1<!--===- docs/OptionComparison.md 2 3 Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 See https://llvm.org/LICENSE.txt for license information. 5 SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 7--> 8 9# Compiler options 10 11This document catalogs the options processed by F18's peers/competitors. Much of the document is taken up by a set of tables that list the options categorized into different topics. Some of the table headings link to more information about the contents of the tables. For example, the table on **Standards conformance** options links to [notes on Standards conformance](#standards). 12 13**There's also important information in the ___[Notes section](#notes)___ near the end of the document on how this data was gathered and what ___is___ and ___is not___ included in this document.** 14 15Note that compilers may support language features without having an option for them. Such cases are frequently, but not always noted in this document. 16 17<table> 18 <tr> 19 <td colspan="7" ><strong><a href="#standards">Standards conformance</a></strong> 20 </td> 21 </tr> 22 <tr> 23 <td><strong>Option</strong> </td> 24 <td><strong>Cray</strong> </td> 25 <td><strong>GNU</strong> </td> 26 <td><strong>IBM</strong> </td> 27 <td><strong>Intel</strong> </td> 28 <td><strong>PGI</strong> </td> 29 <td><strong>Flang</strong> </td> 30 </tr> 31 <tr> 32 <td>Overall conformance </td> 33 <td>en, 34<p> 35eN 36 </td> 37 <td>std=<em>level</em> </td> 38 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=210">qlanglvl</a>, <a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=257">qsaa</a> 39 </td> 40 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-stand">stand level</a> 41 </td> 42 <td>Mstandard 43 </td> 44 <td>Mstandard 45 </td> 46 </tr> 47 <tr> 48 <td>Compatibility with previous standards or implementations 49 </td> 50 <td>N/A 51 </td> 52 <td>fdec, 53<p> 54fall-instrinsics 55 </td> 56 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=297">qxlf77</a>, 57<p> 58<a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=299">qxlf90</a>, 59<p> 60<a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=301">qxlf2003</a>, 61<p> 62<a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=305">qxfl2008</a>, 63<p> 64<a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=245">qport</a> 65 </td> 66 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-f66">f66</a>, 67<p> 68<a href="https://software.intel.com/node/a8bfa478-22d5-4000-b0ac-b881804a7611">f77rtl</a>, 69<p> 70<a href="https://software.intel.com/node/647820a0-fc53-4252-a858-46feb012a281">fpscomp</a>, 71<p> 72<a href="https://software.intel.com/node/e610682a-00fe-4881-9cf7-8eee08c5f2a2">Intconstant</a>, 73<p> 74<a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-standard-realloc-lhs">nostandard-realloc-lhs</a>, 75<p> 76<a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-standard-semantics">standard-semantics</a>, 77<p> 78<a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-assume">assume nostd_intent_in</a>, 79<p> 80<a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-assume">assume nostd_value</a>, 81<p> 82<a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-assume">assume norealloc_lhs</a> 83 </td> 84 <td>Mallocatable=95|03 85 </td> 86 <td>Mallocatable=95|03 87 </td> 88 </tr> 89</table> 90 91 92 93 94 95<table> 96 <tr> 97 <td colspan="7" ><strong><a href="#source">Source format</a></strong> 98 </td> 99 </tr> 100 <tr> 101 <td><strong>Option</strong> 102 </td> 103 <td><strong>Cray</strong> 104 </td> 105 <td><strong>GNU</strong> 106 </td> 107 <td><strong>IBM</strong> 108 </td> 109 <td><strong>Intel</strong> 110 </td> 111 <td><strong>PGI</strong> 112 </td> 113 <td><strong>Flang</strong> 114 </td> 115 </tr> 116 <tr> 117 <td>Fixed or free source 118 </td> 119 <td>f free, 120<p> 121f fixed 122 </td> 123 <td>ffree-form, 124<p> 125ffixed-form 126 </td> 127 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=179">qfree</a>, 128<p> 129<a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=169">qfixed</a> 130 </td> 131 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-fixed">fixed</a>, 132<p> 133<a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-free">free</a> 134 </td> 135 <td>Mfree, 136<p> 137Mfixed 138 </td> 139 <td>Mfreeform, 140<p> 141Mfixed 142 </td> 143 </tr> 144 <tr> 145 <td>Source line length 146 </td> 147 <td>N <em>col</em> 148 </td> 149 <td>ffixed-line-length-n, 150<p> 151ffree-line-length-n 152 </td> 153 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=169">qfixed=n</a> 154 </td> 155 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-extend-source">extend-source [size]</a> 156 </td> 157 <td>Mextend 158 </td> 159 <td>Mextend 160 </td> 161 </tr> 162 <tr> 163 <td>Column 1 comment specifier 164 </td> 165 <td>ed 166 </td> 