SmHasher breaks without -fno-strict-aliasing

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A change in revision 145 caused MurmurHash3 to start failing the "keyset 
'Window' tests" with:

  Keyset 'Windowed' -  64-bit key,  20-bit window - 64 tests, 1048576 keys per test
  Window at   0 - Testing collisions   - Expected   128.00, actual 1048575.00 (8192.00x) !!!!!
  Window at   1 - Testing collisions   - Expected   128.00, actual 1048575.00 (8192.00x) !!!!!
  ... etc ...

I applies the r145 changes one by one to r144 and found that the removal of the 
following line from CMakeLists.txt is the cause.

  set(CMAKE_CXX_FLAGS "-g -fno-strict-aliasing -Wall")

After about an hour I've come to the conclusion that strict-aliasing is complex 
:). GCC has __attribute__((__may_alias__)) that I believe should allow 
strict-aliasing to be enabled project wide but disabled in the places that 
cause the problem, but I can't get it to work.

Adding the line back into CMakeLists.txt fixes the problem, but the logs say it 
was removed to stop Visual Studio from complaining. Perhaps that problem can be 
solved by some other means.

(I'm using Debian-6 with GCC 4.4.5)

Shane Day

Original issue reported on code.google.com by shane.a....@gmail.com on 16 Jul 2012 at 4:33