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< title > LLVM 1.2 Release Notes< / title >
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< / head >
< body >
< div class = "doc_title" >
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LLVM 1.2 Release Notes
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< / div >
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< ol >
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< li > < a href = "#intro" > Introduction< / a > < / li >
< li > < a href = "#whatsnew" > What's New?< / a > < / li >
< li > < a href = "#portability" > Portability and Supported Platforms< / a > < / li >
< li > < a href = "#install-instructions" > Installation Instructions< / a > < / li >
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< li > < a href = "#knownproblems" > Known Problems< / a >
< ul >
< li > < a href = "#core" > Known problems with the LLVM Core< / a >
< li > < a href = "#c-fe" > Known problems with the C Front-end< / a >
< li > < a href = "#c++-fe" > Known problems with the C++ Front-end< / a >
< li > < a href = "#x86-be" > Known problems with the X86 Back-end< / a >
< li > < a href = "#sparc-be" > Known problems with the Sparc Back-end< / a >
< li > < a href = "#c-be" > Known problems with the C back-end< / a >
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< / ul > < / li >
< li > < a href = "#additionalinfo" > Additional Information< / a > < / li >
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< / ol >
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< div class = "doc_text" >
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< p > < b > Written by the < a href = "http://llvm.cs.uiuc.edu" > LLVM team< / a > < / b > < p >
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< / div >
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<!-- *********************************************************************** -->
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< div class = "doc_section" >
< a name = "intro" > Introduction< / a >
< / div >
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<!-- *********************************************************************** -->
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< div class = "doc_text" >
< p > This document contains the release notes for the LLVM compiler
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infrastructure, release 1.2. Here we describe the status of LLVM, including any
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known problems and bug fixes from the previous release. The most up-to-date
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version of this document can be found on the < a
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href="http://llvm.cs.uiuc.edu/releases/1.2/">LLVM 1.2 web site< / a > . If you are
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not reading this on the LLVM web pages, you should probably go there because
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this document may be updated after the release.< / p >
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< p > For more information about LLVM, including information about potentially more
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current releases, please check out the < a href = "http://llvm.cs.uiuc.edu" > main
web site< / a > . If you have questions or comments, the < a
href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
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list< / a > is a good place to send them.< / p >
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< p > Note that if you are reading this file from CVS, this document applies
to the < i > next< / i > release, not the current one. To see the release notes for
the current or previous releases, see the < a
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href="http://llvm.cs.uiuc.edu/releases/">releases page< / a > .< / p >
< / div >
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<!-- *********************************************************************** -->
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< div class = "doc_section" >
< a name = "whatsnew" > What's New?< / a >
< / div >
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<!-- *********************************************************************** -->
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< div class = "doc_text" >
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< p > This is the third public release of the LLVM compiler infrastructure.
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< / p >
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< p > At this time, LLVM is known to correctly compile and run all non-unwinding C
& C++ SPEC CPU2000 benchmarks, the Olden benchmarks, and the Ptrdist
benchmarks. It has also been used to compile < b > many< / b > other programs. LLVM
now also works with a broad variety of C++ programs, though it has still
received much less testing than the C front-end.
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< / p >
< p >
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The LLVM native code generators are very stable but do not currently support
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unwinding (exception throwing or < tt > longjmp< / tt > ing), which prevent them from
working with programs like the < tt > 253.perlbmk< / tt > in SPEC CPU2000. The C
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backend and the rest of LLVM supports these programs, so you can
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still use LLVM with them. Support for unwinding will be added in a future
release.