167 <td>fd-lines-as-code, 168<p> 169fd-lines-as-comments 170 </td> 171 <td>D, 172<p> 173<a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=161">qdlines</a>, 174<p> 175<a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=306">qxlines</a> 176 </td> 177 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-d-lines-qd-lines">d-lines</a> 178 </td> 179 <td>Mdlines 180 </td> 181 <td>N/A 182 </td> 183 </tr> 184 <tr> 185 <td>Don't treat CR character as a line terminator 186 </td> 187 <td>NA 188 </td> 189 <td>N/A 190 </td> 191 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=153">qnocr</a> 192 </td> 193 <td>N/A 194 </td> 195 <td>N/A 196 </td> 197 <td>N/A 198 </td> 199 </tr> 200 <tr> 201 <td>Source file naming 202 </td> 203 <td>N/A 204 </td> 205 <td>N/A 206 </td> 207 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=282">qsuffix</a> 208 </td> 209 <td><a href="https://software.intel.com/node/84174680-3c7d-4225-9611-6083f496aa9b">extfor</a>, 210<p> 211<a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-tf">Tf filename</a> 212 </td> 213 <td>N/A 214 </td> 215 <td>N/A 216 </td> 217 </tr> 218</table> 219 220 221 222 223 224<table> 225 <tr> 226 <td colspan="7" ><strong><a href="#names">Names, Literals, and other tokens</a></strong> 227 </td> 228 </tr> 229 <tr> 230 <td><strong>Option</strong> 231 </td> 232 <td><strong>Cray</strong> 233 </td> 234 <td><strong>GNU</strong> 235 </td> 236 <td><strong>IBM</strong> 237 </td> 238 <td><strong>Intel</strong> 239 </td> 240 <td><strong>PGI</strong> 241 </td> 242 <td><strong>Flang</strong> 243 </td> 244 </tr> 245 <tr> 246 <td>Max identifier length 247 </td> 248 <td>N/A 249 </td> 250 <td>fmax-identifier-length=<em>n</em> 251 </td> 252 <td>N/A 253 </td> 254 <td>N/A 255 </td> 256 <td>N/A 257 </td> 258 <td>N/A 259 </td> 260 </tr> 261 <tr> 262 <td>"$" in symbol names 263 </td> 264 <td>N/A 265 </td> 266 <td>fdollar-ok 267 </td> 268 <td>default 269 </td> 270 <td>default 271 </td> 272 <td>N/A 273 </td> 274 <td>N/A 275 </td> 276 </tr> 277 <tr> 278 <td>Allow names with leading "_" 279 </td> 280 <td>eQ 281 </td> 282 <td>N/A 283 </td> 284 <td>N/A 285 </td> 286 <td>N/A 287 </td> 288 <td>N/A 289 </td> 290 <td>N/A 291 </td> 292 </tr> 293 <tr> 294 <td>Specify name format 295 </td> 296 <td>N/A 297 </td> 298 <td>N/A 299 </td> 300 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=296">U</a> 301 </td> 302 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-names">names=keyword</a> 303 </td> 304 <td>Mupcase 305 </td> 306 <td>NA 307 </td> 308 </tr> 309 <tr> 310 <td>Escapes in literals 311 </td> 312 <td>N/A 313 </td> 314 <td>fbackslash 315 </td> 316 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=163">qescape</a> 317 </td> 318 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-assume">assume bscc</a> 319 </td> 320 <td>Mbackslash 321 </td> 322 <td>Mbackslash 323 </td> 324 </tr> 325 <tr> 326 <td>Allow multibyte characters in strings 327 </td> 328 <td>N/A 329 </td> 330 <td>N/A 331 </td> 332 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=223">qmbcs</a> 333 </td> 334 <td>N/A 335 </td> 336 <td>N/A 337 </td> 338 <td>N/A 339 </td> 340 </tr> 341 <tr> 342 <td>Create null terminated strings 343 </td> 344 <td>N/A 345 </td> 346 <td>N/A 347 </td> 348 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=228">qnullterm</a> 349 </td> 350 <td>N/A 351 </td> 352 <td>N/A 353 </td> 354 <td>N/A 355 </td> 356 </tr> 357 <tr> 358 <td>Character to use for "$" 359 </td> 360 <td>N/A 361 </td> 362 <td>N/A 363 </td> 364 <td>N/A 365 </td> 366 <td>N/A 367 </td> 368 <td>Mdollar,<em>char</em> 369 </td> 370 <td> 371 </td> 372 </tr> 373 <tr> 374 <td>Allow PARAMETER statements without parentheses 375 </td> 376 <td>N/A 377 </td> 378 <td>N/A 379 </td> 380 <td>N/A 381 </td> 382 <td><a href="https://software.intel.com/node/42e8ec08-64cc-44ba-a636-20ed50c682cd">altparam</a> 383 </td> 384 <td>N?A 385 </td> 386 <td>N/A 387 </td> 388 </tr> 389</table> 390 391 392 393<table> 394 <tr> 395 <td colspan="7" ><strong><a href="#do">DO loop handling</a></strong> 396 </td> 397 </tr> 398 <tr> 399 <td><strong>Option</strong> 400 </td> 401 <td><strong>Cray</strong> 402 </td> 403 <td><strong>GNU</strong> 404 </td> 405 <td><strong>IBM</strong> 406 </td> 407 <td><strong>Intel</strong> 408 </td> 409 <td><strong>PGI</strong> 410 </td> 411 <td><strong>Flang</strong> 412 </td> 413 </tr> 414 <tr> 415 <td>One trip DO loops 416 </td> 417 <td>ej 418 </td> 419 <td>N/A 420 </td> 421 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=113">1</a>, 422<p> 423<a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=231">qonetrip</a> 424 </td> 425 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-f66">f66</a> 426 </td> 427 <td>Monetrip 428 </td> 429 <td>N/A 430 </td> 431 </tr> 432 <tr> 433 <td>Allow branching into loops 434 </td> 435 <td>eg 