/usr/share/doc/gcc-4.4-base/NEWS.html is in gcc-4.4 4.4.7-8ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 | <?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<link rev="made" href="mailto:gcc@gcc.gnu.org" />
<link rel="shortcut icon" href="http://gcc.gnu.org/favicon.ico" />
<link rel="stylesheet" type="text/css" href="/gnu.css" />
<link rel="stylesheet" type="text/css" href="http://gcc.gnu.org/gcc.css" />
<title>
GCC 4.4 Release Series — Changes, New Features, and Fixes
- GNU Project - Free Software Foundation (FSF)</title>
</head>
<!-- GCC maintainers, please do not hesitate to update/contribute entries
concerning those part of GCC you maintain! 2002-03-23, Gerald.
-->
<body bgcolor="#FFFFFF" text="#000000" link="#1F00FF" alink="#FF0000" vlink="#9900DD">
<h1 align="center">
GCC 4.4 Release Series<br />Changes, New Features, and Fixes
</h1>
<h2>Caveats</h2>
<ul>
<li><code>__builtin_stdarg_start</code> has been completely
removed from GCC. Support for <code><varargs.h></code> had
been deprecated since GCC 4.0. Use
<code>__builtin_va_start</code> as a replacement. </li>
<li>Some of the errors issued by the C++ front end that could be
downgraded to warnings in previous releases by using
<code>-fpermissive</code> are now warnings by default. They can be
converted into errors by using <code>-pedantic-errors</code>.</li>
<li>Use of the cpp assertion extension will now emit a warning
when <code>-Wdeprecated</code> or <code>-pedantic</code> is used.
This extension has been deprecated for many years, but never
warned about.</li>
<li>Packed bit-fields of type <code>char</code> were not properly
bit-packed on many targets prior to GCC 4.4. On these targets, the fix in
GCC 4.4 causes an ABI change. For example there is no longer a 4-bit
padding between field <code>a</code> and <code>b</code> in this structure:
<pre>
struct foo
{
char a:4;
char b:8;
} __attribute__ ((packed));</pre>
<p>There is a new warning to help identify fields that are affected:</p>
<pre>
foo.c:5: note: Offset of packed bit-field 'b' has changed in GCC 4.4</pre>
<p>The warning can be disabled with
<code>-Wno-packed-bitfield-compat</code>.</p></li>
<li>On ARM EABI targets, the C++ mangling of
the <code>va_list</code> type has been changed to conform to the
current revision of the EABI. This does not affect the libstdc++
library included with GCC.</li>
<li>The SCOUNT and POS bits of the MIPS DSP control register are now
treated as global. Previous versions of GCC treated these fields as
call-clobbered instead.</li>
<li>The MIPS port no longer recognizes the <code>h</code>
<code>asm</code> constraint. It was necessary to remove
this constraint in order to avoid generating unpredictable
code sequences.
<p>One of the main uses of the <code>h</code> constraint
was to extract the high part of a multiplication on
64-bit targets. For example:</p>
<pre>
asm ("dmultu\t%1,%2" : "=h" (result) : "r" (x), "r" (y));</pre>
<p>You can now achieve the same effect using 128-bit types:</p>
<pre>
typedef unsigned int uint128_t __attribute__((mode(TI)));
result = ((uint128_t) x * y) >> 64;</pre>
<p>The second sequence is better in many ways. For example,
if <code>x</code> and <code>y</code> are constants, the
compiler can perform the multiplication at compile time.