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< / p >
<!-- ========================================================================= -->
< div class = "doc_subsubsection" >
This release implements the following new features:
< / div >
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< ol >
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< li > < / li >
< li > < / li >
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< / ol >
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<!-- ========================================================================= -->
< div class = "doc_subsubsection" >
In this release, the following missing features were implemented:
< / div >
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< ol >
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< li > < / li >
< li > < / li >
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< / ol >
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<!-- ========================================================================= -->
< div class = "doc_subsubsection" >
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In this release, the following Quality of Implementation issues were fixed:
< / div >
< ol >
< li > < a href = "http://llvm.cs.uiuc.edu/PR135" > JIT should lazily initialize global variables< / a > < / li >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR192" > [X86] X86 Backend never releases memory for machine code structures< / a > < / li >
2003-12-23 23:50:31 +00:00
< li > < a href = "http://llvm.cs.uiuc.edu/PR196" > [vmcore] OpaqueType objects memory leak< / a > < / li >
2004-01-08 17:20:50 +00:00
< li > < a href = "http://llvm.cs.uiuc.edu/PR182" > [llvmgcc] C front-end does not compile "extern inline" into linkonce< / a > < / li >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR73" > Bytecode format inconsistent< / a > < / li >
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< / ol >
<!-- ========================================================================= -->
< div class = "doc_subsubsection" >
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In this release, the following build problems were fixed:
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< / div >
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< ol >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR210" > [build] Makefiles break if C frontend target string has unexpected value< / a > < / li >
< / ol >
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<!-- ========================================================================= -->
< div class = "doc_subsubsection" >
In this release, the following Code Quality issues were fixed:
< / div >
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< ol >
< li > < a href = "http://llvm.cs.uiuc.edu/PR187" > [loopsimplify] Many pointless phi nodes are created< / a > < / li >
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< / ol >
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<!-- ========================================================================= -->
< div class = "doc_subsubsection" >
In this release, the following bugs in the previous release were fixed:
< / div >
< p > Bugs in the LLVM Core:< / p >
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< ol >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR179" > [licm] LICM promotes volatile memory
locations to registers< / a > < / li >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR191" > [licm] Memory read after free causes
infrequent crash< / a > < / li >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR194" > [indvars] Induction variable
canonicalization always makes 32-bit indvars< / a > < / li >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR193" > [constantmerge] Merging globals can
cause use of invalid pointers!< / a > < / li >
2004-01-20 19:16:50 +00:00
< li > < a href = "http://llvm.cs.uiuc.edu/PR212" > [bcreader] Bytecode reader misreads 'long -9223372036854775808'!< / a > < / li >
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< / ol >
< p > Bugs in the C/C++ front-end:< / p >
< ol >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR186" > Need weak linkage on memory
management functions in libc runtime to allow them to be overriden< / a > < / li >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR202" > [llvm-gcc] asserts when an extern inline function is redefined< / a > < / li >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR204" > [llvmg++] Dynamically initialized constants cannot be marked 'constant'< / a > < / li >
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< / ol >
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< / div >
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<!-- *********************************************************************** -->
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< div class = "doc_section" >
< a name = "portability" > Portability and Supported Platforms< / a >
< / div >
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<!-- *********************************************************************** -->
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< div class = "doc_text" >
< p > LLVM has been extensively tested on Intel and AMD machines running Red
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Hat Linux and FreeBSD. It has also been tested on Sun UltraSPARC workstations running Solaris 8.
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Additionally,
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LLVM works on Mac OS X 10.3 and above, but only with the C backend or
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interpreter (no native backend for the PowerPC is available yet).
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The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
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work on more platforms than that. However, it is likely that we
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missed something and that minor porting is required to get LLVM to work on
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new platforms. We welcome portability patches and error messages.< / p >
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< / div >
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<!-- *********************************************************************** -->
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< div class = "doc_section" >
< a name = "knownproblems" > Known Problems< / a >
< / div >
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<!-- *********************************************************************** -->
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< div class = "doc_text" >
< p > This section contains all known problems with the LLVM system, listed by
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component. As new problems are discovered, they will be added to these
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sections. If you run into a problem, please check the < a
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href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database< / a > and submit a bug if
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there isn't already one.< / p >
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< / div >
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<!-- _______________________________________________________________________ -->
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<!--
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< / ul > < h4 > < a name = "portability" > < hr size = 0 > Portability Problems< / h4 > < ul >
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-->
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<!-- ======================================================================= -->
< div class = "doc_subsection" >
< a name = "core" > Known problems with the LLVM Core< / a >
< / div >
< div class = "doc_text" >
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< ul >
< li > In the JIT, < tt > dlsym< / tt > on a symbol compiled by the JIT will not
work.< / li >
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< li > The JIT does not use mutexes to protect its internal data structures. As
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such, execution of a threaded program could cause these data structures to be
corrupted.< / li >
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< li > It is not possible to < tt > dlopen< / tt > an LLVM bytecode file in the JIT.< / li >
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< li > Linking in static archive files (.a files) is very slow (there is no symbol
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table in the archive).< / li >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR82" > LLVM cannot handle structures with
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more than 256 elements< / a > .< / li >
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< li >
The gccld program
< a href = "http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=139" >
does not link objects/archives in the order specified on the command line.
