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2 <html><head><title>LLVM 1.1 Release Notes</title></head>
5 <table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
6 <tr><td> <font size=+3 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>LLVM 1.1 Release Notes</b></font></td>
10 <li><a href="#intro">Introduction</a>
11 <li><a href="#whatsnew">What's New?</a>
12 <li><a href="#portability">Portability and Supported Platforms</a>
13 <li><a href="#install-instructions">Installation Instructions</a>
14 <li><a href="#knownproblems">Known Problems</a>
16 <!-- <li><a href="#portabilityprobs">Portability Problems</a> -->
17 <li><a href="#core">Known problems with the LLVM Core</a>
18 <li><a href="#c-fe">Known problems with the C Front-end</a>
19 <li><a href="#c++-fe">Known problems with the C++ Front-end</a>
20 <li><a href="#x86-be">Known problems with the X86 Back-end</a>
21 <li><a href="#sparc-be">Known problems with the Sparc Back-end</a>
22 <li><a href="#c-be">Known problems with the C back-end</a>
24 <li><a href="#additionalinfo">Additional Information</a>
27 <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></b><p>
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32 <table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
33 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
34 <a name="intro">Introduction
35 </b></font></td></tr></table><ul>
36 <!-- *********************************************************************** -->
38 This document contains the release notes for the LLVM compiler infrastructure,
39 release 1.1. Here we describe the status of LLVM, including any known problems,
40 and bug fixes from the previous release. The most up-to-date version of this
41 document can be found on the <a
42 href="http://llvm.cs.uiuc.edu/releases/1.1/">LLVM 1.1 web site</a>. If you are
43 not reading this on the LLVM web pages, you should probably go there, because
44 this document may be updated after the release.<p>
46 For more information about LLVM, including information about potentially more
47 current releases, please check out the <a href="http://llvm.cs.uiuc.edu">main
48 web site</a>. If you have questions or comments, the <a
49 href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
50 list</a> is a good place to send them.<p>
52 Note that if you are reading this file from CVS, that this document applies to
53 the <i>next</i> release, not the previous one. To see the release notes for the
54 previous release, see the <a href="http://llvm.cs.uiuc.edu/releases/">releases
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58 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
59 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
60 <a name="whatsnew">What's New?
61 </b></font></td></tr></table><ul>
62 <!-- *********************************************************************** -->
64 This is the second public release of the LLVM compiler infrastructure. This
65 release implements the following new features:<p>
69 href="http://mail.cs.uiuc.edu/pipermail/llvmdev/2003-November/000528.html">A new
70 LLVM profiler, similar to gprof</a> is available</li></p>
72 <p><li>LLVM and the C/C++ front-end now compile on Mac OSX! Mac OSX users can
73 now explore the LLVM optimizer with the C backend (note that LLVM requires GCC
74 3.3 on Mac OSX).</li></p>
76 <p><li>LLVM has been <a
77 href="http://mail.cs.uiuc.edu/pipermail/llvmdev/2003-November/000554.html">moved
78 into an 'llvm' C++ namespace</a>, for easier integration with third-party
79 code.</a> Note that due to a bug in GDB 5.x, to debug namespacified LLVM code,
80 you will need to upgrade to GDB 6.</li></p>
83 In this release, the following missing features were implemented:<p>
