[LLVMdev] Non-deterministic builds

Chris Lattner clattner at apple.com
Fri Nov 12 09:19:16 PST 2010


Yes, this is controlled by the -frandom-seed flag.  Sadly, it is expected behavior.

-Chris

On Nov 12, 2010, at 7:10 AM, Sebastian Redl <sebastian.redl at getdesigned.at> wrote:

> On 12.11.2010 15:26, Erik Cederstrand wrote:
>> I have noticed that two consecutive builds of clang, clang++ and tblgen don't produce identical binaries (as in md5 sums) on identical source code (I'm on FreeBSD). I ran strings(1) on the two clang binaries, and I get the following:
>> 251862c251862
>> <  N4llvm3sys11ThreadLocalIKN144_GLOBAL__N__usr_home_erik_freebsd_head_src_lib_clang_libllvmsupport_.._.._.._contrib_llvm_lib_Support_CrashRecoveryContext.cpp_00000000_BFDB511124CrashRecoveryContextImplEEE
>> ---
>>> N4llvm3sys11ThreadLocalIKN144_GLOBAL__N__usr_home_erik_freebsd_head_src_lib_clang_libllvmsupport_.._.._.._contrib_llvm_lib_Support_CrashRecoveryContext.cpp_00000000_A7307A7424CrashRecoveryContextImplEEE
>> 
> Urgh, are we using random elements in the unnamed namespace symbol 
> generation?
> 
> Sebastian
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