< / a >
< / li >
< li >
< a href = "http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=174" >
Tail duplication does not update SSA form correctly.
< / a >
< / li >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR16" > [lowerinvoke] The -lowerinvoke pass
does not insert calls to setjmp/longjmp< / a > .< / li >
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< / ul >
< / div >
<!-- ======================================================================= -->
< div class = "doc_subsection" >
< a name = "c-fe" > Known problems with the C front-end< / a >
< / div >
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<!-- _______________________________________________________________________ -->
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< div class = "doc_subsubsection" > Bugs< / div >
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< div class = "doc_text" >
< ul >
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< li > C99 Variable sized arrays do not release stack memory when they go out of
scope. Thus, the following program may run out of stack space:
< pre >
for (i = 0; i != 1000000; ++i) {
int X[n];
foo(X);
}
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< / pre > < / li >
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< li >
Initialization of global union variables can only be done
< a href = "http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162" > with the largest
union member< / a > .
< / li >
< li >
< a href = "http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=182" >
Functions marked "extern inline" are not compiled into LLVM with linkonce
linkage.
< / a >
< / li >
< li >
The memory management functions in the libc runtime
< a href = "http://llvm.cs.uiuc.edu/PR186" > need weak linkage so that they can be
overridden.
< / a >
< / li >
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< / ul >
< / div >
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<!-- _______________________________________________________________________ -->
< div class = "doc_subsubsection" >
Notes
< / div >
< div class = "doc_text" >
< ul >
< li > Inline assembly is not yet supported.< / li >
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< li > "long double" is transformed by the front-end into "double". There is no
support for floating point data types of any size other than 32 and 64
bits.< / li >
< li > The following Unix system functionality has not been tested and may not
work:
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< ol >
< li > < tt > sigsetjmp< / tt > , < tt > siglongjmp< / tt > - These are not turned into the
appropriate < tt > invoke< / tt > /< tt > unwind< / tt > instructions. Note that
< tt > setjmp< / tt > and < tt > longjmp< / tt > < em > are< / em > compiled correctly.
< li > < tt > getcontext< / tt > , < tt > setcontext< / tt > , < tt > makecontext< / tt >
- These functions have not been tested.
< / ol > < / li >
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< li > Although many GCC extensions are supported, some are not. In particular,
the following extensions are known to < b > not be< / b > supported:
< ol >
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< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels" > Local Labels< / a > : Labels local to a block.< / li >
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< 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.< / li >
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< 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.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls" > Constructing Calls< / a > : Dispatching a call to another function.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm" > Extended Asm< / a > : Assembler instructions with C expressions as operands.< / li >
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< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints" > Constraints< / a > : Constraints for asm operands.< / li >
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< 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.< / li >
< 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.< / li >
< 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.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions" > Vector Extensions< / a > : Using vector instructions through built-in functions.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins" > Target Builtins< / a > : Built-in functions specific to particular targets.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local" > Thread-Local< / a > : Per-thread variables.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas" > Pragmas< / a > : Pragmas accepted by GCC.< / li >
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< / ol >
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< p > The following GCC extensions are < b > partially< / b > supported. An ignored
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attribute means that the LLVM compiler ignores the presence of the attribute,
but the code should still work. An unsupported attribute is one which is
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ignored by the LLVM compiler and will cause a different interpretation of
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the program.< / p >
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< ol >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length" > Variable Length< / a > :
Arrays whose length is computed at run time.< br >
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Supported, but allocated stack space is not freed until the function returns (noted above).< / li >
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< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes" > Function Attributes< / a > :
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Declaring that functions have no side effects or that they can never
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return.< br >
< 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 > , < tt > warn_unused_result< / tt > , < tt > weak< / tt > < br >
< 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 > , < tt > no_instrument_function< / tt > , < tt > cdecl< / tt > < br >
< b > Unsupported:< / b > < tt > used< / tt > , < tt > section< / tt > , < tt > alias< / tt > ,
< tt > visibility< / tt > , < tt > regparm< / tt > , < tt > stdcall< / tt > ,
< tt > fastcall< / tt > , all other target specific attributes< / li >
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< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes" > Variable Attributes< / a > :