86 <li><a href="http://llvm.cs.uiuc.edu/PR88">The interpreter does not support
87 invoke or unwind</a></li>
89 <li><a href="http://llvm.cs.uiuc.edu/PR99">Interpreter does not support the
90 <tt>vaarg</tt> instruction</a></li>
92 <li><a href="http://llvm.cs.uiuc.edu/PR117">llvm-nm cannot read archive
97 In this release, the following Quality of Implementation issues were fixed:<p>
101 <li><a href="http://llvm.cs.uiuc.edu/PR29">C++ front-end is not generating
102 linkonce linkage type when it can</a></li>
104 <li><a href="http://llvm.cs.uiuc.edu/PR84">C front-end doesn't emit
105 getelementptr for address of array element</a></li>
107 <li><a href="http://llvm.cs.uiuc.edu/PR96">Bad path to the C/C++ frontend causes
108 build problems</a></li>
110 <li><a href="http://llvm.cs.uiuc.edu/PR114">LLVM header files should be -Wold-style-cast clean</a></li>
113 <li>The LLVM bytecode reader has been <a
114 href="http://llvm.cs.uiuc.edu/PR127">sped up a lot</a> (up to 4x in some
120 In this release, the following bugs in the previous release were fixed:<p>
123 <li><a href="http://llvm.cs.uiuc.edu/PR57">[inliner] Inlining invoke with PHI in unwind target is broken</a></li>
124 <li><a href="http://llvm.cs.uiuc.edu/PR58">[linker] linkonce globals should link successfully to external globals</a></li>
125 <li><a href="http://llvm.cs.uiuc.edu/PR59">C++ frontend can crash when compiling virtual base classes</a></li>
126 <li><a href="http://llvm.cs.uiuc.edu/PR62">C backend fails on constant cast expr to ptr-to-anonymous struct</a></li>
127 <li><a href="http://llvm.cs.uiuc.edu/PR63">#ident is not recognized by C frontend</a></li>
128 <li><a href="http://llvm.cs.uiuc.edu/PR64">[constmerge] Constant merging pass merges constants with external linkage</a></li>
129 <li><a href="http://llvm.cs.uiuc.edu/PR65">C front-end miscompiles the builtin_expect intrinsic!</a></li>
130 <li><a href="http://llvm.cs.uiuc.edu/PR66">[scalarrepl] Scalar Replacement of aggregates is decimating structures it shouldn't be</a></li>
131 <li><a href="http://llvm.cs.uiuc.edu/PR67">1.0 precompiled libstdc++ does not include wchar_t support</a></li>
132 <li><a href="http://llvm.cs.uiuc.edu/PR68">llvmgcc asserts when compiling functions renamed with asm's</a></li>
133 <li><a href="http://llvm.cs.uiuc.edu/PR69">C frontend crashes on some programs with lots of types.</a></li>
134 <li><a href="http://llvm.cs.uiuc.edu/PR70">[instcombine] Resolving invoke inserts cast after terminator</a></li>
135 <li><a href="http://llvm.cs.uiuc.edu/PR71">llvm-as crashes when labels are used in phi nodes</a></li>
136 <li><a href="http://llvm.cs.uiuc.edu/PR72">[build problem] Callgraph.cpp not pulled in from libipa.a</a></li>
137 <li><a href="http://llvm.cs.uiuc.edu/PR77">Variables in scope of output setjmp
138 calls should be volatile</a>. Note that this does not effect correctness on
139 many platforms, such as X86.
140 <li><a href="http://llvm.cs.uiuc.edu/PR79">llvm-gcc crashes compiling global union initializer</a></li>
141 <li><a href="http://llvm.cs.uiuc.edu/PR80">C front-end crash on empty structure</a></li>
142 <li><a href="http://llvm.cs.uiuc.edu/PR81">CFrontend crashes when compiling C99 compound expressions</a></li>
143 <li><a href="http://llvm.cs.uiuc.edu/PR83">[X86] Emission of global bool initializers broken</a></li>
144 <li><a href="http://llvm.cs.uiuc.edu/PR87">llvm-gcc infinite loops on "case MAXINT:"</a></li>
145 <li><a href="http://llvm.cs.uiuc.edu/PR89">[C++] Catch blocks make unparsable labels</a></li>
146 <li><a href="http://llvm.cs.uiuc.edu/PR90">[C++] Initializing array with constructable objects fail</a></li>
147 <li><a href="http://llvm.cs.uiuc.edu/PR91">[gccld] The -r (relinking) option does not work correctly</a></li>
