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11 <h1>The Mesa
3D Graphics Library
</h1>
14 <iframe src=
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20 The Gallium llvmpipe driver is a software rasterizer that uses LLVM to
21 do runtime code generation.
22 Shaders, point/line/triangle rasterization and vertex processing are
23 implemented with LLVM IR which is translated to x86 or x86-
64 machine
25 Also, the driver is multithreaded to take advantage of multiple CPU cores
26 (up to
8 at this time).
27 It's the fastest software rasterizer for Mesa.
35 <p>An x86 or amd64 processor;
64-bit mode recommended.
</p>
37 Support for SSE2 is strongly encouraged. Support for SSSE3 and SSE4.1 will
38 yield the most efficient code. The fewer features the CPU has the more
39 likely is that you run into underperforming, buggy, or incomplete code.
42 See /proc/cpuinfo to know what your CPU supports.
46 <p>LLVM: version
3.4 recommended;
3.3 or later required.
</p>
48 For Linux, on a recent Debian based distribution do:
51 aptitude install llvm-dev
54 For a RPM-based distribution do:
57 yum install llvm-devel
61 For Windows you will need to build LLVM from source with MSVC or MINGW
62 (either natively or through cross compilers) and CMake, and set the LLVM
63 environment variable to the directory you installed it to.
65 LLVM will be statically linked, so when building on MSVC it needs to be
66 built with a matching CRT as Mesa, and you'll need to pass
67 <code>-DLLVM_USE_CRT_xxx=yyy
</code> as described below.
72 <th rowspan=
"2">LLVM build-type
</th>
73 <th colspan=
"2" align=
"center">Mesa build-type
</th>
76 <th>debug,checked
</th>
77 <th>release,profile
</th>
81 <td><code>-DLLVM_USE_CRT_DEBUG=MTd
</code></td>
82 <td><code>-DLLVM_USE_CRT_DEBUG=MT
</code></td>
86 <td><code>-DLLVM_USE_CRT_RELEASE=MTd
</code></td>
87 <td><code>-DLLVM_USE_CRT_RELEASE=MT
</code></td>
92 You can build only the x86 target by passing -DLLVM_TARGETS_TO_BUILD=X86
98 <p>scons (optional)
</p>
105 To build everything on Linux invoke scons as:
108 scons build=debug libgl-xlib
111 Alternatively, you can build it with GNU make, if you prefer, by invoking it as
117 but the rest of these instructions assume that scons is used.
119 For Windows the procedure is similar except the target:
122 scons platform=windows build=debug libgl-gdi
130 <p>On Linux, building will create a drop-in alternative for libGL.so into
</p>
133 build/foo/gallium/targets/libgl-xlib/libGL.so
140 <p>To use it set the LD_LIBRARY_PATH environment variable accordingly.
</p>
142 <p>For performance evaluation pass build=release to scons, and use the corresponding
143 lib directory without the
"-debug" suffix.
</p>
149 On Windows, building will create
150 <code>build/windows-x86-debug/gallium/targets/libgl-gdi/opengl32.dll
</code>
151 which is a drop-in alternative for system's
<code>opengl32.dll
</code>. To use
152 it put it in the same directory as your application. It can also be used by
153 replacing the native ICD driver, but it's quite an advanced usage, so if you
154 need to ask, don't even try it.
158 There is however an easy way to replace the OpenGL software renderer that comes
159 with Microsoft Windows
7 (or later) with llvmpipe (that is, on systems without
164 <li><p>copy build/windows-x86-debug/gallium/targets/libgl-gdi/opengl32.dll to C:\Windows\SysWOW64\mesadrv.dll
</p></li>
165 <li><p>load this registry settings:
</p>
168 ; http://technet.microsoft.com/en-us/library/cc749368.aspx
169 ; http://www.msfn.org/board/topic/
143241-portable-windows-
7-build-from-winpe-
30/page-
5#entry942596
170 [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\OpenGLDrivers\MSOGL]
172 "DriverVersion"=dword:
00000001
173 "Flags"=dword:
00000001
174 "Version"=dword:
00000002
177 <li>Ditto for
64 bits drivers if you need them.
</li>
184 To profile llvmpipe you should build as
187 scons build=profile
<same-as-before
>
191 This will ensure that frame pointers are used both in C and JIT functions, and
192 that no tail call optimizations are done by gcc.
195 <h2>Linux perf integration
</h2>
198 On Linux, it is possible to have symbol resolution of JIT code with
<a href=
"http://perf.wiki.kernel.org/">Linux perf
</a>:
202 perf record -g /my/application
207 When run inside Linux perf, llvmpipe will create a /tmp/perf-XXXXX.map file with
208 symbol address table. It also dumps assembly code to /tmp/perf-XXXXX.map.asm,
209 which can be used by the bin/perf-annotate-jit script to produce disassembly of
210 the generated code annotated with the samples.
