<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Issue</th>
<td>
<a href=https://github.com/llvm/llvm-project/issues/63921>63921</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>
nondeterministic dwarfdump
</td>
</tr>
<tr>
<th>Labels</th>
<td>
</td>
</tr>
<tr>
<th>Assignees</th>
<td>
</td>
</tr>
<tr>
<th>Reporter</th>
<td>
fangism
</td>
</tr>
</table>
<pre>
We've observed some local build nondeterminism in clang outputs.
The following command produces different .o outputs (with some non-zero probability).
```shell
$ ../../prebuilt/third_party/clang/linux-x64/bin/clang++ -MD -MF host_x64-asan-ubsan/obj/src/storage/minfs/libminfs.vnode.cc.o.d -DTOOLCHAIN_VERSION=AD59JKqO1TWgxp7uA0Fq99aIrVCXG2i4HShWi6sFFV8C -DFUCHSIA_API_LEVEL=13 -D_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS -D_LIBCPP_REMOVE_TRANSITIVE_INCLUDES -I../.. -Ihost_x64-asan-ubsan/gen -I../../zircon/system/ulib/zx/include -I../../sdk/lib/fit/include -I../../sdk/lib/stdcompat/include -I../../zircon/system/public -I../../src/zircon/lib/zircon/include -Ifidling/gen/zircon/vdso/zx/zither/legacy_syscall_cdecl -I../../sdk/lib/fit-promise/include -I../../zircon/system/ulib/fbl/include -I../../zircon/system/ulib/storage/buffer/include -Ifidling/gen/sdk/fidl/fuchsia.hardware.block.driver/fuchsia.hardware.block.driver/banjo/cpp -Ibanjoing/gen -Ifidling/gen/sdk/fidl/fuchsia.hardware.block.driver/fuchsia.hardware.block.driver/banjo/c -I../../src/lib/ddk/include -I../../sdk/lib/driver/runtime/include -I../../zircon/system/ulib/async/include -I../../sdk/lib/zbi-format/include -I../../zircon/system/ulib/ddk-platform-defs/include -I../../zircon/system/ulib/syslog/include -Ifidling/gen/sdk/fidl/fuchsia.hardware.block/fuchsia.hardware.block/banjo/c -Ifidling/gen/sdk/fidl/fuchsia.storage.metrics/fuchsia.storage.metrics/banjo/c -Ifidling/gen/sdk/fidl/fuchsia.unknown/fuchsia.unknown/banjo/c -Ifidling/gen/zircon/vdso/zx/zx/banjo/c -I../../src/lib/ddktl/include -I../../sdk/lib/fidl/cpp/wire/include -I../../sdk -Ihost_x64-asan-ubsan/gen/sdk -I../../sdk/lib/fidl_base/include -Ifidling/gen/sdk/fidl/fuchsia.hardware.block/fuchsia.hardware.block/banjo/cpp -Ifidling/gen/sdk/fidl/fuchsia.storage.metrics/fuchsia.storage.metrics/banjo/cpp -Ifidling/gen/sdk/fidl/fuchsia.unknown/fuchsia.unknown/banjo/cpp -Ifidling/gen/zircon/vdso/zx/zx/banjo/cpp -I../../zircon/system/ulib/storage/operation/include -I../../zircon/system/ulib/zircon-internal/include -I../../sdk/lib/fdio/include -I../../src/storage/gpt/include -Ifidling/gen/sdk/fidl/fuchsia.device/fuchsia.device/cpp -Ifidling/gen/sdk/fidl/fuchsia.logger/fuchsia.logger/cpp -Ifidling/gen/sdk/fidl/fuchsia.diagnostics/fuchsia.diagnostics/cpp -Ifidling/gen/sdk/fidl/fuchsia.mem/fuchsia.mem/cpp -Ifidling/gen/sdk/fidl/fuchsia.hardware.block/fuchsia.hardware.block/cpp -Ifidling/gen/sdk/fidl/fuchsia.storage.metrics/fuchsia.storage.metrics/cpp -Ifidling/gen/sdk/fidl/fuchsia.unknown/fuchsia.unknown/cpp -I../../zircon/third_party/ulib/lz4/include -I../../src/storage/lib/disk_inspector/include -I../../zircon/system/ulib/bitmap/include -I../../zircon/system/ulib/range/include -I../../zircon/third_party/ulib/cksum/include -I../../zircon/third_party/ulib/safemath/include -fcolor-diagnostics -fcrash-diagnostics-dir=clang-crashreports -fcrash-diagnostics=all -ffp-contract=off --sysroot=../../prebuilt/third_party/sysroot/linux --target=x86_64-unknown-linux-gnu -ffile-compilation-dir=. -no-canonical-prefixes -fdata-sections -ffunction-sections -O1 -gdwarf-5 -Xclang -debug-info-kind=constructor -g3 -Wall -Wextra -Wconversion -Wextra-semi -Wimplicit-fallthrough -Wnewline-eof -Wstrict-prototypes -Wwrite-strings -Wno-sign-conversion -Wno-unused-parameter -Wnonportable-system-include-path -Wno-type-limits -fvisibility=hidden -Werror -Wno-error=deprecated-declarations -Wa,--fatal-warnings --sysroot=../../prebuilt/third_party/sysroot/linux --target=x86_64-unknown-linux-gnu -fPIE -mllvm -asan-use-private-alias=1 -fno-sanitize-address-use-odr-indicator -fsanitize=address -fno-omit-frame-pointer -fsanitize=undefined -fno-sanitize=vptr -fvisibility-inlines-hidden -stdlib=libc++ -std=c++17 -fno-exceptions -stdlib=libc++ -c ../../src/storage/minfs/vnode.cc -o host_x64-asan-ubsan/obj/src/storage/minfs/libminfs.vnode.cc.o
```
A recent local experiment took about 40 attempts before a difference was observed.
A dwarfdump diff looks like:
```shell
$ diff -u <(../../prebuilt/third_party/clang/linux-x64/bin/llvm-dwarfdump -a host_x64-asan-ubsan/obj/src/storage/minfs/libminfs.vnode.cc.o) <(../../prebuilt/third_party/clang/linux-x64/bin/llvm-dwarfdump -a host_x64-asan-ubsan/obj/src/storage/minfs/tmp-libminfs.vnode.cc.o)
```
```diff
--- /dev/fd/63 2023-07-17 18:55:26.925479892 +0000
+++ /dev/fd/62 2023-07-17 18:55:26.925479892 +0000
