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<base href="https://bugs.freedesktop.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Provide option for llvmpipe JIT code to run cleanly under valgrind"
href="https://bugs.freedesktop.org/show_bug.cgi?id=99527">99527</a>
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<tr>
<th>Summary</th>
<td>Provide option for llvmpipe JIT code to run cleanly under valgrind
</td>
</tr>
<tr>
<th>Product</th>
<td>Mesa
</td>
</tr>
<tr>
<th>Version</th>
<td>13.0
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
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<th>OS</th>
<td>Linux (All)
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Component</th>
<td>Other
</td>
</tr>
<tr>
<th>Assignee</th>
<td>mesa-dev@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>john.firebaugh@gmail.com
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>mesa-dev@lists.freedesktop.org
</td>
</tr></table>
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<pre>Currently llvmpipe JIT code is known to trigger errors when run under valgrind.
For example, <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WONTFIX - [llvmpipe] piglit valgrind uninitialised value lp_rast_shade_quads_mask (lp_rast.c:473)"
href="show_bug.cgi?id=29922">bug #29922</a> reports the following, which I also observe:
==17795== Conditional jump or move depends on uninitialised value(s)
==17795== at 0x573F792: ???
==17795== by 0x4171342: lp_rast_shade_quads_mask (lp_rast.c:473)
==17795== by 0x4173EE9: do_block_4_3 (lp_rast_tri_tmp.h:61)
==17795== by 0x4178087: lp_rast_triangle_3_16 (lp_rast_tri.c:229)
==17795== by 0x4171913: rasterize_bin (lp_rast.c:667)
==17795== by 0x4171ACE: rasterize_scene (lp_rast.c:766)
==17795== by 0x4171BA4: lp_rast_queue_scene (lp_rast.c:791)
==17795== by 0x4178EB4: lp_scene_rasterize (lp_scene.c:405)
==17795== by 0x4179DF4: lp_setup_rasterize_scene (lp_setup.c:158)
==17795== by 0x417A296: set_scene_state (lp_setup.c:260)
==17795== by 0x417A39C: lp_setup_flush (lp_setup.c:295)
==17795== by 0x416E756: llvmpipe_flush (lp_flush.c:56)
That bug is closed as RESOLVED WONTFIX but I would like to ask that this be
reconsidered. Conscientious downstream developers want to make sure their code
runs cleanly under valgrind. If libraries they use trigger lots of errors, it
makes this task more difficult. For instance, I first had to determine whether
or not this error represented a misuse of OpenGL by my own code. In this case,
it's possible to search for "valgrind lp_rast_shade_quads_mask" and find the
above bug report, so I was able to reasonably conclude that this was not a bug
I was responsible for. In many of the other errors in JIT code that valgrind
reports, that's not the case, and I'm still not 100% sure of the status --
whether it's a bug in my code, a bug in llvm, a supposedly harmless use of an
uninitialized value, or a true false positive.
I'm not the only one dissatisfied with the status quo. For a more strongly
worded opinion, see
<a href="http://www.americanteeth.org/2013/08/14/valgrind-is-not-optional/">http://www.americanteeth.org/2013/08/14/valgrind-is-not-optional/</a>.
If you believe that fixing these errors would harm performance of production
builds, please consider using the `--enable-valgrind` configure flag as an
explicit opt-in mechanism.
For reference, here are some of the other errors I have received:
==9337== Conditional jump or move depends on uninitialised value(s)
==9337== at 0x402E63D: ???
