[LLVMbugs] [Bug 10923] Optimiser problem: shows up in Python's pow()

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Tue Sep 13 06:44:00 PDT 2011


http://llvm.org/bugs/show_bug.cgi?id=10923

Duncan Sands <baldrick at free.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |baldrick at free.fr
         Resolution|                            |INVALID

--- Comment #1 from Duncan Sands <baldrick at free.fr> 2011-09-13 08:44:00 CDT ---
The C language standard says that overflowing signed arithmetic results in
undefined behaviour.  Since temp / prev != prev can only be true if there
was a signed arithmetic overflow, the compiler is allowed to assume that
this never occurs.  Use unsigned arithmetic instead.

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