 629     undef $opcode;
 630     undef $sz;
 631     undef @args;
 632
 633     if ($label=label->re(\$line))       { print $label->out(); }
 634
 635     if (directive->re(\$line)) {
 636         printf "%s",directive->out();
 637     } elsif ($opcode=opcode->re(\$line)) { ARGUMENT: while (1) {
 638         my $arg;
 639
 640         if ($arg=register->re(\$line))  { opcode->size($arg->size()); }
 641         elsif ($arg=const->re(\$line))  { }
 642         elsif ($arg=ea->re(\$line))     { }
 643         elsif ($arg=expr->re(\$line))   { }
 644         else                            { last ARGUMENT; }
 645
 646         push @args,$arg;
 647
 648         last ARGUMENT if ($line !~ /^,/);
 649
 650         $line =~ s/^,\s*//;
 651         } # ARGUMENT:
 652
 653         $sz=opcode->size();
 654
 655         if ($#args>=0) {
 656             my $insn;
 657             if ($gas) {
 658                 $insn = $opcode->out($#args>=1?$args[$#args]->size():$sz);
 659             } else {
 660                 $insn = $opcode->out();
 661                 @args = reverse(@args);
 662                 undef $sz if ($nasm && $opcode->mnemonic() eq "lea");
 663             }
 664             for (@args) { $_ = $_->out($sz); }
 665             printf "\t%s\t%s", $insn, join(",",@args);
 666         } else {
 667             printf "\t%s",$opcode->out();
 668         }
 669     }
 670
 671     print $line,"\n";
 672 }
 673
 674 print "\n$current_segment\tENDS\n"      if ($current_segment && $masm);
 675 print "END\n"                           if ($masm);
 676
 677 close STDOUT;
 678
 679 \f#################################################
 680 # Cross-reference x86_64 ABI "card"
 681 #
 682 #               Unix            Win64
 683 # %rax          *               *
 684 # %rbx          -               -
 685 # %rcx          #4              #1
 686 # %rdx          #3              #2
 687 # %rsi          #2              -
 688 # %rdi          #1              -
 689 # %rbp          -               -
 690 # %rsp          -               -
 691 # %r8           #5              #3
 692 # %r9           #6              #4
 693 # %r10          *               *
 694 # %r11          *               *
 695 # %r12          -               -
 696 # %r13          -               -
 697 # %r14          -               -
 698 # %r15          -               -
 699 #
 700 # (*)   volatile register
 701 # (-)   preserved by callee
 702 # (#)   Nth argument, volatile
 703 #
 704 # In Unix terms top of stack is argument transfer area for arguments
 705 # which could not be accomodated in registers. Or in other words 7th
 706 # [integer] argument resides at 8(%rsp) upon function entry point.
 707 # 128 bytes above %rsp constitute a "red zone" which is not touched
 708 # by signal handlers and can be used as temporal storage without
 709 # allocating a frame.
 710 #
 711 # In Win64 terms N*8 bytes on top of stack is argument transfer area,
 712 # which belongs to/can be overwritten by callee. N is the number of
 713 # arguments passed to callee, *but* not less than 4! This means that
 714 # upon function entry point 5th argument resides at 40(%rsp), as well
 715 # as that 32 bytes from 8(%rsp) can always be used as temporal
 716 # storage [without allocating a frame]. One can actually argue that
 717 # one can assume a "red zone" above stack pointer under Win64 as well.
 718 # Point is that at apparently no occasion Windows kernel would alter
 719 # the area above user stack pointer in true asynchronous manner...
 720 #
 721 # All the above means that if assembler programmer adheres to Unix
 722 # register and stack layout, but disregards the "red zone" existense,
 723 # it's possible to use following prologue and epilogue to "gear" from
 724 # Unix to Win64 ABI in leaf functions with not more than 6 arguments.
 725 #
 726 # omnipotent_function:
 727 # ifdef WIN64
 728 #       movq    %rdi,8(%rsp)
 729 #       movq    %rsi,16(%rsp)
 730 #       movq    %rcx,%rdi       ; if 1st argument is actually present
 731 #       movq    %rdx,%rsi       ; if 2nd argument is actually ...
 732 #       movq    %r8,%rdx        ; if 3rd argument is ...
 733 #       movq    %r9,%rcx        ; if 4th argument ...