@@ -1,4 +1,4 @@
-host_x64-asan-ubsan/obj/src/storage/minfs/libminfs.vnode.cc.o: file format elf64-x86-64
+host_x64-asan-ubsan/obj/src/storage/minfs/tmp-libminfs.vnode.cc.o: file format elf64-x86-64
.debug_abbrev contents:
Abbrev table for offset: 0x00000000
@@ -54937,7 +54937,7 @@
[0x000000000000045f, 0x000000000000047b))
0x0000fd7f: DW_TAG_variable
- DW_AT_location (indexed (0x1c) loclist = 0x00000a67:
+ DW_AT_location (indexed (0x1b) loclist = 0x00000a3d:
[0x00000000000002cc, 0x00000000000002d7): DW_OP_breg14 R14+0, DW_OP_convert (0x00000030) "DW_ATE_unsigned_64", DW_OP_convert (0x00000035) "DW_ATE_unsigned_32", DW_OP_stack_value, DW_OP_piece 0x4, DW_OP_breg14 R14+0, DW_OP_constu 0x20, DW_OP_shr, DW_OP_convert (0x00000030) "DW_ATE_unsigned_64", DW_OP_convert (0x00000035) "DW_ATE_unsigned_32", DW_OP_stack_value, DW_OP_piece 0x4
[0x000000000000046d, 0x000000000000047b): DW_OP_breg14 R14+0, DW_OP_convert (0x00000030) "DW_ATE_unsigned_64", DW_OP_convert (0x00000035) "DW_ATE_unsigned_32", DW_OP_stack_value, DW_OP_piece 0x4, DW_OP_breg14 R14+0, DW_OP_constu 0x20, DW_OP_shr, DW_OP_convert (0x00000030) "DW_ATE_unsigned_64", DW_OP_convert (0x00000035) "DW_ATE_unsigned_32", DW_OP_stack_value, DW_OP_piece 0x4)
DW_AT_name ("status")
@@ -55077,7 +55077,7 @@
DW_AT_high_pc (0x00000000000004c3)
0x0000fe2a: DW_TAG_variable
- DW_AT_location (indexed (0x1b) loclist = 0x00000a3d:
+ DW_AT_location (indexed (0x1c) loclist = 0x00000a8e:
[0x00000000000004bd, 0x00000000000004c3): DW_OP_breg14 R14+0, DW_OP_convert (0x00000030) "DW_ATE_unsigned_64", DW_OP_convert (0x00000035) "DW_ATE_unsigned_32", DW_OP_stack_value, DW_OP_piece 0x4, DW_OP_breg14 R14+0, DW_OP_constu 0x20, DW_OP_shr, DW_OP_convert (0x00000030) "DW_ATE_unsigned_64", DW_OP_convert (0x00000035) "DW_ATE_unsigned_32", DW_OP_stack_value, DW_OP_piece 0x4)
DW_AT_name ("status")
DW_AT_decl_file ("./../../src/storage/minfs/vnode.cc")
@@ -73993,7 +73993,7 @@
0x000009cf
0x00000a00
0x00000a31
-0x00000a5b
+0x00000a82
0x00000aac
0x00000ad6
0x00000b00
@@ -74533,13 +74533,13 @@
0x00000a3d:
DW_LLE_base_addressx (0x0000000000000028)
- DW_LLE_offset_pair (0x00000000000004bd, 0x00000000000004c3): DW_OP_breg14 R14+0, DW_OP_convert 0x30, DW_OP_convert 0x35, DW_OP_stack_value, DW_OP_piece 0x4, DW_OP_breg14 R14+0, DW_OP_constu 0x20, DW_OP_shr, DW_OP_convert 0x30, DW_OP_convert 0x35, DW_OP_stack_value, DW_OP_piece 0x4
-
-0x00000a67:
- DW_LLE_base_addressx (0x0000000000000028)
DW_LLE_offset_pair (0x00000000000002cc, 0x00000000000002d7): DW_OP_breg14 R14+0, DW_OP_convert 0x30, DW_OP_convert 0x35, DW_OP_stack_value, DW_OP_piece 0x4, DW_OP_breg14 R14+0, DW_OP_constu 0x20, DW_OP_shr, DW_OP_convert 0x30, DW_OP_convert 0x35, DW_OP_stack_value, DW_OP_piece 0x4
DW_LLE_offset_pair (0x000000000000046d, 0x000000000000047b): DW_OP_breg14 R14+0, DW_OP_convert 0x30, DW_OP_convert 0x35, DW_OP_stack_value, DW_OP_piece 0x4, DW_OP_breg14 R14+0, DW_OP_constu 0x20, DW_OP_shr, DW_OP_convert 0x30, DW_OP_convert 0x35, DW_OP_stack_value, DW_OP_piece 0x4
+0x00000a8e:
+ DW_LLE_base_addressx (0x0000000000000028)
+ DW_LLE_offset_pair (0x00000000000004bd, 0x00000000000004c3): DW_OP_breg14 R14+0, DW_OP_convert 0x30, DW_OP_convert 0x35, DW_OP_stack_value, DW_OP_piece 0x4, DW_OP_breg14 R14+0, DW_OP_constu 0x20, DW_OP_shr, DW_OP_convert 0x30, DW_OP_convert 0x35, DW_OP_stack_value, DW_OP_piece 0x4
+
0x00000ab8:
DW_LLE_base_addressx (0x0000000000000028)
DW_LLE_offset_pair (0x000000000000042f, 0x000000000000043b): DW_OP_breg14 R14+0, DW_OP_convert 0x30, DW_OP_convert 0x35, DW_OP_stack_value, DW_OP_piece 0x4, DW_OP_breg14 R14+0, DW_OP_constu 0x20, DW_OP_shr, DW_OP_convert 0x30, DW_OP_convert 0x35, DW_OP_stack_value, DW_OP_piece 0x4
```
[llvm-nondet.zip](https://github.com/llvm/llvm-project/files/12072985/llvm-nondet.zip)
Attachment contains:
* vnode.ii (from --save-temps)
* libminfs.vnode.cc.o
* tmp-libminfs.vnode.cc.o (saved copy of the first run)
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzsWl1z46jS_jXkhsIlI3_pIhdOHO_6fbPJ1CQb77lSIUAyGwRaQI6TX38K5O-xs_ZMZs_U1rimEtN0N0330w30hFgrCsX5Jehege7ogtRups1lTlQhbHmRafZ6OeUA9-cc6sxyM-cMWl1yKDUlEma1kAwqrRh33JRCCVtCoSCVRBVQ166qnW2BaASiYfPzccZhrqXUL0IVkOqyJIrBymhWU24hE3nODVcOtvRKHgI8eBFu1iystEJv3Ggvk5FMSOFeAU52FgG9qPlnZ1zKJQ13YKsF8Dj8qAz3tjuAx24mDEsrYryecbAc4LEUql6gRa8D8DgTajNzBfAVRL-NIPptDGfaunTR6yBiiUJ1Zonn1NmfAI-tof6n04YUHOBxKVRug-YsfG3NlWa8RWlLtxhEo8f7-9vrX4eTu_Tp5vPD5P4OxKPhqJv83___dd9-nBaLql8Po_FfSUIm5un6j1-w6Pz6MJuKnh2PnwbXEI3Gv1__-jAZpsNPk_T25unmFsSjdgzRKL2dXF1_-pSOJg_Dq9ub9GnyMLma3E4e_5MO7-7uH4ePk_u7hy3Gzze_3T_dpI-fh3cPk8fJ0006ubu-_X108wDRZOlGiCaH919wteECePwmDNV-wr5ax0uAx7UUmZ9YADwWisqa8R0Jy54bTwE8zoU7gcs6RnVZkWO8X9pQ1ZkUdFdhCNmadWnkarhRmwsmRYBJwdU2y5xZvdrXm3AzbrwaXhD6mtpXS4mUKWWcyvd2iyqjS2H5yTtZejPP5LkiG3RmtU-8d3fZmOmp_ldNZ1aQ1owY9kIMb2VS0-cWM2Ie1PzdfEbUn95VtKogmoTReq1_bO0DwW_8wsJyf4e5tUJTKyfKswNG7KuiJ6zzlgmUa1OeAe56vQ9USeK8NGI81J_zAPJqpS6-FRbvTWwH4yTVS8y2Su6MoPbdmbOV1-pZ6Rd1kPKessMVYHEq2NyxzN0tDcFUWlUAj1-EOYY3y57fK81rjuOrpBnZKz_fK-gh-79f2E9Xf1LgD6o7IfRB7qxyrCtuiBN7584pR2qYQEI5bhQ5CVZM6GNse1eYonLno4LxuaD8EOGM8EhdFDu1fU04QwkTpFDaul347FLPUFcGv--OzhA_PVu-U5Z8UHYcRffuxXqJT_nWORFsy-Io7HMqlK04ddqcmw2ZcCWpzpUyRBV_e5gf3B19tnX5VZKW5LwkbrYtnFMttUFbAPU0Q-xsm4aYMCAehecJCrOGV9q4g8wgHhEpIcrzClGtnCHUgXik8xwiZF-t0dqPT3gorZiXTyWIkCOm4F56MeilvQ5aQgQ1T6lC1X5ZITnyF3UhQ3lbGt-CSGlEidJKUCJRZXguFtxvgRFHkOXUc_txXqvwfYt234ao8CmToy5EfzSPT8R4VhdIqFyjZ6GYd5FW1pnaAwmiIoZoGnwx5QtnCERTqtWcGyu0WhGR5aWAaCrKSgoqHMqJlG5mdF3MIJoq_iKF4ojrHKKp9YkVbu9Ou9fKWz99McJx5GdU4cdKI__iRjtLKY1qVVvOUEUMKf1TOlCVDyPJJEcNQtESGagibtbI-XWQFKUI4Z4LK5Yv4ng0E4zxsBNjdKMQha8gHjFeGU6J4wz51whpzhpvIAH4GqGcOCLRCzGqsfufgManyQ1EpZTzEi7vLJajyog5cRwRKYgHbxui3PuQKOHEG0eEMcOtDbyaGSQUE5SEAOcrJo_5hq0R1qUPpHc0qnQ4KHeZa8V4LhRnu2uBeDSvnNlxMxLKA8CilbOtYz6f45EUGV01C6wL6GuG7X6jli8or5ZePyhF4fHauOolrFoIEOmP6kXsdVCa4RAaTrlyy7YPX1TciNITnNbPkGS6drATQeIcLytnYcZzbTgk64YO5fCF2HUTaaddM4QheVldVoEfSq2fLZTimYN4eEpjJ0ihGoL4GuDBN7V5PADRxh5EPsyxOPlx7HNlhQ7beDD-66F3dENCCEF_PvN5uEMCPO7FIEpwhGMU9VG7D9sDEA-7XRAPca-V4G6nnwwSDAG-iqJopTiA3eN9Txf-Cl2dCHQiiNoAX3f81PJLIC-N_qhYelgm_jCDzcMccpn3Omgx6KFeZ721j4zMCSvC5a9WOPpSkmWGz6E_5rlydp1KcNhMhKPFa4M6z60vz0MYLaLlZ9en3U4S9wG-7nu_bg22fAtB92ojHj6dbg7wNdyn9jOPsxXUVlY3XDnr596Q0TR9HP6SzokR3sxl-ODBz2iaDh9TX5rCiylKAB4IxfiCMwjwIFq0qU8-qakU1kEQj1YmkV7fL7YO2Nfqz47pj9lG_wEHYUoPOAizvvdO44X7T2lmeNHuwM_tjse7F2jozSXCNTY0onEUygzGweabtFahwc9SX0Hw-6LdI6Ix3hG1jtDndE5kzTfESnDKYbTobEjvWG1dDaMF3iLamfnB93UU4z12HOM_Q_hD7WtVcZqEVqTkTTIDjK0jrrZBW7JX-rpRf1P6NoPt0tconIlilla00bkPCBofq3gck_Mq3gfVoyP17huq6YBvVbsjnwMZlB3MoMZhPzPoh9rXWRm05PIvzNTfXNas6_vvSY-bQ0nZj5MkXiXl1mA7KZd7T2i-SyDRHgeJ28tsWxG62TpF1tjGe0KE7hFYb5eQ7V-i-p1u7O1sx8HqrdHONWrPtu0bxGia3t7ehPZ8unzTLnxOfVFuIu_nZFVDlmLNNS-tiDBNKn5ZpT4kFaNFfJja_V8k0AdY07hxDyPbV0e0V0DPD9LpMfqYO-O_M0ZnIP1Drm3_Ui9-Wfz40WvDV6Hd6_hZlD4gVABf7Z0X2eDIHew7l6UOPvjWj38m1BfNyx1i9yp09Jq_oWu9iQp0RwAPZs5VoWWDxwCPC-Fmddaiulx2AFeNwMroPzl14X_sJPe3pjaO-jgZdFccW4rX2dd0XZ0jdBaauFQrR4TatIgAHsLm-iWEj3VudAkRsmTOkeNlZbcyeQiPd5HxEB7pZ3mtXh2DVFevUOfQzTjMhbEOmlqt9V-wy5glcUIu-GW7N0h6OGon_YvZZdRNOlGPtXm_g1mSddvtuM9ZB9NeL4t6PXohLnGE46jf7rcH3V7cb9GoH_fipI8J430WtUEn4iURsuX91NKmuBDW1vyyFye4fSFJxqVd_WGkuQzOzOrCgk7kHz52I-aEk_xy568gnaCbpvZFbeTl2QENxtjQV01w-78BAAD__zIjs54">