436 </td> 437 <td>N/A 438 </td> 439 <td>N/A 440 </td> 441 <td>N/A 442 </td> 443 <td>N/A 444 </td> 445 <td>N/A 446 </td> 447 </tr> 448</table> 449 450 451 452 453 454<table> 455 <tr> 456 <td colspan="7" ><strong><a href="#real">REAL, DOUBLE PRECISION, and COMPLEX Data</a></strong> 457 </td> 458 </tr> 459 <tr> 460 <td><strong>Option</strong> 461 </td> 462 <td><strong>Cray</strong> 463 </td> 464 <td><strong>GNU</strong> 465 </td> 466 <td><strong>IBM</strong> 467 </td> 468 <td><strong>Intel</strong> 469 </td> 470 <td><strong>PGI</strong> 471 </td> 472 <td><strong>Flang</strong> 473 </td> 474 </tr> 475 <tr> 476 <td>Default REAL size 477 </td> 478 <td>s real32, 479<p> 480s real64, 481<p> 482s default32, 483<p> 484s default64 485 </td> 486 <td>fdefault-real-[8|10|16] 487 </td> 488 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=252">qrealsize=[4|8]</a> 489 </td> 490 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-real-size">real-size [32|64|128]</a> 491 </td> 492 <td>r[4|8] 493 </td> 494 <td>r8, 495<p> 496fdefault-real-8 497 </td> 498 </tr> 499 <tr> 500 <td>Default DOUBLE PRECISION size 501 </td> 502 <td>ep 503 </td> 504 <td>fdefault-double-8 505 </td> 506 <td>N/A 507 </td> 508 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-double-size">double-size[64|128]</a> 509 </td> 510 <td>N/A 511 </td> 512 <td>N/A 513 </td> 514 </tr> 515 <tr> 516 <td>Make real constants DOUBLE PRECISION 517 </td> 518 <td>N/A 519 </td> 520 <td>N/A 521 </td> 522 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=161">qdpc</a> 523 </td> 524 <td>N/A 525 </td> 526 <td>N/A 527 </td> 528 <td>N/A 529 </td> 530 </tr> 531 <tr> 532 <td>Promote or demote REAL type sizes 533 </td> 534 <td>N/A 535 </td> 536 <td>freal-[4|8]-real[4|8|10|16] 537 </td> 538 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=144">qautodbl=size</a> 539 </td> 540 <td>N/A 541 </td> 542 <td>Mr8, 543<p> 544Mr8intrinsics 545 </td> 546 <td>N/A 547 </td> 548 </tr> 549 <tr> 550 <td>Rounding mode 551 </td> 552 <td>N/A 553 </td> 554 <td>N/A 555 </td> 556 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=190">qieee</a> 557 </td> 558 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-assume">assume std_minus0_rounding</a> 559 </td> 560 <td>N/A 561 </td> 562 <td>N/A 563 </td> 564 </tr> 565 <tr> 566 <td>Treatment of -0.0 567 </td> 568 <td>N/A 569 </td> 570 <td>N/A 571 </td> 572 <td>N/A 573 </td> 574 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-assume">assume minus0</a> 575 </td> 576 <td> 577 </td> 578 <td> 579 </td> 580 </tr> 581</table> 582 583 584 585 586 587<table> 588 <tr> 589 <td colspan="7" ><strong><a href="#integer">INTEGER and LOGICAL Data</a></strong> 590 </td> 591 </tr> 592 <tr> 593 <td><strong>Option</strong> 594 </td> 595 <td><strong>Cray</strong> 596 </td> 597 <td><strong>GNU</strong> 598 </td> 599 <td><strong>IBM</strong> 600 </td> 601 <td><strong>Intel</strong> 602 </td> 603 <td><strong>PGI</strong> 604 </td> 605 <td><strong>Flang</strong> 606 </td> 607 </tr> 608 <tr> 609 <td>Default INTEGER size 610 </td> 611 <td>s integer32, 612<p> 613s integer64, 614<p> 615s default32, 616<p> 617s default64 618 </td> 619 <td>fdefault-integer-8 620 </td> 621 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=202">qintsize=[2|4|8]</a> 622 </td> 623 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-integer-size">integer-size [32|64|128]</a> 624 </td> 625 <td>I[2|4|8], 626<p> 627Mi4, 628<p> 629Mnoi4 630 </td> 631 <td>i8, 632<p> 633fdefault-integer-8 634 </td> 635 </tr> 636 <tr> 637 <td>Promote INTEGER sizes 638 </td> 639 <td>N/A 640 </td> 641 <td>finteger-4-integer-8 642 </td> 643 <td>N/A 644 </td> 645 <td>N/A 646 </td> 647 <td>N/A 648 </td> 649 <td>N/A 650 </td> 651 </tr> 652 <tr> 653 <td>Enable 8 and 16 bit INTEGER and LOGICALS 654 </td> 655 <td>eh 656 </td> 657 <td>N/A 658 </td> 659 <td>N/A 660 </td> 661 <td>N/A 662 </td> 663 <td>N/A 664 </td> 665 <td>N/A 666 </td> 667 </tr> 668 <tr> 669 <td>Change how the compiler treats LOGICAL 670 </td> 671 <td>N/A 672 </td> 673 <td>N/A 674 </td> 675 <td>N/A 676 </td> 677 <td>N/A 678 </td> 679 <td>Munixlogical 680 </td> 681 <td> 682 </td> 683 </tr> 684 <tr> 685 <td>Treatment of numeric constants as arguments 686 </td> 687 <td>N/A 688 </td> 689 <td>N/A 690 </td> 691 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=297">qxlf77 oldboz</a> 692 </td> 693 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-assume">assume old_boz</a> 694 </td> 695 <td>N/A 696 </td> 697 <td>N/A 698 </td> 699 </tr> 700 <tr> 701 <td>Treatment of assignment between numerics and logicals 702 </td> 703 <td>N/A 704 </td> 705 <td>N/A 706 </td> 707 <td>N/A 708 </td> 709 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-assume">assume old_logical_assign</a> 710 </td> 711 <td>N/A 712 </td> 713 <td>N/A 714 </td> 715 </tr> 716</table> 