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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>For x86 or amd64 processors,
64-bit mode is recommended.
</p>
37 Support for SSE2 is strongly encouraged. Support for SSE3 and SSE4.1 will
38 yield the most efficient code. The fewer features the CPU has the more
39 likely it is that you will 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 If you want development snapshot builds of LLVM for Debian and derived
55 distributions like Ubuntu, you can use the APT repository at
<a
56 href=
"https://apt.llvm.org/" title=
"Debian Development packages for LLVM"
57 >apt.llvm.org
</a>, which are maintained by Debian's LLVM maintainer.
60 For a RPM-based distribution do:
63 yum install llvm-devel
67 For Windows you will need to build LLVM from source with MSVC or MINGW
68 (either natively or through cross compilers) and CMake, and set the LLVM
69 environment variable to the directory you installed it to.
71 LLVM will be statically linked, so when building on MSVC it needs to be
72 built with a matching CRT as Mesa, and you'll need to pass
73 <code>-DLLVM_USE_CRT_xxx=yyy
</code> as described below.
78 <th rowspan=
"2">LLVM build-type
</th>
79 <th colspan=
"2" align=
"center">Mesa build-type
</th>
82 <th>debug,checked
</th>
83 <th>release,profile
</th>
87 <td><code>-DLLVM_USE_CRT_DEBUG=MTd
</code></td>
88 <td><code>-DLLVM_USE_CRT_DEBUG=MT
</code></td>
92 <td><code>-DLLVM_USE_CRT_RELEASE=MTd
</code></td>
93 <td><code>-DLLVM_USE_CRT_RELEASE=MT
</code></td>
98 You can build only the x86 target by passing -DLLVM_TARGETS_TO_BUILD=X86
104 <p>scons (optional)
</p>
111 To build everything on Linux invoke scons as:
114 scons build=debug libgl-xlib
117 Alternatively, you can build it with autoconf/make with:
119 ./configure --enable-glx=gallium-xlib --with-gallium-drivers=swrast --disable-dri --disable-gbm --disable-egl
123 but the rest of these instructions assume that scons is used.
125 For Windows the procedure is similar except the target:
128 scons platform=windows build=debug libgl-gdi
136 <p>On Linux, building will create a drop-in alternative for libGL.so into
</p>
139 build/foo/gallium/targets/libgl-xlib/libGL.so
146 <p>To use it set the LD_LIBRARY_PATH environment variable accordingly.
</p>
148 <p>For performance evaluation pass build=release to scons, and use the corresponding
149 lib directory without the
"-debug" suffix.
</p>
155 On Windows, building will create
156 <code>build/windows-x86-debug/gallium/targets/libgl-gdi/opengl32.dll
</code>
157 which is a drop-in alternative for system's
<code>opengl32.dll
</code>. To use
158 it put it in the same directory as your application. It can also be used by
159 replacing the native ICD driver, but it's quite an advanced usage, so if you
160 need to ask, don't even try it.
164 There is however an easy way to replace the OpenGL software renderer that comes
165 with Microsoft Windows
7 (or later) with llvmpipe (that is, on systems without
170 <li><p>copy build/windows-x86-debug/gallium/targets/libgl-gdi/opengl32.dll to C:\Windows\SysWOW64\mesadrv.dll
</p></li>
171 <li><p>load this registry settings:
</p>
174 ; https://technet.microsoft.com/en-us/library/cc749368.aspx
175 ; https://www.msfn.org/board/topic/
143241-portable-windows-
7-build-from-winpe-
30/page-
5#entry942596
176 [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\OpenGLDrivers\MSOGL]
178 "DriverVersion"=dword:
00000001
179 "Flags"=dword:
00000001
180 "Version"=dword:
00000002
183 <li>Ditto for
64 bits drivers if you need them.
</li>
190 To profile llvmpipe you should build as
193 scons build=profile
<same-as-before
>
197 This will ensure that frame pointers are used both in C and JIT functions, and
198 that no tail call optimizations are done by gcc.
201 <h2>Linux perf integration
</h2>
204 On Linux, it is possible to have symbol resolution of JIT code with
<a href=
"https://perf.wiki.kernel.org/">Linux perf
</a>:
208 perf record -g /my/application
213 When run inside Linux perf, llvmpipe will create a /tmp/perf-XXXXX.map file with
214 symbol address table. It also dumps assembly code to /tmp/perf-XXXXX.map.asm,
215 which can be used by the bin/perf-annotate-jit.py script to produce disassembly of
216 the generated code annotated with the samples.