148 <li><a href="http://llvm.cs.uiuc.edu/PR92">[bcreader] Cannot read shift constant expressions from bytecode file</a></li>
149 <li><a href="http://llvm.cs.uiuc.edu/PR93">[lowersetjmp] Lowersetjmp pass breaks dominance properties!</a></li>
150 <li><a href="http://llvm.cs.uiuc.edu/PR94">llvm-gcc tries to add bools</a></li>
151 <li><a href="http://llvm.cs.uiuc.edu/PR95">SymbolTable::getUniqueName is very inefficient</a></li>
152 <li><a href="http://llvm.cs.uiuc.edu/PR98">[buildscripts] Building into objdir with .o in it fails</a></li>
153 <li><a href="http://llvm.cs.uiuc.edu/PR101">[setjmp/longjmp] Linking C programs which use setjmp/longjmp sometimes fail with references to the C++ runtime library!</a></li>
154 <li><a href="http://llvm.cs.uiuc.edu/PR104">[c++] C++ Frontend lays out superclasses like anonymous bitfields!</a></li>
155 <li><a href="http://llvm.cs.uiuc.edu/PR107">AsmParser Misses Symbol Redefinition Error</a></li>
156 <li><a href="http://llvm.cs.uiuc.edu/PR108">gccld -Lfoo -lfoo fails to find ./foo/libfoo.a</a></li>
157 <li><a href="http://llvm.cs.uiuc.edu/PR110">[bcreader] Incorrect cast causes misread forward constant references</a></li>
158 <li><a href="http://llvm.cs.uiuc.edu/PR112">Casting a string constant to void crashes llvm-gcc</a></li>
159 <li><a href="http://llvm.cs.uiuc.edu/PR116">[adce] ADCE considers blocks without postdominators to be unreachable</a></li>
160 <li><a href="http://llvm.cs.uiuc.edu/PR54">C front-end miscompiles unsigned enums whose LLVM types are signed</a></li>
161 <li><a href="http://llvm.cs.uiuc.edu/PR123">[X86] div and rem constant exprs invalidate iterators!</a></li>
162 <li><a href="http://llvm.cs.uiuc.edu/PR125">[llvmg++] Enum types are incorrectly shrunk to smaller than 'int' size</a></li>
163 <li><a href="http://llvm.cs.uiuc.edu/PR128">[llvmg++] Cannot use pointer to member to initialize global</a></li>
164 <li><a href="http://llvm.cs.uiuc.edu/PR130">[vmcore] Symbol table doesn't rename colliding variables during type resolution</a></li>
165 <li><a href="http://llvm.cs.uiuc.edu/PR131">[llvm-gcc] ?: operator as lvalue not implemented</a></li>
166 <li><a href="http://llvm.cs.uiuc.edu/PR133">[C/C++] Bogus warning about taking the address of 'register' variable</a></li>
167 <li><a href="http://llvm.cs.uiuc.edu/PR97">bugpoint must not pass -R<directory> to Mach-O linker</a></li>
168 <li><a href="http://llvm.cs.uiuc.edu/PR113">crash assigning into an array in a struct which contains a bitfield</a>.</li>
169 <li><a href="http://llvm.cs.uiuc.edu/PR6">Oversized integer bitfields cause crash</a></li>
170 <li><a href="http://llvm.cs.uiuc.edu/PR141">[llvm-gcc] Bitfields & large array don't mix well</a></li>
171 <li><a href="http://llvm.cs.uiuc.edu/PR132">[llvm-gcc] Complex division is not supported</a></li>
172 <li><a href="http://llvm.cs.uiuc.edu/PR143">[llvm-gcc] Illegal union field reference</a></li>
175 At this time, LLVM is known to work properly with SPEC CPU 2000, the Olden
176 benchmarks, and the Ptrdist benchmarks among many other programs. Note however
177 that the Sparc and X86 backends do not currently support exception throwing or
178 long jumping (including 253.perlbmk in SPEC). For these programs you must use
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184 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
185 <a name="portability">Portability and Supported Platforms
186 </b></font></td></tr></table><ul>
187 <!-- *********************************************************************** -->
189 LLVM has been extensively tested on Intel and AMD machines running Red
190 Hat Linux, and Sun UltraSPARC workstations running Solaris 8. Additionally,
191 LLVM works on Mac OS/X 10.3 and above, but only with the C back-end (no native
192 backend for the PowerPC is available yet).