717 718 719 720 721 722<table> 723 <tr> 724 <td colspan="7" ><strong>CHARACTER and Pointer Data</strong> 725 </td> 726 </tr> 727 <tr> 728 <td><strong>Option</strong> 729 </td> 730 <td><strong>Cray</strong> 731 </td> 732 <td><strong>GNU</strong> 733 </td> 734 <td><strong>IBM</strong> 735 </td> 736 <td><strong>Intel</strong> 737 </td> 738 <td><strong>PGI</strong> 739 </td> 740 <td><strong>Flang</strong> 741 </td> 742 </tr> 743 <tr> 744 <td>Use bytes for pointer arithmetic 745 </td> 746 <td>s byte_pointer 747 </td> 748 <td>N/A 749 </td> 750 <td>N/A 751 </td> 752 <td>N/A 753 </td> 754 <td>N/A 755 </td> 756 <td>N/A 757 </td> 758 </tr> 759 <tr> 760 <td>Use words for pointer arithmetic 761 </td> 762 <td>S word_pointer 763 </td> 764 <td>N/A 765 </td> 766 <td>N/A 767 </td> 768 <td>N/A 769 </td> 770 <td>N/A 771 </td> 772 <td>N/A 773 </td> 774 </tr> 775 <tr> 776 <td>Allow character constants for typeless constants 777 </td> 778 <td>N/A 779 </td> 780 <td>N/A 781 </td> 782 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=153">qctyplss</a> 783 </td> 784 <td>N/A 785 </td> 786 <td>N/A 787 </td> 788 <td>N/A 789 </td> 790 </tr> 791</table> 792 793<table> 794 <tr> 795 <td colspan="7" ><strong>Data types and allocation</strong> 796 </td> 797 </tr> 798 <tr> 799 <td><strong>Option</strong> 800 </td> 801 <td><strong>Cray</strong> 802 </td> 803 <td><strong>GNU</strong> 804 </td> 805 <td><strong>IBM</strong> 806 </td> 807 <td><strong>Intel</strong> 808 </td> 809 <td><strong>PGI</strong> 810 </td> 811 <td><strong>Flang</strong> 812 </td> 813 </tr> 814 <tr> 815 <td>Default to IMPLICIT NONE 816 </td> 817 <td>eI 818 </td> 819 <td>fimplicit-none 820 </td> 821 <td>u, <a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=291">qundef</a> 822 </td> 823 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-warn">warn declarations</a> 824 </td> 825 <td>Mdclchk 826 </td> 827 <td>N/A 828 </td> 829 </tr> 830 <tr> 831 <td>Enable DEC STRUCTURE extensions 832 </td> 833 <td>N/A 834 </td> 835 <td><a href="https://gcc.gnu.org/onlinedocs/gfortran/STRUCTURE-and-RECORD.html">fdec-structure</a> 836 </td> 837 <td>N/A 838 </td> 839 <td>N/A 840 </td> 841 <td><a href="https://www.pgroup.com/doc/pgi15fortref.pdf#page=86">default</a> 842 </td> 843 <td>N/A 844 </td> 845 </tr> 846 <tr> 847 <td>Enable <a href="https://pubs.cray.com/content/S-3901/8.7/cray-fortran-reference-manual/types">Cray pointers</a> 848 </td> 849 <td>default 850 </td> 851 <td>fcray-pointer 852 </td> 853 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024776&aid=1#page=432">Default (near equivalent)</a> 854 </td> 855 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-pointer-integer">Default (near equivalent)</a> 856 </td> 857 <td>Mcray 858 </td> 859 <td>N/A 860 </td> 861 </tr> 862 <tr> 863 <td>Allow bitwise logical operations on numeric 864 </td> 865 <td>ee 866 </td> 867 <td>N/A 868 </td> 869 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=201">qintlog</a> 870 </td> 871 <td>N/A 872 </td> 873 <td>N/A 874 </td> 875 <td>N/A 876 </td> 877 </tr> 878 <tr> 879 <td>Allow DEC STATIC and AUTOMATIC declarations 880 </td> 881 <td>default 882 </td> 883 <td>fdec-static 884 </td> 885 <td>Default, see <a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024776&aid=1#page=393">IMPLICIT STATIC</a> and <a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024776&aid=1#page=393">IMPLICIT AUTOMATIC</a> 886 </td> 887 <td>Default, see <a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-automatic">AUTOMATIC</a> and <a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-static-1#408BC4E6-7AA7-4475-A280-205D34AE2E4F">STATIC</a> 888 </td> 889 <td><a href="https://www.pgroup.com/doc/pgi15fortref.pdf#page=86">Default</a> 890 </td> 891 <td>N/A 892 </td> 893 </tr> 894 <tr> 895 <td>Allocate variables to static storage 896 </td> 897 <td>ev 898 </td> 899 <td>fno-automatic 900 </td> 901 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=258">qsave</a> 902 </td> 903 <td><a href="https://software.intel.com/node/3ed16417-6eed-4e09-9edd-4ae03e77c6cf">save</a>, 904<p> 905<a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-auto">noauto</a> 906 </td> 907 <td>Mnorecursive, 908<p> 909Msave 910 </td> 911 <td>N/A 912 </td> 913 </tr> 914 <tr> 915 <td>Compile procedures as if RECURSIVE 916 </td> 917 <td>eR 918 </td> 919 <td>frecursive 920 </td> 921 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=254">q recur</a> 922 </td> 923 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-assume">assume recursion</a>, 924<p> 925<a href="https://software.intel.com/node/1c3820b4-42a1-48ea-887a-2cf39a41ce53">recursive</a> 926 </td> 927 <td>Mrecursive 928 </td> 929 <td>Mrecursive 930 </td> 931 </tr> 932</table> 933 934 935<table> 936 <tr> 937 <td colspan="7" ><strong><a href="#arrays">Arrays</strong> 938 </td> 939 </tr> 940 <tr> 941 <td><strong>Option</strong> 942 </td> 943 <td><strong>Cray</strong> 944 </td> 945 <td><strong>GNU</strong> 946 </td> 947 <td><strong>IBM</strong> 948 </td> 949 <td><strong>Intel</strong> 950 </td> 951 <td><strong>PGI</strong> 952 </td> 953 <td><strong>Flang</strong> 954 </td> 955 </tr> 956 <tr> 957 <tr> 958 <td>Enable coarrays 959 </td> 960 <td>h caf 961 </td> 962 <td>fcoarray=<em>key</em> 963 </td> 964 <td>N/A 965 </td> 966 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-coarray-qcoarray">coarray[=keyword]</a> 967 </td> 968 <td>N/A 969 </td> 970 <td>N/A 971 </td> 972 </tr> 973 <tr> 974 <td>Contiguous array pointers 975 </td> 976 <td>h contiguous 977 </td> 978 <td>N/A 979 </td> 980 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=142">qassert=contig</a> 981 </td> 982 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-assume">assume contiguous_pointer</a> 983 </td> 984 <td>N/A 985 </td> 986 <td>N/A 987 </td> 988 </tr> 989 <tr> 990 <td>Contiguous assumed shape dummy arguments 991 </td> 992 <td>h contiguous_assumed_shape 993 </td> 994 <td>frepack-arrays 995 </td> 996 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=142">qassert=contig</a> 997 </td> 998 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-assume">assume contiguous_assumed_shape</a> 999 </td> 1000 <td>N/A 1001 </td> 1002 <td>N/A 1003 </td> 1004 </tr> 1005</table> 1006 1007 1008 1009 1010<table> 1011 <tr> 1012 <td colspan="7" ><strong>OpenACC, OpenMP, and CUDA</strong> 1013 </td> 1014 </tr> 1015 <tr> 1016 <td><strong>Option</strong> 1017 </td> 1018 <td><strong>Cray</strong> 1019 </td> 1020 <td><strong>GNU</strong> 1021 </td> 1022 <td><strong>IBM</strong> 1023 </td> 1024 <td><strong>Intel</strong> 1025 </td> 1026 <td><strong>PGI</strong> 1027 </td> 1028 <td><strong>Flang</strong> 1029 </td> 1030 </tr> 1031 <tr> 1032 <td>Enable OpenACC 1033 </td> 1034 <td> <a href="https://pubs.cray.com/content/S-3901/8.7/cray-fortran-reference-manual/program-model-specific-options">h acc</a> 1035 </td> 1036 <td>fopenacc 1037 </td> 1038 <td>N/A 1039 </td> 1040 <td>N/A 1041 </td> 1042 <td><a href="https://www.pgroup.com/resources/docs/19.1/x86/pgi-ref-guide/index.htm#acc">acc</a> 1043 </td> 1044 <td>N/A 1045 </td> 1046 </tr> 1047 <tr> 1048 <td>Enable OpenMP 1049 </td> 1050 <td> <a href="https://pubs.cray.com/content/S-3901/8.7/cray-fortran-reference-manual/program-model-specific-options">h omp</a> 1051 </td> 1052 <td>fopenmp 1053 </td> 1054 <td><a href="https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=285">qswapomp</a> 1055 </td> 1056 <td><a href="https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-qopenmp-qopenmp">qopenmp</a>, 1057<p> 1058<a href="https://software.intel.com/node/26d2aef3-9c68-4ef2-9241-bce168a48629">qopenmp-lib</a>, 1059<p> 1060<a href="https://software.intel.com/node/f8d22e40-7ed0-4ec6-8e80-d4d27010ca8b">qopenmp-link</a>, 1061<p> 1062<a href="https://software.intel.com/node/2cc99a64-9605-44e2-b40a-1409ba459a62">qopenmp-offload</a>, 1063<p> 1064<a href="https://software.intel.com/node/02ef8658-3e66-4634-8a11-68eec60322c1">qopenmp-simd</a>, 1065<p> 1066<a href="https://software.intel.com/node/088272f2-5eae-42c2-a053-20f42022343d">qopenmp-stubs</a>, 1067<p> 1068<a href="https://software.intel.com/node/0ed8bee0-62b4-4266-8cbb-f25b585d4800">qopenmp-threadprivate</a> 1069 </td> 1070 <td><a href="https://www.pgroup.com/resources/docs/19.1/x86/pgi-ref-guide/index.htm#mp">mp</a>, 1071<p> 1072Mcuda 1073 </td> 1074 <td>-mp 1075 </td> 1076 </tr> 1077</table> 1078 1079 1080 1081<table> 1082 <tr> 1083 <td colspan="7" ><strong><a href="#miscellaneous">Miscellaneous</a></strong> 1084 </td> 1085 </tr> 1086 <tr> 1087 <td><strong>Option</strong> 1088 </td> 1089 <td><strong>Cray</strong> 1090 </td> 1091 <td><strong>GNU</strong> 1092 </td> 1093 <td><strong>IBM</strong> 1094 </td> 1095 <td><strong>Intel</strong> 1096 </td> 1097 <td><strong>PGI</strong> 1098 </td> 1099 <td><strong>Flang</strong> 1100 </td> 1101 </tr> 1102 <tr> 1103 <td>Disable compile time range checking 1104 </td> 1105 <td> N/A 1106 </td> 1107 <td>fno-range-check 1108 </td> 1109 <td>N/A 1110 </td> 1111 <td>N/A 1112 </td> 1113 <td>N/A 1114 </td> 1115 <td>N/A 1116 </td> 1117 </tr> 1118 <tr> 1119 <td>Disable call site checking 1120 </td> 1121 <td>dC 1122 </td> 1123 <td>N/A 1124 </td> 1125 <td>N/A 1126 </td> 1127 <td>N/A 1128 </td> 1129 <td>N/A 1130 </td> 1131 <td>N/A 1132 </td> 1133 </tr> 1134 <tr> 1135 <td>Warn for bad call checking 1136 </td> 1137 <td>eb 1138 </td> 1139 <td>N/A 1140 </td> 1141 <td>N/A 1142 </td> 1143 <td>N/A 1144 </td> 1145 <td>N/A 1146 </td> 1147 <td>N/A 1148 </td> 1149 </tr> 1150 <tr> 1151 <td>Set default accessibility of module entities to PRIVATE 1152 </td> 1153 <td>N/A 1154 </td> 1155 <td>fmodule-private 1156 </td> 1157 <td>N/A 1158 </td> 1159 <td>N/A 1160 </td> 1161 <td>N/A 1162 </td> 1163 <td>N/A 1164 </td> 1165 </tr> 1166 <tr> 1167 <td>Force FORALL to use temp 1168 </td> 1169 <td>N/A 1170 </td> 1171 <td>ftest-forall-temp 1172 </td> 1173 <td>N/A 1174 </td> 1175 <td>N/A 1176 </td> 1177 <td>N/A 1178 </td> 1179 <td>N/A 1180 </td> 1181 </tr> 1182</table> 1183 1184 1185 1186## <a name="notes"></a>Notes 1187 1188**<a name="standards"></a>Standards conformance:** 1189 1190All conformance options are similar -- they issue warnings if non-standard features are used. All defaults are to allow extensions without warnings. The GNU, IBM, and Intel compilers allow multiple standard levels to be specified. 