| LLVMPIPE -- a fork of softpipe that employs LLVM for code generation. |
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| |
| Requirements |
| ============ |
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| - A x86 or amd64 processor. 64bit mode is preferred. |
| |
| Support for sse2 is strongly encouraged. Support for ssse3, and sse4.1 will |
| yield the most efficient code. The less features the CPU has the more |
| likely is that you ran into underperforming, buggy, or incomplete code. |
| |
| See /proc/cpuinfo to know what your CPU supports. |
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| - LLVM 2.6 (or later) |
| |
| For Linux, on a recent Debian based distribution do: |
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| aptitude install llvm-dev |
| |
| For Windows download pre-built MSVC 9.0 or MinGW binaries from |
| http://people.freedesktop.org/~jrfonseca/llvm/ and set the LLVM environment |
| variable to the extracted path. |
| |
| For MSVC there are two set of binaries: llvm-x.x-msvc32mt.7z and |
| llvm-x.x-msvc32mtd.7z . |
| |
| You have to set the LLVM=/path/to/llvm-x.x-msvc32mtd env var when passing |
| debug=yes to scons, and LLVM=/path/to/llvm-x.x-msvc32mt when building with |
| debug=no. This is necessary as LLVM builds as static library so the chosen |
| MS CRT must match. |
| |
| The version of LLVM from SVN ("2.7svn") from mid-March 2010 is pretty |
| stable and has some features not in version 2.6. |
| |
| - scons (optional) |
| |
| - udis86, http://udis86.sourceforge.net/ (optional). My personal repository |
| supports more opcodes which haven't been merged upstream yet: |
| |
| git clone git://anongit.freedesktop.org/~jrfonseca/udis86 |
| cd udis86 |
| ./autogen.sh |
| ./configure --with-pic |
| make |
| sudo make install |
| |
| |
| Building |
| ======== |
| |
| To build everything on Linux invoke scons as: |
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| scons build=debug libgl-xlib |
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| Alternatively, you can build it with GNU make, if you prefer, by invoking it as |
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| make linux-llvm |
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| but the rest of these instructions assume that scons is used. |
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| For windows is everything the except except the winsys: |
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| scons build=debug libgl-gdi |
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| Using |
| ===== |
| |
| On Linux, building will create a drop-in alternative for libGL.so into |
| |
| build/foo/gallium/targets/libgl-xlib/libGL.so |
| |
| 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. |
| |
| |
| Profiling |
| ========= |
| |
| To profile llvmpipe you should pass the options |
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| 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. |
| |
| source_dir=$PWD/llvm-2.6 |
| build_dir=$source_dir/build/profile |
| install_dir=$source_dir-profile |
| |
| mkdir -p "$build_dir" |
| cd "$build_dir" && \ |
| $source_dir/configure \ |
| --prefix=$install_dir \ |
| --enable-optimized \ |
| --disable-profiling \ |
| --enable-targets=host-only \ |
| --with-oprofile |
| |
| make -C "$build_dir" |
| make -C "$build_dir" install |
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| find "$install_dir/lib" -iname '*.a' -print0 | xargs -0 strip --strip-debug |
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| The you should define |
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| export LLVM=/path/to/llvm-2.6-profile |
| |
| and rebuild. |
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| |
| Unit testing |
| ============ |
| |
| Building will also create several unit tests in |
| build/linux-???-debug/gallium/drivers/llvmpipe: |
| |
| - lp_test_blend: blending |
| - lp_test_conv: SIMD vector conversion |
| - lp_test_format: pixel unpacking/packing |
| |
| 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 |
| ================= |
| |
| - When looking to this code by the first time start in lp_state_fs.c, and |
| then skim through the lp_bld_* functions called in there, and the comments |
| at the top of the lp_bld_*.c functions. |
| |
| - The driver-independent parts of the LLVM / Gallium code are found in |
| src/gallium/auxiliary/gallivm/. The filenames and function prefixes |
| need to be renamed from "lp_bld_" to something else though. |
| |
| - We use LLVM-C bindings for now. They are not documented, but follow the C++ |
| interfaces very closely, and appear to be complete enough for code |
| generation. See |
| http://npcontemplation.blogspot.com/2008/06/secret-of-llvm-c-bindings.html |
| for a stand-alone example. See the llvm-c/Core.h file for reference. |