If <code>x</code> and <code>y</code> are not constants,
the compiler can schedule the runtime multiplication
better than it can schedule an <code>asm</code> statement.</p>
</li>
<li><p>Support for a number of older systems and recently
unmaintained or untested target ports of GCC has been declared
obsolete in GCC 4.4. Unless there is activity to revive them, the
next release of GCC will have their sources permanently
<strong>removed</strong>.</p>
<p>The following ports for individual systems on particular
architectures have been obsoleted:</p>
<ul>
<li>Generic a.out on IA32 and m68k (i[34567]86-*-aout*,
m68k-*-aout*)</li>
<li>Generic COFF on ARM, H8300, IA32, m68k and SH (arm-*-coff*,
armel-*-coff*, h8300-*-*, i[34567]86-*-coff*, m68k-*-coff*,
sh-*-*). This does not affect other more specific targets
using the COFF object format on those architectures, or the
more specific H8300 and SH targets (h8300-*-rtems*,
h8300-*-elf*, sh-*-elf*, sh-*-symbianelf*, sh-*-linux*,
sh-*-netbsdelf*, sh-*-rtems*, sh-wrs-vxworks).</li>
<li>2BSD on PDP-11 (pdp11-*-bsd)</li>
<li>AIX 4.1 and 4.2 on PowerPC (rs6000-ibm-aix4.[12]*,
powerpc-ibm-aix4.[12]*)</li>
<li>Tuning support for Itanium1 (Merced) variants. Note that
code tuned for Itanium2 should also run correctly on Itanium1.</li>
</ul>
</li>
<li>The <code>protoize</code> and <code>unprotoize</code>
utilities have been obsoleted and will be removed in GCC 4.5.
These utilities have not been installed by default since GCC
3.0.</li>
<li>Support has been removed for all the <a
href="../gcc-4.3/changes.html#obsoleted">configurations obsoleted
in GCC 4.3</a>.</li>
<li>Unknown <code>-Wno-*</code> options are now silently ignored
by GCC if no other diagnostics are issued. If other diagnostics
are issued, then GCC warns about the unknown options.</li>
<li>More information on porting to GCC 4.4 from previous versions
of GCC can be found in
the <a href="http://gcc.gnu.org/gcc-4.4/porting_to.html">porting
guide</a> for this release.</li>
</ul>
<h2>General Optimizer Improvements</h2>
<ul>
<li>A new command-line switch <code>-findirect-inlining</code> has been
added. When turned on it allows the inliner to also inline indirect
calls that are discovered to have known targets at compile time
thanks to previous inlining. </li>
<li>A new command-line switch <code>-ftree-switch-conversion</code> has
been added. This new pass turns simple initializations of scalar
variables in switch statements into initializations from a static array,
given that all the values are known at compile time and the ratio between
the new array size and the original switch branches does not exceed
the parameter <code>--param switch-conversion-max-branch-ratio</code>
(default is eight). </li>
<li>A new command-line switch <code>-ftree-builtin-call-dce</code>
has been added. This optimization eliminates unnecessary calls
to certain builtin functions when the return value is not used,
in cases where the calls can not be eliminated entirely because
the function may set <code>errno</code>. This optimization is
on by default at <code>-O2</code> and above.</li>
<li>A new command-line switch <code>-fconserve-stack</code>
directs the compiler to minimize stack usage even if it makes
the generated code slower. This affects inlining
decisions.</li>
<li>When the assembler supports it, the compiler will now emit
unwind information using assembler <code>.cfi</code> directives.
This makes it possible to use such directives in inline
assembler code. The new option <code>-fno-dwarf2-cfi-asm</code>
directs the compiler to not use <code>.cfi</code>
directives.</li>
<li><p>The <a href="http://gcc.gnu.org/wiki/Graphite">Graphite</a>
branch has been merged. This merge has brought in a new
framework for loop optimizations based on a polyhedral
intermediate representation. These optimizations apply to all
the languages supported by GCC. The following new code
transformations are available in GCC 4.4:</p>
<ul>
<li><code>-floop-interchange</code>
performs loop interchange transformations on loops. Interchanging two
nested loops switches the inner and outer loops. For example, given a
loop like:
<pre>
DO J = 1, M
DO I = 1, N
A(J, I) = A(J, I) * C
ENDDO
ENDDO
</pre>
<p>loop interchange will transform the loop as if the user had written:</p>
<pre>
DO I = 1, N
DO J = 1, M
A(J, I) = A(J, I) * C
ENDDO
ENDDO
</pre>
<p>which can be beneficial when <code>N</code> is larger than the caches,
because in Fortran, the elements of an array are stored in memory
contiguously by column, and the original loop iterates over rows,
potentially creating at each access a cache miss.</p>
</li>
<li><code>-floop-strip-mine</code>
performs loop strip mining transformations on loops. Strip mining
splits a loop into two nested loops. The outer loop has strides