1191 1192 1193 1194* **Cray**: The capital "-eN" option specifies to issue error messages for non-compliance rather than warnings. 1195* **GNU:** The "std=_level_" option specifies the standard to which the program is expected to conform. The default value for std is 'gnu', which specifies a superset of the latest Fortran standard that includes all of the extensions supported by GNU Fortran, although warnings will be given for obsolete extensions not recommended for use in new code. The 'legacy' value is equivalent but without the warnings for obsolete extensions. The 'f95', 'f2003', 'f2008', and 'f2018' values specify strict conformance to the respective standards. Errors are given for all extensions beyond the relevant language standard, and warnings are given for the Fortran 77 features that are permitted but obsolescent in later standards. '-std=f2008ts' allows the Fortran 2008 standard including the additions of the Technical Specification (TS) 29113 on Further Interoperability of Fortran with C and TS 18508 on Additional Parallel Features in Fortran. Values for "_level_" are f_95, f2003, f2008, f2008ts, f2018, gnu,_ and _legacy._ 1196 1197**<a name="source"></a>Source format:** 1198 1199**Fixed or free source:** Cray, IBM, and Intel default the source format based on the source file suffix as follows: 1200 1201 1202 1203* **Cray** 1204 * **Free:** .f90, .F90, .f95, .F95, .f03, .F03, .f08, .F08, .ftn, .FTN 1205 * **Fixed:** .f, .F, .for, .FOR 1206* **Intel** 1207 * **Free:** .f90, .F90, .i90 1208 * **Fixed:** .f, .for, .FOR, .ftn, .FTN, .fpp, .FPP, .i 1209 1210IBM Fortran's options allow the source line length to be specified with the option, e.g., "-qfixed=72". IBM bases the default on the name of the command used to invoke the compiler. IBM has 16 different commands that invoke the Fortran compiler, and the default use of free or fixed format and the line length are based on the command name. -qfixed=72 is the default for the xlf, xlf_r, f77, and fort77 commands. -qfree=f90is the default for the f90, xlf90, xlf90_r, f95, xlf95, xlf95_r, f2003, xlf2003, xlf2003_r, f2008, xlf2008, and xlf2008_r commands. The maximum line length for either source format is 132 characters. 1211 1212**Column 1 comment specifier:** All compilers allow "D" in column 1 to specify that the line contains a comment and have this as the default for fixed format source. IBM also supports an "X" in column 1 with the option "-qxlines". 1213 1214**Source line length:** 1215 1216 1217* **Cray:** The "-N _col_" option specifies the line width for fixed- and free-format source lines. The value used for col specifies the maximum number of columns per line. For free form sources, col can be set to 132, 255, or 1023. For fixed form sources, col can be set to 72, 80, 132, 255, or 1023. Characters in columns beyond the col specification are ignored. By default, lines are 72 characters wide for fixed-format sources and 255 characters wide for free-form sources. 1218* **GNU:** For both "ffixed-line-length-_n_" and "ffree-line-length-_n_" options, characters are ignored after the specified length. The default for fixed is 72. The default for free is 132. For free, you can specify 'none' as the length, which means that all characters in the line are meaningful. 1219* **IBM:** For **fixed**, the default is 72. For **free**, there's no default, but the maximum length for either form is 132. 1220* **Intel:** The default is 72 for **fixed** and 132 for **free**. 1221* **PGI, Flang:** 1222 * in free form, it is an error if the line is longer than 1000 characters 1223 * in fixed form by default, characters after column 72 are ignored 1224 * in fixed form with -Mextend, characters after column 132 are ignored 1225 1226**<a name="names"></a>Names, Literals, and other tokens** 1227 1228**Escapes in literals:** 1229 1230 1231* **GNU:** The "-fbackslash" option the interpretation of backslashes in string literals from a single backslash character to "C-style" escape characters. The following combinations are expanded \a, \b, \f, \n, \r, \t, \v, \\, and \0 to the ASCII characters alert, backspace, form feed, newline, carriage return, horizontal tab, vertical tab, backslash, and NUL, respectively. Additionally, \xnn, \unnnn and \Unnnnnnnn (where each n is a hexadecimal digit) are translated into the Unicode characters corresponding to the specified code points. All other combinations of a character preceded by \ are unexpanded. 