LLVM 1.4 Release Notes
  1. Introduction
  2. What's New?
  3. Installation Instructions
  4. Portability and Supported Platforms
  5. Known Problems
  6. Additional Information

Written by the LLVM team


This document contains the release notes for the LLVM compiler infrastructure, release 1.4. Here we describe the status of LLVM, including any known problems and improvements from the previous release. The most up-to-date version of this document can be found on the LLVM 1.4 web site. If you are not reading this on the LLVM web pages, you should probably go there because this document may be updated after the release.

For more information about LLVM, including information about the latest release, please check out the main LLVM web site. If you have questions or comments, the LLVM developer's mailing list is a good place to send them.

Note that if you are reading this file from CVS, this document applies to the next release, not the current one. To see the release notes for the current or previous releases, see the releases page.

What's New?

This is the fifth public release of the LLVM compiler infrastructure.

At this time, LLVM is known to correctly compile a broad range of C and C++ programs, including the SPEC CPU95 & 2000 suite. This release includes several major enhancements to the LLVM system, including a new PowerPC JIT, enhancements to the C/C++ front-end to provide source line number information in LLVM, a new compiler driver, and several other enhancements listed below. It also includes bug fixes for those problems found since the 1.3 release.

Note that this release seperates the LLVM Program Testsuite out of the main LLVM distribution into a seperate CVS repository and tarball. This reduces the size of the main LLVM distribution. Also note that LLVM now builds tools into llvm/Debug/bin by default instead of llvm/tools/Debug.

This release implements the following new features:
  1. LLVM now includes a Just-In-Time compiler for the PowerPC target.
  2. llvmgcc and llvmg++ now emit source line number information when '-g' is passed in, making it possible to map from LLVM code back to source. This information is currently used by llvm-db and can be used with other tools and passes.
  3. The test/Programs hierarchy has been moved out of the main LLVM tree into a separate CVS repository and tarball. This shrinks the distribution size of LLVM itself significantly.
  4. LLVM now optimizes global variables more aggressively than it did before.
  5. LLVM now includes the new 'undef' value and unreachable instruction, which give the optimizer more information about the behavior of the program.
  6. Bytecode compression with bzip2 has been implemented. All bytecode files generated by LLVM will now be compressed by default. Compression can be disabled with the -disable-compression option to the tools that can generate bytecode files.
  7. A generic compiler driver (llvmc) and an associated generic linker (llvm-ld) have been added. The compiler driver is generic because it can be configured to pre-process, translate, optimize, assemble, and link code from any source language with an LLVM front-end. This makes it easier for compiler writers to hide the multiple steps required to compile a program (compiling, optimizing, linking runtime libraries, etc) in one simple command.
  8. The dependent libraries feature has been implemented. This allows front end compilers to indicate in the bytecode which libraries the bytecode needs to be linked with. Both the C/C++ and Stacker front ends support generating the required dependencies. The linker now supports using this information to ensure required libaries are linked into the module. This minimizes the need to use the -l option when using llvmc.
  9. The LLVM makefiles have been improved to build LLVM much faster and includes new targets (like dist-check, uninstall). One important user-visible change is that libraries and tools will now be built into $builddir/Debug/{bin,lib} instead of $builddir/tools/Debug and $builddir/lib/Debug (Similarly for Release and Profile builds).
  10. The LLVM source code is much more compatible with Microsoft Visual C++, including the JIT and runtime-code generation, though the entire system may not work with it.
  11. The JIT-Target interfaces are now much simpler and more powerful.
  12. LLVM now provides llvm-ar and llvm-ranlib tools for working with archives of LLVM bytecode files.
  13. zlib and libpng are no longer included in the main LLVM tarball.
  14. The LLVM code generator now automatically generates assembly code writers from an abstract target descriptions, eliminating the need to write assembly printers manually.
  15. LLVM regression and feature tests now use DejaGNU instead of QMTest.
In this release, the following missing features were implemented:
  1. JIT interface should support arbitrary calls
  2. The llvm-ar tool was previously incomplete and didn't properly support other ar(1) implementations. This has been corrected. llvm-ar now fully supports all archive editing functions, table of contents listing, extraction, and printing. It can also read BSD4.4/MacOSX and SVR4 style archives. See llvm-ar for details.
In this release, the following Quality of Implementation issues were fixed:
  1. The linker no longer emits many useless warnings when linking C++ programs.
  2. The LLVM #include namespace has been made consistent. Files in llvm/include/{Support,Config} are now located in llvm/include/llvm/{Support,Config}.
  3. The names of the libraries generated by compiling LLVM source have been changed to ensure they do not conflict with other packages upon installation. Each LLVM library is now prefixed with LLVM and uses mixed clase. For example, the library libasmparser.a in 1.3 has become libLLVMAsmParser.a in release 1.4.
  4. The C++ frontend no longer expands and emits all inline functions, even if they are unused. It now properly tracks which functions are needed and only compiles those.
  5. Many improvements in the autoconf and makefile systems have been implemented.
This release includes the following Code Quality improvements:
  1. The optimizer produces more efficient code for std::min/std::max and other similar functions.
  2. The X86 backend generates substantially faster code for floating point intensive programs.
  3. The PowerPC backend generates more efficient code in many common scenarios.
In this release, the following bugs in the previous release were fixed:

Bugs fixed in the LLVM Core:

  1. [licm] LICM invalidates alias analysis info and uses broken information (optimizer crash)
  2. [asmwriter] Asmwriter is really slow for functions with lots of values
  3. [anders-aa] Andersen's AA is completely broken in LLVM 1.3
  4. [bcwriter] Empty compaction tables defined
  5. [X86] llc output for functions w/certain names tickles GNU 'as' bugs
  6. [cbackend] Static globals are prototyped as 'extern'

Bugs in the C/C++ front-end:

  1. [llvmg++] not enough templates are instantiated
  2. [llvmg++] Extern const globals cannot be marked 'constant' if they have nontrivial ctors or dtors
  3. [llvmgcc] Crash compiling unnamed bitfield which does not increase struct size
  4. [llvmgcc] llvmgcc emits invalid constant exprs
  5. [llvmg++] Crash initializing array with constructors in hard EH situations
  6. [llvm-gcc] Inline function redefinitions error due to 'asm' function rename
  7. [llvm-gcc] Error when an implicitly external function is re-declared as static
  8. [llvmgcc] Structure field with non-constant offset crashes llvmgcc
  9. [llvmg++] Crash compiling friend with default argument

Bugs fixed in the Sparc V9 back-end:

  1. [sparcv9] regalloc assertion failure with certain indirect calls
Portability and Supported Platforms

LLVM is known to work on the following platforms:

The core LLVM infrastructure uses GNU autoconf to adapt itself to the machine and operating system on which it is built. However, minor porting may be required to get LLVM to work on new platforms. We welcome your portability patches and reports of successful builds or error messages.

Known Problems

This section contains all known problems with the LLVM system, listed by component. As new problems are discovered, they will be added to these sections. If you run into a problem, please check the LLVM bug database and submit a bug if there isn't already one.

Experimental features included with this release

The following components of this LLVM release are either untested, known to be broken or unreliable, or are in early development. These components should not be relied on, and bugs should not be filed against them, but they may be useful to some people. In particular, if you would like to work on one of these components, please contact us on the llvmdev list.

Known problems with the LLVM Build
Known problems with the LLVM Core

Fixed in LLVM 1.5

Known problems with the C front-end

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).

Known problems with the C++ front-end

For this release, the C++ front-end is considered to be fully tested and works for a number of non-trivial programs, including LLVM itself.


Fixed in LLVM 1.5:

Known problems with the X86 back-end
Known problems with the SparcV9 back-end
Known problems with the PowerPC back-end
Known problems with the C back-end

Fixed in LLVM 1.5

Additional Information

A wide variety of additional information is available on the LLVM web page, including mailing lists and publications describing algorithms and components 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 the "llvm/doc/" directory in the LLVM tree.

If you have any questions or comments about LLVM, please feel free to contact us via the mailing lists.

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Last modified: $Date: 2005/02/11 19:30:30 $