193 The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
194 work on more platforms than that. However, it is likely that we
195 missed something, and that minor porting is required to get LLVM to work on
196 new platforms. We welcome portability patches and error messages.<p>
199 <!-- *********************************************************************** -->
200 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
201 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
202 <a name="knownproblems">Known Problems
203 </b></font></td></tr></table><ul>
204 <!-- *********************************************************************** -->
206 This section contains all known problems with the LLVM system, listed by
207 component. As new problems are discovered, they will be added to these
211 <!-- _______________________________________________________________________ -->
213 </ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
217 <!-- _______________________________________________________________________ -->
218 </ul><h4><a name="core"><hr size=0>Known problems with the LLVM Core</h4><ul>
220 <li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not work.<p>
222 <li>The JIT does not use mutexes to protect its internal data structures. As
223 such, execution of a threaded program could cause these data structures to
226 <li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.<p>
228 <li>Linking in static archive files (.a files) is very slow (there is no symbol
229 table in the archive).<p>
231 <li><a href="http://llvm.cs.uiuc.edu/PR82">LLVM cannot handle structures with
232 more than 256 elements</a>.<p>
234 <!-- _______________________________________________________________________ -->
235 </ul><h4><a name="c-fe"><hr size=0>Known problems with the C front-end</h4><ul>
237 </ul><b>Bugs:</b><ul><p>
239 <li>C99 Variable sized arrays do not release stack memory when they go out of
240 scope. Thus, the following program may run out of stack space:
242 for (i = 0; i != 1000000; ++i) {
248 </ul><b>Notes:</b><ul><p>
250 <li>Inline assembly is not yet supported.<p>
252 <li>"long double" is transformed by the front-end into "double". There is no
253 support for floating point data types of any size other than 32 and 64 bits.
256 <li>The following Unix system functionality has not been tested and may not work:
258 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
259 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
260 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
261 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
262 - These functions have not been tested.
265 <li>Although many GCC extensions are supported, some are not. In particular,
266 the following extensions are known to <b>not be</b> supported:
268 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.
269 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html#Labels%20as%20Values">Labels as Values</a>: Getting pointers to labels, and computed gotos.
270 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>: As in Algol and Pascal, lexical scoping of functions.
271 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.
272 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.
273 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands
274 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Asm-Labels.html#Asm%20Labels">Asm Labels</a>: Specifying the assembler name to use for a C symbol.
275 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>: Defining variables residing in specified registers.
276 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Return-Address.html#Return%20Address">Return Address</a>: Getting the return or frame address of a function.
277 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.
278 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.
279 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.
280 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.
283 The following GCC extensions are <b>partially</b> supported. An ignored
284 attribute means that the LLVM compiler ignores the presence of the attribute,
285 but the code should still work. An unsupported attribute is one which is
286 ignored by the LLVM compiler, which will cause a different interpretation of
290 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
291 Arrays whose length is computed at run time.<br>
292 Supported, but allocated stack space is not freed until the function returns (noted above).
294 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
295 Declaring that functions have no side effects, or that they can never return.<br>
296 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>, <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>, <tt>deprecated</tt>,
297 <tt>warn_unused_result</tt>, <tt>weak</tt><br>
298 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>, <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>, <tt>malloc</tt>
299 <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
300 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>, <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
301 <tt>fastcall</tt>, all other target specific attributes
303 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
304 Specifying attributes of variables.<br>
305 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
306 <tt>deprecated</tt>, <tt>transparent_union</tt>,
307 <tt>unused</tt>, <tt>weak</tt><br>
308 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
309 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
310 <tt>vector_size</tt>, <tt>dllimport</tt>,
311 <tt>dllexport</tt>, all target specific attributes.<br>
313 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.
314 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
315 <tt>deprecated</tt>, <tt>may_alias</tt>
316 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>
317 all target specific attributes.<br>
318 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
319 Other built-in functions.<br>
320 We support all builtins which have a C language equivalent (e.g.,
321 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
322 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
323 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).
327 The following extensions <b>are</b> known to be supported:
329 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.
330 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.
331 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.
332 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.
333 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.
334 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.
335 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.
336 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.
337 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.
338 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.
339 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.
340 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.
341 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html#Pointer%20Arith">Pointer Arith</a>:Arithmetic on <code>void</code>-pointers and function pointers.
342 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.
343 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions or arrays as values.
344 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.
346 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Cast-to-Union.html#Cast%20to%20Union">Cast to Union</a>:Casting to union type from any member of the union.
347 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.
348 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.
350 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.
351 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.
352 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.
353 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Character-Escapes.html#Character%20Escapes">Character Escapes</a>: <code>\e</code> stands for the character <ESC>.
354 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.
355 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).
356 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alternate-Keywords.html#Alternate%20Keywords">Alternate Keywords</a>:<code>__const__</code>, <code>__asm__</code>, etc., for header files.
357 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Incomplete-Enums.html#Incomplete%20Enums">Incomplete Enums</a>: <code>enum foo;</code>, with details to follow.