1232* **Intel:** The option "-assume bscc" tells the compiler to treat the backslash character (\) as a C-style control (escape) character syntax in character literals. "nobscc" specifies that the backslash character is treated as a normal character in character literals. This is the default. 1233 1234**"$" in symbol names:** Allowing "$" in names is controlled by an option in GNU and is the default behavior in IBM and Intel. Presumably, these compilers issue warnings when standard conformance options are enabled. Dollar signs in names don't seem to be allowed in Cray, PGI, or Flang. 1235 1236**<a name="do"></a>DO loop handling** 1237 1238**One trip:** 1239 1240 1241 1242* **IBM:** IBM has two options that do the same thing: "-1" and "-qonetrip". 1243* **Intel:** Intel used to support a "-onetrip" option, but it has been removed. Intel now supports a "-f66" option that ensures that DO loops are executed at least once in addition to [several other Fortran 66 semantic features](https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-f66#320D769C-7C41-4A84-AE0E-50A72296A838). 1244 1245**<a name="real"></a>REAL, DOUBLE PRECISION, and COMPLEX Data** 1246 1247These size options affect the sizes of variables, literals, and intrinsic function results. 1248 1249**Default REAL sizes:** These options do not affect the size of explicitly declared data (for example, REAL(KIND=4). 1250 1251 1252 1253* **Cray:** The "-s default32" and "-s default64" options affect both REAL, INTEGER, and LOGICAL types. 1254 1255**Default DOUBLE PRECISION:** These options allow control of the size of DOUBLE PRECISION types in conjunction with controlling REAL types. 1256 1257 1258 1259* **Cray:** The "-ep" option controls DOUBLE PRECISION. This option can only be enabled when the default data size is 64 bits ("-s default64" or "-s real64"). When "-s default64" or "-s real64" is specified, and double precision arithmetic is disabled, DOUBLE PRECISION variables and constants specified with the D exponent are converted to default real type (64-bit). If double precision is enabled ("-ep"), they are handled as a double precision type (128-bit). Similarly when the "-s default64" or" -s real64" option is used, variables declared on a DOUBLE COMPLEX statement and complex constants specified with the D exponent are mapped to the complex type in which each part has a default real type, so the complex variable is 128-bit. If double precision is enabled ("-ep"), each part has double precision type, so the double complex variable is 256-bit. 1260* **GNU:** The "-fdefault-double-8" option sets the DOUBLE PRECISION type to an 8 byte wide type. Do nothing if this is already the default. If "-fdefault-real-8" is given, DOUBLE PRECISION would instead be promoted to 16 bytes if possible, and "-fdefault-double-8" can be used to prevent this. The kind of real constants like 1.d0 will not be changed by "-fdefault-real-8" though, so also "-fdefault-double-8" does not affect it. 1261 1262**Promote or demote REAL type sizes:** These options change the meaning of data types specified by declarations of the form REAL(KIND=_N_), except, perhaps for PGI. 1263 1264* **GNU:** The allowable combinations are "-freal-4-real-8", "-freal-4-real-10", "-freal-4-real-16", "-freal-8-real-4", "-freal-8-real-10", and "-freal-8-real-16". 1265* **IBM:** The "-qautodbl" option is documented [here](https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=144). 1266* **PGI:** The "-Mr8" option promotes REAL variables and constants to DOUBLE PRECISION variables and constants, respectively. DOUBLE PRECISION elements are 8 bytes in length. The "-Mr8intrinsics" option promotes the intrinsics CMPLX and REAL as DCMPLX and DBLE, respectively. 1267 1268**<a name="integer"></a>INTEGER and LOGICAL Data** 1269 1270These size options affect the sizes of variables, literals, and intrinsic function results. 1271 1272**Default INTEGER sizes:** For all compilers, these options affect both INTEGER and LOGICAL types. 