Specifying attributes of variables.< br >
< b > Supported:< / b > < tt > cleanup< / tt > , < tt > common< / tt > , < tt > nocommon< / tt > ,
< tt > deprecated< / tt > , < tt > transparent_union< / tt > ,
< tt > unused< / tt > , < tt > weak< / tt > < br >
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< b > Unsupported:< / b > < tt > aligned< / tt > , < tt > mode< / tt > , < tt > packed< / tt > ,
< tt > section< / tt > , < tt > shared< / tt > , < tt > tls_model< / tt > ,
< tt > vector_size< / tt > , < tt > dllimport< / tt > ,
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< tt > dllexport< / tt > , all target specific attributes.< / li >
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< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes" > Type Attributes< / a > : Specifying attributes of types.< br >
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< b > Supported:< / b > < tt > transparent_union< / tt > , < tt > unused< / tt > ,
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< tt > deprecated< / tt > , < tt > may_alias< / tt > < br >
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< b > Unsupported:< / b > < tt > aligned< / tt > , < tt > packed< / tt > ,
all target specific attributes.< / li >
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< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins" > Other Builtins< / a > :
Other built-in functions.< br >
We support all builtins which have a C language equivalent (e.g.,
< tt > __builtin_cos< / tt > ), < tt > __builtin_alloca< / tt > ,
< tt > __builtin_types_compatible_p< / tt > , < tt > __builtin_choose_expr< / tt > ,
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< tt > __builtin_constant_p< / tt > , and < tt > __builtin_expect< / tt > (ignored).< / li >
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< / ol >
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< p > The following extensions < b > are< / b > known to be supported:< / p >
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< ol >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs" > Statement Exprs< / a > : Putting statements and declarations inside expressions.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof" > Typeof< / a > : < code > typeof< / code > : referring to the type of an expression.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues" > Lvalues< / a > : Using < code > ?:< / code > , "< code > ,< / code > " and casts in lvalues.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals" > Conditionals< / a > : Omitting the middle operand of a < code > ?:< / code > expression.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long" > Long Long< / a > : Double-word integers.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex" > Complex< / a > : Data types for complex numbers.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats" > Hex Floats< / a > :Hexadecimal floating-point constants.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length" > Zero Length< / a > : Zero-length arrays.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures" > Empty Structures< / a > : Structures with no members.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros" > Variadic Macros< / a > : Macros with a variable number of arguments.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines" > Escaped Newlines< / a > : Slightly looser rules for escaped newlines.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting" > Subscripting< / a > : Any array can be subscripted, even if not an lvalue.< / li >
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< 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.< / li >
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< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers" > Initializers< / a > : Non-constant initializers.< / li >
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< 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.< / li >
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< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits" > Designated Inits< / a > : Labeling elements of initializers.< / li >
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< 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.< / li >
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< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges" > Case Ranges< / a > : `case 1 ... 9' and such.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations" > Mixed Declarations< / a > : Mixing declarations and code.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes" > Function Prototypes< / a > : Prototype declarations and old-style definitions.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments" > C++ Comments< / a > : C++ comments are recognized.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs" > Dollar Signs< / a > : Dollar sign is allowed in identifiers.< / li >
< 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> .< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment" > Alignment< / a > : Inquiring about the alignment of a type or variable.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline" > Inline< / a > : Defining inline functions (as fast as macros).< / li >
< 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.< / li >
< 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.< / li >
< 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.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields" > Unnamed Fields< / a > : Unnamed struct/union fields within structs/unions.< / li >
< li > < a href = "http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax" > Attribute Syntax< / a > : Formal syntax for attributes.< / li >
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< / ol > < / li >
< / ul >
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< p > If you run into GCC extensions which have not been included in any of these
lists, please let us know (also including whether or not they work).< / p >
< / div >
<!-- ======================================================================= -->
< div class = "doc_subsection" >
< a name = "c++-fe" > Known problems with the C++ front-end< / a >
< / div >
< div class = "doc_text" >
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< p > For this release, the C++ front-end is considered to be fully functional but
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has not been tested as thoroughly as the C front-end. It has been tested and
works for a number of non-trivial programs, but there may be lurking bugs.