 734 #       movq    40(%rsp),%r8    ; if 5th ...
 735 #       movq    48(%rsp),%r9    ; if 6th ...
 736 # endif
 737 #       ...
 738 # ifdef WIN64
 739 #       movq    8(%rsp),%rdi
 740 #       movq    16(%rsp),%rsi
 741 # endif
 742 #       ret
 743 #
 744 \f#################################################
 745 # Win64 SEH, Structured Exception Handling.
 746 #
 747 # Unlike on Unix systems(*) lack of Win64 stack unwinding information
 748 # has undesired side-effect at run-time: if an exception is raised in
 749 # assembler subroutine such as those in question (basically we're
 750 # referring to segmentation violations caused by malformed input
 751 # parameters), the application is briskly terminated without invoking
 752 # any exception handlers, most notably without generating memory dump
 753 # or any user notification whatsoever. This poses a problem. It's
 754 # possible to address it by registering custom language-specific
 755 # handler that would restore processor context to the state at
 756 # subroutine entry point and return "exception is not handled, keep
 757 # unwinding" code. Writing such handler can be a challenge... But it's
 758 # doable, though requires certain coding convention. Consider following
 759 # snippet:
 760 #
 761 # .type function,@function
 762 # function:
 763 #       movq    %rsp,%rax       # copy rsp to volatile register
 764 #       pushq   %r15            # save non-volatile registers
 765 #       pushq   %rbx
 766 #       pushq   %rbp
 767 #       movq    %rsp,%r11
 768 #       subq    %rdi,%r11       # prepare [variable] stack frame
 769 #       andq    $-64,%r11
 770 #       movq    %rax,0(%r11)    # check for exceptions
 771 #       movq    %r11,%rsp       # allocate [variable] stack frame
 772 #       movq    %rax,0(%rsp)    # save original rsp value
 773 # magic_point:
 774 #       ...
 775 #       movq    0(%rsp),%rcx    # pull original rsp value
 776 #       movq    -24(%rcx),%rbp  # restore non-volatile registers
 777 #       movq    -16(%rcx),%rbx
 778 #       movq    -8(%rcx),%r15
 779 #       movq    %rcx,%rsp       # restore original rsp
 780 #       ret
 781 # .size function,.-function
 782 #
 783 # The key is that up to magic_point copy of original rsp value remains
 784 # in chosen volatile register and no non-volatile register, except for
 785 # rsp, is modified. While past magic_point rsp remains constant till
 786 # the very end of the function. In this case custom language-specific
 787 # exception handler would look like this:
 788 #
 789 # EXCEPTION_DISPOSITION handler (EXCEPTION_RECORD *rec,ULONG64 frame,
 790 #               CONTEXT *context,DISPATCHER_CONTEXT *disp)
 791 # {     ULONG64 *rsp = (ULONG64 *)context->Rax;
 792 #       if (context->Rip >= magic_point)
 793 #       {   rsp = ((ULONG64 **)context->Rsp)[0];
 794 #           context->Rbp = rsp[-3];
 795 #           context->Rbx = rsp[-2];
 796 #           context->R15 = rsp[-1];
 797 #       }
 798 #       context->Rsp = (ULONG64)rsp;
 799 #       context->Rdi = rsp[1];
 800 #       context->Rsi = rsp[2];
 801 #
 802 #       memcpy (disp->ContextRecord,context,sizeof(CONTEXT));
 803 #       RtlVirtualUnwind(UNW_FLAG_NHANDLER,disp->ImageBase,
 804 #               dips->ControlPc,disp->FunctionEntry,disp->ContextRecord,
 805 #               &disp->HandlerData,&disp->EstablisherFrame,NULL);
 806 #       return ExceptionContinueSearch;
 807 # }
 808 #
 809 # It's appropriate to implement this handler in assembler, directly in
 810 # function's module. In order to do that one has to know members'
 811 # offsets in CONTEXT and DISPATCHER_CONTEXT structures and some constant
 812 # values. Here they are:
 813 #
 814 #       CONTEXT.Rax                             120
 815 #       CONTEXT.Rcx                             128
 816 #       CONTEXT.Rdx                             136
 817 #       CONTEXT.Rbx                             144
 818 #       CONTEXT.Rsp                             152
 819 #       CONTEXT.Rbp                             160
 820 #       CONTEXT.Rsi                             168
 821 #       CONTEXT.Rdi                             176
 822 #       CONTEXT.R8                              184
 823 #       CONTEXT.R9                              192