219 <p>You can obtain a call graph via
220 <a href=
"https://github.com/jrfonseca/gprof2dot#linux-perf">Gprof2Dot
</a>.
</p>
223 <h1>Unit testing
</h1>
226 Building will also create several unit tests in
227 build/linux-???-debug/gallium/drivers/llvmpipe:
231 <li> lp_test_blend: blending
232 <li> lp_test_conv: SIMD vector conversion
233 <li> lp_test_format: pixel unpacking/packing
237 Some of these tests can output results and benchmarks to a tab-separated file
238 for later analysis, e.g.:
241 build/linux-x86_64-debug/gallium/drivers/llvmpipe/lp_test_blend -o blend.tsv
245 <h1>Development Notes
</h1>
249 When looking at this code for the first time, start in lp_state_fs.c, and
250 then skim through the lp_bld_* functions called there, and the comments
251 at the top of the lp_bld_*.c functions.
254 The driver-independent parts of the LLVM / Gallium code are found in
255 src/gallium/auxiliary/gallivm/. The filenames and function prefixes
256 need to be renamed from
"lp_bld_" to something else though.
259 We use LLVM-C bindings for now. They are not documented, but follow the C++
260 interfaces very closely, and appear to be complete enough for code
262 <a href=
"https://npcontemplation.blogspot.com/2008/06/secret-of-llvm-c-bindings.html">
263 this stand-alone example
</a>. See the llvm-c/Core.h file for reference.
267 <h1 id=
"recommended_reading">Recommended Reading
</h1>
273 <li><a href=
"https://www.cs.unc.edu/~olano/papers/2dh-tri/">Triangle Scan Conversion using
2D Homogeneous Coordinates
</a></li>
274 <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>
275 <li><a href=
"http://devmaster.net/posts/6133/rasterization-using-half-space-functions">Rasterization using half-space functions
</a></li>
276 <li><a href=
"http://devmaster.net/posts/6145/advanced-rasterization">Advanced Rasterization
</a></li>
277 <li><a href=
"https://fgiesen.wordpress.com/2013/02/17/optimizing-sw-occlusion-culling-index/">Optimizing Software Occlusion Culling
</a></li>
281 <p>Texture sampling
</p>
283 <li><a href=
"http://chrishecker.com/Miscellaneous_Technical_Articles#Perspective_Texture_Mapping">Perspective Texture Mapping
</a></li>
284 <li><a href=
"https://www.flipcode.com/archives/Texturing_As_In_Unreal.shtml">Texturing As In Unreal
</a></li>
285 <li><a href=
"http://www.gamasutra.com/view/feature/3301/runtime_mipmap_filtering.php">Run-Time MIP-Map Filtering
</a></li>
286 <li><a href=
"http://alt.3dcenter.org/artikel/2003/10-26_a_english.php">Will
"brilinear" filtering persist?
</a></li>
287 <li><a href=
"http://ixbtlabs.com/articles2/gffx/nv40-rx800-3.html">Trilinear filtering
</a></li>
288 <li><a href=
"http://devmaster.net/posts/12785/texture-swizzling">Texture Swizzling
</a></li>
294 <li><a href=
"http://www.cdl.uni-saarland.de/projects/wfv/#header4">Whole-Function Vectorization
</a></li>
300 <li><a href=
"http://www.drdobbs.com/optimizing-pixomatic-for-modern-x86-proc/184405807">Optimizing Pixomatic For Modern x86 Processors
</a></li>
301 <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>
302 <li><a href=
"http://www.agner.org/optimize/">Software optimization resources
</a></li>
303 <li><a href=
"https://software.intel.com/en-us/articles/intel-intrinsics-guide">Intel Intrinsics Guide
</a><li>
309 <li><a href=
"http://llvm.org/docs/LangRef.html">LLVM Language Reference Manual
</a></li>
310 <li><a href=
"https://npcontemplation.blogspot.co.uk/2008/06/secret-of-llvm-c-bindings.html">The secret of LLVM C bindings
</a></li>
316 <li><a href=
"https://fgiesen.wordpress.com/2011/07/09/a-trip-through-the-graphics-pipeline-2011-index/">A trip through the Graphics Pipeline
</a></li>
317 <li><a href=
"https://msdn.microsoft.com/en-us/library/gg615082.aspx#architecture">WARP Architecture and Performance
</a></li>