213 <p>You can obtain a call graph via
214 <a href=
"http://code.google.com/p/jrfonseca/wiki/Gprof2Dot#linux_perf">Gprof2Dot
</a>.
</p>
217 <h1>Unit testing
</h1>
220 Building will also create several unit tests in
221 build/linux-???-debug/gallium/drivers/llvmpipe:
225 <li> lp_test_blend: blending
226 <li> lp_test_conv: SIMD vector conversion
227 <li> lp_test_format: pixel unpacking/packing
231 Some of this tests can output results and benchmarks to a tab-separated-file
232 for posterior analysis, e.g.:
235 build/linux-x86_64-debug/gallium/drivers/llvmpipe/lp_test_blend -o blend.tsv
239 <h1>Development Notes
</h1>
243 When looking to this code by the first time start in lp_state_fs.c, and
244 then skim through the lp_bld_* functions called in there, and the comments
245 at the top of the lp_bld_*.c functions.
248 The driver-independent parts of the LLVM / Gallium code are found in
249 src/gallium/auxiliary/gallivm/. The filenames and function prefixes
250 need to be renamed from
"lp_bld_" to something else though.
253 We use LLVM-C bindings for now. They are not documented, but follow the C++
254 interfaces very closely, and appear to be complete enough for code
256 <a href=
"http://npcontemplation.blogspot.com/2008/06/secret-of-llvm-c-bindings.html">
257 this stand-alone example
</a>. See the llvm-c/Core.h file for reference.
261 <h1 id=
"recommended_reading">Recommended Reading
</h1>
267 <li><a href=
"http://www.cs.unc.edu/~olano/papers/2dh-tri/">Triangle Scan Conversion using
2D Homogeneous Coordinates
</a></li>
268 <li><a href=
"http://www.drdobbs.com/parallel/rasterization-on-larrabee/217200602">Rasterization on Larrabee
</a> (
<a href=
"http://devmaster.net/posts/2887/rasterization-on-larrabee">DevMaster copy
</a>)
</li>
269 <li><a href=
"http://devmaster.net/posts/6133/rasterization-using-half-space-functions">Rasterization using half-space functions
</a></li>
270 <li><a href=
"http://devmaster.net/posts/6145/advanced-rasterization">Advanced Rasterization
</a></li>
271 <li><a href=
"http://fgiesen.wordpress.com/2013/02/17/optimizing-sw-occlusion-culling-index/">Optimizing Software Occlusion Culling
</a></li>
275 <p>Texture sampling
</p>
277 <li><a href=
"http://chrishecker.com/Miscellaneous_Technical_Articles#Perspective_Texture_Mapping">Perspective Texture Mapping
</a></li>
278 <li><a href=
"http://www.flipcode.com/archives/Texturing_As_In_Unreal.shtml">Texturing As In Unreal
</a></li>
279 <li><a href=
"http://www.gamasutra.com/view/feature/3301/runtime_mipmap_filtering.php">Run-Time MIP-Map Filtering
</a></li>
280 <li><a href=
"http://alt.3dcenter.org/artikel/2003/10-26_a_english.php">Will
"brilinear" filtering persist?
</a></li>
281 <li><a href=
"http://ixbtlabs.com/articles2/gffx/nv40-rx800-3.html">Trilinear filtering
</a></li>
282 <li><a href=
"http://devmaster.net/posts/12785/texture-swizzling">Texture Swizzling
</a></li>
288 <li><a href=
"http://www.cdl.uni-saarland.de/projects/wfv/#header4">Whole-Function Vectorization
</a></li>
294 <li><a href=
"http://www.drdobbs.com/optimizing-pixomatic-for-modern-x86-proc/184405807">Optimizing Pixomatic For Modern x86 Processors
</a></li>
295 <li><a href=
"http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-optimization-manual.html">Intel
64 and IA-
32 Architectures Optimization Reference Manual
</a></li>
296 <li><a href=
"http://www.agner.org/optimize/">Software optimization resources
</a></li>
297 <li><a href=
"http://software.intel.com/en-us/articles/intel-intrinsics-guide">Intel Intrinsics Guide
</a><li>
303 <li><a href=
"http://llvm.org/docs/LangRef.html">LLVM Language Reference Manual
</a></li>
304 <li><a href=
"http://npcontemplation.blogspot.co.uk/2008/06/secret-of-llvm-c-bindings.html">The secret of LLVM C bindings
</a></li>
310 <li><a href=
"http://fgiesen.wordpress.com/2011/07/09/a-trip-through-the-graphics-pipeline-2011-index/">A trip through the Graphics Pipeline
</a></li>
311 <li><a href=
"http://msdn.microsoft.com/en-us/library/gg615082.aspx#architecture">WARP Architecture and Performance
</a></li>