1273 1274**Enable 8 and 16 bit INTEGER and LOGICAL:** This Cray option ("-eh") enables support for 8-bit and 16-bit INTEGER and LOGICAL types that use explicit kind or star values. By default ("-eh"), data objects declared as INTEGER(kind=1) or LOGICAL(kind=1) are 8 bits long, and objects declared as INTEGER(kind=2) or LOGICAL(kind=2) are 16 bits long. When this option is disabled ("-dh"), data objects declared as INTEGER(kind=1), INTEGER(kind=2), LOGICAL(kind=1), or LOGICAL(kind=2) are 32 bits long. 1275 1276**Intrinsic functions** 1277 1278GNU is the only compiler with options governing the use of non-standard intrinsics. For more information on the GNU options, see [here](https://gcc.gnu.org/onlinedocs/gcc-8.3.0/gfortran/Fortran-Dialect-Options.html#Fortran-Dialect-Options). All compilers implement non-standard intrinsics but don't have options that affect access to them. 1279 1280**<a name="arrays"></a>Arrays** 1281 1282**Contiguous array pointers:** All vendors that implement this option (Cray, IBM, and Intel) seem to have apply to all pointer targets. Assuming that the arrays that are targeted by the pointers allows greater optimization. 1283 1284**Contiguous assumed shape dummy arguments:** Cray and Intel have a separate argument that's specific to assumed shape dummy arguments. 1285 1286**<a name="miscellaneous"></a>Miscellaneous** 1287 1288**Disable call site checking:** This Cray option ("-dC") disables some types of standard call site checking. The current Fortran standard requires that the number and types of arguments must agree between the caller and callee. These constraints are enforced in cases where the compiler can detect them, however, specifying "-dC" disables some of this error checking, which may be necessary in order to get some older Fortran codes to compile. If error checking is disabled, unexpected compile-time or run time results may occur. The compiler by default attempts to detect situations in which an interface block should be specified but is not. Specifying "-dC" disables this type of checking as well. 1289 1290**Warn for bad call checking**: This Cray option ("-eb") issues a warning message rather than an error message when the compiler detects a call to a procedure with one or more dummy arguments having the TARGET, VOLATILE or ASYNCHRONOUS attribute and there is not an explicit interface definition. 1291 1292 1293## Notes 1294 1295 1296### What is and is not included 1297 1298This document focuses on options relevant to the Fortran language. This includes some features (such as recursion) that are only indirectly related. Options related to the following areas are not included: 1299 1300 1301 1302* Input/Output 1303* Optimization 1304* Preprocessing 1305* Inlining 1306* Alternate library definition or linking 1307* Choosing file locations for compiler input or output 1308* Modules 1309* Warning and error messages and listing output 1310* Data initialization 1311* Run time checks 1312* Debugging 1313* Specification of operating system 1314* Target architecture 1315* Assembler generation 1316* Threads or parallelization 1317* Profiling and code coverage 1318 1319 1320### Data sources 1321 1322Here's the list of compilers surveyed, hot linked to the source of data on it. Note that this is the only mention of the Oracle and NAG compilers in this document. 1323 1324 1325 1326* [Cray Fortran Reference Manual version 8.7](https://pubs.cray.com/content/S-3901/8.7/cray-fortran-reference-manual/compiler-command-line-options) 1327* IBM (XLF) version 14.1 -- [Compiler Referenc](https://www-01.ibm.com/support/docview.wss?uid=swg27024803&aid=1#page=93)e, [Language Reference](https://www-01.ibm.com/support/docview.wss?uid=swg27024776&aid=1) 1328* [Intel Fortran version 19.0](https://software.intel.com/en-us/fortran-compiler-developer-guide-and-reference-alphabetical-list-of-compiler-options) 1329* [GNU Fortran Compiler version 8.3.0](https://gcc.gnu.org/onlinedocs/gcc-8.3.0/gfortran/Option-Summary.html) 1330* [NAG Fortran Release 6.2](https://www.nag.co.uk/nagware/np/r62_doc/manual/compiler_2_4.html) 1331* [Oracle Fortran version 819-0492-10](https://docs.oracle.com/cd/E19059-01/stud.10/819-0492/3_options.html) 1332* PGI -- [Compiler Reference version 19.1](https://www.pgroup.com/resources/docs/19.1/x86/pgi-ref-guide/index.htm#cmdln-options-ref), [Fortran Reference Guide version 17](https://www.pgroup.com/doc/pgi17fortref.pdf) 1333* [Flang](https://github.com/flang-compiler/flang/wiki/Using-Flang) -- information from GitHub 1334 1335This document has been kept relatively small by providing links to much of the information about options rather than duplicating that information. For IBM, Intel, and some PGI options, there are direct links. But direct links were not possible for Cray, GNU and some PGI options. 1336 1337Many compilers have options that can either be enabled or disabled. Some compilers indicate this by the presence or absence of the letters "no" in the option name (IBM, Intel, and PGI) while Cray precedes many options with either "e" for enabled or "d" for disabled. This document only includes the enabled version of the option specification. 1338 1339Deprecated options were generally ignored, even though they were documented. 1340