Please report any bugs or problems.< / p >
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< / div >
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<!-- _______________________________________________________________________ -->
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< div class = "doc_subsubsection" >
Bugs
< / div >
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< div class = "doc_text" >
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< ul >
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< li > The C++ front-end inherits all problems afflicting the < a href = "#c-fe" > C
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front-end< / a > .< / li >
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< li >
< a href = "http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=137" >
Code is generated for empty classes.
< / a >
< / li >
< / ul >
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< / div >
<!-- _______________________________________________________________________ -->
< div class = "doc_subsubsection" >
Notes
< / div >
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< div class = "doc_text" >
< ul >
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< li > The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
parser is significantly more standards compliant (and picky) than prior GCC
versions. For more information, see the C++ section of the < a
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href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes< / a > .< / li >
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< li > Destructors for local objects are not always run when a < tt > longjmp< / tt > is
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performed. In particular, destructors for objects in the < tt > longjmp< / tt > ing
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function and in the < tt > setjmp< / tt > receiver function may not be run.
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Objects in intervening stack frames will be destroyed, however (which is
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better than most compilers).< / li >
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< li > The LLVM C++ front-end follows the < a
href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI< / a > .
This document, which is not Itanium specific, specifies a standard for name
mangling, class layout, v-table layout, RTTI formats, and other C++
representation issues. Because we use this API, code generated by the LLVM
compilers should be binary compatible with machine code generated by other
Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
< i > However< / i > , the exception handling mechanism used by LLVM is very
different from the model used in the Itanium ABI, so < b > exceptions will not
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interact correctly< / b > . < / li >
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< / ul >
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< / div >
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<!-- ======================================================================= -->
< div class = "doc_subsection" >
< a name = "x86-be" > Known problems with the X86 back-end< / a >
< / div >
< div class = "doc_text" >
< ul >
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< li > The X86 code generator < a
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href="http://llvm.cs.uiuc.edu/PR16">does not currently
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support the < tt > unwind< / tt > instruction< / a > , so code that throws a C++ exception
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or calls the C < tt > longjmp< / tt > function will abort.< / li >
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< / ul >
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< / div >
<!-- ======================================================================= -->
< div class = "doc_subsection" >
< a name = "sparc-be" > Known problems with the Sparc back-end< / a >
< / div >
< div class = "doc_text" >
< ul >
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< li > The Sparc code generator < a
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href="http://llvm.cs.uiuc.edu/PR16">does not currently
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support the < tt > unwind< / tt > instruction< / a > , so code that throws a C++ exception
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or calls the C < tt > longjmp< / tt > function will abort.< / li >
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< li >
< a href = "http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=167" >
The llc program can crash on legal code.
< / a >
< / li >
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< / ul >
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< / div >
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<!-- ======================================================================= -->
< div class = "doc_subsection" >
< a name = "c-be" > Known problems with the C back-end< / a >
< / div >
< div class = "doc_text" >
< ul >
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< li > The C back-end produces code that violates the ANSI C Type-Based Alias
Analysis rules. As such, special options may be necessary to compile the code
(for example, GCC requires the < tt > -fno-strict-aliasing< / tt > option). This
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problem probably cannot be fixed.< / li >
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2003-10-20 19:05:03 +00:00
< li > < a href = "http://llvm.cs.uiuc.edu/PR33" > Initializers for global variables< / a >
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cannot include special floating point numbers like Not-A-Number or
Infinity.< / li >
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< li > < a href = "http://llvm.cs.uiuc.edu/PR56" > Zero arg vararg functions are not
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supported< / a > . This should not affect LLVM produced by the C or C++
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frontends.< / li >
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< / ul >
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< / div >
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<!-- *********************************************************************** -->
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< div class = "doc_section" >
< a name = "additionalinfo" > Additional Information< / a >
< / div >
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<!-- *********************************************************************** -->
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< div class = "doc_text" >
< p > A wide variety of additional information is available on the LLVM web page,
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including mailing lists and publications describing algorithms and components
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implemented in LLVM. The web page also contains versions of the API
documentation which is up-to-date with the CVS version of the source code. You
can access versions of these documents specific to this release by going into
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the "< tt > llvm/doc/< / tt > " directory in the LLVM tree.< / p >
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< p > If you have any questions or comments about LLVM, please feel free to contact
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us via the < a href = "http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev" > mailing
lists< / a > .< / p >
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< / div >
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<!-- *********************************************************************** -->
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