Bus error from MachineLICM.o arises during buildworld of i386 pentium3 systems on (uname -aKU) 
FreeBSD hathor 10.1-STABLE FreeBSD 10.1-STABLE #0 r282448M: Wed May  6 02:20:33 AEST 2015     root@hathor:/usr/obj/prod/100102/D/K8/usr/src/sys/hqdev-amd64-smp-vga                          amd64 1001514 1001514

from svnlite, Last Changed Rev: 283021

I perform a build sequence which includes using CPUTYPE's c3-2, pentium3, prescott (plus a few amd64 worlds).  During the last three cycles (about 2 weeks apart) only ONE of the i386 build worlds will fail (none fail for amd64 targets)

They use a common set of scripts where MAKEOBJPREFIX, CPUTYPE, TARGET_CPUTYPE  and -march= or -mtune= variables are changed.

Aside typically each has 4 kernels, also all of these build without error.

The following is taken from the pentium3 failure which occurred last night.  Yesterday if failed for the c3-2 build.  Very puzzling.

Hardware: Xeon E3-1230L, build disk SSD (Kingston SV300).
smartctl reports overall health: Passed

--- MachineLICM.o ---
Stack dump:
0.      Program arguments: /usr/bin/c++ -cc1 -triple x86_64-unknown-freebsd10.1 -emit-obj -disable-free -disable-llvm-verifier -main-file-name MachineLICM.cpp -mrelocation-model static -mdisable-fp-elim -relaxed-aliasing -masm-verbose -mconstructor-aliases -munwind-tables -target-cpu x86-64 -coverage-file /usr/obj/prod/100102/P/P3/i386.i386/usr/src/tmp/usr/src/lib/clang/libllvmcodegen/MachineLICM.o -resource-dir /usr/bin/../lib/clang/3.4.1 -D STRIP_FBSDID -U DEBUGGING -U DEBUG -D USB_HAVE_DISABLE_ENUM -D LLVM_ON_UNIX -D LLVM_ON_FREEBSD -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D NDEBUG -D LLVM_DEFAULT_TARGET_TRIPLE="i386-unknown-freebsd10.1" -D LLVM_HOST_TRIPLE="x86_64-unknown-freebsd10.1" -D DEFAULT_SYSROOT="/usr/obj/prod/100102/P/P3/i386.i386/usr/src/tmp" -D NDEBUG -I /usr/src/lib/clang/libllvmcodegen/../../../contrib/llvm/include -I /usr/src/lib/clang/libllvmcodegen/../../../contrib/llvm/tools/clang/include -I /usr/src/lib/clang/libllvmcodegen/../../../contrib/llvm/lib/CodeGen -I . -I /usr/src/lib/clang/libllvmcodegen/../../../contrib/llvm/../../lib/clang/include -I /usr/obj/prod/100102/P/P3/i386.i386/usr/src/tmp/legacy/usr/include -internal-isystem /usr/include/c++/v1 -O2 -fdeprecated-macro -fdebug-compilation-dir /usr/obj/prod/100102/P/P3/i386.i386/usr/src/tmp/usr/src/lib/clang/libllvmcodegen -ferror-limit 19 -fmessage-length 0 -mstackrealign -fno-rtti -fobjc-runtime=gnustep -fdiagnostics-show-option -vectorize-loops -vectorize-slp -o MachineLICM.o -x c++ /usr/src/lib/clang/libllvmcodegen/../../../contrib/llvm/lib/CodeGen/MachineLICM.cpp
1.      <eof> parser at end of file
2.      Per-module optimization passes
3.      Running pass 'CallGraph Pass Manager' on module '/usr/src/lib/clang/libllvmcodegen/../../../contrib/llvm/lib/CodeGen/MachineLICM.cpp'.
4.      Releasing pass 'Scalar Evolution Analysis'
c++: error: unable to execute command: Bus error
c++: error: clang frontend command failed due to signal (use -v to see invocation)
FreeBSD clang version 3.4.1 (tags/RELEASE_34/dot1-final 208032) 20140512
Target: x86_64-unknown-freebsd10.1
Thread model: posix
c++: note: diagnostic msg: PLEASE submit a bug report to https://bugs.freebsd.org/submit/ and include the crash backtrace, preprocessed source, and associated run script.
--- all_subdir_libllvmmcparser ---
--- MCTargetAsmParser.o ---
c++  -O2 -pipe -g0 -ggdb0 -DSTRIP_FBSDID -UDEBUGGING -UDEBUG -DUSB_HAVE_DISABLE_ENUM -I/usr/src/lib/clang/libllvmmcparser/../../../contrib/llvm/include -I/usr/src/lib/clang/libllvmmcparser/../../../contrib/llvm/tools/clang/include -I/usr/src/lib/clang/libllvmmcparser/../../../contrib/llvm/lib/MC/MCParser -I. -I/usr/src/lib/clang/libllvmmcparser/../../../contrib/llvm/../../lib/clang/include -DLLVM_ON_UNIX -DLLVM_ON_FREEBSD -D__STDC_LIMIT_MACROS -D__STDC_CONSTANT_MACROS -DNDEBUG -fno-strict-aliasing -DLLVM_DEFAULT_TARGET_TRIPLE=\"i386-unknown-freebsd10.1\" -DLLVM_HOST_TRIPLE=\"x86_64-unknown-freebsd10.1\" -DDEFAULT_SYSROOT=\"/usr/obj/prod/100102/P/P3/i386.i386/usr/src/tmp\" -DNDEBUG -I/usr/obj/prod/100102/P/P3/i386.i386/usr/src/tmp/legacy/usr/include  -fno-exceptions -fno-rtti -c /usr/src/lib/clang/libllvmmcparser/../../../contrib/llvm/lib/MC/MCParser/MCTargetAsmParser.cpp -o MCTargetAsmParser.o
--- all_subdir_libllvmmc ---
--- MCObjectFileInfo.o ---
--- all_subdir_libllvmcodegen ---
c++: note: diagnostic msg:
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
c++: note: diagnostic msg: /tmp/MachineLICM-6b8ca7.cpp
c++: note: diagnostic msg: /tmp/MachineLICM-6b8ca7.sh
c++: note: diagnostic msg:

********************
*** [MachineLICM.o] Error code 254