The Mesa 3D Graphics Library


The Gallium llvmpipe driver is a software rasterizer that uses LLVM to do runtime code generation. Shaders, point/line/triangle rasterization and vertex processing are implemented with LLVM IR which is translated to x86 or x86-64 machine code. Also, the driver is multithreaded to take advantage of multiple CPU cores (up to 8 at this time). It's the fastest software rasterizer for Mesa.



To build everything on Linux invoke scons as:
  scons build=debug libgl-xlib
Alternatively, you can build it with GNU make, if you prefer, by invoking it as
  make linux-llvm
but the rest of these instructions assume that scons is used. For Windows the procedure is similar except the target:
  scons build=debug libgl-gdi


On Linux, building will create a drop-in alternative for into
To use it set the LD_LIBRARY_PATH environment variable accordingly. For performance evaluation pass debug=no to scons, and use the corresponding lib directory without the "-debug" suffix. On Windows, building will create a drop-in alternative for opengl32.dll. To use it put it in the same directory as the application. It can also be used by replacing the native ICD driver, but it's quite an advanced usage, so if you need to ask, don't even try it.


To profile llvmpipe you should pass the options
  scons build=profile <same-as-before>
This will ensure that frame pointers are used both in C and JIT functions, and that no tail call optimizations are done by gcc. To better profile JIT code you'll need to build LLVM with oprofile integration.
  ./configure \
      --prefix=$install_dir \
      --enable-optimized \
      --disable-profiling \
      --enable-targets=host-only \

  make -C "$build_dir"
  make -C "$build_dir" install

  find "$install_dir/lib" -iname '*.a' -print0 | xargs -0 strip --strip-debug
The you should define
  export LLVM=/path/to/llvm-2.6-profile
and rebuild.

Unit testing

Building will also create several unit tests in build/linux-???-debug/gallium/drivers/llvmpipe:

Some of this tests can output results and benchmarks to a tab-separated-file for posterior analysis, e.g.:

  build/linux-x86_64-debug/gallium/drivers/llvmpipe/lp_test_blend -o blend.tsv

Development Notes