==9337== by 0xD32C84D: lp_rast_shade_quads_all (lp_rast_priv.h:271)
==9337== by 0xD32C368: block_full_4 (lp_rast_tri.c:46)
==9337== by 0xD329222: do_block_16_32_3 (lp_rast_tri_tmp.h:167)
==9337== by 0xD328E52: lp_rast_triangle_32_3 (lp_rast_tri_tmp.h:305)
==9337== by 0xD32073C: do_rasterize_bin (lp_rast.c:609)
==9337== by 0xD3203EB: rasterize_bin (lp_rast.c:628)
==9337== by 0xD31FBD1: rasterize_scene (lp_rast.c:688)
==9337== by 0xD321823: thread_function (lp_rast.c:828)
==9337== by 0xD321A61: impl_thrd_routine (threads_posix.h:87)
==9337== by 0x4E42183: start_thread (pthread_create.c:312)
==9337== by 0x6A6E37C: clone (clone.S:111)
==9337== Uninitialised value was created by a heap allocation
==9337== at 0x4C2B221: operator new(unsigned long) (in
/home/travis/build/mapbox/mapbox-gl-native/mason_packages/linux-x86_64/valgrind/3.12.0/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==9337== by 0xDB14217: llvm::User::operator new(unsigned long, unsigned int)
(in
/home/travis/build/mapbox/mapbox-gl-native/mason_packages/linux-x86_64/mesa/13.0.3/lib/dri/swrast_dri.so)
==9337== by 0xDA60CDA: llvm::ConstantFP::get(llvm::LLVMContext&,
llvm::APFloat const&) (in
/home/travis/build/mapbox/mapbox-gl-native/mason_packages/linux-x86_64/mesa/13.0.3/lib/dri/swrast_dri.so)
==9337== by 0xDA629BD: llvm::ConstantFP::get(llvm::Type*, double) (in
/home/travis/build/mapbox/mapbox-gl-native/mason_packages/linux-x86_64/mesa/13.0.3/lib/dri/swrast_dri.so)
==9337== by 0xD29993E: lp_build_const_elem (lp_bld_const.c:309)
==9337== by 0xD2999F0: lp_build_const_vec (lp_bld_const.c:333)
==9337== by 0xD29B902: lp_build_conv (lp_bld_conv.c:654)
==9337== by 0xD29B08E: lp_build_conv_auto (lp_bld_conv.c:491)
==9337== by 0xD344C3C: generate_unswizzled_blend (lp_state_fs.c:1884)
==9337== by 0xD342505: generate_fragment (lp_state_fs.c:2452)
==9337== by 0xD340947: generate_variant (lp_state_fs.c:2637)
==9337== by 0xD33FC79: llvmpipe_update_fs (lp_state_fs.c:3204)
==9337==
==9337== Thread 3 llvmpipe-1:
==9337== Use of uninitialised value of size 8
==9337== at 0x4035AEE: ???
==9337== by 0x40354D4: ???
==9337== by 0xD31F6A6: lp_rast_shade_quads_mask (lp_rast.c:457)
==9337== by 0xD32D069: do_block_4_32_2 (lp_rast_tri_tmp.h:67)
==9337== by 0xD328943: do_block_16_32_2 (lp_rast_tri_tmp.h:152)
==9337== by 0xD328610: lp_rast_triangle_32_2 (lp_rast_tri_tmp.h:305)
==9337== by 0xD32073C: do_rasterize_bin (lp_rast.c:609)
==9337== by 0xD3203EB: rasterize_bin (lp_rast.c:628)
==9337== by 0xD31FBD1: rasterize_scene (lp_rast.c:688)
==9337== by 0xD321823: thread_function (lp_rast.c:828)
==9337== by 0xD321A61: impl_thrd_routine (threads_posix.h:87)
==9337== by 0x4E42183: start_thread (pthread_create.c:312)
==9337== Uninitialised value was created by a heap allocation
==9337== at 0x4C2B221: operator new(unsigned long) (in
/home/travis/build/mapbox/mapbox-gl-native/mason_packages/linux-x86_64/valgrind/3.12.0/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==9337== by 0xDB14217: llvm::User::operator new(unsigned long, unsigned int)
(in
/home/travis/build/mapbox/mapbox-gl-native/mason_packages/linux-x86_64/mesa/13.0.3/lib/dri/swrast_dri.so)
==9337== by 0xDA60CDA: llvm::ConstantFP::get(llvm::LLVMContext&,
llvm::APFloat const&) (in
/home/travis/build/mapbox/mapbox-gl-native/mason_packages/linux-x86_64/mesa/13.0.3/lib/dri/swrast_dri.so)
==9337== by 0xDA629BD: llvm::ConstantFP::get(llvm::Type*, double) (in
/home/travis/build/mapbox/mapbox-gl-native/mason_packages/linux-x86_64/mesa/13.0.3/lib/dri/swrast_dri.so)
==9337== by 0xD29993E: lp_build_const_elem (lp_bld_const.c:309)
==9337== by 0xD2999F0: lp_build_const_vec (lp_bld_const.c:333)
==9337== by 0xD296F04: lp_build_sin_or_cos (lp_bld_arit.c:2914)
==9337== by 0xD2965EE: lp_build_sin (lp_bld_arit.c:2930)
==9337== by 0xD2C9A63: sin_emit_cpu (lp_bld_tgsi_action.c:2028)
==9337== by 0xD2CC759: lp_build_tgsi_inst_llvm (lp_bld_tgsi.c:306)
==9337== by 0xD2CCD79: lp_build_tgsi_llvm (lp_bld_tgsi.c:523)
==9337== by 0xD2CF475: lp_build_tgsi_soa (lp_bld_tgsi_soa.c:4058)
==9337==</pre>
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</p>
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