[Bug rtl-optimization/17958] New: expand_divmod fails to optimize division of 64-bit quantity by small constant when BITS_PER_WORD is 32

[zack at gcc dot gnu dot org]

expand_divmod cannot optimize code such as

long long div10(long long n) { return n / 10; }

when BITS_PER_WORD is 32.  A call to __divdi3 gets generated.  By contrast, when
BITS_PER_WORD is 64, this is optimized to a multiply and a shift.  I noticed
this problem on powerpc32, but it ought to affect any 32-bit target.

-- 
           Summary: expand_divmod fails to optimize division of 64-bit
                    quantity by small constant when BITS_PER_WORD is 32
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P2
         Component: rtl-optimization
        AssignedTo: roger at eyesopen dot com
        ReportedBy: zack at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: powerpc-*-*


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17958