358 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Names.html#Function%20Names">Function Names</a>: Printable strings which are the name of the current function.
359 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.
360 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.
363 If you run into GCC extensions which have not been included in any of these
364 lists, please let us know (also including whether or not they work).
367 <!-- _______________________________________________________________________ -->
368 </ul><h4><a name="c++-fe"><hr size=0>Known problems with the C++ front-end</h4><ul>
370 For this release, the C++ front-end is considered to be fully functional but
371 of <b>beta</b> quality. It has been tested and works for a number of simple programs that collectively exercise most of the language. Nevertheless, it has not been in use as long as the C front-end. Please report any bugs or problems.<p>
373 </ul><b>Bugs</b>:<ul><p>
375 <li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
378 </ul><b>Notes</b>:<ul><p>
380 <li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
381 parser is significantly more standards compliant (and picky) than prior GCC
382 versions. For more information, see the C++ section of the <a
383 href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.<p>
385 <li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
386 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
387 function and in the <tt>setjmp</tt> receiver function may not be run.
388 Objects in intervening stack frames will be destroyed however (which is
389 better than most compilers).<p>
391 <li>The LLVM C++ front-end follows the <a
392 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
393 This document, which is not Itanium specific, specifies a standard for name
394 mangling, class layout, v-table layout, RTTI formats, and other C++
395 representation issues. Because we use this API, code generated by the LLVM
396 compilers should be binary compatible with machine code generated by other
397 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
398 <i>However</i>, the exception handling mechanism used by LLVM is very
399 different from the model used in the Itanium ABI, so <b>exceptions will not
400 interact correctly</b> .
402 <li><a href="http://llvm.cs.uiuc.edu/PR11">Code for executing destructors when
403 unwinding is not shared</a> (this is a quality of implementation problem,
404 which does not effect functionality).<p>
407 <!-- _______________________________________________________________________ -->
408 </ul><h4><a name="x86-be"><hr size=0>Known problems with the X86 back-end</h4><ul>
410 <li>The X86 code generator <a
411 href="http://llvm.cs.uiuc.edu/PR16">does not currently
412 support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
413 or calls the C <tt>longjmp</tt> function will abort.<p>
416 <!-- _______________________________________________________________________ -->
417 </ul><h4><a name="sparc-be"><hr size=0>Known problems with the Sparc back-end</h4><ul>
419 <li>The Sparc code generator <a
420 href="http://llvm.cs.uiuc.edu/PR15">does not currently
421 support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
422 or calls the C <tt>longjmp</tt> function will abort.<p>
425 <!-- _______________________________________________________________________ -->
426 </ul><h4><a name="c-be"><hr size=0>Known problems with the C back-end</h4><ul>
428 <li>The C back-end produces code that violates the ANSI C Type-Based Alias
429 Analysis rules. As such, special options may be necessary to compile the code
430 (for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
431 problem probably cannot be fixed.<p>
433 <li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
434 cannot include special floating point numbers like Not-A-Number or Infinity.<p>
436 <li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
437 supported</a>. This should not affect LLVM produced by the C or C++
440 <li>The code produces by the C back-end has only been tested with the Sun CC,
441 GCC, and Intel compilers. It is possible that it will have to be adjusted to
442 support other C compilers.<p>
446 <!-- *********************************************************************** -->
447 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
448 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
449 <a name="additionalinfo">Additional Information
450 </b></font></td></tr></table><ul>
451 <!-- *********************************************************************** -->
453 A wide variety of additional information is available on the LLVM web page,
454 including mailing lists publications describing algorithms and components
455 implemented in LLVM. The web page also contains versions of the API
456 documentation which is up-to-date with the CVS version of the source code. You
457 can access versions of these documents specific to this release by going into
458 the "<tt>llvm/doc/</tt>" directory in the LLVM tree.<p>
460 If you have any questions or comments about LLVM, please feel free to contact us
461 via the mailing lists.<p>
464 <!-- *********************************************************************** -->
466 <!-- *********************************************************************** -->
470 Maintained By: <a href="http://llvm.cs.uiuc.edu/">The LLVM Team</a><br>
471 <!-- Created: Wed Oct 1 17:38:54 CDT 2003 -->
473 Last modified: Thu Nov 20 14:59:29 CST 2003