equal to the strip size and the inner loop has strides of the
original loop within a strip. For example, given a loop like:
<pre>
DO I = 1, N
A(I) = A(I) + C
ENDDO
</pre>
<p>loop strip mining will transform the loop as if the user had written:</p>
<pre>
DO II = 1, N, 4
DO I = II, min (II + 3, N)
A(I) = A(I) + C
ENDDO
ENDDO
</pre>
</li>
<li><code>-floop-block</code>
performs loop blocking transformations on loops. Blocking strip mines
each loop in the loop nest such that the memory accesses of the
element loops fit inside caches. For example, given a loop like:
<pre>
DO I = 1, N
DO J = 1, M
A(J, I) = B(I) + C(J)
ENDDO
ENDDO
</pre>
<p>loop blocking will transform the loop as if the user had written:</p>
<pre>
DO II = 1, N, 64
DO JJ = 1, M, 64
DO I = II, min (II + 63, N)
DO J = JJ, min (JJ + 63, M)
A(J, I) = B(I) + C(J)
ENDDO
ENDDO
ENDDO
ENDDO
</pre>
<p>which can be beneficial when <code>M</code> is larger than the caches,
because the innermost loop will iterate over a smaller amount of data
that can be kept in the caches.</p>
</li>
</ul>
</li>
<li>A new register allocator has replaced the old one. It is
called <em>integrated register allocator</em> (<em>IRA</em>)
because coalescing, register live range splitting, and hard
register preferencing are done on-the-fly during coloring. It
also has better integration with the reload pass. IRA is a
regional register allocator which uses modern Chaitin-Briggs
coloring instead of Chow's priority coloring used in the old
register allocator. More info about IRA internals and options
can be found in the GCC manuals.
</li>
<li>A new instruction scheduler and software pipeliner, based on
the selective scheduling approach, has been added. The new pass
performs instruction unification, register renaming, substitution
through register copies, and speculation during scheduling.
The software pipeliner is able to pipeline non-countable loops.
The new pass is targeted at scheduling-eager in-order platforms.
In GCC 4.4 it is available for the Intel Itanium platform
working by default as the second scheduling pass (after register
allocation) at the <code>-O3</code> optimization level.
</li>
<li>When using <code>-fprofile-generate</code> with a
multi-threaded program, the profile counts may be slightly wrong
due to race conditions. The
new <code>-fprofile-correction</code> option directs the
compiler to apply heuristics to smooth out the inconsistencies.
By default the compiler will give an error message when it finds
an inconsistent profile.</li>
<li>The new <code>-fprofile-dir=PATH</code> option permits setting
the directory where profile data files are stored when
using <code>-fprofile-generate</code> and friends, and the
directory used when reading profile data files
using <code>-fprofile-use</code> and friends.</li>
</ul>
<h2>New warning options</h2>
<ul>
<li>The new <code>-Wframe-larger-than=NUMBER</code> option directs
GCC to emit a warning if any stack frame is larger
than <code>NUMBER</code> bytes. This may be used to help ensure that
code fits within a limited amount of stack space.</li>
<li>The new <code>-Wno-mudflap</code> option disables warnings
about constructs which can not be instrumented when
using <code>-fmudflap</code>.</li>
</ul>
<h2>New Languages and Language specific improvements</h2>
<ul>
<li>Version 3.0 of the <a
href="http://openmp.org/wp/openmp-specifications/">OpenMP specification</a>
is now supported for the C, C++, and Fortran compilers.</li>
</ul>
<h3>C family</h3>
<ul>
<li>A new <code>optimize</code> attribute was added to allow programmers to
change the optimization level and particular optimization options for an
individual function. You can also change the optimization options via the
<code>GCC optimize</code> pragma for functions defined after the pragma.
The <code>GCC push_options</code> pragma and the
<code>GCC pop_options</code> pragma allow you temporarily save and restore
the options used. The <code>GCC reset_options</code> pragma restores the
options to what was specified on the command line.
</li>
<li>Uninitialized warnings do not require enabling optimization
anymore, that is, <code>-Wuninitialized</code> can be used
together with <code>-O0</code>. Nonetheless, the warnings given
by <code>-Wuninitialized</code> will probably be more accurate if
optimization is enabled.
</li>
<li><code>-Wparentheses</code> now warns about expressions such as
<code>(!x | y)</code> and <code>(!x & y)</code>. Using explicit
parentheses, such as in <code>((!x) | y)</code>, silences this
warning.</li>
<li><code>-Wsequence-points</code> now warns within
<code>if</code>, <code>while</code>,<code>do while</code>
and <code>for</code> conditions, and within <code>for</code>
begin/end expressions.