 824 #       CONTEXT.R10                             200
 825 #       CONTEXT.R11                             208
 826 #       CONTEXT.R12                             216
 827 #       CONTEXT.R13                             224
 828 #       CONTEXT.R14                             232
 829 #       CONTEXT.R15                             240
 830 #       CONTEXT.Rip                             248
 831 #       sizeof(CONTEXT)                         1232
 832 #       DISPATCHER_CONTEXT.ControlPc            0
 833 #       DISPATCHER_CONTEXT.ImageBase            8
 834 #       DISPATCHER_CONTEXT.FunctionEntry        16
 835 #       DISPATCHER_CONTEXT.EstablisherFrame     24
 836 #       DISPATCHER_CONTEXT.TargetIp             32
 837 #       DISPATCHER_CONTEXT.ContextRecord        40
 838 #       DISPATCHER_CONTEXT.LanguageHandler      48
 839 #       DISPATCHER_CONTEXT.HandlerData          56
 840 #       UNW_FLAG_NHANDLER                       0
 841 #       ExceptionContinueSearch                 1
 842 #
 843 # In order to tie the handler to the function one has to compose
 844 # couple of structures: one for .xdata segment and one for .pdata.
 845 #
 846 # UNWIND_INFO structure for .xdata segment would be
 847 #
 848 # function_unwind_info:
 849 #       .byte   9,0,0,0
 850 #       .rva    handler
 851 #
 852 # This structure designates exception handler for a function with
 853 # zero-length prologue, no stack frame or frame register.
 854 #
 855 # To facilitate composing of .pdata structures, auto-generated "gear"
 856 # prologue copies rsp value to rax and denotes next instruction with
 857 # .LSEH_begin_{function_name} label. This essentially defines the SEH
 858 # styling rule mentioned in the beginning. Position of this label is
 859 # chosen in such manner that possible exceptions raised in the "gear"
 860 # prologue would be accounted to caller and unwound from latter's frame.
 861 # End of function is marked with respective .LSEH_end_{function_name}
 862 # label. To summarize, .pdata segment would contain
 863 #
 864 #       .rva    .LSEH_begin_function
 865 #       .rva    .LSEH_end_function
 866 #       .rva    function_unwind_info
 867 #
 868 # Reference to functon_unwind_info from .xdata segment is the anchor.
 869 # In case you wonder why references are 32-bit .rvas and not 64-bit
 870 # .quads. References put into these two segments are required to be
 871 # *relative* to the base address of the current binary module, a.k.a.
 872 # image base. No Win64 module, be it .exe or .dll, can be larger than
 873 # 2GB and thus such relative references can be and are accommodated in
 874 # 32 bits.
 875 #
 876 # Having reviewed the example function code, one can argue that "movq
 877 # %rsp,%rax" above is redundant. It is not! Keep in mind that on Unix
 878 # rax would contain an undefined value. If this "offends" you, use
 879 # another register and refrain from modifying rax till magic_point is
 880 # reached, i.e. as if it was a non-volatile register. If more registers
 881 # are required prior [variable] frame setup is completed, note that
 882 # nobody says that you can have only one "magic point." You can
 883 # "liberate" non-volatile registers by denoting last stack off-load
 884 # instruction and reflecting it in finer grade unwind logic in handler.
 885 # After all, isn't it why it's called *language-specific* handler...
 886 #
 887 # Attentive reader can notice that exceptions would be mishandled in
 888 # auto-generated "gear" epilogue. Well, exception effectively can't
 889 # occur there, because if memory area used by it was subject to
 890 # segmentation violation, then it would be raised upon call to the
 891 # function (and as already mentioned be accounted to caller, which is
 892 # not a problem). If you're still not comfortable, then define tail
 893 # "magic point" just prior ret instruction and have handler treat it...
 894 #
 895 # (*)   Note that we're talking about run-time, not debug-time. Lack of
 896 #       unwind information makes debugging hard on both Windows and
 897 #       Unix. "Unlike" referes to the fact that on Unix signal handler
 898 #       will always be invoked, core dumped and appropriate exit code
 899 #       returned to parent (for user notification).