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

Introduction

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 bug fixes 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 potentially more current releases, please check out the main 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 and run all C & C++ SPEC CPU95 & 2000 benchmarks, the Olden benchmarks, and the Ptrdist benchmarks, and many other C and C++ programs.

This release implements the following new features:
  1. LLVM now includes a JIT for the PowerPC target.
  2. LLVM now optimizes global variables significantly more than it did before.
  3. LLVM now includes the new 'undef' value and unreachable instruction, which give the optimizer more information about the behavior of the program.
  4. llvmgcc and llvmg++ now emit source line number information when '-g' is passed in. This information can be used with llvm-db or other tools and passes.
  5. 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.
  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 and an associated generic linker have been implemented. The compiler driver is generic because it can be configured to pre-process, translate, optimize, assemble, and link code from any source language. This aids compiler writers because all that is needed is a source-to-bytecode or source-to-assembly translator and a configuration file. The linker is generic because it allows dynamically loadable optimization modules to be executed for link-time optimization. Language specific link-time optimization modules can be created and executed automatically.
  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++ front end and Stacker support generating the required libraries. 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 faster (2x) and includes new targets (like dist-check, uninstall). One important change is associated with PR456. The 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 target-to-JIT interfaces are now much simpler and more powerful.
  12. zlib and libpng are no longer included in the main LLVM tarball.
  13. The LLVM code generator now generates asm writers for the target from an abstract target description, instead of requiring them to be hand written.
  14. LLVM regression and feature tests can now be run with DejaGNU.
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. [llvmg++] Tons of warnings are spewed when linking to libstdc++
  2. include/{Support,Config} -> 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. [llvmg++] C++ frontend is expanding lots of unused inline functions
In this release, the following build problems were fixed:
  1. [autoconf] further standardizing autoconf usage. Various improvements in the configure.ac script were made as well as the makefile system.
This release includes the following Code Quality improvements:
  1. Ugly code generated for std::min/std::max
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

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 in initializing array with constructors in hard EH situations

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 in 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.

Note that the LLVM build system does not currently support directories with spaces on them when running on Win32/cygwin. We strongly recommend running LLVM and the C frontend out of a top-level directory without spaces (e.g., /cygdrive/c/llvm). Also, make sure to install all of the cygwin packages. By default, many important tools are not installed that are needed by the LLVM build process or test suite (e.g., /bin/time). Finally, please make sure that there are no directories with spaces in them in your PATH environment variable.

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 Core
Known problems with the C front-end
Bugs
Notes

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 functional but 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.

Bugs
Notes
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
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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