</li>
<li>A new option <code>-dU</code> is available to dump definitions
of preprocessor macros that are tested or expanded.</li>
</ul>
<h3>C++</h3>
<ul>
<li><a href="cxx0x_status.html">Improved experimental support for
the upcoming ISO C++ standard, C++0x</a>. Including support
for <code>auto</code>, inline namespaces, generalized initializer
lists, defaulted and deleted functions, new character types, and
scoped enums.</li>
<li> Those errors that may be downgraded to warnings to build
legacy code now mention <code>-fpermissive</code> when
<code>-fdiagnostics-show-option</code> is enabled.</li>
<li><code>-Wconversion</code> now warns if the result of a
<code>static_cast</code> to enumeral type is unspecified because
the value is outside the range of the enumeral type.
</li>
<li><code>-Wuninitialized</code> now warns if a non-static
reference or non-static <code>const</code> member appears in a
class without constructors.
</li>
<li>G++ now properly implements value-initialization, so objects with
an initializer of <code>()</code> and an implicitly defined default
constructor will be zero-initialized before the default constructor is
called.</li>
</ul>
<h4>Runtime Library (libstdc++)</h4>
<ul>
<li><a href="http://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#id476343">
Improved experimental support for the upcoming ISO C++ standard,
C++0x</a>, including:
<ul>
<li>Support for <chrono>, <condition_variable>,
<cstdatomic>, <forward_list>, <initializer_list>,
<mutex>, <ratio>, <system_error>, and
<thread>.</li>
<li><code>unique_ptr</code>, <algorithm>
additions, exception propagation, and support for the new
character types in <string> and <limits>.</li>
<li>Existing facilities now exploit initializer lists, defaulted and
deleted functions, and the newly implemented core C++0x features.</li>
<li>The standard containers are more efficient together with stateful
allocators.</li>
</ul>
</li>
<li>Experimental support for non-standard pointer types in containers.</li>
<li>The long standing libstdc++/30928 has been fixed for targets running
glibc 2.10 or later.</li>
<li>As usual, many small and larger bug fixes, in particular quite a few
corner cases in <locale>.</li>
</ul>
<h3>Fortran</h3>
<ul>
<li>GNU Fortran now employs libcpp directly instead of using cc1 as an
external preprocessor. The <a
href="http://gcc.gnu.org/onlinedocs/gfortran/Preprocessing-Options.html">
<code>-cpp</code></a> option was added to allow manual invocation of the
preprocessor without relying on filename extensions.</li>
<li>The <a
href="http://gcc.gnu.org/onlinedocs/gfortran/Error-and-Warning-Options.html#index-g_t_0040code_007bWarray-temporaries_007d-125">
<code>-Warray-temporaries</code></a> option warns about array temporaries
generated by the compiler, as an aid to optimization.</li>
<li>The <a
href="http://gcc.gnu.org/onlinedocs/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfcheck-array-temporaries_007d-221">
<code>-fcheck-array-temporaries</code></a> option has been added, printing
a notification at run time, when an array temporary had to be created for
an function argument. Contrary to <code>-Warray-temporaries</code> the
warning is only printed if the array is noncontiguous.</li>
<li>Improved generation of DWARF debugging symbols</li>
<li>If using an intrinsic not part of the selected standard (via
<code>-std=</code> and <code>-fall-intrinsics</code>) gfortran will now
treat it as if this procedure were declared <code>EXTERNAL</code> and
try to link to a user-supplied procedure. <code>-Wintrinsics-std</code>
will warn whenever this happens. The now-useless option
<code>-Wnonstd-intrinsic</code> was removed.</li>
<li>The flag <code>-falign-commons</code> has been added to control the
alignment of variables in COMMON blocks, which is enabled by default in
line with previous GCC version. Using <code>-fno-align-commons</code> one
can force commons to be contiguous in memory as required by the Fortran
standard, however, this slows down the memory access. The option
<code>-Walign-commons</code>, which is enabled by default, warns when
padding bytes were added for alignment. The proper solution is to sort
the common objects by decreasing storage size, which avoids the alignment
problems.</li>
<li>Fortran 2003 support has been extended:
<ul>
<li>Wide characters (ISO 10646, UCS-4, <code>kind=4</code>) and UTF-8
I/O is now supported (except internal reads from/writes to wide
strings). <a
href="http://gcc.gnu.org/onlinedocs/gfortran/Fortran-Dialect-Options.html#index-g_t_0040code_007bbackslash_007d-34">
<code>-fbackslash</code></a> now supports also
<code>\u<em>nnnn</em></code> and <code>\U<em>nnnnnnnn</em></code>
to enter Unicode characters.</li>
<li>Asynchronous I/O (implemented as synchronous I/O) and the
<code>decimal=</code>, <code>size=</code>, <code>sign=</code>,
<code>pad=</code>, <code>blank=</code>, and <code>delim=</code>
specifiers are now supported in I/O statements.</li>
<li>Support for Fortran 2003 structure constructors and for
array constructor with typespec has been added.</li>
<li>Procedure Pointers (but not yet as component in derived types
and as function results) are now supported.</li>
<li>Abstract types, type extension, and type-bound procedures (both
<code>PROCEDURE</code> and <code>GENERIC</code> but not as
operators). Note: As <code>CLASS</code>/polymorphyic types are
not implemented, type-bound procedures with <code>PASS</code>
accept as non-standard extension <code>TYPE</code> arguments.</li>
</ul>
</li>
<li>Fortran 2008 support has been added:
<ul>
<li>The <code>-std=f2008</code> option and support for the file
extensions <code>.f2008</code> and <code>.F2008</code> has been
added.</li>
<li>The g0 format descriptor is now supported.</li>
<li>The Fortran 2008 mathematical intrinsics <code>ASINH</code>,
<code>ACOSH</code>, <code>ATANH</code>, <code>ERF</code>,
<code>ERFC</code>, <code>GAMMA</code>, <code>LOG_GAMMA</code>,
<code>BESSEL_*</code>, <code>HYPOT</code>,
and <code>ERFC_SCALED</code> are now available
(some of them existed as GNU extension before). Note: The hyperbolic
functions are not yet supporting complex arguments and the three-
argument version of <code>BESSEL_*N</code> is not available.</li>
<li>The bit intrinsics <code>LEADZ</code> and <code>TRAILZ</code>
have been added.</li>
</ul>
</li>
</ul>
<h3>Java (GCJ)</h3>
<h3>Ada</h3>
<ul>
<li>The Ada runtime now supports multilibs on many platforms including
x86_64, SPARC and PowerPC. Their build is enabled by default.</li>
</ul>
<h2 id="targets">New Targets and Target Specific Improvements</h2>
<h3>ARM</h3>
<ul>
<li>GCC now supports optimizing for the Cortex-A9, Cortex-R4 and
Cortex-R4F processors and has many other improvements to
optimization for ARM processors.</li>
<li>GCC now supports the VFPv3 variant with 16 double-precision
registers with <code>-mfpu=vfpv3-d16</code>. The
option <code>-mfpu=vfp3</code> has been renamed
to <code>-mfpu=vfpv3</code>.</li>
<li>GCC now supports the <code>-mfix-cortex-m3-ldrd</code> option
to work around an erratum on Cortex-M3 processors.</li>
<li>GCC now supports the <code>__sync_*</code> atomic operations
for ARM EABI GNU/Linux.</li>
<li>The section anchors optimization is now enabled by default
when optimizing for ARM.</li>
<li>GCC now uses a new EABI-compatible profiling interface for
EABI targets. This requires a
function <code>__gnu_mcount_nc</code>, which is provided by GNU
libc versions 2.8 and later.</li>
</ul>
<h3>AVR</h3>
<ul>
<li>The <code>-mno-tablejump</code> option has been deprecated because
it has the same effect as the <code>-fno-jump-tables</code> option.</li>
<li>Added support for these new AVR devices:
<ul>
<li>ATA6289</li>
<li>ATtiny13A</li>
<li>ATtiny87</li>
<li>ATtiny167</li>
<li>ATtiny327</li>
<li>ATmega8C1</li>
<li>ATmega16C1</li>
<li>ATmega32C1</li>
<li>ATmega8M1</li>
<li>ATmega16M1</li>
<li>ATmega32M1</li>
<li>ATmega32U4</li>
<li>ATmega16HVB</li>
<li>ATmega4HVD</li>
<li>ATmega8HVD</li>
<li>ATmega64C1</li>
<li>ATmega64M1</li>
<li>ATmega16U4</li>
<li>ATmega32U6</li>
<li>ATmega128RFA1</li>
<li>AT90PWM81</li>
<li>AT90SCR100</li>
<li>M3000F</li>
<li>M3000S</li>
<li>M3001B</li>
</ul>
</li>
</ul>
<h3>IA-32/x86-64</h3>
<ul>
<li>Support for Intel AES built-in functions and code generation is
available via <code>-maes</code>.</li>
<li>Support for Intel PCLMUL built-in function and code generation is
available via <code>-mpclmul</code>.</li>
<li>Support for Intel AVX built-in functions and code generation is
available via <code>-mavx</code>.</li>
<li>Automatically align the stack for local variables with alignment
requirement. </li>
<li>GCC can now utilize the SVML library for vectorizing calls to
a set of C99 functions if <code>-mveclibabi=svml</code> is specified
and you link to an SVML ABI compatible library.</li>
<li>A new <code>target</code> attribute was added to allow programmers to change the target options like <code>-msse2</code> or <code>-march=k8</code> for an individual function. You can also change the target options via the <code>GCC target</code> pragma for functions defined after the pragma.</li>
<li>GCC can now be configured with
options <code>--with-arch-32</code>, <code>--with-arch-64</code>,
<code>--with-cpu-32</code>, <code>--with-cpu-64</code>,
<code>--with-tune-32</code> and <code>--with-tune-64</code> to
control the default optimization separately for 32-bit and 64-bit
modes.</li>
</ul>
<h3>IA-32/IA64</h3>
<ul>
<li>Support for <code>__float128</code> (TFmode) IEEE quad type and
corresponding TCmode IEEE complex quad type is available
via the soft-fp library on <code>IA-32/IA64</code> targets.
This includes basic arithmetic operations (addition, subtraction,
negation, multiplication and division) on <code>__float128</code>
real and TCmode complex values, the full set of IEEE comparisons
between <code>__float128</code> values, conversions to and from
<code>float</code>, <code>double</code> and <code>long double</code>
floating point types, as well as conversions to and from
<code>signed</code> or <code>unsigned</code> integer,
<code>signed</code> or <code>unsigned long</code> integer and
<code>signed</code> or <code>unsigned</code> quad
(TImode, <code>IA64</code> only) integer types. Additionally,
all operations generate the full set of IEEE exceptions and support
the full set of IEEE rounding modes.</li>
</ul>
<h3>M68K/ColdFire</h3>
<ul>
<li>GCC now supports instruction scheduling for ColdFire V1, V3
and V4 processors. (Scheduling support for ColdFire V2 processors
was added in GCC 4.3.)</li>
<li>GCC now supports the <code>-mxgot</code> option to support
programs requiring many GOT entries on ColdFire.</li>
<li>The m68k-*-linux-gnu target now builds multilibs by
default.</li>
</ul>
<h3>MIPS</h3>
<ul>
<li><p>MIPS Technologies have extended the original MIPS SVR4 ABI
to include support for procedure linkage tables (PLTs)
and copy relocations. These extensions allow GNU/Linux
executables to use a significantly more efficient code
model than the one defined by the original ABI.</p>
<p>GCC support for this code model is available via a
new command-line option, <code>-mplt</code>. There is also
a new configure-time option, <code>--with-mips-plt</code>,
to make <code>-mplt</code> the default.</p>
<p>The new code model requires support from the assembler,
the linker, and the runtime C library. This support is available
in binutils 2.19 and GLIBC 2.9.</p></li>
<li>GCC can now generate MIPS16 code for 32-bit GNU/Linux executables
and 32-bit GNU/Linux shared libraries. This feature requires
GNU binutils 2.19 or above.</li>
<li>Support for RMI's XLR processor is now available through the
<code>-march=xlr</code> and <code>-mtune=xlr</code> options.</li>
<li>64-bit targets can now perform 128-bit multiplications inline,
instead of relying on a <code>libgcc</code> function.</li>
<li>Native GNU/Linux toolchains now support <code>-march=native</code>
and <code>-mtune=native</code>, which select the host processor.</li>
<li>GCC now supports the R10K, R12K, R14K and R16K processors. The
canonical <code>-march=</code> and <code>-mtune=</code> names for
these processors are <code>r10000</code>, <code>r12000</code>,
<code>r14000</code> and <code>r16000</code> respectively.</li>
<li>GCC can now work around the side effects of speculative execution
on R10K processors. Please see the documentation of the
<code>-mr10k-cache-barrier</code> option for details.</li>
<li>Support for the MIPS64 Release 2 instruction set has been added. The
option <code>-march=mips64r2</code> enables generation of these
instructions.</li>
<li>GCC now supports Cavium Networks' Octeon processor. This support is
available through the <code>-march=octeon</code> and
<code>-mtune=octeon</code> options.</li>
<li>GCC now supports STMicroelectronics' Loongson 2E/2F processors. The
canonical <code>-march=</code> and <code>-mtune=</code> names for
these processors are <code>loongson2e</code> and
<code>loongson2f</code>.</li>
</ul>
<h3 id="picochip">picochip</h3>
<p>Picochip is a 16-bit processor. A typical picoChip contains over 250
small cores, each with small amounts of memory. There are three processor
variants (STAN, MEM and CTRL) with different instruction sets and memory
configurations and they can be chosen using the <code>-mae</code> option.
</p>
<p>This port is intended to be a "C" only port.</p>
<h3>Power Architecture and PowerPC</h3>
<ul>
<li>GCC now supports the e300c2, e300c3 and e500mc processors.</li>
<li>GCC now supports Xilinx processors with a single-precision FPU.</li>
<li>Decimal floating point is now supported for e500 processors.</li>
</ul>
<h3>S/390, zSeries and System z9/z10</h3>
<ul>
<li>Support for the IBM System z10 EC/BC processor has
been added. When using the <code>-march=z10</code> option,
the compiler will generate code making use of instructions
provided by the General-Instruction-Extension Facility and the
Execute-Extension Facility.</li>
</ul>
<h3>VxWorks</h3>
<ul>
<li>GCC now supports the thread-local storage mechanism used on
VxWorks.</li>
</ul>
<h3>Xtensa</h3>
<ul>
<li>GCC now supports thread-local storage (TLS) for Xtensa processor
configurations that include the Thread Pointer option. TLS also requires
support from the assembler and linker; this support is provided in the
GNU binutils beginning with version 2.19.</li>
</ul>
<h2>Documentation improvements</h2>
<h2>Other significant improvements</h2>
<!-- ==================================================================== -->
<div class="copyright">
<p>Please send FSF & GNU inquiries & questions to
<a href="mailto:gnu@gnu.org">gnu@gnu.org</a>.
There are also <a href="http://www.gnu.org/home.html#ContactInfo">other ways
to contact</a> the FSF.</p>
<p>These pages are maintained by
<a href="http://gcc.gnu.org/about.html">the GCC team</a>.</p>
<address>For questions related to the use of GCC, please consult these web
pages and the <a href="http://gcc.gnu.org/onlinedocs/">GCC manuals</a>. If
that fails, the <a href="mailto:gcc-help@gcc.gnu.org">gcc-help@gcc.gnu.org</a>
mailing list might help.<br />
Please send comments on these web pages and the development of GCC to our
developer mailing list at <a href="mailto:gcc@gnu.org">gcc@gnu.org</a>
or <a href="mailto:gcc@gcc.gnu.org">gcc@gcc.gnu.org</a>. All of our lists
have <a href="http://gcc.gnu.org/lists.html">public archives</a>.
</address>
<p>Copyright (C) Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110, USA.</p>
<p>Verbatim copying and distribution of this entire article is
permitted in any medium, provided this notice is preserved.</p>
<table width="100%" border="0"><tr><td>
<!-- IGNORE DIFF -->Last modified 2009-04-21
</td><td align="right" valign="bottom">
<a href="http://validator.w3.org/check/referer">
<img src="http://www.w3.org/Icons/valid-xhtml10"
alt="Valid XHTML 1.0" border="0" width="88" height="31" />
</a>
</td></tr></table>
</div>
<!-- ==================================================================== -->
</body>
</html>
|